Car is a 1986 V-6 Camaro that suddenly stopped after hitting a bump. Motor cranks good but won't start, pop, fart, or weeze. Car has strong spark (jumps 1/4"). Timing still set at 6 degrees (hasn't changed). All 6 plugs clean & dry. Cranking pressure 110-120 psi. Fuel pressure 45 psi at fuel rail. Disconnect fuel pump fuse and pressure slowly decreases as engine cranks (injectors firing). Checked injectors with noid light - all firing properly.

Somebody please tell me what I'm missing? Spark and gas at proper time should fire!!!! I even checked the exhaust for restrictions, and purged the fuel line in case gas was bad. I've never been stumped before-but must be missing something obvious. HELP.

 

PS I forgot to mention that there are no error codes on the ECM The computer flashes 12, and therefore is working?

 

Bob,

Since you asked for an expert, that left me out of the thread. But since no one has replied, I'll give it a stab anyway.

First, a few questions. How friggin' big was that bump? It must have been a little more than just a seam in the pavement (just curious).

Do you have cranking compression, or does the engine just spin freely while cranking?

In case the system has an inopereative cold start injector, have you tried to manually add a little fuel? That's usually good for at least a couple of pops. However, if the service injectors are working, you should eventually build up enough fuel to at least get some combustion, either in a cylinder or not.

Have you checked the ECM connections? EST connections? I understand that you are getting injector pulses and ignition, but if the ECM is getting poor inputs, the timing and length of the injector pulses may be insufficient.

I guess you DO need an expert, since I'm a little baffled.

 

Engine seems to spin freely, but its only a V-6, so I'm thinking that may be normal. Does have 110-120 psi cranking pressure. I'm thinking problem is electrical, not mechanical, due to the bump. I'm totally befuddled. (technical term) Car belongs to a friend, but was towed to my house since I'm the "Camaro exert".

I disconnected and connected every electrical plug in sight, including the ECM under the dash, EST, Dist, Injectors, etc. No spit, sputter, or pop. It's difficult to get gas into the cylinders with fuel injection. Its a long way from the MAF to the valves. I read about other people blowing off the plenum using starting fluid. Don't want that. I did put small amount of gas (used a shot glass) into each cylinder port when I had the plenum off (checking injectors). Didn't even fire, but I may have flooded it. I've even checked spark at several cylinders, and cranking timing (using light) on both 1 and 2 cylinders (damper marked every 120 degrees) Everything checks out.

I'm sure the I've overlooked something! At this point, it's becoming personal between me and "the car". I refuse to be defeated. Any suggestions welcomed.

 

One more thing. I removed, cleaned, and retightend all the ground connections at the front and back of motor. Then tried jumper cables between the frame, coil mount, and motor. Still won't fire. I'll send a case of beer (your choice) to anyone who can solve my problem!!!

 

Could the "bump" have crushed/collapsed the exhaust somewhere?

 

Checked out the exhaust pipes previously. No obvious dents. I even thought about the cat being damaged, but I can feel air coming from the tail pipes as the engine cranks.

 

I've no experience with V6's, but the compression test woud be low...if it were a stock cammed V8...that's why I was thinking exhaust could be restricted...but thinking about it, should be enough pressure to fire something off.

Did your buddy say it died immediately after the bump, or started to run rough, etc...or what?

Did he try to "fix" it, before he gave it to you?

Bump could or could not be related.

 

BTW, I'm no expert...I'm just bucking for a free case of beer.

 

Car died immediately after bump. Bump was not that severe - normal parking lot/speed bump type. Car was not touched by anyone but myself. While still in the lot, I checked spark with an extra spark plug. Spark was good. I could hear the fuel pump run, then shut off (normal). Since I figured it would take some checking, had it towed to my house. I now have several weeks invested and I am no closer to solving the problem. Sound desparate enough?

 

Späten Optimator. Second shoice would be Guiness.

Have you tried checking spark at more than one plug?

Have you removed the distributor cap to check for a damaged rotor (had that happen once)?

Have you tried manually adding fuel (ala top-fuel engine starts)?

Just throwing out some more ideas...

 

Alread checked spark on several cylinders. I have removed and inspected cap and rotor. Got to admit I'm hung up on the fact that it has spark and fuel, but won't fire. Like my friend said, "yeah, but it's not a 57 Chevy". Can't imagine what computer control might prevent starting, yet still have spark. I've even considered the timing chain, but yet the timing still fires at appropriate time while cranking. If the chain was loose or damage, the timing should have changed. Please keep thinking, because I'm sure I've missed the obvious. I continue to be amazed that it doesn't even pop, shudder, or attempt to start!!!

 

I wanna say restricted cat. choking the motor with exhaust. possibly. When you hit the bump you may have knocked something loose in the cat or a piece may have already been broken inside and when you hit the bump, something collapsed in there and is now possibly causing a restriction.

 

so you have spark, good compression, fuel, ...have you checked vacuum? check vacuum if you haven't already and tell me the readings. what are the numbers and how is the needle acting.

 

Needle fluctuates rapidly between 1 and 3 inches at cranking. I never checked vacuum at cranking, so I don't know what it means. Vacuum line was connected at the back of the air plenum, adjacent the power brake vacuum line.

 

just to state the obvious, have you made sure that the plug wires are in the right order?

 

Jack the car up and hit the cats with your hand and see if it rattles really badly like there are rocks or sand in there. If so, then your cats may be trashed.

If you feel up to it, you could always disconnect the exaust and try starting it without the backpresure......

 

according to your vacuum readings you could have an intake leak, your muffler or cat could be choked or, a stuck valve but I need more info to be able to really tell for sure. so far it supports my theory of a choke in the exhaust but, before you spend money, i need to know, does it stay at 3 in. and drop quickly to 1 bouncing right back to 3? or does it vibrate violently between 1 and 3?

