johnnys150shotZ

93 z 142k ..started car this morning and left it to warm up..(its 28 in detroit) i heard it die after about three minutes. now all it will do is crank crank crank....took out the battery charged it..just cranking..two hours later i try again fires right up!! ..i gently press the pedal to keep it alive, seems okay then just dies..volts still read good..still have oil pressure...any clues???? now just cranking again an again..i hear the fuel pump priming..there is spark since it starts and ran smooth?? sensors?

jlpz

iTrader: (8)

Had the same problem on my brother in laws 94' TA it was the opti that was crapping out..he bought a new one and turned on in the first try..

93 LT1 Vette

Install an inline fuel pressure gauge on the fuel rail schrader valve to see if pressure is dropping and starving the engine. sounds like a fuel pump or fuel filter problem. If it won't start now pull a plug and ground it to see if spark is the problem. Could be a plugged cat choking it out also, if no code are being thrown. Good luck

johnnys150shotZ

it did something very similar bout 3-4 months back, it was the icm ..could that have gone out again??if my opti is going could it be shorting out the icm over and over

a97transam

Another vote for the opti from me.
My friends 94 Formula was doing the same thing. Replaced the opti for him Friday and now starts/runs fine.

96TransAmboosted

iTrader: (8)

A vote for the opti? Wtf you guys just guess at what the problems are vs checking the car out and figuring what the issue is. Blame the opti every time time. If your not going to contribute to a helpful answer then don't post.

First thing you need to make sure you have proper spark and fuel!
After that you can check other thing out like the ICM you mentioned. Coil pack ect. Start simple and move from there.

1963SS

Why would anyone vote on a problem instead of a little troubleshooting. I'd be willing to bet that people that have never had an Opti problem are saying it's the bad component.

You said: and did you mean to say that there WAS spark since it ran smoothly. Shoebox has a pretty simple test for the Opti and the required diagnostics to find your problem. Look for "Cranks but doesn't start" or something like that.

Opti test from shbox site. http://shbox.com/1/4th_gen_tech2.html#opti_test

No start diagnostic test procedure. Your problem is probably in here.

http://www.mainstreamtopics.com/foru...rt-diagnostic/

a97transam

Well sorry for trying to help the OP.
On my friends 94 formy, toubleshooting had been done. Just because I didn't mention the fault diagnosis that had been done you should not just assume it hasn't.
I posted because the symptoms I witnessed were identical to the OP's - Started fine, ran for two - three mins and then died.
After other things had been eliminated, changing the opti has fixed it.
In the future I guess I won't bother trying to help someone out.... I'll just return to lurk mode.

1963SS

Sorry if my post offended you. That wasn't the intent. Please continue to share your knowledge. That's what makes the forums a valuable tool, the opinions of many. It just seems that the Opti is blamed a lot more than it deserves. From the OP's post it seems that it could be an intermittent fuel problem, an ICM problem, an Opti problem or a few other things including grounds.

It's not a good troubleshooting practice to jump to a conclusion and start changing expensive parts based on a vote. I am a person that doesn't mind spending money but I'd rather not waste it.

a97transam

In all seriousness I would not have posted if my experience had not been so recent and relevant.
This forum is a wealth of knowledge, and I usually find what I need by searching (which explains my low post count despite years of forum membership).
However, I felt this was something I could contribute to, perhaps give something back for the knowledge I have gained from lurking here.
I haven't taken any offence, but I will be careful to justify any future posts with details before I venture an opinion.

To the OP, I hope you get your problem sorted.

azlt

iTrader: (2)

buddy of mine just had this happen, it was starving for fuel, we replaced the pump and it runs perfect, id get the fuel pressure gauge put in.

jester1614

iTrader: (13)

I agree on the need for more diagnosis.... as well as more info. are there any codes??? another possible culprit based on me working on a friends car (93 Z28) that would do the same thing is the water pumps coolant temperature sensor.

as you can see there are several possible options that could be causing this

here is a list of some of the diagnosis that needs to be done

check for codes (just because there is no light doesnt mean no codes)
Check the fuel pressure
check for spark at the opti
check for spark at the plugs
clean and check your opti connection


and not that i recommend this but if you are going to just throw parts at it.... start with the coolant temp sensor as its only 15 bucks and can be changed easily

96TransAmboosted

iTrader: (8)

All of these experience and could be is great but the most important question is do you have a Multimeter and can you use it? A paper clip and a note pad to check for codes. Could be many things but I would start at the basics. Spark and fuel if you have those and compression it should fire. If fuel or spark stop after the 2-3 min then start checking the system that failed spec.

blownbird355

Do as others have suggested see what the engine loses to make it quit. Check fuel pressure and do the test listed on shoebox's site to see if ignition system is still doing what it should. I had same problem few years back that ended up being ECM. So do as much troubleshooting as possible before throwing money at it. Also may be good to have a friend with same car to swap out with if you have to.

johnnys150shotZ

after testing many things you guys mentioned thanks BTW ...i got no where..took it in to auto lab ..was the idle air temp sensor...100$ i got off easy

96TransAmboosted

iTrader: (8)

you mean the intake air temp sensor? the one in the elbow on the intake?

dumbcreep

I had the same problem on my 93. It was a closed loop problem. I changed the coolant temp sensor, the one in the water pump and it runs perfect. Try it before an opti, it was 20+/- at the dealer. I hope I helped.