RottenApple311

So my 95 LT1 wouldn't start the other day. Engine cranks, tries to start, hiccups and burps gas puffs out the intake. Spark plugs are not old but look black when checked. Fuel injectors replaced not to long ago (may be wrong size?). Intake EVAP vacuum lines are dry as when they are wet I know that to be a symptom of a bad fuel pressure regulator and so are black spark plugs. Fuel pressure 38-40 PSI so fuel pump works. Refilled the gas tank a day before. Thought it might be bad gas so I treated with HEET. No results.

I'm thinking more leaky fuel injectors or bad fuel pressure regulator. The engine has always started right on the turn of the key but it has had a few moments when just starting that it cant find the right idle RPM.

Any suggestions?

Thanks a bunch in advance !

ghoastrider1

hope its not your timing.

Cliff Harris

"burps gas puffs out the intake" sounds like the timing chain has jumped a tooth or two.

lt4obsesses

I had this exact same issue a couple of years ago. The FPR was my culprit, however, the fuel pump wasn't too far behind it.

RottenApple311

Good to know LT4obsesses, and thanks for the input guys. I went ahead and bought a new FPR so I'll give it a shot today sometime and reply back. Don't know when though as theres hordes of mosquitos around my house from all this rain down here in Corpus Christi. Its hard enough just to walk to the car keep them off you...

don hall

Hope the FPR solves the problem...... you might research an opti source, just in case,

RottenApple311

Mosquitos went away so I got the FPR in... the car starts now without puffing smoke but dies immediately after so progress is happening haha. I have fuel pressure and spark and the only thing in between those two is flow which probably means I have a clogged fuel filter so I'm gonna go ahead and replace that. Hope that does the trick.

don hall

Fuel is filtered so many times before it enters your tank that a clogged filter should not exist, unless your tank becomes contaminated.

See if anything is this link helps:

https://www.corvetteforum.com/forums...very-time.html

RottenApple311

Thanks for the vid seabright. I rented those noid lights and all the injectors checked out fine. I put a new fuel filter on and it seems I'm back where I started. The engines back to not starting at all and puffing smoke again. I'm gonna start checking into the optispark now.

don hall

A failed/failing opti may not set a trouble code. You might research
an opti from SacCityCorvette: http://www.saccitycorvette.com/AIPOptiSpark.html

I have replace 4 using NOS, now using a SacCity opti..... so far, so good.

1993C4LT1

on both statements. OP, do you know how to test for a bad opti? I have the saccity opti in my C4. Had it in my other LT1 C4 also.

RottenApple311

I actually do not know how to test a bad opti. Any insight on how to do so? Thanks!

1993C4LT1

1. Get noid light for LT1 engine
2. Disconnect the connection(the one that is held with the small metal clip) on fuel injector number 1
3. Connect the noid light
4. While engine is cranking over, see if the noid light is flashing.
5. If not flashing while cranking, opti is bad.

RottenApple311

Oh ok well I guess that check is also the the same as checking the injector pulse. I did that one already and it flashed on all injectors. Thanks for the clarification.

desertmike1

I'm thinking you have a weak ignition!

You can pick up an inexpensive "Ignition Spark" tester from one of the big box retailers fairly cheap and do a Spark test.

http://easyautodiagnostics.com/misc-...i-spark-tester

one example..

RottenApple311

Well I got spark so guess its time to look into the timing chain...

RottenApple311

Hey guys so I had to put this job off for a little while, but now the car is all back together with a new timing chain, optispark, sparkplugs, spark plug wires, fuel pressure regulator, and fuel filter.

The engine started right back up on sunday.
It ran great on Monday and Tuesday.
It started cranking for a few seconds longer on Wednesday.
Today its back to not starting and misfiring in the same manner it was before.

What can cause this to happen?
Can an optispark go bad in a week? Or can a timing set work its way out of time if not EXACTLY in the right position? (The dots on the gears were definately aligned at 6 and 12 oclock I made sure of this plenty of times)

Any thoughts? and thank you guys for all the past responses it greatly helps

Tom400CFI

Lots of things...did you ever actually diagnose the original problem? Had the timing chain slipped? Was the Opti bad? My guess is that the original problem is still there, and it is coincidence that it started and ran for a couple days. Don't know for sure though, w/o being there.


Yes.


No.

RottenApple311

The timing chain was actually just fine. Not too much slack and had not slipped.
I pulled the opti and it looked like hell and smelled like a fried computer. I was pretty sure the opti was the problem.

RottenApple311

Turns out I've had a faulty ground strap. I googled the right search terms for bad optisparks and turns out that this is a common problem that gives the computer a false code for the optispark and makes the engine act like the optispark isn't functioning right. I saw the ground strap touching the exhaust pipe which I felt couldn't be good so I wiggled it off and the car starts right up again. I guess this explains why it ran great and then wont start the next day after all the replacements.