ndndndnd

Ok,

After owning my car for nearly a year, I finally got to drive it at the weekend.

It lasted 2 miles.

Car's an '85 IROC HO/L69 with an Autoline Reman CCC Quadrajet and a T5.

Car currently has open headers (creates quite a stir in the English countryside, I can tell you!) and has been starting and idling, but due to the noise I've not let it really warm through. Starting is a little hard, but the car does stand for 2-3- weeks between being started. Usually takes a 3-4 second crank after a single pump of the throttle, then fires on the next turn of the key.

At the weekend, I drove it out of the shed and up the road for it's MOT. After about a mile, it started cutting out between gearshifts. At the next junction I struggled to keep the car running by staying in the throttle, but it stalled and refused to restart. We got it dragged back home, where it half-fired, sputtered like it was only running on a couple of cylinders and cut out. Trying again after an hour or so, the car would fire up with the throttle pinned, but immediately died. My other half's Dad said the exhaust smelt of raw fuel.

The next morning it started up fine. First turn of the key.

The carb airhorn gasket is wet with petrol. Is this a sign of carb flooding? I read on cliffshighperformance forum, that a wet air horn gasket is normal…

Car has new plugs, wires, coil, dizzy cap and rotor, and the carb is a new Autoline Reman with the correct numbers, but hasn't been set up as I haven't got the car properly warm. Should the IAB and idle mixtures screws be able to make the car run this badly? It's not merely the idle, as I can't keep it running by holding the revs up.

There's a pusher pump in the tank, but it blows the fuse when I try to start. However, I don't think these symptoms match Vapour lock.

Would a badly adjusted float present these symptoms? I'm going to try to get the top off the carb at the weekend, and see what I find, but unfortunately I don't fully know what I'm looking for!

Sorry for the essay, and thanks for any pointers or advice!

N

bigal55

iTrader: (1)

Definitely sounds like the float is set wrong, allowing raw fuel to dump into the engine. Flooding is also indicated by the raw fuel smell, the wet air horn and the fact you need to pin the throttle to try keep it running. You would think the float level would cause it to flood immediately but maybe the pusher pump not working causes enough of a restriction that it takes some time for the fuel bowl to over fill. If you look down the air horn, do you see fuel dripping into the carb when running? What do the spark plugs look like? All wet? All would indicate flooding. HTH!

bigal55

iTrader: (1)

Being a new reman carb, wouldn't you want to return it for replacement? If it is out of warranty and you do decide to take the air horn/float assembly off, hold the air horn upside down so the float holds the needle valve into the seat (closed). The float should be level with a small gap between it and the air horn. If the float is metal (not foam material), see if there is any fuel inside, sometimes the metal floats have pin holes and leak fuel and then no longer "float" to close off the needle valve. Check your needle and seat assembly to be sure there is no gunk holding the needle valve open. Just a couple of things to look at if you take the air horn off. GL!

ndndndnd

Thanks for the replies! Reassuring to hear it does sound like a float-adjustment issue.

I won't return the carb, as being in the UK, posting it back and forth would be time consuming and expensive. One reason I was nervous of buying one in the first place!

I've heard people mention seeing fuel drip before. Where should I be looking? Or if I look down into the primaries with the car running, will it be obvious?

I don't quite understand about holding the air-horn upside down… Is this with the carb completely removed? Maybe it makes sense when I get down to it.

My first plan is to get a length of card and poke it down into the float chamber to see if the float moves or is stuck (saw it in a youtube video!). The guy also suggested running the car, then shutting it off and using the card to hold down the float while the fuel pressure is still up - the extra pressure might clean dirt out of the needle seat. Hopefully not too much fuel comes gushing out…

If I do pull off the airhorn (and I guess I will to be sure if anything is actually wrong) will I need to use a new airhorn gasket or will reusing the one I have be ok? I can't pop to Autozone for a re-build kit here!

