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Hi All,
I'm trying to understand why I'm not getting fuel delivered to the engine on my 1990 740 Turbo. Here is my problem:
I know both the in-tank and main fuel pumps work because when I jumper the fuel pump relay, both pumps run and fuel is delivered to the engine with good pressure. However, when I crank the engine (with the fuel pump relay in place), no fuel is delivered to the engine, and I don't hear the fuel pumps turning on. And yes, I have already replaced the fuel pump relay.
My real question is: Is there something that 'tells' the fuel pump relay to turn on during cranking? Why does jumpering the relay turn on the pumps but cranking the engine does not? Also, does the radio suppression relay give the fuel pump relay a signal to turn on?
Deeply appreciate your inputs!
-Kef
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