Fuel pump never primes

edfiero1

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My ECM doesn't seem to ever command the 2 second pulse of the fuel pump at key on time. I've checked the fuel pressure. Its 0 at key on.

The car will start up after you crank the keyfor a while. But because there is no prime, it always is a good long crank to get her started when cold.

Is there anything else that controls this prime other than the ECM? Anything else that could prevent it from happening?

As long as the fuel rail still has pressure on it from the last time it was started it, it starts right up.
 

Chuck Leeper

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Relay?
Sounds like the pump is being powered thru the oil pressure bypass sw.
 

dank GN

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Are you having some short of issue or does it just bother you it’s not priming?
 

edfiero1

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I've replaced the relay, but no change.
No specific issue other than I have to crank the starter for 10+ seconds to build the pressure, and get 'er started, when I know it should start in 2 seconds.
 

edfiero1

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Thanks Rick. I could certainly buy that. Let me see if I can locate that transistor in the ECM.
 

dank GN

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Even with out a prime it should build FP a lot faster then 10sec . My car doesn’t prime but as soon as the pump comes on I have FP within a sec or so
 

RED LS1

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Subscribed. I'm having the same issue. What relay is related to this near the Map Sensor.
 

TurboBuRick

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There are 2 relays by the map sensor. One for A/C and the other for fuel pump. The fuel pump relay has a grey plug.