Thanks for the help!

naf

iTrader: (7)

before opening it, does the MCS click with the ignition key in 'run'? you should be able to hear it click for about a minute once the key is turned, and it should continue to click while the engine is running (although harder to hear)

ndndndnd

Yup, MCS clicks like a good 'un:

https://www.youtube.com/watch?v=5BuJ...ature=youtu.be

nhgator

My electronic q-jet would do similar things when the throttle position sensor was failing,after being rebuilt with new sensors and all that by a local carb guru I haven't had any trouble with it.

ndndndnd

Ah, interesting! I haven't checked the voltage on the TPS yet - maybe that's something I should have a look at too. Would the wrong voltage possibly have this result?

Looks I'm just gonna have to check everything on this 'reman' carb...

naf

iTrader: (7)

Failed TPS can cause rich running but not likely to the extent of your issues. Check the idle mixture screws and the IAB. Ensure each is 3-4 turns out.

Next it cuts out, ensure there is fuel in the carb by observing for a pump shot into the primary venturies when the throttle is opened.

When it next fails to start, add a small amount of fuel to the carb through the vent and see if it makes a difference.

You know you've got a fuel delivery problem with the in-tank pump. Rule lack of fuel out before proceeding.

ndndndnd

Sounds a good idea to confirm fuel delivery - next time it stalls, I'll try both of those.

I did check the IAB: it was about three turns out from lightly seated, so I backed it out to 4 turns. I've not started the car since, so not sure how much difference it'll make. I've bought a flexible carb tool with a double-d head, so I'll check what the idle mixture screws are doing next time I get to the car.

Is it possible to check float adjustment without removing the airhorn? I can prod it and see if it moves through the vent, but do I have to get the airhorn off to make any measurements?

Can I get the in-tank pump wiring diagrams anywhere? The ones in the sticky don't seem to be available any more. I'm wondering if an under-dash wiring issue might be tripping the fuse rather than the pump being shot...

nhgator

When I was having the issues it was like what the op described,only run choppy at full throttle,gas stink everywhere let it sit an hour it would go away for a week or 2,as long as you didn't floor it,if you pinned is it would go into connipition almost instantly.
One spring,it just wouldn't come out of it,had Hobbs the carb master rebuild it and haven't had the issue in 3 years with 2 different motors.

Damon

Is the choke opening fully as the motor warms up (choke plate perfectly vertical)? It's REALLY common for the power wire to the choke to get knocked off, broken, not supply 12V to the choke coil heater for whatever reason on these cc-QJet carbs. THat would explain the running rich and getting worse as it warms up (but perfectly fine on an overnight-cold start).

sofakingdom

iTrader: (1)

Since it has to do with heat, I'd bet it also has something to do with getting hot. (forgive me)

I'd suspect, assuming the choke is OK, the fuel pump is too closely coupled, thermally, to the block. What that of course does, is heat up the fuel. What that in turn does, is send HOT fuel up tot he carb, that's maybe still liquid while it's under pressure in the fuel line, but the INSTANT it reaches the lower (atmospheric) pressure of the fuel bowl, EXPLODES into foam. Think, shaking up a beer, then popping the top off... gasoline goes EVERYWHERE, spews out of every hole in the carb, including into the intake. You can just drive it until it does it, and shut it off and get out and look, and see if there's fuel EVERYWHERE.

Definitely check the choke as Damon pointed out. That's the very first common-sense place to start. Then if that seems to be OK (blade hangs mostly or entirely open even after it's started malfunctioning) then consider the fuel pump scenario.

Cure is something like:

https://www.cantonracingproducts.com...&category=8510

Or even, if you put the fuel pump (or block-off plate) on with no gasket and just sealer, just put a freakin gasket in it. Maybe even 2.

