Mechanics

CHEVY NO POWER AT FUEL PUMP RELAY

1997 Chevrolet Express

Electrical problem
1997 Chevy Express V8 Two Wheel Drive Automatic 155000 miles

1997 Chevy Express 2500 Van 155,000miles, Engine died in parking lot, we installed a new fuel pump, but noticed no power to Grey wire going to pump. Check the relay and it bench tests fine, however, no power is sensed at the proper terminal to turn on the relay. Not even a 2 second pulse when cycling the key of and on. Whats the next step I should take?
thanks a lot
Michael
Avatar
Mdm6713
October 24, 2008.



Hi mdm6713 and welcome to 2carpros

Check ECM B fuse 20 amp if okay-test for power at the fuel pump relay terminal B1 orange wire if okay test the computer fuel pump relay feed

Rasmataz
Oct 24, 2008.
Actually I was wrong, I did have the 2 secs worth of power at the relay. This is what Im expeirencing now, The fuel pump will cut on for the 2 secs time only if the oil pressure switch at the rear of the engine is disconnected. Does it sound faulty? Another thing, I can jump the wires on the oi pressure switch and the pump will operate. However, it will only blow air, no fuel. I re-assemblied this twice already. Can you think of what Im doing wrong? Thanks a lot for your help
Michael

Tiny
Mdm6713
Oct 24, 2008.
Hi mdm6713 and welcome to 2carpros

If the fuel pump comes On for 2secs it should produce pressure -check it with a fuel pressure gauge and report back your readings. When the engine fires up this is where the oil pressure sending unit powers the fuel pump.Also check for injection pulse width with a noid light

Your OPSU is okay if it turns On the pump while jumpered and key at run


http://www.2carpros.com/forum/automotive_pictures/12900_oil_sending_unit_and_fuel_pump_circuit_80.gif


Rasmataz
Oct 24, 2008.
Ok, I bench tested the pump to make sure I wasnt crazy, pumped fine. What I did was fill up the capsule with fuel while inserting into the tank, (primed it in a way) Well, started right up.
I dont know if thats a common problem but I was suprised not to find anything online about priming the pump.
Michael

Tiny
Mdm6713
Oct 24, 2008.