Joetro

My '91 started giving me fits one day. I left work to go to the bank and it was cutting out on me when I got on it through an intersection (playing with a buddy in his Audi). Got to the bank, shut it off, did my errand, started the car drove out of the parking lot and the car died on me. I coasted into another parking lot, turned the key and it started. Got back to work and parked it and it wouldn't start after that. It tries, but just won't go, like a fuel delivery issue. Turn the key, vroom and dies immediately. 3.1L V6. I haven't done any testing yet. I figured I'd throw this out and see what you all thought. ANy ideas?

Thanks in advance.

RBob

iTrader: (1)

Usually this is one of two things: either the ignition module died or the injectors have finally shorted out.

Check for spark, if there is then most likely the ignition module is OK.

Then check the resistance of the injectors. Any that are lower then 12 ohms are definitely bad. In reality, they should all be about 16 ohms. If they are still the original injectors my money is on several of them being shorted.

RBob.

Joetro

Okay, I'll check those out. I was hoping for a warm and fuzzy "Aw, that's just your ______(insert cheap part here)".
I should know better.

Thanks for the help!

Joetro

So, I stuck the key in it Saturday, just to see and, after a couple false starts like I was having (where it would start, run for a second or a second and a half then die), it started and ran. Revved it up and it did fine.
This morning, I started it, drove around the block, pulled back in the driveway and let it run for a bit. After a while, it died. Turned the key and it started, faltered and died. Started it again and it ran okay. Revved it a little and it seemed okay, but I wasn't going to take a chance driving it to work and having it strand me.

I haven't checked the injector resistance as I'm not sure how to do that. I doubt it's the ignition module or the thing wouldn't start at all. Before this weekend, it would start every time, but would not run for more than a second, or two, but now it will start and run, although I don't trust it to keep running and not start this whole thing over.

This is maddening.

Joetro

So, does this still sound like an injector issue? Would it even run if it were?

Maverick H1L

iTrader: (8)

You have to take the injector off of each injector to test them one by one. The info above is slightly incorrect--each injector should have around 12 ohms resistance, with no more than 1.2 ohms difference between the highest and lowest readings.

However, this sounds like a MAP issue to me. You would have to remove it and take it to AutoZone or somewhere to have it tested.

RBob

iTrader: (1)

It could be the ignition module. When they fail many times it is as they heat up. Turn off the ignition they cool off and start working again. Which also brings up the pickup coil in the distributor. They too can do this, but not as often as the ignition module.

Next time the engine flat out won't run check for spark. It should be a repetitive spark that is bright & hot.

To check the injectors the upper plenum needs to be pulled. Can leave the TB and cables connected to the TB. Then remove the upper bolts and rotate the plenum from the back upward and over toward the front. Leave it sit there upside down.

Need a DVM on the ohms scale to measure the injector resistance. The injector connectors are removed by pressing in on the moon shaped metal clip and pulling the connector straight off.

With the DVM measure the resistance between the two pins of each injector. The stock Multec injectors that came in that engine will be 16 ohms when new. With the way the engine is cutting out, if it is an injector problem, you will most likely find some of them in the 2 to 5 ohm range.

If so, then just replace the whole set and be done with it.

Note that the order of the connectors to each injector doesn't matter. So if you switch a connector or two between injectors it doesn't matter. If you need injectors there is another thread that covers various possibilities.

RBob.

Joetro

Thanks, RBob and Maverick! You are appreciated! I'll get on it this weekend.
I'll let you know what turns up.

dracoar

Just my 2 cents, but I had a similar issue when my fuel pump went out.

Have you checked fuel pressure yet? There is a schrader valve on the injector rail, should have a cap similar to a valve stem cap on your tires. Hook up a fuel pressure gauge there (one designed for fuel injection!) and get us a reading. Try to get a reading when it is running fine, stumbling, and when it wont start.

Maverick H1L

iTrader: (8)

When was the last time the fuel filter was changed? Also, can you hear the pump run when you turn the key on before you crank the engine?

Joetro

I have no idea when the filter was last changed. I have never changed it and have owned the car for seven years, so there's no tellin' how old the thing is. I didn't get to it this weekend like I wanted (went hunting, instead).

87IROCZ350TPI

J, I'm having the same issue. If you figure this out please post your results. I'll do the same. Thanks.

