green95vert

iTrader: (2)

OK, a little background info. I'm a tech. for Saturn (only 19 so im no car genius, i just do fuel pumps, reprogram PCMs and BCMs, stuff like that) and one of the Service Writes knew of a girl selling a 1995 Z28 'vert with 96k miles for $3000. So I went and looked at it, it needed a new back window. LOVED the car, so I bought it and took it to have the new window put in it a few days later (cost me $500). Drive it for a day and the fuel pump dies. The girl said that once in a while it would die on her and shed wait a few minutes and it would start right back up and run again. Well, I went and priced a new fuel pump at Autozone, decided to go grab a Walbro 255 from Summit Racing instead sine it was cheaper and I plan on modding it quite a bit later anyways. Put the pump in and the car runs beautifully for 3 weeks. Then me, my girlfriend, and my friend take it to Paris in Illinois to look for a TA for him (30 miles one way). Didn't find anything so we go to Indy (60 mile drive one way). Well, it dies in Indy and I can't get it to run for a good 2-3 hours. FINALLY unplugged the IAT and MAF and it decides to run just fine, so I drive it home (In limp mode). Get it home , clean the MAF the next day with carb cleaner (thinkin its the MAF). Runs fine for 4 days, then it does it again at my other friends house. I take the MAF off, clean it and it runs great until today... It dies again, i unplug the MAF and IAT (no carb cleaner with me) and it wont even try to run. Let it sit for an hour, starts and runs fine with the MAF and IAT unplugged. Get about 3 miles down the road and it starts up again (remember the MAF and IAT are still unplugged) so I just limp it back to my apartment and here I am. I thought it was the MAF but today's incident ruled out that idea. I was thinking the TPS, FPR, or maybe the car was getting hot and the fuel boiled (can't think of the technical term for taht) and when I let it sit it stopped. Lastly I'm thinkin OptiSpark. It only does it when I've driven it for a while (2+hrs) and its hot (1 line down from the red on the temp. gauge). Also, right before it dies, it missed BAD and backfires through the TB. No codes set except for MAF and IAT since I unplug them when it does this hoping limp mode will get me home. I am open to any suggestions. Sorry for the long story, I just didn't want people asking for more details when I posted this. Any ideas are GREATLY appreciated!! Thanks.

LT1Formula007

iTrader: (66)

I'd make sure you have spark first...if not check to see if there is power to the Ign. Module, coil, and last the opti. If all is ok then check to see if you get fuel pressure. sometimes you can get a bad pump even if it's new it could still be defective. If all that checks out I'd go to the injectors to see if they have pulse while cranking. You can get an injector test tool from any tool truck or maybe a local part store....good luck. Keep us informed. Also if it does it while it's hot alot of times the Ign. Module will fail when hot, just before it goes all the way out. Intermittent problems suck so bad.

green95vert

iTrader: (2)

The only problem is I guarantee if I go out there right now, it'll start and run fine for the next 3-4 days :-/. I just talked to a good friend of mine though, he says that some cars have a protection thing that makes the car not run if the temp gets too high. When it's in limp mopde, the fan is constantly on so it can't get hot. This may be why it doesn't do it in limp mode. I believe SLP makes a connector and a switch so I can manually turn on my fans (I want to do it right on this car and not do it like I did my 3rdgen). Good ideas though. Tomorrow at work I might pull it into my bay and check those. Thanks for the reply. Can I get a module separate from buying the whole OptiSpark uunit?

LT1Formula007

iTrader: (66)

The ignition module I'm talking about is on the back of the coil on the drivers side head....good luck. Your right about the car having a safety when the car gets too hot, it will shut it down. but sometimes not until it's too late.-----> I'd check to see if you have a blown head gasket....you'll have to get a tester but it's worth it...LT1's are common for blowing head gaskets if you run them hot LMK. Good luck.

green95vert

iTrader: (2)

Hmm, alright. Are the modules expensive? I'll check for a head gasket at work tomorrow, check the oil for coolant tonight. Should I invest in a switch for my cooling fans? Maybe try a new thermostat? Thanks for all your help, I appreciate it a LOT.