ybslow

My 1992 six speed unmodified LT1 with 100,000 miles has been giving me starting problems for the past two years.
The problem is intermittent and it seems to act up more frequently when it has been sitting outside in the heat. Although there is a component of randomness it seems.
When I put the key in I can hear the fuel pump priming. When it fires up it stalls after half a second. Further cranking of the engine fails to start it. It is as if it is not getting gas or spark. Taking the key out and retrying often solves the problem and it starts. Occasionally this is not enough and it will not start after several attempts. This has occurred on two occasions when it was very hot outside. Once the temperature cooled down at night the car would fire up right away.

Two years ago when the problem started I took it in and they could not reproduce the problem. I had the fuel filter replaced partially as routine maintanence and in hopes of finding a cure. It continued to happen but since it always started eventually and only happened occasionally I decide not to spend mega bucks chasing down the problem.

After leaving me somewhat stranded last week I took it into the garage and had new plugs(NGK platinum) and wires(Taylor) installed along with an engine flush in hopes this might solve the problem and they were due for a change anyways. It runs better but the starting issue is still there when it is out in the sun. The garage told me it wasn't idling properly and they were "99.9% sure it was the opti". They wanted to hose me for $1200 parts and $800 labour as a modest estimate. I decided to hold off on the opti and hope the forum members could provide me with more insight as I do not trust this diagnosis of 99.9% certainty. I drove it home and it has run better than ever so I don't know where the idling thing came from and my mileage is >30 on the highway.

Any suggestions? I've ruled out fuel filter, plugs, wires, air filter, and fuses. My hunch is that the problem lies in the fuel pump and system.

Anyone ever hear of this problem before? Please don't tell me they are right and it is the opti.

jfb

It is ok to think that this that or the other thing is the cause of your starting problem, what isn't ok is to put a new this/that/other thing on and then find out that wasn't it. This is the absolute most expensive and worst possible way to repair anything!!!!!!!!!!!!!!! When it won't start, THAT is the time to do some diagnostic testing to find what is causing the no start. First use your timing light to determine if you have spark and spark at the right time while someone cranks. Also, pull a plug wire and use a clip lead (wire with an alligator clip on each end) and connect one end to ground and bring the other within 1/2 inch of the plug wire while someone cranks a few revs, you should easily be able to see a 1/2 inch spark with a nice snap. Weak or no spark won't allow an engine to start. Next, put a fuel pressure gauge on the end of the fuel rail and see if you have normal 40 psi pressure and observe if the pressure holds for a long time or drops rapidly with the ignition turned off. Rapid drop can indicate a leaky injector causing a too rich condition to start. Unplug an injector and connect a noid light (available at a parts house) or use a low power 12v lamp like a #194 side marker light across the injector socket and observe if the lamp pulses during cranking proving that the ECM is pulsing the injectors. Get your PCM read for stored error codes. You can buy all of the above tools for less than one hour of your mechanics time and they are reuseable ! Also, always ask your mechanic , "If you replace the opti like you are so sure is the cause of my starting problems, what recourse do I have if the problem doesn't go away"?
Come back and post your findings and we will have more to go on for further diagnostics or a solution .

draakarmaul

almost sounds like a dirty vats pellet......

ybslow

[QUOTE=jfb;1561185189]It is ok to think that this that or the other thing is the cause of your starting problem, what isn't ok is to put a new this/that/other thing on and then find out that wasn't it. This is the absolute most expensive and worst possible way to repair anything!!!!!!!!!!!!!!!

I totally agree. I guess I gave the wrong impression in my initial post. All the work that has been done has been routine and not specifically directed to this problem. The only thing that has been suggested to specifically fix this problem was the opti. I just mentioned the things that had been replaced to help give more information in hopes that a diagnosis could be ascertained.

When it won't start, THAT is the time to do some diagnostic testing to find what is causing the no start.

This is a random event. Sometimes it will not be for several months. If it does happen it usually is when I am out doing errands or at work so dropping everything and doing diagnostic testing at that time is a little unreasonalbe.

