BushyTea

Well searching around and found some helpful into that got me to where I am now. The car is a 90 3.1 camaro and the engine is recently rebuilt. It has a new TPS, plugs, gas and temp cooling sensor as well. Fuel pump is recently replaced also.

The car turns over and tries to fire but usually spits then dies. I can hit the gas while starting and it will start and I can keep it running but once I let go is makes its way down the RPM's then dies. This generally happens no matter where I turn the distributor for timing and really not sure how to time the car since it will not idle for me to time it.

Any ideas would be great.

Thanks!

ScottieB

vacuum lines

BushyTea

Well I haven't found any vaccum leaks yet as I thought that was the issue as well.

I did find out that the #2 plug is not getting spark but the #4 and #6 plugs are. What would cause only a few to not get spark?

Plug wires are basically new as well.

BushyTea

Alright,

I used the test light method to check for spark and it looks like only the passenger side plugs #1, #3, and #5 have spark and the drivers side has no spark. Not sure how reliable this method is but always worked for me in the past.

Any ideas how only one side would have spark?

Thanks!

enswrob

sounds like a bad coil

BushyTea

Yeah, the coil isn't that old but who knows right now lol.

The spark on the ones that fire more regularly isn't a steady pulse though. It has some pauses and such so I am not getting a very good spark even to those.

BushyTea

New coil.......nothing changed.

enswrob

check the dist cap and pick up coil..

BushyTea

How do you check the pickup coil?

I have a new cap and rotor already on it.

Thanks

BushyTea

Well pulled the dist. and just went and swapped it on the lifetime warranty but have to wait until monday/tuesday for it to get here.

On a side note I did find that one of the metal tabs were bent completely down touching the magnet and warped it some. Here is a pic even though it is not that good I circled the spot.



Could that have caused the problem and possibly ruined the dist.?

enswrob

yes it could have

BushyTea

Well, dist did not fix the problem however I might have found the issue.

I took the top end apart down to the heads and lower intake manifold. Looking to see if the valve lash is set properly.

Have a few issues though. Now that it's apart whats the best way to go about finding TDC for the #1 plug? The valve cover is off as well.

I think I have it set correctly now and if so most of my pushrods spin freely and that is a big problem.

Thanks!

Drew

iTrader: (58)

It's probably not a mechanical problem in the engine. Even if the engine has a mechanical problem it'll still start and run. You're just getting yourself needlessly deeper into it. Drop back to basics... Fuel and fire. Check spark, check fuel. If you think the timing is off, set the engine to TDC and doublecheck your firing order. You might also consider having someone that knows what they're doing take a look at it, before you have the engine sitting on a stand for a single failed component.

BushyTea

Well the thing is I know what I am doing but I am just at a loss. Almost everything is new for fuel and spark as well.

What else can control spark? That seems to be the one things that keeps now working as it should. Using the timing gun method still, some show spark and some do not. Everything I can think of has been replaced in reguards to spark.

Any ideas?

BushyTea

Well spent the night messing with it more and just still the same thing. It just seems spark isn't working as it should.

Not sure what else can be wrong with everything is new.

Drew

iTrader: (58)

I assume you already checked the codes? And when it was rebuilt the timing chain was replaced, i.e. the rotor turns when you crank the engine? And you've doublechecked the firing order and have it set correctly for a 3.1? New distributor, new cap, new rotor, new ignition module, new coil, etc?
I'd start looking really close at the wiring. Try wiggling the wires at the ignition module and the coil. If you're getting spark at some cylinders and not the others it could be an intermittent open in the wiring. ECM would be the next suspect. I'd double check all of the above before throwing any more parts at it. Even if only 3 cylinders are firing, the engine should still start and run. Not smoothly cause it'll have dead cylinders but it should still run.

Also doublecheck your plugs. If you've been fighting with it for a while, it doesn't take much for them to get fouled with gas in which case even if you get the problem resolved it might not fire and run.

BushyTea

Yeah, there are no codes at this point and time. I wish there was as that would give me a certain direction to go with it. Only parts used in the motor are the crank/mains and the rods. Everything else was replaced with new parts.