Joetro

I'll definitely post my results as soon as I can get to it. The weather hasn't been cooperating, so I've been hunting instead.

ohiotemplar

I'm putting my 2 cents in for the IAC motor

Daves03

sounds like the fuel pump is heating up and dieing, my fathers truck did that on the second fuel pump, run shutoff, run shutoff and finally it got to where it wouldnt start at all, the first time the pump went we pulled up to a store to get a drink shut the truck off and it never would start back.

i know when the wife ran our camaro out of gas you could hear the pump in the tank the buzzing would get loud and then quiet down loud and then quiet down and you could hear the engine do the same eventually the pump would get quieter and quieter untill the car would just die, have someone turn the key on and put your ear to the floor under the rear hatch and listen to the fuel pump or when your car is about to die put your ear and listen for the eratic noise should be a steady buzz if the pump is working but if not the pump will get quieter untill it dies.

Joetro

Hey, all. I apologize for not following up on this. I snapped my bicep tendon in my right arm and, as a result, haven't done much of anything at all, let alone work on the car.

Last weekend, I started on her and found that the cap and rotor were horribly corroded. How the thing would run even for a second is beyond me.

Anyhow, I changed the cap, rotor, plugs and wires. I was going to replace the pickup coil, but I couldn't get the distributor out as I still don't have much in the way of strength in my arm. Fired her up and she runs beautifully... well, she did for a day, anyhow.

Drove her to physical therapy, shut her off for 30 minutes, or so, to work, shut her off for 8 hours, to the kid's school, dropped the kid off at the library and to the store. FYI, the trip included a 7 mile stretch of interstate. After the library, which was right after getting off the interstate, I noticed the SES light on. When I came out of the store, she wouldn't run. Start and chug real hard for a few seconds, but not run and forget touching the throttle as that killed it. Went back a few hours later after she had a chance to cool down and tried again with no luck.

Next morning, before work, I went back to where I left her armed with some tools and my trusty paperclip, thinking I would definitely get a code from the SES. Nope, just the 12 code. I tried one more time before heading off to work. She started and chugged like she had been doing and then, out of nowhere, poof, she was idling normally, as if something had been stuck and now wasn't. Weird stuff. I drove her to the house and parked her and haven't had a chance to do anything further.
One thing I forgot to mention above is that, at one point, I forgot I had the paperclip in the ALDL when I tried to start. Makes the fan stay on, I noticed. Pulled the paperclip, and that's when I started her and she chugged before resuming normal idle.

I know this post is long-winded and I apologize for it, but I wanted to make sure there was plenty of info available. If the above is confusing, please let me know and I'll clear it up.

You know, if it were my '77 T/A, I wouldn't be having these issues.

Thanks for all the help.

Maverick H1L

iTrader: (8)

Have you checked the injectors yet? It sounds like there's WAY too much fuel in the mix from somewhere. The IAC won't prevent the engine from starting if it gets stuck, but your idle quality will be affected (ran without a working one for over 4 years, never had a problem starting except for leaking injectors not holding fuel pressure).
With the paperclip in the ALDL, the IAC is commanded to the "closed" position, as this is the second step to adjusting the hot idle speed (first is to warm it up to operating temp, 180*). If the engine chugged with the IAC closed instead of either not going or running like it should, my guess would be that the engine is flooding itself, almost to the point of a fuel-induced hydro lock. Pull your dipstick (yes, the one for the engine oil) and see if the oil smells like gas. I'll bet it does.
Now that I think about it, it's either that the engine is bringing in so much fuel somehow that the plugs can't burn it all properly (possibly a bad FPR diaphragm leaking into the vacuum hose and down into the intake), or your spark is so weak (coil, wires, plugs) that the engine can't fire properly for too long. Or, it could be a combination of the 2. Have you had the ignition module tested yet? That would be another thing to try.

Joetro

Thanks, Maverick, I'll give those a try. I've had the car for 8 years and haven't replaced or checked many of the components, so it's probably about time.

Joetro

Maverick, you were right. The dipstick smells like gas. Where would be a good starting point, armed with that info?

Maverick H1L

iTrader: (8)

Sorry, been busy with my 3.1 harness swap. Anyways, I would start by having the ignition module tested, like I said before, or you could check the color of the spark with a new plug right off of the coil.

But, even before you went that far, all you have to do is pull the vacuum line that runs to the FPR out of the TB and see if it either drips or smells like gas. Or you could do this at the FPR, but that line's a real bitch to get back on with the upper plenum in place.

If everything is normal, as far as you can tell, then we'll keep going. Meanwhile, I'm going to find a way to fix my code 43 (now that I have gotten rid of the code 46 and fixed the code 23... lol)

Joetro

Thanks a ton, Maverick! I'll try to get to it tonight and see where we are. I didn't get a chance to try it this weekend, between moving and helping my little brother with his engine swap.
Hey, at least you get a code. Mine's not telling me anything. LOL.

cwi inspector

Joetro

I have a 91 camaro with a 3.1, Fuel injectors are prone to go bad in this engine. I was having the same problem as you. I check the reistance of the fuel injectors and found a bad one. Go to autopartswarehouse.com and you can an entire set of injectors for about $205.00 plus core charge.

