Slowmo_Bird94

Stock 1994 Formula. Usually the car will start very easily. Sometimes this car takes about 10 seconds to crank, but has recently randomly shut off going down the road and will take a lot of cranking to start. Other times I will go out to start it and it just refuses to start. When I come back later, it cranks up like a champ. Cycling the key does not seem to help, so I kind of doubt it is my fuel pump. It has retained power in high rpms until today when it cut out badly on two consecutive first gear pulls.

Plugs, wires, and Opti were all replaced about 8K miles ago. I have tried wiggling connectors and wires with no results. A fresh fuel filter was also installed last week.

I went to get it scanned and apparently there is a loose connection somewhere under the dash because the man said that "it won't let the scanner into the computer and it appeared to be ignition related." I figured that my next step was to check power to the Opti and coil when it won't start and then find the loose connection under the dash. Anyone got ideas? I really don't have the money for another damned Optispark.

ChandlerMotorsports

iTrader: (3)

Codes?

You're going to have to get access to the scanner codes to really nail it down.

Slowmo_Bird94

What about the V.A.T.S.? I switched to my spare key and so far it has been starting for me. Only three times so far, but what happens when the V.A.T.S. triggers? Any chance at all this is related?

Slowmo_Bird94

Anyone?

Jameslt1TA

My camaro did the same thing after it would warm up it would die, then you would have to let it cool down before it would start. turned out to be a bad optical sensor.

It could also be a bad icm, autozone can test them, I would start there.

idformula

Get a fuel pressure gauge, the schrader valve is on the back of the intake. Also unplug the fpr see if it makes a difference.

Slowmo_Bird94

Thanks guys, I will get to work on those suggestions this weekend. Anyone else want to chime in with an idea?

95z28onjuice

iTrader: (-2)

why dont you start diag the issue? get a fuel pressure reading, check spark and go from there. you need to verify that fuel pressure is ggod when your having this issue.

Slowmo_Bird94

This weekend I will at very least check power to the opti and get a fuel pressure gauge hooked up. Proper pressure is well into the 40's right? 48 I think I heard.

Slowmo_Bird94

Well I checked my fuel pressure, the Haynes manual I have says 41-47 psi with the key on motor not running and 3-10 lbs less with motor running. I am getting about 35-37 psi in both cases. The pressure spikes to about 42-44 lbs when the key is first turned on, the motor is started, or if I give it some throttle.

I am going to go ahead and replace the fuel pump and see what happens. My new question is, if I get the Walbro 255 lph in tank pump for the LT-1, will it support the 55-60 lbs of pressure needed if I swap over to a LS based motor? From what I have heard, these pumps can support about 500hp, is that true?

Jameslt1TA

I'm running a single walbro in my camaro...seems to be working fine. Also have you checked if you if your plugs are sparking? The first thing i do when my car dies is take out a plug, hook it back up the the plug wire and lay the plug on the headers. Then i have someone crank it over while I watch for spark. If no spark then I pull the coil wire off of the opti and have someone crank it over and see if it archs. The past three times my car died there was no spark at the plug, but the coil was sparking, indicating the cap and rotor were trashed.

If the coil doesn't spark then it could be the optical sensor.

1994Sleeper

http://www.mainstreamtopics.com/foru...p?showtopic=78

Try the above link. Its a step by step write up to help you diagnose the problem.

Slowmo_Bird94

Thanks for the link, very insightful. Next time it does not start, I will check for spark if it isn't too hot to get a plug off or get the coil wire off.