The rotor is turning and I have checked timing 100 times over and the firing order is as it says it should be. 1-2-3-4-5-6 cw. I have a new dist, cap, rotor, ign module, coil, wires, and plugs. Some of these parts had lifetime warranties so that helped in just replacing them.

How often do the ECM's go out? Other than wiring that would seem to be my last part used that controls this.

Yeah, the plugs have got flooded a few times in all this and they are all black. The car will run but you have to give it gas to get it going and keep it going.

Drew

iTrader: (58)

You do know that cyl #1 is the passengers front, opposite from a SBC?

If the plugs are fouled you at least need to clean them... A wire brush usually will get them clean enough to fire but you will want to replace them soon anyway.

How does it run when you hold the throttlebody partially open? If it runs but just won't idle, then that's a seperate issue. Get yourself a spare spark plug, a good, clean, preferably new spark plug, start at cylinder #1, pull the plug wire off the plug in the head, insert the known good plug and lay the plug so the steel base is laying on a metal part of the engine. Have a helper crank the engine and watch for sparks at the electrode. Check all six plug wires. If you're getting spark at all six it's not a spark issue beyond the plugs. If it's only sparking some wires, go one step further back and check for spark at the cap.

ECMs get blamed often, but usually they're just fine. I've had to replace one faulty ECM out of all the cars I've ever owned. They just simply don't go bad that often. Wiring on the other hand... Weatherpack connectors can get hot and warp, wires and connectors can take a beating, especially if some ham-handed mechanic has been backprobing or the car has been left in a barn or field with mice.

BushyTea

Thanks Drew. That method worked better than the timing light method. I am getting constant spark to all plugs and now I think the problem is fuel.

Not that there isn't enough but that I am getting to much and it keeps soaking my plugs. I went and got new plugs again today and they are already wet with fuel.

So I guess start with the fuel pressure regulator?

Thanks!

Drew

iTrader: (58)

Yep, just work your way through it one step at a time. Pull the vacuum line to the regulator and cycle the key from off to run a few times to build pressure and see if gas comes out the vacuum nipple. If it does it's a bad regulator. If you have a fuel pressure tester, check the fuel pressure. It shouldn't change much between key on, engine running, and it should hold pressure for a while after the key is turned off. Should be close to 43 psi. If it bleeds down very quickly it could be an injector stuck open. Check the resistence of the injectors with a DVOM, they should all be pretty closely matched around 11-12 ohms usually. Bad injectors are pretty common with these cars. I used to check every set of used 3.1 injectors I could find, and kept a few extras on hand at all times. It's not difficult to find replacements since the FWD 3.1's use the same parts. Z24 Cavaliers, Luminas, Grand Prixs, etc all use the same injectors.

BushyTea

Yeah, I did the voltage test and it showed the injectors were still good with the meter but just keeps dumping fuel to the point of flooding. Every plug has a ton of gas on it, not just certain ones.

Not sure what all can cause flooding like this other than the regulator.

BushyTea

Alright, did a fuel pressure test and when I first turn the key to ON it goes up to 42-43 psi. After 5 min. it was down to 28-30 psi. All this was with the key ON.

Drew

iTrader: (58)

Clean the plugs and reinstall them, pull the coil wire so the engine can't start, hold the gas pedal to the floor while you crank the key, that will put it into clear flood mode. It should completely cut the injectors off completely. Crank the engine with it floored for about 10 seconds at a time, a few times... Pull the plugs and see if they're wet again. If they are it could be an indication the ECM isn't functioning.

When you check the codes you're getting the all clear code 12 right? If not I'd start looking really close at the ecm. Other possible causes for flooding are a faulty CTS telling the computer the engine is always cold and putting it into enrichment mode, but that should set a code, faulty fuel pressure regulator, but that would show up as a grossly high fuel pressure (over 50psi), a restriction in the fuel system return line, etc. O2 shouldn't matter since it's not in closed loop. If you have a faulty injector, sometimes one bad injector can cause the injector driver circuits in the ECM to freak out and usually you'll have an entire bank of injectors wig out. As long as the resistence values are closely matched that shouldn't be a problem. Got another ECM you can try? A 7730 ECM usually is a $30-40 item on ebay or the junkyard. Be sure to swap in your prom unless the donor car is the same combo of engine, transmission, and platform.