But check the choke first.

steve87ta

iTrader: (4)

I agree with above. You have been to Cliffs site, that is good. If it were mine I would be checking the needle/seat too. He says most reman ones will destroy themselves instantly from the E10 we have here.
I always use his kits when I do one. He has a book too, it is good.

ndndndnd

Ha! The first thing my Dad said was 'check the choke'! I *think* the choke is ok - I had to solder on a new connector myself as the old one was smashed and disconnected (old carb didn't have a choke). I've observed the choke over a couple of minutes go pretty much vertical, albeit a little loose. I think vertical enough that it doesn't impeded airflow. I should have whipped off the aircleaner lid and checked the choke when it first stopped - probably the warmest the car's been in my ownership. Should the plate be absolutely locked vertical?

ndndndnd

Hmmm, the engine was rebuilt by the PO, so who the hell knows what he did. Would the car be warm enough for this to happen? I had only driven about a mile before it started stumbling, and before two miles it cut out and wouldn't restart - I never managed more than about a quarter throttle (except when desperately trying to start it) and no more than 25mph. Would the car be hot enough for this to happen?

ndndndnd

We don't generally have E10 available here - and if it is it's a choice from normal unleaded. I was torn between Cliff's book and the Haynes book, and went with the Haynes. Maybe I ought to get both!

Damon

Yeah, the spring action of the choke should hold the choke plate in a vertical position when the choke heats up. There might be a little slop to it, but not much.

naf

iTrader: (7)

A failed in-tank pump will exacerbate the situation that Sofa explained. The in-tank pump helps cycles fuel through the lines, keeping them cool. A failed in-tank becomes a restriction in the line that impedes the flow of fuel and its recirculation.

Best to get it to mess up again and observe what is going on.

ndndndnd

Thanks for the advice guys - I'll keep a close eye on the choke next time the car fires up.

Just stumbled on this thread: http://cliffshighperformance.com/sim...p?topic=2508.0

Guy's suffering hard starts from a vacuum leak. I've been chasing vacuum leaks from the intake gasket - the PO bodged them odd with a ton of RTV. I thought I'd cured it, but I might try a concerted effort to track down any vacuum leaks, as well as taking the top off the carb and having a look.

Are there any ways I can check the in-tank pump? The fuse blows each time I go to start, but I think I read somewhere there's a way of jumping the pump to see if it spins... (via a relay somewhere?)

Cheers!

dtees

ndndndnd. A Qjet carb is very easy to rebuild. The trick is not to take too much apart. When I say that I mean I've seen some guys take the throttle valves out. don't do that. Once apart soak in carb cleaner then blow all the passages out with compressed air. There are many many manuals out there on Qjets. I remember one in particular. The auther had taught his 8 year old daughter how to rebuild them. Its easy enough for an 8 year old. Don't discount your ability. There is a guage you can buy that measures the float level. You just stick it down the vent tube on the air horn and read the scale. Also a trick on qjets is you need to put some jb weld on the plugs on the bottom of the float bowl. Most kits come with a piece of rubber to put in this area but that doesn't work like jb weld. This will keep the fuel from draining out causing an extended crank after sitting for a few days.

dtees

ndndndnd One more tip. Sometimes the emulsion tubes drop out of the air horn in the float bowl. just take a small hammer and tap them back in place. Be sure not to use too much force and dont flare the ends of the tubes. The emulsion tubes are for the secondaries. The symptom would be and engine stall on full throttle accel. Sometimes the primary emulsion tubes will fall out as well. Same proceedure. Just tap them back in place. Brass hammer. Steel is ok if your carefull.

dtees

ndndndnd. On a 70 deg day (you have to convert to c) the bimetal chock spring should be turned to just hold the choke closed. Open the throttle to make sure the linkage is not holding the choke open. Check the resistance of the electric choke thermostat. I forgot the spec. It should be around a hundred ohms. Check with on probe of ohm meter on engine block to make sure you choke thermostat has a good connection to ground. Don't install a gasket on an electric choke thermostat. It has to ground to the carb. These fail often. Then make sure you have 12 volts to the choke thermostat when key is on or engine is running. The choke connectors are horrible and become brittle with age. I usually solder the wire to the choke terminal for trouble free operation.

ndndndnd

Cheers for the advice!

Like I say, it's a reman carb so hopefully it'll be pretty clean and I hope I won't have to pull it off and rebuild it again myself - but it's good to be aware of the symptoms I need to look out for. It's also a new choke, but I'll definitely check it, especially to ground, just to make sure.

