I have a 1990 iroc-z tpi 350 I replaced the fuel pump and tank but im not getting fire to the pump I checked all fuses and the relay but they checked ok is there anything else that could cause it not to come on

 

the oil pressure sensor doubles as a fuel pump cut-off. if it leaks, as we all know they do, might be worth looking into. had it happen to me last year.

 

No it doesn't

 

Maybe you have a bad connection at tank somewhere as a result of the pump swap?
Can you hear pump relay click when key 1st turned on?

Putting 12V to terminal G of the ALDL connector should make the pump run if the relay and pump fuse good

 

I forgot to mention I replaced that sensor to thinking that would solve the problem

 

I hear the relay when I turn the key on im thinking it is a bad connection at the tank to its a trans-am tank and the plug was different from mine and I took the end from mine and swapped them but the wires might be different on that tank I need to find out

 

actually it does, thought i'd negate the argument by including that it had happened to me, apparently it didn't work.

 

Actually it doesn't work as a cut off
When engine is running ;
fuel pump gets power from pump relay AND the Oil Pressure switch so if OP switch was to cut off from low oil pressure then fuel pump ( and engine ) would continue to run from power supplied through relay

 

Would be a good starting point, should have mentioned that up front

 

almost correct....low oil pressure results in interrupted power to fuel pump, so the engine isn't destroyed by lack of oil. speaking from experience. A short in the switch resulted in loss of power to fuel pump, on the advise of a 25 year gm tech, replaced oil pressure sensor and power was restored to fuel pump. This is why I almost never post in these forums, someone else always wants to share their "knowledge"

 

I put the wires back on the same way I took them off the old plug it didnt look like it was any different the plug end was just different

 

still no power?

 

nothing

 

So in your infinite wisdom , looking at the typical GM EFI pump wiring below ;
HOW does the OP switch shut off power to the pump when it is also getting power from the fuel pump relay which is energized by the ECM anytime the engine is running????

 

Almost correct.
OP switch performs two functions ;
OP indicator to ECM during cranking only and power supply to fuel pump
If the OP switch does not close during cranking ( only ) then the ECM will not enable the injectors because it is not seeing the relay input signal from the OP switch ; consequently engine won't fire
Read
http://www.corvettebuyers.com/c4vettes/l98.htm

This is why I always post in these forums,
because someone else always wants to share their "knowledge" that is wrong or at best misguided

 

Did you try 12V direct to the pump as I suggested above?

 

alright look, you can post all the diagrams you want, I don't care. it's not that important to me to prove this one way or another. I simply told of my personal experience, and a possible solution. congrats on turning this into a pissing contest. Again, just stating my experience, obviously schematic MUST disprove actual events. have a nice day d-bag.

 

Love how guys resort to name calling when on the losing end of a argument.

If you actually READ what I wrote above ,
you will see I agreed that OP switch was your problem but not for the reasons you state
OP switch on these systems is NOT a low oil pressure cut off switch
It is there as backup to keep the fuel pump running should the Pri power source aka the fuel pump relay go faulty and to allow you to start the engine ( with extra cranking to build oil pressure ) for same reason.

In your case , it is possible the faulty OP switch was not supplying the correct signal to the ECM while cranking ;hence no start

 

yes, that was my problem. i never said that it cut off due to low oil pressure, i said it cut off due to a fault in the switch. you just focused on one part of my statement to argue with.

 

Because ,irrespective of your particular problem with the switch;
you have incorrectly maintained all along that the OP switch is a safety switch to shut the engine down at low oil pressure by killing the fuel pump.

 

I have maintained that because of the information provided me by multiple sources, most of whom have years of experience not only in the automotive industry, but specifically GM vehicles. I don't really care if you think i'm wrong, i'd rather help the person with the problem than sit and argue with you. Now if were finished, i'll get back to the thread on emissions equipment removal.

 

I know this is an old *** thread but I think both of you having your argument might of been wrong. I appreciate whoever posted the schematic because I have been looking for this for like 3 hours. So the only way I can see it working is the relay switching over once the key is put in the on position, this turns the pump on then after a duration of time the ecm cuts power to the relay switching the pump off. This primes the system and once the ecm sees the 12volt input from engine cranking, the oil pressure switch, then the ecm re energizes the relay keeping the pump on while driving. This is the only way I can see this schematic making since, btw Im assuming the timer is in the ecm if Im wrong let me know because I cannot find it anywhere else.