# Fuel Pump Relay mystery



## lotar_6 (Jan 16, 2004)

OK... so a lil' help here on my 2001.5 V6 4-mo wagoon. Backstory: I replaced the alternator and engine mounts and then went to start the car to no avail. It ran for a second, then sputtered and died. It wants to start, but can't. I replaced some parts... Engine Speed Sensor, Ignition Switch, MAF, plugs, and wires. Coils test fine, and I'm getting strong spark at each plug, tested with ignition tester. The fuel pump was replaced less than 2 years ago. *All* fuses are fine.

The fuel pump doesn't prime in the ON position, but does run when cranking. Also, it runs when I jump pins 30 & 87. I do not always (I did see 12v once or twice while testing) see voltage on pins 1 & 4 at the fuel pump connection when switched to the ON position. I've not tested the fuel pressure (another need for another tool). I'm getting 8.5v at the fuel pump relay activation pins on the relay block (T & 86) when I turn the switch to on. I was able to trip the relay with a 9v battery, so I assume this is enough. I wanted to test it though, and just feeling the relay on the board doesn't help. So I have a pair of test wires w/ alligator clips plugged into the slots. The reading at the alligators is still 8.5v when switched. However, when I clip them to the relay, it doesn't trip the relay. When I measure across the activation pins on the relay (alligator clipped) with the ignition ON, I get 0.05v. It's like the relay is sucking up the voltage. The problem is, I don't know if 8.5v is good enough to make it work, or if it's not enough juice. In other words, is the relay bad (should trip at 8.5v) or is the voltage too low to the activation pins? If 8.5v is too low at the relay, then what could cause this?

any insight??

relay 372 (PN: 4D0 951 253)


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## lotar_6 (Jan 16, 2004)

Ok... so the coil pins on the relay (T & 86) read 41.7Ω... THIS LINK says that the coil pins on most relays should read between 50Ω - 120Ω. If the 372 relay should read 50Ω (let's say) and mine is lower, then it would take more voltage to trip the relay, right? It could be a slow-failing relay. Of course, it would still be good to know what volts I should be reading on the relay pannel. I do know most relays are designed to work on way less than 12v.


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