BushyTea

I will try the clear flood method to see what that will do.

When I do the codes all I get is the 12 so nothing is throwing any codes. I found a fuel pressure reg. cheap so its new and the CTS is new as well. Alot of parts have been replaced. The car stat for about 4 years but I did the whole tune up with new gas and of course alot of other new parts. The O2 was replaced before it was parked so it's even new.

I do not have a spare PCM but I will start searching for one just in case.

I appreciate all the help. This has me banging my head against a wall.

BushyTea

Alright, did the clear flood. Did it 3 times then pulled a few plugs and not a drop of fuel on any of them so the ECM seems to be working fine in that sense.

Does not seem to be much left for fuel. The injectors are the only part of the fuel system that are the originals.

*EDIT* After the tests I put my hand on the purge sensor and it was burning up. Could that be an issue?

Drew

iTrader: (58)

Weird... Hit the local junkyards and see if you can find a 3.1 Cavalier, or Sunbird, to snag the computer and injectors from. Before buying injectors, check em with a dvom and make sure they're all in the 11-12ohm ballpark..

My Firebird sat for years with a no start condition or would run on 3 cylinders. Turned out there were several bad injectors causing the injector drivers to crash and turn off one bank. The guy that fought with it before me had cut out all the wires to the injector harness and run new wire from the fuse box to the injector harness... Also the weatherpack between the injector harness and main harness was fouled up so there was an intermittent issue. Ended up with the injector power tapped into the coil power wires, and injectors from several 3.1 Lumina's and Grand Prixs. It just takes a while to work through issues, keep at it and you'll find the problem eventually.

BushyTea

Thanks for the help drew.

Is there a way to test the computer? I took mine out and apparantly it was replaced before I got the car. I have had the car sine 98 so it was replace sometime between 90 and 98. The tag on it says "Factory Authorized Remanufactured Module for Delphi Delco Electronics Systems". Doesnt mean it's bad but I didn't know it was replaced before.

Or is this a part you just have to replace and see?

Thanks!

BushyTea

Well after tracing some wiring again I did find 2 of the ground wires on the back of the drivers side head had fused together somehow. Not sure if that could be the issue but they are suppose to be 2 individual grounds but they had fused on a section and started to corrod.

Isphius

I know this is old, but did you ever find the cause? my 2.8 died in the middle of the road and has not started since. I swapped the coil with an msd coil i had for my s10, not bolted in just sitting there, and it fired and died right away and did not fire again. plugs looked clean. I havent had much time to check it out because i wasnt driving the car when it happened but i have a few days off now. Also got a code 12 where it had an EGR and some other code before. I think 40 something. Ill have to look

BushyTea

unfortunatly I have not found the problem but I am only left with about 4 different options at this point.

One would be wiring that I just haven't seen that needs to be fixed, replace the injectors, replace the ECU and/or the O2 sensor.

Other than those everything involving fuel/spark and air have been replaced.

Isphius

If i understand correctly, the o2 sensor should never prevent the car from running, just mess with your a/f ratios after its warmed. Check all your harness plugs with the key on. Coil, TPS, maf sensor, injectors, etc. Make sure they all have power, and in some spots(rty all combinations of pins for plugs with 3 or more) resistance. I think some of them should have 5 volts. Which plugs have what voltage and resistance should be available somewhere. I beleiev my car has a fried ecm. It is flashing a code 12 now, when it had 3 before, EGR, and 2 40 somethings when it ran. That is a bad indication i think

fbodyalltheway

not sure if this will help but i had this same problem ounce in my 92 firebird 3.1L when i replaced my faulty computer with a junkyard computer. the car would only start if i held down the gas and stay running only if i held the gas, as soon as i let go of the gas it died. my problem ended up being that the replacement computer had a different memcal in it then my old one, so as soon as i replaced the memcal with the correct one (i just took the memcal out of my old computer and put it in the new one) the car fired right up and stayed running. it just had to relearn idle so it only died when i would come to a stop but would fire right back up. and after about a week the car was back to normal idle and i had no more problems. like i said not sure if that will help since u didnt replace your computers but maybe your memcal went bad or something like that.