I didn't get much chance to tinker this weekend, but I did tentatively poke a small bit of plastic into the bowl vent. Not sure what I felt but there was a resistance. I pushed a bit harder, gave it a tap or two and *sploink* something gave... then prodding the bit of plastic yielded a bobbing motion as the float bobbed up and down. I think the float was hooked up on something inside the bowl! Quite understandable given it's journey across the Atlantic...

I also checked the idle mixture screws with my snazzy new double-d adjuster thingummy. They kept turning and turning and turning... They were set at about 7.5 turns each side! I re-set them to 3.5.

Unfortunately I couldn't start the car as the damn battery was flat and I had to head out. Hopefully I'll get a chance during the week to charge it up and see how it runs.

Not 100% convinced it's cured, but it's certainly a step in the right direction!

Oh, and 70 degrees fahrenheit is about 21 degrees celsius. FYI!

Fingers crossed!

naf

iTrader: (7)

a small guage tool or rod when placed into one of the vents each side of the IAB should strike the mixture control solenoid, which should be observed to click up and down with 1/8" of travel. This may be what you felt.

If this was 'stuck' then you would not have heard the clicking with the key in 'run'. If it were stuck and not clicking, it would lead to a rich condition.

ndndndnd

Hi naf,

I was prodding about in the vent slot between the primaries and secondaries, next to the aircleaner stud...

ndndndnd

A little update.

Car's still not really running. I made my own smoke detector and pumped smoke into the intake and found a leak at the hose running to the heater vacuum tank. Replaced it and I think that's all the vacuum leaks dealt with. Unfortunately the car still doesn't run.

I fired it up yesterday afternoon and it started first touch of the key (yay!) and drove it out into the sunshine and across the yard to wash it. The car dropped off the fast idle cam and the choke opened fully. The car ju-ust idled - I needed to feather the throttle for a minute or so to warm the block a little, and then it sat there idling happily, albeit perhaps a little slowly (I've not had a chance to set the idle with the car warm before). The car eventually stalled after a minute or two, but I put it down to the slow idle.

After washing it (the first in a year owning it!) I let it sit in the sunshine to dry off before putting it back in the shed. Went back about an hour and a half later and the damn thing just didn't want to know. It would barely start with full throttle and then it took big stamps of throttle to keep the thing running. I reversed it back a little way, and then it stalled when I couldn't catch it putting it into first.

I took the aircleaner lid off to see the choke fully open. I was surprised as the car had sat for quite a while, although the block was still warm. Should the choke have closed by now? I tried to trigger the fast idle mechanism by twisting the throttle, but a wisp of white petrol vapour came out the top of the carb.

So, what's my next move? Does this sound like heatsoak through the carb? I didn't check the temperature of the fuel supply lines. Is this even normal?! Could it even be because my timing's retarded (I've not yet been able to run the car long enough to check the timing...)? (the retarded timing sound a long shot, but I've seen cars with similar symptoms on other threads cured by the timing).

Or am I gonna have to bite the bullet and drop the tank and replace the pump, and open the carb and re-build it...? I really don't have the time for those right now.....

Damon

It's not heat soak. You had the car off long enough that wouldn't be the problem (wash + dry time is at least an hour, I'm guessing).

The white "vapor" is just fuel vapor from it hitting a warm intake manifold. It builds up inside there and then drifts out the carb venturis when you open the throttle.

Doesn't sound like a fuel delivery problem to me- you've got fuel at the carb. That generally rules out the tank, lines and the fuel pump.

Can't say for sure what it IS, but I'm hoping to help you avoid chasing your tail based on what it ISN'T.

How's your ignition system doing? Fresh plugs, wires, cap, rotor, coil? Washing = water. If you got something going flaky in the ignition system, especially on the high voltage side, you can end up with a no-start after you're finished washing it.

ndndndnd

Hi Damon,

Thanks for the input and reassurance.

Dizzy cap, rotor, coil, leads and plugs are new (although the plugs are already blackened from over-rich mixture…)

Giving it some thought, I've begrudgingly come to what's probably an obvious answer: my 'remanufactured' qjet has leaking well plugs.

