Quote: Originally Posted by 87GTAj So I was in the process of changing the fuel injectors While you have it apart remove the coil spark wire, raise the the fuel rails with injectors attached, put glass containers under them, then crank the engine to see if the injectors are flowing.

If you heared it backfire, this tells me one thing TIMING IS NOT CORRECT. Do you have any way of recording a video or audio of the car trying to start? If I could hear what it's doing I might be able to tell what's happening.

It's got an aftermarket high speed harmonic balancer and racing flexplate.
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I can definitely get audio; I'll be at work all day but I'll see what I can do tonight.

OK, so I tried starting it again today and I got two audio clips for anyone who's interested. I didn't hear the motor backfiring today, however. If these clips help pin point the problem, that'd be great.

Sounds like a slipped balancer, not because I can hear it, but because at this point it should be purring like a kitten.
It may be a waste of time, but I'd really would have to verify timing alignment.
You can buy a piston stop, or make your own, use an old spark plug, gut the center and used a piece of treaded rod through the center with a nut on either side to adjust the length.
If the balancer has slipped, replace it, or mark the new location so you can set #1 to true TDC.

I don't know if the attached .zip worked, because I couldn't get it to open right, so if you couldn't get it to work but want to hear it, message me and I can send it to you via email or some other method.

87GTAj

You need to use Firefox browser to download zipped files. Micro$oft explorer has a well know bug that prevents these downloads.

After listening to both clips - EngineCrank2 appears to have some resemblance of ignition. Cranking speed is a bit slow - battery is probably dead tired after many cranks. Even though, it should have fired provided that timing was close enough. I did not hear fuel pump coming on during ignition key cycling - are you getting Fuel pump to run??

//RF

The fuel pump primes, I can hear it...it may be that the microphone was too close to the engine (I had it pretty close to the motor). Yeah, I have recharged the battery a couple of times during the whole process, and it was getting tired after the several attempts I made at starting it.

That's what I thought since I set the dizzy so the #1 wire is connected at the point that the rotor had just passed when the piston was on it's downstroke (thinking that it had just passed it's ignition point for the #1 cylinder)

I run win2000/IE ver. 6- SP1 and i don't have any problems downloading. What I can't do is open the zip from within IE - that is I can open it but, the archive is empty, I first have to save and then open it.

I had expected to hear the fuel prime as well. The starter motor rpm seems quite slow.

rgarcia63

Yea, that's the bug - IE just does not download zip file completely. As a result zip is corrupted and when opened it is empty!


87GTA

Just as a sanity check - check your plugs. If injectors are firing up there should be some fuel on them (they will appear a bit wet). Try twisting dizzy clockwise a bit - see if you get an ignition. I know - it has been a while now.

//RF

Sorry if you already checked it, But replace the Maf. The computer will richen the mixture if the maf is bad to keep from severe lean cond. It will also run like it has a miss and act like the timing is off. Just unplug the maf and see if anything changes. If it doesn't then that is your problem.

Maybe I read that wrong, but are you saying that if disconnecting the MAF does nothing, then my problem is the MAF? Because I tried that several times and it didn't help. I understood that meant it wasn't the problem. If you are only referring to the running rich issue, I am not to that point yet; because as of now the car is not running, period. Please clarify.

I just checked the fuel pressure, and it didn't look good. When I turn on the key, the pressure jumps to about 50psi, then falls rapidly to about 20psi. From there, it slowly drops to zero (while the key is still in the 'on' position). Bad fuel pump?

GTA

No, Fuel Pump is only on for about 2 seconds during ignition key off to on transition. To check Fuel Pump pressure you'll have to connect Pin G (test fuel pump pin) of the ALDL connector to a fused 10 AMP +12 VDC circuit. While it (FP) is continuously running observe Fuel Pressure. For TPI car with a stock FPR it should be between 39 to 47 PSI.
During start-up cranking ECM should be receiving DRP pulses from dizzy. If ECM sees DRP signal it will enable fuel pump, or otherwise fuel pump may eventually turn when oil pressure switch closes only after engine oil pressure builds up past 4PSI.

Verify that fuel pump gets enabled during cranking - once cranking starts fuel pump should turn on almost immediately. Otherwise, you have ignition issues!

//RF

OK, so to check proper fuel pressure, connect lead to pin G - just run a fused wire right from battery + to G? Would that work?

Also, to verify cranking initiation of the fuel pump, just crank it and hope to see the pressure remain in the normal range?

Thanks for all the help.

The reason I thought it was bad was because the manual I have says, "...as the pump runs the pressure should be 34 to 47 psi. When the pump stops running the pressure should drop slightly and hold steady." And I gathered that it shot to ~50 when the pump was on because I heard it turn off, but I thought the pressure would have held at some point.

