can the fuel/oil pressure switch cause the fuel pump to not come on?
- Anonymous1 decade agoFavorite Answer
I own a shop, and have done extensive fuel systems work. Most GM vehicles are wired through the oil pressure sending unit (located by the oil filter, or top back of engine) and is done so as a safety feature. When involved in an accident, the engine stops running. As it stops running, it also looses oil pressure, and since the fuel pump is wired through this switch, no oil pressure equals no fuel pump. When you turn your ignition switch to the on position, you hear the fuel pump come on momentarily for 3-4 seconds. This primes the fuel pump pressure that may have leaked off, but does not run the pump. The system has a momentary relay (latch) that pulls in when energised to supply the pump with power, but once the latch heats up, the circuit opens, and if no oil pressure is there, the engine doesn't run. One can test this circuit simply by purchasing a spray can of carburetor/choke cleaner, spray 3-4 seconds into intake of engine (with throttle held wide open). Remove spray, and start the engine. If it runs for a few seconds and stalls, repeat the procedure. This test primes the fuel system, checks the fire from the ignition, and isolates the problem to the fuel delivery system. All GM systems has a fuel pump test wire (usually around the brake booster or left fender) that is red. Connect a 12 (+) wire momentarily to this wire, and the pump should run as long as you keep this wire hooked up. Many fuel delivery problems can be resolved due to grounding issues such as; no ground strap from engine to fire wall, or no ground at tank to frame. Even the ground at the battery (-) terminal has a wire that bolts to the body, and/or the frame that can cause all kinds of problems. Finally the fuel pressure regulator can have a vacuum hose that is sucking air around the hose, cracked, fell off, collapsing, or clogged keeping the fuel pressure from building up enough to run the engine. As always; One must have a clean fuel filter, no leaks in the line, and the return line to the tank must be free, and without clogs.
Glad to help out, Good Luck!!!Source(s): Certified Master Mechanic, Shop Owner, 40 yrs. experience.
- Anonymous5 years ago
Check for power at the electric fuel pump. If you have power then you have a defective pump, if no power then you need to check backwards until you locate the break in wire or fuel pump relay or fuse and possibly the oil pressure switch. GM built in a safety into the switch for the oil pressure. If low on oil or loss of pressure, the switch would cut power to the pump so you dont blow the engine. Basically the same principle as if you got into an accident, the pump would cut out. But more than likely you have a bad fuel pump. Did you try tapping on the bottom of the tank? May be the pump is stuck, if it works and the engine starts, then you still need to replace the pump in the tank...gl
- Anonymous4 years ago
Fuel Pressure SwitchSource(s): https://shrinks.im/a9I5R
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- Anonymous5 years ago
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can the fuel/oil pressure switch cause the fuel pump to not come on?Source(s): fuel oil pressure switch fuel pump on: https://tr.im/PvOwl
- Anonymous1 decade ago
Yes. Most newer vehicles have the oil switch control the fuel pump power. Should the vehicle run too low on oil, the pressure will drop, the fuel pump will turn off and the engine will shut down preventing serious damage.Source(s): LIFE
- 1 decade ago
need more info but if you have a Chevy they use the oil presser switch as a safety in case of role over if there is know oil presser it will shut the fuel pump offSource(s): auto tech
- 6 years ago
I just got a truck with that same issue hoping a new sensor or wiring will fix the problem
- BLv 41 decade ago
maybe if your motor has low oil pressure cutoff switch, but most cars don't.
- 1 decade ago
what kind of car? year make model
newer cars - yes
older cars - no