The symptoms seem to match it quite closely: hard starts, long cranking, flooding on starting, post shutdown flooding…

This morning I went over to the car and stuck a bit of plastic into the float bowl vent and found the level very low - I'll admit some should evaporate off in the three days since it ran, but it was much lower than it is after running the car and almost immediately checking. So, I treated the car as if the well-plugs had been leaking. I held the throttle down for 20-30 seconds to allow fuel to evaporate out of the intake, and then cranked with my foot off the throttle. After 4-5 seconds cranking, the car fired right up. I manoeuvred it around and let it settle to a steady idle… and there it sat, idling steadily. I actually had to switch it off!!

The car was then loaded onto a flatbed and taken away to have an exhaust fitted, so I probably won't see it for a couple of weeks now.

Ok, question 1:
I don't have any JB weld, but I do have some metal epoxy. Can I use this to mend the well plugs? (I have already used some to mend a gearbox bellhousing on another car!)

Q2: Is there a visual check I can make to confirm the plugs are leaking without disassembling the entire carb?

Q3: I need to get the car back from the exhaust shop. Logic says 'pay for a flatbed you plonker', but the over-eager part of me wants to drive my car back. Now, the last time I drove my car it ran two miles before flooding out. But since then, I've found and plugged a fairly big vacuum leak (used an 8mm hose instead of a 6mm to the vacuum tank) and dialled back the carb idle mixture screws from 7 (!) turns out to 3.5 and reset the IAB from 3 turns to 4. I've read on here that cars with leaking plugs SHOULD run, albeit thirstily… so do you reckon my car will make the 20 miles back, given the vacuum leak I've plugged, and settings I've leaned off on the carb?

I won't hold you to it, obviously!

Damon

Drive the car back. The more you drive it, the better it will run, especially if the plugs are semi-fouled from just cold starts and idling.

Checking for leaking well plugs: After you get it home, remove the carb, keeping it upright. Clean off the bottom and set it on some clean paper towels (i.e. there is a still a full float bowl of fuel). Check back in a few hours. Paper towels wet?

Get it? If it doesn't leak fuel onto the paper towels, it's not leaking fuel into your engine while sitting for extended periods of time.

QJets will often leak fuel back through the inlet valve after a while. That's not uncommon- the standing height of the fuel in the float bowl is well above the inlet valve height. There's a reason they build a check valve into the fuel filter. Don't confuse that with leaking well plugs, though. Watch WHERE the paper towels get wet (or plug the inlet while doing that test).

An actual leaking well plug is much more rare than internet lore would have you believe.

ndndndnd

Cheers Damon!

One thing counting against the leaking well plugs theory, is that when the carb arrived (shipped from US to UK) it still had fuel in it. I didn't realise at the time. I bolted it to the car and undid the inlet pipe to connect it up and out popped a fresh filter and a small amount of petrol all over the intake!

That said, the amount of fuel that came out was quite small - and my other half, who opened the box with her dad - said the stench of petrol when the box opened was overpowering... So maybe some petrol could have oozed out the well plugs and evaporated off in transit.

Hmmm...

Looking at the schematic in the stickies, it's possible the float bowl emptied and left a small amount sitting in with the filter - so long as the box was kept upright!

I have read that the leaking well plug problem is overstated (it might have been you I read!) and is more limited to the earlier qjets with their brass or lead plugs... but as someone else said, qjets that don't have problems don't tend to get turned in as cores for remanufacturing...

I might ask the exhaust guy to set the car running after he's fitted the exhaust, and if it'll idle without dying until the coolant gauge starts showing temperature, I'll assume the car's ok to drive.

naf

iTrader: (7)

I would attempt to drive it home, but during working hours equipped with the phone number for a local tow, just in case.

It is possible that your flooding issues are, at least in part, caused by a mal-adjusted carburetor. Adjusting the IAB and idle mixture screws requires a dwell meter or scanner that will display percentage of time the Mixture Control Solenoid is in the 'down' position, restricting fuel flow.

I would attempt to set correct dwell prior to additional trouble shooting. The process may indicate other issues, such as vacuum leaks, that may be affecting the mixture. We can provide a step by step method for this when you're ready, depending on whether a scanner or dwell meter is used.

