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Fuel pump testing
Posted to Technical Tips Forum on 1/13/2012 17 Replies

Had a ranger fail to start a couple days ago in a neighboring town. A shop there said it was a bad fuel pump. As I found out it had failed to start about a month ago also but with the "final try" it started.

When it got off the tow truck it started normally. Fuel pump amp scope had one segment that was not like the rest but it was putting out 60 PSI running with 7-8 amps.

Looking in the archives I found several post of intermittent fuel pump caused no starts. But this pump was 4 months old, From Ford, so how to prove the pump failure for warranty. There was a reply that made the proof possible. I thank the person who told how to use a remoter starter switch in place of the relay to turn the pump on and off repeatedly while scoping. Doing so let me capture the fail of the pump to spin several times, shown by the spike to 19 amps.

A nice method for intermittents.

Russel from Arizona

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car Vehicle Data

2004 Ford Ranger XL 3.0L

Engine3.0 L
Trans5-speed Automatic (Electronic)