billybengal

Hi all,
89 Iroc, 5.7, 81,700 miles, all stock (except for minor things, the "biggest" after market upgrade is an afpr).
Recent tune up (less than 1000 miles, plugs, wires, K&N cleaned).
PROBLEM:
For the past 2 months I put less than 1000 miles on the car. The problem occured 4 times and only on hot days (85 degrees outside or more). Once I drive it and I park it (go to store etc) when I come back it won't start. It does crank so it is not the starter solenoid (had this problem, I put a remote solenoid). The first time it happened I waited for about 30 mins (tried every 5 mins to start) and after 30 mins it finally did like nothing ever happened. 2nd time (temperature outside also around 85 but parked in direct sunlight) I waited for about 50 mins. Third time (temp in 90s) I waited over an hour. This happened 3 times within last 2 months. Never happened when it was less than 80 degrees outside.
Today the temp outside was around 98degrees (felt well over in direct sunlight). I made a short trip to a bank. After 15 mins inside, I get in my car, start it and about a minute later when I was leaving the parking lot it just died. I tried to start it every 5 mins, then after an hour I changed to every 10 mins. It finally started after over 4 hours!!!!
I need to drive it from LA to Chicago on Sunday but I can't like this.

I saw many posts with similar problems. I got more info on my problem so hoperfully maybe one of you can help me.

1. Happens only when it's hot outside, especially if the car sits in direct sunlight and not while driving so it has to do with something overheating. The engine does NOT overheat.
2. Car tuned properly (fuel pressure correct, timing correct, cap and rotor less than 1000 miles, new cables, plugs etc).
3. Engine has proper operating temperature and is NOT overheating.
4. Engine cranking and battery strong (not battery, not starter motor)
5. NOT the fuel pump (while sitting for 4 hours I connected power to the G terminal and tested the pump and the pressure at the rail is fine.
6. Engine DOES get a spark (kinda hard to test by 1 person but I happened to have a timing light in my trunk so I plugged it in and cranked it and it did flash meaning spark was going thru wires.
7. I read a post with someone saying the ECM in his car was overheating. Mine was pretty hot too, although I don't know how "hot" they can be. Anyways, I took it out from under the dash and cooled it and it did not help.
8. Since the fuel pump is fine, fuel pressure is fine AND the spark does go to the engine and the engine cranks...... what's wrong?

Fuel injectors working whenever they feel like it?
Ignition coil failing but then repairing itself?
Ignition pick up coing failing and then repairing itself?
Ignition module failing and repairing itself?
Could any of these overheat, malfunction but go back to a proper working order once they cool off?

Could it be something else?

Thanks so much in advance for all your help guys. Sorry for making it so long but I wanted to be very specific.

ntomsheck

iTrader: (1)

Are you any good with a multimeter? Remove a connector from an injector when it's failing, ground one probe of the multimeter to the engine, and test both contacts in the connector. The injectors have a constant 12v when on (even when not cranking). If you don't have that 12v, check your fuse block; it may be a bad connection. If you have the 12v, switch the mutlimeter to continuity. Keep the other multimeter probe grounded, and touch the other contact. Crank the engine. If you have no continuity ever, then it's either a bad sensor (one of the primary sensors) or the ECM. The ecm uses a ground signal to complete the circuit on the injectors, as it's less demanding on the little relays they put in the ECM. If you are getting continuity, that means the ECU is telling the injectors to fire. If you're also getting spark at this time, replace your injectors.

billybengal

Thanks Douchermann. I tried to make it fail today for almost two hours but today it's around 80 degrees and it's cloudy. I also disconnected fan relays and let engine temp go up to about 240-250 degrees but it didn't die and keptrestarting fine. I guess I'll take my chances and drive to chicago during nights when it's cool. I'll repost when I find out what's going on.

ntomsheck

iTrader: (1)

Take the multimeter with you, and 2-300 extra bucks in case it is the injectors. Many parts stores carry them. You might be able to get it to fail while you're heading up through nevada and southern utah. What route are you taking? I live in the western suburbs of chicago - if you figure out what you need, feel free to stop by and borrow some tools - take I-80 to I-88 and you'll be about 5mi from my house at one point haha

ninetyone

iTrader: (2)

Sounds like a bad fuel injector(s). My car did the same thing. Sometimes it would not start or when i came to a stop sign it would just die on me.LOL No codes either. Just ohm each injector until you come to the culprit!

ninetyone

iTrader: (2)

Oh and Ford 24 lb/hr work fine on mine. Actually turned the fuel pressure down a couple lbs also for good measure. Runs good. Having 24 lb/hr injectors in a stock 350 TPI is like having an adjustable fuel pressure regulator and having it set at the magical 50 psi !!