BushyTea

All of my sensor are getting voltage and most have been replaced either due to hunting down this problem or in the recent past.

The O2 was new before this problem and I have no codes for it so I would not think it would be hat.

I hate to just start guessing but it seems it points to being a faulty computer. I show no signs of leaky injectors and my fuel pressure is fine when the key is on.

As I stated above 2 of the grounds on the back of the drivers side head has melted together but I fixed that and still the same issue.

I assume to figure out the computer issue is to just spend the money and replace it? Where I live junkyards and such do not really get camaros in so I don't have that option.

88RS19

First; a ground is a ground. I would not imagine that being a problem since in an electrical circuit, the electrons flow in the same direction b/c it is all DC current. They both go for the same purpose so they shouldn't interfere with each other.

Next; the 3.1L V-6 in the Camaros are the same as the ones in the Cavaliers and the firing order is 1-6-5-4-3-2 NOT 1-2-3-4-5-6. double check the firing order and make sure and make DOUBLE sure that you have the plug wires going to the correct cylinders and that they have great connection. (Another easy way to check for spark is to take an old, big philips screw driver, stick it into the plug end of the wire and hold it close to the head or any grounded area and have someone else crank the key over quick. If it sparks, you have spark.)

After that; turn the engine over by hand to TDC and be sure the dist. is starting/pointing (I believe) toward the front left (driver's side front) b/c it should go counter-clockwise. This should be approximately pointing directly to the #1 cylinder.

If this doesn't work, then your problem is probably in the ECM.



To my knowledge, I know this to be correct but don't have anything on hand to reference this. But please, ANYONE correct me if I am wrong! I do not want to be responsible for giving out incorrect/improper information.

88RS19

Sorry, I found my repair book and the firing order of the 3.1L IS 1-2-3-4-5-6 and the distributor DOES go clockwise. I was wrong, but when I looked it up on the internet yesterday, it said the firing order is what I had said previously. I apologize for the incorrect information.

BushyTea

I know this is an old thread of mine but wanted to update what my problem was for future people who search the boards.

The problem ended up being with my heads. Pulled them off, had them redone and the car starts up and runs strong.

Now, this brings on another issue right now. The car runs great but the idle gets to around 1k and doesn't drop down to normal idle. It is running rich where you can smell it out of the exhaust. Then if you turn the car off and go to refire it sometimes its is flooded where it won't start.

I plan to check the injectors and some vaccum lines but any other ideas would be great.

Thanks!

Maverick H1L

iTrader: (8)

Voltage signals from the MAP sensor and the TPS would be where I would start. Also check for fuel in the TB vacuum lines, especially from the fuel pressure regulator and the charcoal canister.

BushyTea

Well I checked my map sensor and here are the readings.

Between Pin A and Pin B: 4.1 Vdc
Between Pin A and Pin C: 4.9 Vdc

Thanks!

Maverick H1L

iTrader: (8)

Pin A to C doesn't matter unless they're lower than say 3.5V... That comes straight from the ECM as reference. The other reading is okay since the engine won't run (this is usually measured at idle but your engine won't do that). Check for a disconnected vacuum hose, probably one of the larger ones at the back of the upper plenum or somewhere off of there.

BushyTea

Yeah, I am looking through my lines but most look to be in good condition. Even tried to spray them to see if the idle changed but nothing.

I pulled out my injectors and have them hanging with the key on but no fuel is coming out of them. So at least using that method there are no signs of leaking injectors which seems to be an issue normally but I see no leaks.

The TPS is new, the map shows fine and I cleaned the IAC.

I did a pressure test and it goes up to 43psi then after about a minute it very went down to 40 psi and continues to drop.

Thanks!

Maverick H1L

iTrader: (8)

Fuel injectors don't have to drip to lose pressure. Don't ask why this is. My set of 3.4 injectors (same as a 3100, that I bought by mistake due to bad eBay listing) never held pressure and caused extended crank times.