Joetro

Thanks! I still haven't done anymore with her. Just been too busy. I'm going to try again this coming weekend to, at least check this stuff.

Joetro

The saga continues...

I finally got to work on her last night. We're moving, so things have been a little busy.
I installed a new ignition module, coil and fuel filter with no change. Still won't run. I pulled the vacuum hose off the FPR (I have a MPFI, by the way), but there was no gas dripping out of it, nor did I smell any. I'm stuck and on the verge of taking it to someone to have it fixed, although that is something I hate to do when I know I can fix it myself, if I just knew what to fix. Frustrating...

I'm really hoping I can get this fixed before July 1, or I'll have to tow it to the new place.

sam24th

iTrader: (1)

I just skimmed the post, but did you change the sparkplugs? It sounds like either its not firing correctly or your fuel system is bringing in too much gas and flooding the engine.

Joetro

As I mentioned earlier, I've changed plugs, wires, cap, rotor, ignition module, coil and fuel filter. I have a couple detailed posts about what it's doing and what's been done.


Thanks

Joetro

One thing I forgot to mention. The fuel hat came out of the filter wasn't exactly clear. Pretty dirty looking.

cwi inspector

Earlier in your post you said you did not know how to check your fuel injectors for resistance. It's pretty easy. Remove the plenum cover, unplug the each fuel injector and with a volt meter (set to the ohm setting) and touch the red probe on one connector prong of the injector and the black probe on the second connector prong of the injector. If the injector doesn't have at least 12 ohms replace it, it's bad.

Joetro

Thanks for the reply, CWI. I did a search of the forums and found a video that outlines the procedure. I'll be trying that next, I suppose. I was kind of hoping that it would be something less invasive (and spendy).

cwi inspector

It's not as invasive as it sounds. I had my injectors replaced and the car running in about an hour and a half. Believe me it is really easy.

Joetro

Yeah, looking at it, I see it isn't too bad. I'll pop the upper off and check them and see what I can find out.
Thanks!

cwi inspector

Hey Joetro
Just wondering if you ever got your bird to fly?

Joetro

Not yet. Been moving and had a tragedy in the family. I'm hoping to get to her in the next week or so. I really want my car back. I'm thinking I'm going to have the MAP sensor checked next.

Ottaviani89

I have a 91 firebird also having the same problems, where is the fuel filter located and what tools do i need to take it off? Thanks

Joetro

It's been awhile since I replaced the filter, so I'm not sure what size wrench you'll need, but I believe I used a 5/8 line wrench and an open end or crescent. It's not a tough job to do and the filter is located under the driver's side, along the frame.

As for me getting mine running; I haven't gotten it done yet, but I've bought a new fuel pump and am going to replace it as soon as I make the time. I've talked to a couple folks and the general consensus is that, while the pump can still be heard to run, it isn't producing enough pressure to make things happen. So, I'll replace that and see where we are.

Joetro

Okay, so the fuel pump is delivering 45-50 psi and I replaced the MAP sensor this morning. No joy. I'm running out of options. Same issue as before: It'll fire and die. Every so often, It'll chug a bit if I feather the accelerator, but will end up dying. I guess my next step is injectors, which I was hoping to avoid as it's the most expensive and I'm also rebuilding the engine and trans in my Tahoe, so money is tight. Weather is getting colder, so the Harley will not really suffice as a mode of transportation for much longer. Running out of vehicles.

Anybody got some miracle cure? Some idea they tried and fixed this issue without having to resort to injector replacement?

firebirdland

i had the exact same problem. after having a new fuel pump installed, and replacing a crapload of parts, i was about ready to sell the car. the next step was injectors, then i found the prob. you'll never guess what it was. the inside of the catalytic conv. had broke apart and clogged the muffler. every so often it would start and run crappy, and stall. iwould keep replacing parts take it out, and have to get it towed home. i replaced the muffler, and the car ran like new. this might not b your problem, but if i would have known my muffler was clogged with converter guts, i would have saved a bunch of money. lol , good luck. (i would say my problem started off as a clogged converter. maybe take it off and try a test pipe.)

Maverick H1L

iTrader: (8)

Check for fouled spark plugs and then check your ignition timing. Then check for a BIG vacuum leak, if you haven't done so already.

Joetro

I have the exhaust pipe from the cat back off the car now as I am replacing it, so I can check that while I'm down there.
Thanks.

Joetro

Plugs are new, as are the cap, rotor, wires, coil, pickup coil, ignition module, fuel filter and, now, MAP sensor. I was going to replace the fuel pump, too, but figured I'd toss a gauge on it before I went to the trouble and found it to be pushing 45-50 psi.
I'll definitely check the timing and vacuum leaks. Thanks for the advice.

