HELP!!! My on-going problems

[3X00-Modified]

Ok, here are my two ideas...

Oil pressure sending unit for the first 88... if you have a cluster that shows it and its reading pressure, that doesnt mean that the digital part of the switch that the fuel pump relies on is working... Another way to test that is find the fuel pump relay and jump it so its on constant and see if the car will stay running, then you can either trouble shoot the wiring going to the oil pressure unit, or just replace the unit itself. I know they had the safety on a 94+ setup, just not sure on the older ones... I assume something is there since the pump knows to prime, then shut off if the car is not started, its waiting for a signal to come on full.

Second 88 I would really lean toward the crank sensor since its a hot re-start condition. Those are known to act up and get worse if the vehicle is hot.

If you still need the ICM I'll send one out for $25 shipped USPS.

[ronaconda]

That safety is not on the older ones...i was running with the oil pressure sending unit unplugged for years because mine did the opposite - kept the pump running even with the key off.

[ErichZ26]

If it starts but dies with throttle. Unplug MAF and and see if the computer willl substitute values to keep the engine running. You may need to check power to MAF. Unfortunately the MAF is a frequency reading and and not voltage and regular DMM will not be able to read it.

[3X00-Modified]

mine did the opposite - kept the pump running even with the key off.

That sounds like a totally differnt deal... Not even sure how that is possible, fuel pump fuse should be hot in run only, not hot always. Also if unplugging the OPSU fixed your problem that means something is there...

[SuzukiGhostRider]

On an '88 all the wire you're referring to in the OPSU wiring does Jon is act as a secondary power source if needed for the fuel pump to operate.

[3X00-Modified]

After looking at a 95 diagram I was really confused... But I read up on it more. Aparently the ECM will control the fuel pump via the Relay on the strut tower, One position of that relay is prime, which that lead gets voltage right when you turn the key on then its de-energized after a few seconds. Once the car is cranked over the ECM sends a signal to the relay again to engage... now if that relay is bad, supposidly the OPSU will complete that circuit to turn the fuel pump on once the oil pressure has reached over 4PSI, so technically its not a safety shut off since there are two different power leads to the fuel pump. It seems more like a redundant power supply rather than a safety feature as some have called it in the past.

I guess things to check then would be ICM since thats sending a signal to the ECM to say the engine is running which in turn sends a signal to the fuel pump relay, Or to just try swapping out the fuel pump relay.

One other test to see if that is even a possiblity would be putting a fuel pressure gauge on it and see what happens to the pressure after you start it... If it drops off down to 0 then the car dies then you know the pump's not kicking back on after it primes, if it's staying up there then its gotta be an ignition problem somewhere.

[SuzukiGhostRider]

After looking at a 95 diagram I was really confused... But I read up on it more. Aparently the ECM will control the fuel pump via the Relay on the strut tower, One position of that relay is prime, which that lead gets voltage right when you turn the key on then its de-energized after a few seconds. Once the car is cranked over the ECM sends a signal to the relay again to engage... now if that relay is bad, supposidly the OPSU will complete that circuit to turn the fuel pump on once the oil pressure has reached over 4PSI, so technically its not a safety shut off since there are two different power leads to the fuel pump. It seems more like a redundant power supply rather than a safety feature as some have called it in the past.

......

Correct. Exactly what I was saying. Never heard of ANY Beretta having the "safety shut off" you're referring to. Most fuel shut offs in GM's are

A. Built into the alarm system.

B. A manual cable or button in the glove box or trunk kick panel.

[3X00-Modified]

Yeah I always heard of the opsu switch as being a safety for the fuel pump, but once I looked at the diagram I realized that just couldn't work with how it was wired.

[Beretta_gal]

well...Still no word on either car as of yet.....Car #2 I cranked it up this morning on a cold start,idled high at like 3500 RPM's...shut it off re-started it and then idled at about 2800 RPM's...I restarted it about 4-5 times and on the last re-start the idle was about 1500,still a bit high,but tolerable...anyway,it started right up,ran great. I let just sit and idle about 20-30 minutes,and finally after warming up I guess,it started idleing like crap and then finally died out...when I went to re-start it,it sounded like crap,and wouldn't stay running. You could also smell the richness of the fuel....I haven't yet tried ICM,as I was waiting to see if car #1 needed it and if not then using the one I bought to put into this car...As for Car #1....It's still sitting at the shop,the mechanic is testing and eliminating---sorta speak,but I did drop off a crank sensor to him to try in it,he had the fan pulled out and what not to put test/put in the new ICM....I sure hope something comes about soon....I miss my babies!!!!

[Beretta_gal]

This is car #1

potential.jpg (7.99 KiB) Viewed 3948 times

This is car #2

[Beretta_gal]

Well just a small update...Still pretty much at square 1.....I had a friend come out today to hook up his scanner to car #2...(black one)...and it pulled up a bad O2 sensor(took care of the richness) and MAP sensor....replaced both those along with the PCV valve...and NOTHING...starts,seems kinda louder than usual though,but the minute you give it gas....it dies out. You can still hear a miss in there as well.....so as stated..STILL AT SQUARE 1....as for car #2,it's still in the shop,had new ICM,CPS,Rail,and still nothing...it has good fuel and oil pressure,so that's not the issue,but same thing...will start,run 10-15 seconds,die??? He's now in the process of checking wires and whatnot......THIS IS MADNING!!!!!!!!!!!!!

[SuzukiGhostRider]

Have you ever had the fuel injectors ohmed out on EITHER car yet? Starting to sound like injector pulse issues.

[ronaconda]

Have you ever had the fuel injectors ohmed out on EITHER car yet? Starting to sound like injector pulse issues.

One bad injector was causing all my pain - it shorted and shorted the ENTIRE injector circuit. Resistance should be between 12-13 ohms.

[Beretta_gal]

Have you ever had the fuel injectors ohmed out on EITHER car yet? Starting to sound like injector pulse issues.

On car #1...the mechanic that has it now never mentioned anything about that so probably not...as for car #2...NO I don't have an Ohm tester....where can I get one? (autozone/Advanced?)..how much do they usually cost? and what should Ohm's be?

[SuzukiGhostRider]

Ohm meters can be had as cheap as $12 at Walmart for an analog or around $20 for a digital.