Yes, it should work, but make sure that you have in line 5 (or 10) AMP fuse. Regardless, double check which pin is Pin 'G' in the ALDL. Connecting +12V to any other pin may cause serious damage! Also, some cars did not had Pin G of ALDL wired for Fuel Pump test. Some had 4" pig tail and connector hanging of the Fuel Pump relay.

Fuel pressure gauge should show that FP is delivering fuel shortly after cranking has started.

//RF

OK, so I hooked up to Pin G and the pressure held steady at 52 psi. Do I have bad return lines, something else, or is this still an acceptable pressure?

The pump is good. Sorry for the confusion what I meant was that if you disconnect it while the engine is running and it runs the same it is the maf. When was the last time you checked the plugs. If it has been a while they might be fouled. You can also spray some starting fluid in the throttle body and if it starts and runs good it could be a fuel delivery issue. If it doesn't it would be the plugs or ignition. The starting fluid will start it as long as you have spark and the plugs aren't fouled.

Next step is too make sure that ECM commands Fuel Pump during cranking. Keep your fuel pressure gauge connected while you are cranking engine. Once ECM sees DRP pulses coming from dizzy it will command fuel pump relay to turn on.

Let us know if FP is turning on during cranking.

//RF

The plugs that are in the car now are brand new...the engine hasn't started with these plugs yet. I tried starting fluid in the TB and it didn't help. I do have spark, so maybe we'll see with the cranking fuel pressure. I have the battery charging right now and I might be able to give it a shot later tonight.

So I charged the battery and tried cranking the engine with the FP gauge attached. While cranking, the gauge showed ~40psi repeatedly (I assume it was seeing the pulses from the ECM). Any insights/ideas?

If the car wouldn't start on ether with new plugs and it is getting spark then you should check timing, or compression. don't worry about fuel if it won't start on the ether. Try pulling the number one plug, Then pull the dist. then turn the motor over until you hear a hiss from the piston coming to top dead center. Just tap the key so it doesn't turn the motor over very fast and it will make it easier to get the piston at tdc. You might want a friend there to help you hear it. Then drop the dist. in with the rotor pointing towards the number one cylinder. It might not fall right in you'll probably have to wiggle it. After you have it all back together then try and spray some ether back in it and try to start it. After it is running turn the dist. until the motor's rpm and roughness even out. That will give you a good start on the timing. If you have already tried this and it didn't work then it will be compression or valve train. I think you said that the motor had been replaced or rebuilt, if all of the above has been checked pull the valve covers and check the rockers. Try and wiggle them. If they wiggle then there loose obviously and you'll have tighten them. don't tighten them too much just a little at a time. Then try and start it again. After it starts tighten the rockers until they stop rattling. If they're not loose they might be over tightened and that won't let the valves close so you won't have compression for the cylinders to fire. I hope this helps. Just remember if it won't fire on the ether with good plugs it is not a fuel delivery issue.

I appreciate all the help you guys are offering, but my only problem with messing with the rockers and things of that nature is this: the motor was rebuilt in 2003-2004. I've been looking at it on and off since then. It never had any problems any of the times I took it out for a drive and it ran fine for 1 week once I bought it. New spark plugs fixed the issue. Then it happened again. I can't see how everything would be fine for so long then something of that magnitude would happen overnight (literally). I guess I'm just having a hard time figuring out exactly what could cause that to happen; I've never heard of a case like this. Can someone explain why the compression would be off after being alright for so long on a new motor?

Well if the motor wasn't put together properly or wasn't broken in properly then the rings might have been toasted. Did the car smoke at all when it ran right before it stopped running. You could have dropped a valve or 3 or 4. Not likely but possible. You could have burnt the exh. valves too. But that normally only happens from a lack of back pressure ie exh. You could have broke a couple of pistons again not likely but possible. If you check the compression and it is bad try and drop a capfull of trans fluid in each throttle bore. The trans fluid helps the rings to swell up and seal the cylinders. It won't be a permanent fix but you'll know what the problem is. Good luck and I will check back and see if I can be of more help.

[quote=85irocz355tpi;3571175] Did the car smoke at all when it ran right before it stopped running. You could have dropped a valve or 3 or 4. Not likely but possible. quote]

No, the car didn't smoke at all...just backfired a few times before it completely died. After I got it running the first time, we ran it on a new tank of gas for 15-20 min, then it was running fine but began backfiring a little, and we ended up putting it away. Next day it wouldn't start.

That sounds like a timing issue. did the tack jump around like it was broke when it was running. It is possible the distributor gear is broke. That happened to me after I changed my motor in my Iroc. Or the distributor jumped time. You'll have to pull the distributor to check though. That is also a sign of a bad maf also.

I don't remember the tach jumping around too much, but I don't think it was idling at a steady RPM either.

Hmm. Have you pulled the distributor yet.

No, I haven't touched the dizzy since I set #1 TDC a couple weeks back.