I assume you have already conducted a visual inspection of the fuel delivery and return system to ensure everything is in place as it should be?

ndndndnd

Hello naf,

I've not yet been able to properly adjust the IAB and mixture needles, as this seems to be the first time the car is able to idle properly - until now I've not been able to get the car to idle enough to warm up. I do however, have a dwell meter and a vacuum gauge handy for when the opportunity finally arises!

The settings for the IAB and mixture needles were based on general guidance settings from on thirdgen.org - the best I could do without a warm car, and it at least allowed me to establish the settings on the carb were probably wrong.

I guess I haven't done a thorough assessment of the fuel delivery system, beyond checking the lines in the engine bay, etc. There's no other evidence of fuel leak or blockage yet (dormant pusher-pump aside), and the symptoms so far seem to suggest fuel over-supply rather than under-supply. That said, the car hasn't been run at any sort of speed for probably three years, so I'm fully aware new issues may arise...

I'm pretty sure there aren't any vacuum leaks now - I cobbled together my own smoke machine a couple of weeks ago and pumped smoke into the intake manifold, which did expose a leak to the vacuum tank. That doesn't exclude hidden issues within the carb or the evap system though. However the car does seem happier since that leak got plugged.

Thanks for the hints though, I'm bracing myself to drop the tank at some point in the future to replace the pusher pump, although it's not a job I'm going to undertake lightly!

ndndndnd

I drove it home!

The car did overheat: despite a new fan switch and connector, the fan didn't kick in. Not sure why. A passing beekeeper lent me some tools and I cut off the connector and wired the fan to ground so it ran permanently. Car got home with the temperature bang on 220F.

Car made no power though and had very poor throttle response, worse than it did before going to the exhaust shop. The guy who fabricated the exhaust said it had been running fine, but started to struggle to idle the day before I picked up. Next morning after bringing it home, I fired up the car and the throttle response had returned! The only difference I could think of was that the car was parked in the sun at the shop, and was a little bit warm (but not much at all) and the next day it was raining and much cooler. I can't believe it would be that sensitive to temperature, though. It was started from cold before driving it home from the shop.

Any ideas?

I've not yet checked the well-plugs - that's next on the list of jobs.

dlinger

iTrader: (4)

How long since you replaced fuel filter?

ndndndnd

The fuel filter was new with the carb - it hasn't had even half a tank of fuel through it. That said, I'm increasingly thinking it's a fuel supply problem. I cut the old fuel filter out of the old carb and I think we found a few flakes of rust (it was a while ago now...) so I'm wondering if I've got a tank-cleaning job in my future.

My other half has an endoscope though, I wonder if I can stick it through the filler cap and get an idea of the condition of the tank...!

ndndndnd

Car still not quite running...

I ran the car till there was heat in the block, then sat the carb on a paper towel... no petrol drips. Let it stand for a couple of hours and checked the bowl - still fuel inside. I guess that means it's not the welch plugs, which is nice.

...which points back to the float bowl overflowing, which would be consistent with the wet airhorn gasket and the fuel pooling around the accelerator pump hole.

I opened up the carb (not quite so scary when you've actually done it!) and had a look inside. Everything seemed to be in order. The only thing I could see missing was the needle clip, so I opened up the old carb and took the clip from that.
Checked the rich stops and confirmed 1/8" of travel.
Float seemed to be set lower than spec, but the measurement was about the same on the old carb.
The whole carb was sparkling clean inside, certainly looked a lot nicer than the old carb! The needle and seat looked spotless, although I didn't remove the seat to check it out further - the needle seemed to move freely. I did empty the petrol out of the carb, and there were black specks in it, so there might be dirt in the carb somewhere.

I put the carb back on the car and it fired up and ran, then started to behave consistently with fuel overflowing the float bowl - hunting, missing and wanting to stall. The airhorn gasket was wet around the secondary rods, there was petrol pooling around the accelerator pump hole and I could see petrol above the float inside the bowl.

So, given the carb seemed pretty clean, new float, new needle and seat, correctly adjusted float, no evidence of anything binding inside the carb.... why would it still flood??

