I posted a question about this a few days ago because I thought it was the opti, but now I'm not sure at all. I just scanned the car and there are no codes present, but the car is very hard to start, it takes about 30 cranks to get it to start and when it does it blows alot of black smoke and runs rough for about 10 seconds and then after that the car runs and drives normal. Before the car used to start on the first crank, so I'm scarred it is not going to start at all one of these times. There where to things I noticed while reading the computer, the tps volts while the car was idling was .64 volts, does this seem low? Also the left oxygen sensor was reading alot lower than the right, but they were replaced about 5 months ago(about 3500 miles on them). Did anyone ever have any similar experiences? Is it common with these systems to have a problem and not have a code triggered? And does anyone have any advice on how to go about solving the problem? Thank you for any help in advance.

 

I forgot to mention one other thing, the car is bone stock other than exhaust.

 

1994 hmmm.....check out your ignition system, fuel filter, if thats all fine. THEN test your fuel presure and see if it holds presure with the car off. Let us know.

 

Forgot to mention that I did check the feul pressure, it holds 40psi with the key on and it is getting spark to everywire. Is there a way to check the opti to see if maybe its a weak spark or something?

 

next time to help narrow this down, hold the gas pedal about 1/8th to 1/4 down and see if she fires off any sooner. sounds like fuel is migrating into the cylinder(s) and delaying the start up till ya crank it thru. this test will help even the mix-more fuel, give er some more air. whats the status of the coolant temp sensor? its not reading -40 hopefully. ck. it out and let me in on the findings.

 

Actually I did notice that if I hold the gas pedal down it helps it start. The actually just kind of stumbles on if you know what I mean. The coolant temp never read a negitive number, but out of curiousity what would it mean if it did? What is causing the fuel to migrate into the cylinders? An open injector? Wouldn't the fuel pressure drop with the KOEO if an injector was stuck open? Thanks for your help.

 

make sure that the coolant temp sensor reads very close to the air temp sensor after an overnite sit. too cool of a reading will enrich the start mix un-necessarily and poof black smoke. check the vacuum line to the regulator, sniffsniff, any gas? also try this: one nite or whenever you know that it will sit long enough where normally it would give you the symptoms you are describing-uncap the schrader and bleed off the fuel pressure and loosely unscrew the gas cap. try starting it in the morning after that and check results. also sounds like you have a scan tool so what are the fuel trim numbers? both long and short. you gotta have a leaky injector(s) or regulator or a screwy cannister purge. try out above tests and reply with results. over and out.

 

TPS volts at idle should be between 1.2-1.6 volts. As the engine rpm's increase the voltage should increase to 4.5-5.0 volts.

 

how hard is it to turn over? If it is hard to turn it over buy a starter and try again.

 

starter? huh? hypothetically-what if its "hard to turn it over" cuz its hydrolocked? hmmmm... guess once the rod gives she will spin like never before.

 

Thank you for all the replies everyone. I found the problem last night, it was the fuel pressure regulator, I pulled the vacum line off and smelled gas so I had someone get in and turn the key while I watched the regulator with the vacum line off and it shot fuel out all over. One problem I also have now is it managed to foul my plugs out which weren't that old. I ordered a new Aeromotive regulator and new NGKs from Summit last night. Thank you for the help everyone.

 

yup-are you wondering why the pressure drop test you did didnt show what you expected? them plugs will clean up on their own. at any rate-drive it around first with the old plugs to burn out as much fuel as you can first.

 

Good idea about the plugs, I don't want to tear up the new ones so I'll definately drive with the old ones for a little bit, thanks for the advice. I am still suprised that was it, my other car had a fuel pressure regulator go bad and it had completely different problems, it would start and then shut off. I'm still getting used to working on the LT1 engine, its by far the hardest engine to work on that I've ever owned!

 

Why would there be gas in the vaccum line for the fuel regulator? Supercharged87, did this fix the problem ?

 

The fuel pressure regulater is a diaphram that is operated by vacum, when it goes, it doesn't seal all the way inside and lets fuel go past it up into the vacum line. Yes, changing the regulator solved my problem.