Joetro

Okay, so here's where I am now (I can't believe I've been battling this for almost two years. Sad.). Tested the injector resistance and came back with four reading 11, one reading 8 and one 6. I'll see about picking up some injectors this weekend, since that's obviously a trouble spot. Going to try the Ford idea.

Question: Even with the two injectors reading so low, would that be enough to not allow the car to run? Still does the same thing; runs for a second and dies. However; it'll stay running on starting fluid.

Thanks again for all the help so far.

RBob

iTrader: (1)

Please see the second post of this thread. Yes, shorted injectors will prevent any of them from firing. I don't know how many people I've told that if the stock Multec injectors are still installed, just replace them. Don't even bother to measure them, just replace them.

RBob.

Maverick H1L

iTrader: (8)

... And if the injectors are shorted for long enough, damage to the ECM driver can result in a big money loss. I'd pick up a spare at the J/Y just in case of this. Or a new/reman one if you can afford it.

Joetro

Thanks, RBob/Maverick. I do appreciate the help. It's been invaluable.
I went and picked up some injectors from the pull & save today. Checked them before I pulled them and they returned a reading of 14 ohms. Checked a new one at the auto parts store and it read 12.5, so I guess I'm good there, right? Thing is, the car I pulled them out of (86 Buick with the 3.0 as suggested in the "Ditch your injectors" thread) had five of the 0-280-150-231 injectors and one 0-280-150-237. Not sure what was up with that. Anyhow, it looks like they'll fit, but they have nipples on the nozzles, with all but the 237 being plastic. The 237 is aluminum. I can post pics if you need me to. I just want to make sure the nozzles won't cause me problems. .

Oh, and I didn't pull any ECMs as there were no Firebirds there.

RBob

iTrader: (1)

I would try to get a set of the same number. There is a slight difference in the flow rates between the '237s and the '231s (about 3%). I prefer the injector with the metal nozzles. It helps prevent carbon build up on the outlet.

For an ECM see the tech pages off the home page here. There is a list of other vehicles that also uses the '7730 ECM. It was quite popular among GM cars.

RBob.

Joetro

Thanks again, RBob.
I've kind of run out of money for this, at the moment, so, with that in mind, let me ask this; Will it harm anything to run the set I have in my possession? What I was thinking was this; Use these to get the car running for now and then order a set from South Bay when I get the funds together. From what I've seen, they have the best prices.
In the meantime, if it turns out the ECM is bad, they sell them for $9 at Pull & Save.

Maverick H1L

iTrader: (8)

You'll be running slightly richer in the cylinder with the metal tip injector due to an increase in flow rate (if it's like ours, around 15.4# ). Shouldn't hurt anything, but I'd take the best ones out of your current set and figure out a set from the combination of both (I've done this several times). If and when you put them on your engine, before you do ANYTHING else, put a fuel pressure gauge on the test port and make sure that the fuel pressure holds. I've bought a set off of eBay that was pulled from a running car that couldn't hold fuel pressure for 20 seconds, much less 20 minutes (factory spec, shouldn't lose more than 3 PSI in 20 minutes, IIRC).

BTW, according to the 92 FSM, any injector over 11.8 ohms is good, but there shouldn't be more than about a 10-15% difference between the highest and lowest readings.

:edit: And, you have one of the most common ECMs out there. The 730 came in just about every 60* V6 equipped car between 86 (FWD only until 89) and 94, except the W-bodies (Grand Prix, Regal, Cutlass Supreme, etc).

Joetro

Okay, so I broke down and ordered some injectors from South Bay (thanks, folks) and she's running. However; now, for some reason, the cooling fan isn't coming on even though the temp was reaching 220. The other thing is the oil pressure is very low. It was doing fine before I had the no start issue and it seemed okay when I first started it tonight (right around 30 lbs). When I got back from the test drive, the oil pressure was hovering just above 0. It would rise just a bit if I revved it, but not much.
Question: I pulled the distributor to change out the pickup coil. Could it be that the shaft isn't quite engaging the oil pump drive shaft? The distributor seems to be seated as it should be.

Maverick H1L

iTrader: (8)

Check to make sure that the dizzy seals aren't leaking oil down the back of the engine.

Joetro

Thanks, Maverick. It looks okay, so far. I checked again this morning, started it and oil pressure shot up to about 70 then settled around 45. Took a chance and drove her to work and everything stayed within normal operating limits, although the SES light came on halfway there. I'll pull codes and see what it tells me when I get home. Running pretty good, but I think I need to adjust timing. Even so, strong as ever, it seems.