My only guess is fuel pressure, which I'll admit I haven't checked - but how much excess pressure could the stock pump be supplying, given its already sucking fuel through a defective pump in the tank?

I'll try to find the chance to open the carb up again at the weekend and see if the seat itself is leaking... my only other guess!

It's not possible for it to be the wrong float is it? I can only see one float listed anywhere for this carb and all the other ones are distinctly different shapes - although the new float is marked as '57078 E30' and the old is marked '57078 M5'. I can't find references to these numbers anywhere...

Any other suggestions or possibilities are welcome!

SouthSide2

Quote [ I'll try to find the chance to open the carb up again at the weekend and see if the seat itself is leaking... my only other guess! ]
I would remove the seat and gasket. Inspect all surfaces for defects. Use a tool that fits the seat squarely or really well.
I have seen gaskets that have shifted off center because of to much clearance on the inside diameter. Use care reinstalling to trap the gasket in the center of the seat.
Hope that is the fix.

ndndndnd

That sounds eminently possible - I have heard of leaking seats where two gaskets have been accidentally installed. However, this seems unlikely given the carb body has clearly been thoroughly cleaned by the remanufacturer prior to reassembly. However, the possibility that the seat gasket has been slightly mis-installed sounds quite likely.

I'll definitely look for that at the weekend!

Any other suggestions are welcome...

naf

iTrader: (7)

trash in the fuel can get trapped under the needle/seat assembly and not allow it to seat properly.

inspect your fuel filter, see that it's properly installed and not bypassing dirty fuel. there should also be a spring behind the filter keeping it tight against the fuel inlet.

if you're concerned about rust in the fuel system it may be wise to install a larger in-line fuel filter to intercept the rust before it reaches the carb's filter, which because it is small, can be easily overwhelmed.

ndndndnd

Is that trash (rubbish! ) in the needle and seat not evident just by looking into it in place? I'll pull out the seat and try to clean where it goes. The filter's pretty new and there's a spring in there behind it. I've a spare filter (bloody rare over here!) so I'm tempted to stick a new one in and cut up the old one to see if there are many rust particles in there.

Where would be the best place to install an in-line filter? In the rubber line upstream of the pump?

naf

iTrader: (7)

Yep. Just install an in-line in the rubber line to the pump. Secure it somewhere so it doesn't bounce around.

After you've run it for a while with the in-carb filter, the lines between it and the carb should be clean enough to, perhaps, do away with the in-carb filter.

May not be your problem, or your only problem, but if you have nastys floating around in your carb bowl, best to get rid of them.

hockeyman48

You could also fit a hose on the fuel inlet line to the carb and, with the carb opened up, blow into the line to check the needle to seat seal .You'll have to gently pull up on the float to see if it blocks air flow completely .If you have a leak you should hear it leaking or not get a complete stoppage of air flow.There is a gasket washer for the seat as it threads into the carb ,so check for that.Good Luck

ndndndnd

No dice unfortunately.

I took off the carb, opened it up and took out the seat. Seat and needle both looked completely clean, but I doused them in carb cleaner anyway. I also pulled the filter (also looks like new, spring in place etc...) and sprayed the carb cleaner back out of the float bowl to clean out any crap in the inlet. Put the seat back in, complete with carefully installed gasket and tightened the seat back down firmly.

Stuck it back on the car and fired it up. Car idles fine when cold - albeit still hunting a little. Choke opened fine and it idled down, but as it warmed up it started loading up, needing revs to keep it going and finally conked out. Trying to restart it was greeted with an impressive fireball out the top of the carb...

I let it sit for a few minutes, then held the throttle down for a minute or so to let any fuel evaporate, then fired it up again, which it did and settled to a reasonable idle. I tried clamping a few vacuum hoses to see if any of them improved the idle, but none seemed to have any effect. Once the car started showing temperature on the gauge (about 100F) the car just didn't want to know any more and wouldn't idle without holding it on the throttle. Tried holding the revs up on the throttle for few second to try to reduce the float bowl level but it would still immediately try to die as soon as I backed off the throttle...

Let it sit and fired it up again. Car seemed to idle quite well and I started to wonder if it was just a matter of letting the car warm up a little. Then it just kinda switched off.