Did it run after that? And how did the dis. gear look when you had it out?

Well it never actually got started then either, unfortunately. I just wanted to get the base timing set for sure...I only had the dizzy cap off to watch where the rotor was when we hit TDC; I didn't have it out at all.

The dist. How well did the rotor turn. Have you tried putting a known good maf in it to see if it did anything different? have you checked the trouble codes from the ecm? How about the coil?

The rotor seemed to turn fine when I cranked the motor by hand if that's what you mean. My cousin that I borrowed the injectors from offered any parts from his car, so I could try the MAF...but would that cause the car to not start, or just run like crap? When I had the ALDL cable connected, it only read the 'spare' ECM data, which had no codes tripped. I haven't been able to get the cable to read off of the stock ECM. I also tried the jumper to get the codes to flash, and that didn't work. What about the coil?

It is possible for it not to start if the maf is bad. Most likely from the extreme rich condition it would cause. If the coil is bad then even though you see spark doesn't mean it is strong enough to ignite the mixture in the cylinders. Did you replace anything with the ignition yet. Like the ignition module or anything.

No, nothing with the ignition. I had asked earlier if it was possible my spark wasn't powerful enough and no one said anything about it. How bad is the coil to test/replace?

When you trip the ecm from the aldl you don't even get a code 12? If you don't get a code 12 which is a reference code meaning that the computer checks out then it could be in the computer. I think I saw that you said you replaced the computer already but it is still a possibility. Did you jump start the car or anyone elses from your car? If so you might have fried the computer from that.
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Do you have the small cap dist. or the one with the coil in cap? Either one is pretty easy to replace and I think you can get a coil for under twenty bux. You can also get one from a junk yard to. I don't know exactly how to test the coil but you might want to check your parts store and see if they can test the coil there. If you have the small cap Dist. the coil should be close to the dist. on either the left or right side of the Dist. follow the middle plug wire to find it. Make sure you disconnect the battery first though. I fried my tach because I didn't.

Earlier on pg 1 of the thread I posted a pic of what my ALDL cable reads off of the stock ECM. And it just flashes a red 5 and I guess that means something isn't right basically. I got a reman. ECM that I tried swapping in, and it does register through the ALDL connector, but doesn't start the car. The only time the car was jumped/jumped another car was about 1 1/2 years ago when I took it for a drive we needed to jump it with a tractor where it was being stored...but that was quite a while ago.

I believe it's the small cap dizzy and the coil is just to the pass. side of it.

I hate to ask but are you sure it has the right computer, and engine combo. I put an 87 350 computer on my 85 and it ran like ****. Is it possible that the ecm or prom isn't for your car or motor or year. GM changed the ecm's for different years. When you just jump the aldl with a jumper what happens?

The ECM in the car is xxx165 and I pulled the ECM from a 5.7 and it's also a xxx165. I checked the PROM on the stock, but not the spare. Do the PROMs have to match, too? And why would I be able to read data off of the spare ECM, then? When I try to jump the A/B (I think) terminals, the car doesn't respond at all. I read it's supposed to flash the code in sequence with the SES light, but nothing happens.

If by ab you mean the two right next to each other on the upper right side of the aldl. Does the ses light work. Does it come on when you turn the car on?
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sorry upper left side.
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You can try and swap proms from the old ecm to the new one.

Sorry again I just went out to my car and checked it is the upper right not left.

Off the top of my head I don't remember which two terminals it was, but it was the two that are 1. ground and 2. diagnostic...whatever they were supposed to be. I have used that on another car before. The SES light does come on when I put the car in 'acc' mode and everything. Maybe I'll try swapping PROMS. The reason I had checked the PROM on the stock ECM is because I read you should be able to smell if anything inside had been fried. Could a faulty PROM be the culprit in the ECM?

It is very possible. I hope this helps. Still check the maf though just in case since your friend has one you can use. And see if your local parts store can check your coil. If you need anything else or have any more questions just send me a message and i'll check back on the thread also.

Alright, thanks alot...I've got a few new things to check out. I'll keep you posted.

cool!

Ok, so I tried swapping the PROMS between the two ECMs and neither one got the car started. I also checked the ignition coil following the test procedures in the manual. Everything is fine according to their tests.

As some others were saying ealier check compression. Maybe piston to valve clearance was not proper and you bent the valves. If you have no or very little comprasion this could be possible cause of no start. Also in checking your timming if you have this at top dead center you can pull cap and see where rotor button is point and then look at cap and see what plug wire it is pointing at on the cap it should be pointing at the number one plug wire on the cap.

dont mean to jump in and oversimpify all the technical support youre getting but....there's spark and there's fuel. you have fuel, so its spark, a rich condition may make it run poorly but youre car isnt running at all so its not sensors. Sounds like it could be a bad dsitributor or a bad coil.