Drove car 30 miles to airport. Parked it there for 4 days. When starting up to return home, car cranked for 5 seconds, not start. Cranked for 10 seconds, no start. Fearing optispark crapped again, tried once more, started and drove 30 mile home no issue.

Since then, car would not start on first 1 or 2 tries after cranking for about 5 seconds. Then start 3rd time just fine. Talked to mechanic friend, he said maybe coolant temp sensor. He said to try just turning key 2-3 times without engaging starter then try. Did this, it started fine. In doing this, noticed fuel pump change tune after 2nd or in middle of third try. So, I hooked fuel pressure guage up. Pressure bled to zero within a few seconds.

So, figured regulator or check valve.

Before I could change, drove car 3 miles to gym. After 1 hour, went to start. It would not. Tried priming pump many times, cranking, etc.. until battery would not turn it over. Went back an hour later with truck to tow home, tried one more time with jumper cables, and started fine.

Put in in-line fuel check valve, not fuel rail holds pressure. Car starts fine, runs great, and thought problem was solve.

Now, in back to back days, after driving 3 miles and car sets for 1 hour, it will not start. First time, crank many times, let it sit for 2 hours, then started fine.

The next time, I had pressure guage with me, and decided to check fuel pressure to rule out. I bumped the shrader trying to put guage on, and it released a small burst of fuel. I decided to not put guage on, knowing it had some pressure. Washed gas off hands, and decided to try once more. Started right up, ran home fine.

Any thoughts on what this could be (run 3 miles, sit 1 hour, then no start)?

Would appreciate any suggestions on how to figure this one out.

Thanks

 

has the optispark ever been replaced? this is a 94 correct?

 

I am original owner. I am on optispark number 5. Number 1 went from waterpump leak, number 2 from coolant line leak, number 3 and 4 were from ebay and went after about a year each. Number 3 symptoms were running rough constantly, number 4 car would die after 20 -30 miles then restart after 15 minutes.

Optispark is what I am thinking. But really dont know without swapping it out.

 

What is the fuel pressure doing now??

 

since installing inline check valve, fuel pressure is holding when shutting car off.

I am going to hook pressure guage up and attempt to force problem again. I will be prepared to check for spark this time as well.

I expect that fuel pressure will be ok, and there will be no spark. Assuming I get no spark, I am wandering what else besides Optispark could be causing this intermittent issue.

Thanks for any help

 

The check valve may cause the fuel rail to hold pressure, but that pressure is all lost the second an injector opens during the start sequence. Then the fuel pump still has to develop the proper line pressure for the rest of the injectors to spray. Bottom line is, make sure the fuel pressure issue is solved before looking to something else as the problem, unless you have clear evidence that something else is a problem.

 

i would look at the fuel pressure first. it sure sounds like a failing fuel pump to me. if no spark i would look to the ignition module first. for some info look at number 33 and 28 here 4th Gen LT1 F-Body Tech Aids and look in the how to and faq sticky at the top of this section.

 

if it is the opti just spend the money on the gm one. we had alot of bad luck with the ebay and msd and cheap ones. i know some people who had the same issues as well

 

oh man u are the original owner, congrats for such car, dont ever get tired of it.
just put a good opti, and god bless u .

 

i have not heard of a chandlermotorsports warrented opti goin bad yet. they are under 100 bucks.