First use your timing light to determine if you have spark and spark at the right time while someone cranks. Also, pull a plug wire and use a clip lead (wire with an alligator clip on each end) and connect one end to ground and bring the other within 1/2 inch of the plug wire while someone cranks a few revs, you should easily be able to see a 1/2 inch spark with a nice snap. Weak or no spark won't allow an engine to start. Next, put a fuel pressure gauge on the end of the fuel rail and see if you have normal 40 psi pressure and observe if the pressure holds for a long time or drops rapidly with the ignition turned off. Rapid drop can indicate a leaky injector causing a too rich condition to start. Unplug an injector and connect a noid light (available at a parts house) or use a low power 12v lamp like a #194 side marker light across the injector socket and observe if the lamp pulses during cranking proving that the ECM is pulsing the injectors. Get your PCM read for stored error codes.

I will try the above suggestions and see what I come up with. Thanks for the advice.

Blak Z06

86PACER

Two grand to replace an opti sound like a ripoff.

These intermittent problems can be a bitch to solve, because you have to diagnose right when it's doing it. Otherwise everything else will check out fine. And often you won't get enough diagnosing time to get to the bottom of it either. These are the kind of problems I hate most.

zr1fred

$1200 for an opti is a rip off. Go to Autozone (or other parts house) and look at one. I kind of doubt that's your problem unless you are getting codes. You might want to try a different shop, $2000 is alot of money to throw at a problem.

enventr

btw is that canadian dollars?what is the exchange rate?For 2k american dollars that is a rip unless waterpump, wires and every gasket and seal are replaced along with a new balancer hub

MR NICE

rip off,does that include KY JELLY ?, get your car out of there while you still have a wallet.

86PACER

No lube, seeing how brand new original AC Delco optis sell on ebay for $269. The shop's $1200 parts quote plus $800 labor on top of that is down right rediculous.

ybslow

That's why I went back to the forum for help and give me time to see what it would cost to order one in from the states. The Canadian dollar is almost at par with the US dollar. $100US = $106 CAN. All parts that have been put on my car aside from oil filters I have purchased in the US and had shipped to Canada.

Another example, the front driver FX3 actuator went two years ago. They wanted $900 for the part alone. It cost me under $300CAN to get a brand new one shipped to my front door from the US.

enventr

When you replace the opti-I believe that you will have to remove the waterpump.It should be replaced at the same time.Mid America has the opti for $400.If you shop around you will probably get it cheaper.You may want to contact a Corvette club in your area for a reputable mechanic that wont rip you off.
good luck

atragichope

Summit Racing has a brand new AC delco opti for $384. I have the same issue with my 92. Runs fine cold and will run for about 13 min. then it just dies. I got codes 42 and 43. 42 is the opti spark code.

CFI-EFI

Test your hunch. Not with a fuel pump...With a gauge.

Speaking of codes (mentioned above). Have you checked for codes?A GREAT big
Air, fuel, spark, compression. What is missing when it won't start?

RACE ON!!!

jhammons01

My only question with that is, What if it is Flooded? Say a leaky injector when it is hot.

I'm not questioning you, rather, I really don't know.

rick lambert

about the cost, and most of the advice. Next time it happens hold the gas pedal all the way to the floor while cranking, this puts the computer into clear flood. It could very well be an injector(s) sticking, flooding the engine. Like CFI-EFI said check the fuel pressure with a guage, should tell you whether you have leaky injector(s) or bad fp regulator.If the pressure holds ohm the injectors. If not you'll need to trouble shoot further( easy) to isolate the problem.

I thought a bad opti would throw a code?

All2kool

Not if it cranks. Bad VATS = No Crank.

I had a 1989 Trans Am that did this very same thing. Turned out to be the Distributor (Opti in your case).

ybslow

Thank you everyone for the advice. I will try to run some diagnostics this weekend. Today would have been good since it was 90 degrees out and it didn't start for me after work. I will go back tonight when it cools off to see if it starts.

One thing that no one has really addressed that is a key component to my history is that the car acts up when the outside temperature is hot, irrespective of engine temperature. It never acts up when it is less than around 65 degrees and much more consistently when greater than 85 degrees as I have found this week during our hot spell.

coupeguy2001

Um, try this if it's hot and won't start.
put the key in the freezer.
If the pellet on the key is borderline with what the vats wants to see, cooling the key off might change the resistance enough to get it to start, and tell you if it's the vats key pellet resistance or resistance reader inside the vats module.

corvette1989bham

ask for written estimate then let us know how that breaks down to $2000.00 . I would LOVE to see a scan of that estimate and know who gave it to you.