90 D150 fuel pump stops getting power..? - DodgeTalk : Dodge Car Forums, Dodge Truck Forums and Ram Forums
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post #1 of 2 Old 06-29-2012, 04:39 PM Thread Starter
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90 D150 fuel pump stops getting power..?

Hi all, new here, and new to dodge trucks.
Recently acquired a 1990 D150 3.9L in "running condition". Yea it doesn't run. I've seen a few similar threads but this seems a little different.

My main question is: with a multimeter, and when the key is turned, i read 13.xx volts at the fuel pump for literally a fraction of a second, then nothing. I did buy a new pump thinking that was the problem, but now not so sure since the power cuts out right away. Plugged up the new pump and it runs for a 1/2 sec, then nothing. The old pump does nothing, so that probably needed to be replaced either way. Am i correct to assume that the fuel pump should continue to receive power for longer that a fraction of a second? If so, what would be causing the power to be cut off?

It starts right up after pouring fuel into the throttle body, so there is spark.

Per the Haynes manual the typical TBI has a ASD, (which checks out on mine), but no fuel pump relay. What appears to be the part throttle unlock relay(?) seems to be faulty as it clicks on only about 1/2 the time the key is turned.

I have power at all of the relay connectors, the only relay that didn't check out is the part throttle unlock relay, don't even know what that means.

Anybody have any ideas, thoughts, comments, suggestions?? they would be greatly appreciated!!
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post #2 of 2 Old 06-30-2012, 11:48 AM Thread Starter
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It was the fuel pump!

Well just went ahead and put it all back together with the new fuel pump and it fired right up!

Talked with a local mechanic here and it turns out that the fuel pump power will be cut off until there is oil pressure.

thanks for all your help!
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