 

also they way it happened helps to support the choked exhaust theory. Did you get any codes?

 

Vacuum vibrates rapidly/violently between 1 and 3. Engine was completely rebuilt two years ago, including new oil pump. Cam was replaced with a "Compucam" (computer compatible). The cat was replaced about 4 months ago with cheapo aftermarket, in order to pass emission test. Should come off easily to verify any back pressure problems. What should the vacuum be at cranking speeds?

 

that vacuum reading seams really low and it shouldnt fluctuate, it should build up to at least 5, 10 even 15 (hg or whatever it is)...make sure that where you have it connected isnt a timed port but it sounds like you have it in the right spot. My dad has an 86 v-6, I will do some vacuum readings for you tomorrow when I go over his house and I will take a look at his car for some ideas, I hope you figure it out before then but Ill try to help...and thanks a lot, Im really intrigued by your problem and I wont be able to sleep tonite thinking about it j/k, but you have to pm and tell me if you figure it out, I really want to know. fuel and spark and no pops, wheezes or farts...damn.

 

have you taken one of the valve covers off to verify that the cam in turning and opening the valves? I would check this pronto, my buddy had his stock timing gear break off, because GM put a plastic timing gear in it, which if u'r buddy had one, and was starting to go bad, a severe bump could break it off, and make u lose all cam movement. lemme know what you find with that, and I prefer corona. goodluck, i'll let u know what else I can think of.

 

i thought of that but wouldnt the spark not pulse if the cam wasnt turning cause it turns the distributor? and yes corona rocks

 

Pretty accurate indeed. but, I think he may have busted a tooth or two, not the whole outer ring. That's rare.

According to your vac. readings, it indicates that you have a vac leak somewhere. possibly a major vac leak because it's so low in numbers. And if your cam wasn't turning, you wouldn't get any vacuum at all. the cam wouldn't open intake valves if this was true. That's does not mean stingraye isn't on the right track. There is a possibility that it could be a broken cam gear. since your readings flucuate rapidly you can rule out exhaust clog. If it was an exhaust clog, The needle would've started at 3 and slowly dropped to 1 without returning to 3. so it's not your exhaust. It's not a stuck valve or flattened cam lobe either because the needle would only drop periodically not rapidly fluctuate. The low reading tells me vac. leak. you should have about 10 hg in cranking and about 20 when the engine is running.

So I think it could be:
broken timing gear
worn valve guides (i doubt that though)
intake manifold leak (due to your low readings)
or even a blown head gasket

Pull a cylinder leak down test. If you don't know what this is email me at 91rs4life@comcast.net and I will be happy to give you instruction how to do it and what to look for. Information collecting is important here before tearing anything apart. let's try to narrow it down first.

your compression test seems norm
you have spark
you have fuel
your vac. readings seem low and unstable
now a leakdown test should help us all to really narrow it down.

Good Luck

 

And the battle CONTINUES!!! Today I pulled off the cat and tried to start with open exhaust system. Nothing, zip, nada. No pop, snort, wheeze, or blip. Can see light thru the cat so its not plugged. Exhaust, muffler and tail pipe not an issue. With no exhaust, the vacuum gauge reading remains as before, rapidly fluctuating between 1 & 3 in hg. Can smell gas in the pipe, so I don't think thats an issue. Where to go from here?

 

have u pulled the valve covers to check for full rocker movement across both heads like I mentioned? I would still check for that asap.

 

Did you try the leakdown test? Try that first before rippin off covers. I have a 6...THOSE COVERS SUCK. gotta rip off everthing just to get at them.

(I got 2. 91 RS - 5.8L & 87 LT 2.8L)
see look....2 :lala: :lala:

 

I really feel for ya! I went thru the same thing with my V6 pickup. It turned out to be the Ignition control module. Took it to the Dealer and all. They couldnt find a thing wrong and all i got was "It should start fine but it just wont". Needless to say i was a bit angry. Took it home and my grandfather suggested the ICM to me. I was like NAW! But sure enough it started with the lil 24 dollar part only after spending around 300. A few years later same thing happened on my Firebird and I replace the ICM. So far no problems. The ICM is located under the distributor cap. You can take it to your local parts place and they should be able to test it. Just giving my two cents cuz i was chasing problems not unlike yourself.

Lates

 

Remove all the wet plugs, spin the engine a few seconds to help dry out the chambers, then screw in clean, dry plugs. Try advancing the timing a bit. You should at least get a backfire.

Corona? Just send a case of lemonade. If these guys aren't going to drink beer, neither am I...

 

He's getting spark. when you ICM goes out it just...goes out. no warning. Your car won't start then because it has no spark. He's gettin spark. So I doubt that's it at all.

 

Aw no I'm cool with corona. twist of lime and a pinch of salt...makes the medicine go down...better.

Yo quero mas cervesa fria por favor. Yo necessito los cervesas.
Yo amo corona. si.

Who's with us?

 

In case anyone's still listening, due to time constrainst and transportation needs, I had the car towed to the local auto repair shop. Turns out "virtualdemo" is the winner - it was the ICM in th distributor. They replaced the ICM and the ignition coil. Life is good.

Amazingly, I showed the spark to several people, and even demonstrated that the spark would jump over 1/4" to the engine block. Using a spare plug, I checked the spark on several cylinders on different sides of the engine. Yet the autoshop said there was no spark. Go figure. Unless the spark would jump in air but not under compression? Or it was just too weak?

Thanks for all the help. If "virtualdemo" wants to e-mail me his address (Bklemm@aol.com), I'll live up to my part of the bargin, even though I didn't get to solve the problem. At least it is solved.

Later.