Cranks but will not start, 1987 Buick Electra 3.8l

[Kyle Gnagy]

I have a 1987 buick electra park avenue sedan 3.8 v6, replaced the fuel pump relay along with it’s ground and the wiring to it, as well as being on the 2nd fuel pump for the car with a new wiring harness and ground directly to the chassis for the pump, System will prime ( I hear the fuel pressure building on the fuel rail as well as the relay clicking once , cue fuel pressure building, and then switches back off after about 3 seconds) and the fuel pump does come on, primes system for about 3 seconds, matches up to what’s going on under the hood, if I push in the valve to read the fuel pressure I get one big squirt but it doesn’t seem to be consistent, it’s like the fuel pump is just on for those 3 seconds and just shuts off entirely, like something is preventing it from working? Help ?

replaced: fuel filter, fuel lines leading from fuel filter on both inlet and outlet sides. (correctly orientated as well). Carter P74006 Fuel pump, new wiring harness, solid ground coming from wiring harness on vehicle to custom chassis ground. Spark plugs are not aged and new spark plug wires, new Mass Air Flow sensor and Crankshaft position sensor.

? I’m thinking it could be timing but the pump failing to keep more than 3 seconds of pressure is saying something? possibly regulator ?

Topic

[Josh G]

“it’s like the fuel pump is just on for those 3 seconds and just shuts off entirely”

I just want to make sure I understand this because I don’t want to assume 😆

I only saw you talk about the prime in your post not what the pump does during running. So I have to ask what you mean…The pump should only run for 3 seconds and then shut off. That’s the prime. Then it will turn on when the engine is running. If you are trying to measure pressure after the prime it will be very inconsistent, as you said, because when you hook up your gauge you are relieving the pressure from the prime. The pump has to be running in order to measure fuel pressure correctly.

Is this vehicle a crank, no start…if it is, are you sure there is a problem with the fuel system and not something else?

[Kyle Gnagy]

Ive tried turning it over, its failing to voltage drop, only primes

[Charles]

How many miles on the engine and has the timing gear been changed? In their infinite wisdom GM used a composite gear molded to an aluminum hub in that year to reduce timing chain noise. Unfortunately these gears have a tendency to fail I caught mine before failure but many people did not. In 1989 GM went back to all steel gears. The fuel pump only runs for prime then after the oil pressure comes up it will run continuously. This is done so that on engine fail, wreck, etc. the fuel will stop flowing even with key on.

[Andrew Harris]

What do you mean by failing the voltage drop. On the wire that caries battery voltage to the pump, you should see very little difference between what the voltage is at the pump and what it is at the battery. On the ground side with the pump running you should see close to 0 volts a couple hundred milli volts at most. Like others have said the pump should only prime for about three seconds and turn off. once the computer sees an rpm signal from the crankshaft position sensor it then turns the fuel pump on. Have you checked for spark or injector pulse. These engines were also notorious for having shorted injectors. since they are group fired it only takes one to shut down the whole system. it sounds like you have a fuel pressure gauge. if so what is the fuel pressure?

[Author]

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