Author Topic: So I'm on my 3rd fuel pump relay... (Read 3610 times)

achtungE30 · « **on:** December 18, 2006, 11:00:31 AM »

as of today...

I have a new fuel pump from June 2006. Since then, well the problem started maybe a month or so after, the fuel pump relays keep getting ruined.

If I hook up a jumper wire, the car will start.

What could cause a relay to go bad after the car sitting a couple of days max?

bmwman91 · « **Reply #1 on:** December 18, 2006, 01:38:27 PM »

Sounds like something is shorting out and drawing a ton of current through it perhaps. Do you have a multimeter?

Does the battery ever come up as dead after the car sits for a long time?

Pull the relay with the car completely off. Get your multimeter. NONE of the sockets in there should read any voltage at all when the car is off. Ground the negative meter lead on the motor some other exposed emtal, and test the 4 spade sockets for voltage. If any of them read other than 0V, the problem can probably be back-traced from there. Let us know.

achtungE30 · « **Reply #2 on:** December 25, 2006, 02:39:25 PM »

Ok it looks like it wasnt the relay. I kept messing with the connections at the fuel pump and that time I heard the fuel pump buzz. The car started up right away. Took it for a quick test drive, then it loss power and shut off. Jiggled the wires again and it ran again!

Ugh, i'm thinking the plastic harnesses at the pump need to be somehow tighter where they are?? What the best/safest way to repair the connectors? Too bad super glue isn't conductive.

D. Clay · « **Reply #3 on:** December 25, 2006, 09:58:03 PM »

This drove me totally insane for over a year. Sometimes no problem for months then 5 times in 2 weeks.
Pry the prongs apart just enough to put pressure on the female socket. I discovered it on my car by accidentally bumping the plug. I think the vibration of the pump causes it.
Any body need a couple of spare relays?

achtungE30 · « **Reply #4 on:** December 26, 2006, 01:42:45 PM »

Ahhh ok, pry the prongs apart on the fuel pump side? Will try that later tonight! Just hope the car doesn't cut out on me while on the highway!!

silverblades181 · « **Reply #5 on:** December 26, 2006, 02:07:03 PM »

Before you change ANY electrical part, relay, sensor etc.. you should always test them. It's easy to do, just get the spec for a sensor and use a multimeter, or power the relay and see if it clicks and if it conducts. It will save you time and money and will narrow down the problem faster.

achtungE30 · « **Reply #6 on:** January 02, 2007, 09:06:52 AM »

Yup, it is def. a loose connection at the power harness to the fuel pump, tried to pry the prongs apart with some pliers today, and its pretty tough to move the harness while plugged in, but it seems the slightest tug on the harness, even though it doesnt physically move much, you can hear an audible change in the pump motor until it cuts out. The wires in the harness are tight for sure. Just seems like a corroded or dirty terminal issue.

Lithium or Dielectric grease anyone? Is there such a thing as electric contact cleaner that will clean terminals inside a harness on contact?