Humph.

There's a hissing noise from the front of the engine when it dies, although I've read this might be a normal sound from cylinder decompression... although it sounds more like it's coming from the charcoal canister area. Clamping the hoses to the canister doesn't seem to make any difference so I'm doubting a vacuum leak. There's a faint rattling coming from the valve cover, but I don't know if this is a normal noise.

A part of me is wondering if the 'switching off' is related to the engine going closed loop. Is there any way to prevent the engine going closed loop? I know I could just unplug the MCS but the jets would just go full rich, which might simply hide any other issues...

Good idea about using a hose to blow to test the needle and seat. Might try that...

Sorry that was just a directionless ramble... any comments or advice/thoughts welcome.

naf

iTrader: (7)

the behavior doesn't appear to be consistent with a stuck float, in that it idles fine cold.

to confuse the ecm into thinking the motor is 'cold', disconnect the two wire connector to the coolant temp sensor on the water neck. if it will idle hot with that disconnected, it's a closed loop issue.

report back and I'll think on it.

ndndndnd

Thanks naf - I'll unplug that connector and I'll see what happens.

It doesn't quite idle fine when cold - it still hunts a little and needs to be caught with the throttle occasionally, but the behaviour suddenly gets much worse all of a sudden and the car goes from idling with occasional encouragement to just dying as soon as you let off the throttle.

I think there are some symptoms of flooding - I can see fuel on the airhorn gasket between the secondary rods, but again... I don't really know what's normal!

Things that might be relevant:
The MCS seems to work - it certainly clicks.
I've checked the rich and lean stops, and they allow 1/8" of movement.
The O2 sensor is located slightly away from the block on the header collector of the left bank - it's still a single wire sensor.
I've not yet checked the TPS.
I've not yet had the car run in a fashion that I can properly check the ignition timing.
I set the valve lash a couple of months ago (engine rebuilt by PO, who hadn't yet set valve lash after reinstalling the engine before selling it to muggins here).

Many thanks,

N

naf

iTrader: (7)

#1 ignition timing. Try turning the dist to get a better quality idle. With everything connected the timing at idle should show around 20 something. It is set with the four-wire ESC connector to distributor unplugged to 0-4 degrees advanced, then the ECM adds timing to it once the connector is plugged back in.

Turn the dist to get a good idle with the light showing 20ish advanced and you should be close enough to get it to idle with the ESC disconnected to properly set it. When setting it with the ESC disconnected it must be idling below 1000 rpms. The ECM should notice that the ESC is disconnected and engage the throttle bump solenoid to help it idle.

Do not chase carb problems with the timing off.



it is unlikely a closed loop problem. the carb is most certainly far enough out of adjustment that it isn't going into closed loop.

ndndndnd

Your hunch that closed loop isn't the issue is probably right - disconnecting the temperature sensor made no difference to the car's behaviour.

I did plug in a vacuum gauge. Plugged in at the brake booster, the gauge showed about 12 or so "Hg. I suspected the PCV of being a vacuum leak, so disconnected it and plugged the line with the vacuum gauge. The gauge then read between 15-18 "hg. Car ran better, but still stalled. Gauge wavered slightly as the idle hunted, but dropped to nearly 0 and bounced back when the throttle was blipped. Car seems to be missing at idle - I can feel the occasional jolt go through the car as it idles. Can still hear a strange his from the front of the engine as it dies - I sprayed carb cleaner around here as it ran, but found nothing.

Thanks for the suggestion on setting the timing - I didn't realise you can set the timing at anywhere under 1000rpm, I assumed it had to be at a warm curb idle.

It'll have to wait till next weekend now. Plus I got frustrated replacing a coolant sensor (again...) and tore an HT lead, so I've got that to fix too...

Sigh...

naf

iTrader: (7)

Focus on the ignition first. Make sure it is without faults.

Only then proceed to the air/fuel issues.

ndndndnd

How do you mean 'too far out of adjustment'? I thought heat alone would dictate when the car went into closed loop? What adjustments on the carb would affect this? I ask just in case there's something else I need to keep an eye on...