What you need to do is grab a couple of rags or well-folded paper towels, and some long-handled pliers, preferably 2 pairs of locking pliers, and someone to cycle the key on and off while you monitor the fuel pressure and the 2 pliers. Pad the jaws of BOTH pliers EXTREMELY well, as you will be pinching off the fuel hoses, and you don't want to damage them. Cycle the key and run the pump until the relay clicks off, and pinch off the larger hose (connected to the larger fuel pipes). If the pressure holds, you have a leak in either the supply pipe, filter, or the fuel pump. If the pressure continues to drop, release the clamp and cycle the key again, pinching off the return hose this time. If the pressure holds, the fuel pressure regulator is leaking. If not, then cycle the key again, leaving the return hose pinched off. Pinch off the pressure line as well. If the pressure still drops, your injectors are leaking somewhere. Ideally, the fuel system should hold pressure for a MINIMUM of 20 minutes without losing even 1 PSI of pressure.

BushyTea

Yeah, mine doesn't get anywhere near 20 minutes of holding pressure. The car fires right up with no issues. The only time is has trouble is if you let it run for a bit, turn it off then try to fire it again. Then it acts flooded and won't start. It will idle and run for as long as you want it just smells of gas and wont start after turning it off unless you wait a bit.

The fuel pressure while running was around 42psi but when I would try to rev it you would feel it kind of stumble alittle at first while climbing through the rpms. Of course once you get to around 1500rpm or so it goes away.

I did do a test like what you described but I wasn't exactly brave enough to clamp on that tight. However, the pressure doesnt seem to change when I did clamp onto the small line. It did slow down when I clamped onto the larger line but of course didn't fully stop since I didn't clamp down hard enough to do that.

I did replace the fpr not to long ago but of course that doesn't mean it couldn't be bad still.

Thanks

Maverick H1L

iTrader: (8)

Trust me, you can pinch the hoses completely off if you pad the jaws properly. That will be just about the only way to know if you have a problem in the supply line or the fuel injectors.

From what you describe, you should start with a fuel injector cleaning (or pick up a cheap set from a junkyard). Sounds as though the fuel injectors are leaking and that's why the engine starts almost instantly when it's cold. When it's hot and you go back to run it again, the fuel hasn't had time to evaporate out of the system, so it's overly rich.

BushyTea

Yeah, I will try some cleaner through it and see what happens.

I am having an issue though with clamping the lines. I build pressure and no matter how hard I clamp the lines the pressure still drops. Doesn't really change on either line. Of course when I clamp the larger line the pressure slows a bit but not much at all.

I appreciate your help

Thanks!

Maverick H1L

iTrader: (8)

If the pressure is still dropping, you need to find a way to clamp both. Usually I can only find one pair of vice grips at a time, so I end up using channel locks on one or the other of the hoses. You have to hold the hose tight when you do this or it won't work.

BushyTea

Well, it seems no matter what I do it never stops losing pressure. However, today I noticed that when I took off my gauge and left off the cap that gas we leaking from the check valve on the back of the fuel rail.

Maybe not the cause of my rich condition but certainly a reason for losing fuel pressure.

Maverick H1L

iTrader: (8)

Well, like I said, if you've clamped both fuel hoses closed and the system still bleeds down, your fuel injectors are stuck open. Luckily there are a couple site sponsors and other places that will clean a full set of injectors for less than what 2 of them would cost to replace.

BushyTea

Well I will probably have the injectors cleaned and flow tested just because they probably need it as well.

I probably phrased it wrong in my previous post but I have a leak from the schrader valve on the fuel lines that connect to the fuel rails.

Maverick H1L

iTrader: (8)

That won't make you run rich. See if you can't put a new valve core in there, or find a cap off of a 3x00 at the junkyard or something to put on it. They're supposed to have caps on the top to prevent leaks.

BushyTea

Alright, well an update after some time away.

The car runs better now. The car had no water in it and I had forgot about the coolant temp sensor so once I added water it ran better and now will start up quickly and run now.

However, there is a new issue. Once the car tries to settle into the normal idle RPM it begin to sputter and run rough. It will run for awhile like this but if it runs long enough eventually it will die. It will rev up fine and even go into a gear without dying. Just won't sit smoothly on the low idle.

Thanks!