90 350 tbi cuts out after a minute

[1998_K1500_Sub]

Regarding the oil pressure switch, you can simply bypass (jumper wire) the one pressure switch that controls the fuel pump, and so determine if it's part of the problem or not.

Now, don't ask me which switch controls the fuel pump, but a wiring diagram will tell you (e.g., via the wire color codes). Let me know if you need one and I'll look.

(Edited: See later posts related to the oil pressure switch)

 

[PlayingWithTBI]

As far as the Oil Pressure Switch, it's a 1 wire switch on the rear china wall. I'm not sure but I think GM changed it to a 3 wire switch somewhere in 92 maybe?
Here's where it is on my 88

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[Schurkey]

1. The only way the oil pressure switch can be a problem is if the fuel pump relay circuit has already failed. Either one--oil pressure switch or fuel pump relay--can operate the fuel pump.

2. Verify fuel pressure.

3. CONNECT A SCAN TOOL, find out what the computer is trying to tell you. Verify all sensors, and computer outputs. Running for a couple minutes then dying is perhaps a symptom of the transition from open-loop operation to closed-loop operation.

 

[1998_K1500_Sub]

1. The only way the oil pressure switch can be a problem is if the fuel pump relay circuit has already failed. Either one--oil pressure switch or fuel pump relay--can operate the fuel pump.

Mmm... yup. I thought it worked a differently, i.e., I thought the loss of oil pressure would kill the engine as a conservative measure, but at least in 1998 the manual jibes with your description:

"Circuit Description

When the ignition switch is turned ON, the VCM turns the in-tank fuel pump ON. The in-tank fuel pump remains ON as long as the engine is cranking or running and the VCM is receiving the distributor reference pulses. If there are no reference pulses, the VCM shuts the fuel pump OFF within 2 seconds after the ignition is ON or the engine stops.

Should the fuel pump relay or the 12 volt relay drive from the VCM fail, the fuel pump receives a supply current through the oil pressure switch backup circuit. The fuel pump test terminal is located in the drivers side of the engine compartment. When the engine is stopped, applying the battery voltage to the test terminal can turn on the fuel pump."

From 1998 manual, Pg. 6-1730 "Engine Controls - 5.0, 5.7L"

 

[Schurkey]

Mmm... yup. I thought it worked a differently, i.e., I thought the loss of oil pressure would kill the engine as a conservative measure,

No. The oil pressure switch is a "safety redundancy" to keep the engine running if the relay system fails. You don't end up stranded with a non-running engine.

A failed fuel pump relay often results in extended cranking time--the engine has to crank long enough to build oil pressure before the fuel pump turns on.

but at least in 1998 the manual jibes with your description:

Pretty-much "Standard Operating Procedure" for GM vehicles going back many years, and across vehicle lines. My '92 Lumina is wired the same way; and I don't think that was the first year of this philosophy.

 

[1993GMCC2500SLX]

So I just purchased this 1990 k2500, Silverado.
Truck runs great for a minute or two then shuts off. PO said fuel pump is new, have one in box to replace,
I replaced the idle air controller, fuel pressure regulator and the distributor.

My next guess is the throttle position sensor?

Any advice would be appreciated, I work mostly on old carbureted motors and am new to the tbi!

Guys remember the early 94 Chevy Silverado Z71 extended cab short bed I traded for that only needed a fuel pump, but I replaced the entire sending unit assembly because it was nasty and judging by the fuel filter they ran whatever this onyx gloss black and quicksilver Z71 would run on,needless to say ever since I got it running it's ran like **** backfiring almost any movement of the throttle,I'm guessing the injectors need replacement and while checking into that I discovered the 350 in this truck has a 5279 305 injector and a 5206 350 injector on the other side, and it always has oil that smells like gas .

 

[1993GMCC2500SLX]

Have you pulled a code?
How's your oil pressure?

Does his truck the guy who bought the 90 Chevy 1500 have a oil pressure sensor with the built in fuel pump cutoff circuit,I don't remember what year they started that I know my 94 Chevy does.

 

[Schurkey]

Does his truck the guy who bought the 90 Chevy 1500 have a oil pressure sensor with the built in fuel pump cutoff circuit,I don't remember what year they started that I know my 94 Chevy does.

The oil pressure "sensor" does not have a fuel pump CUTOFF circuit. It is a fuel pump ENABLE circuit, so the engine can run even if the fuel pump relay is damaged.

The fuel pump is not turned off if the engine loses oil pressure unless the fuel pump relay circuit has already failed.

 

[1993GMCC2500SLX]

The oil pressure "sensor" does not have a fuel pump CUTOFF circuit. It is a fuel pump ENABLE circuit, so the engine can run even if the fuel pump relay is damaged.

The fuel pump is not turned off if the engine loses oil pressure unless the fuel pump relay circuit has already failed.

I was thinking in the case of a accident it did kill the fuel pump like in a rollover?!

 

[PlayingWithTBI]

I was thinking in the case of a accident it did kill the fuel pump like in a rollover?!

Nope but, as soon as the ECM doesn't receive any DRPs (Distributor Reference Pulses) from the ICM for 2 seconds, and oil pressure drops below ~4 PSI the fuel pump will shut off.

Edit: the fuel pump SHOULD shut off.