K guys....need a clue here. Found a problem with the fuel pump relay...it was going nutz this morning and smoking hot, not to mention starving the car for fuel. We took it out and it was the wrong one (right number of pins, right V's, wrong OEM #) Figured maybe this was the problem. Skipped over to BAP and got the right relay, put it in and it did the same thing. SO just put the old one (wrong OEM#) back in and it seems fine for the moment. He has just reported the damn A/C fan is working now???? <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" /> (earlier post "no ac in Az"
Question is this, I don't particulary trust this relay seeing what it's been doing the last couple of days....has anyone else dealt with this gremlin and have some ideas? Seems she's being a tad moody and can't make up her mind which relay she wants

 

My advice is to replace every relay and every fuse. Disconnect the battery prior to doing so. Clean all the fuse contacts, slide the old relays in and out repeatedly to try to clean up the female connectors; disconnect, clean, reassemble the grounds at the battery negative (wingnut), engine to frame on passenger side, jump start terminal wire nexus. Pull it apart, clean it, replace with fresh stuff. It will save you a ton of niggling things over the coming months/years and your beast will love it.

I also carry a spare fuel pump relay and jumper in each car.

 

Anne, I've heard and read here about people rewiring the fuel pump to some other ingnition related curciut like the the key switch. I've even heard of pople makeing a specialtoggle switch to run the fuel pum totally independently.

However, I woudn't do any of these. Wally P. convinced me of that with one of his "waht if" scenarios on this topic not long ago. Search the forum for fuel pump related topics and you'll find all sorts of idea on what to do.
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In the mean time, I"m curious if the "new" relay will work now that the "old"one does. - Ruf

 

The right relay for your car is 928 615 113 00. The most common cause of electrical problems is bad grounds and connections, clean all the grounds, clean the fuel pump connections. Make sure the right amp fuse is installed. The two fuel pumps could also be pulling too many amps. Bad pumps

<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

 

Thanks guys. We've gone over the fuse panel several times since we got the car So I think this weekend we're going to pull the fuel pumps. I have a feeling the check valve in the in-tank pump is shot or missing anyway as the pump doesn't ever shut off with the key on. I'll let you know what happens...

 

The check valve has nothing to do with the running of the pump. Its only function is to hold fuel pressure after the pump starts running.

If your pump is running without the engine running, you have a problem. The main function of the fuel pump relay is to serve as a safety device to stop the fuel pump when the engine isn't running. This keeps the pump from pumping fuel nto the fire after the crash. It also keeps the pump from filling the engine with fuel if it dies while idling unattended.

The fuel pump should not run unless the engine is running, except for a two-second span when you hit the starter.

If yours is running, either the fuel pump relay is sticking, or the pump has been rewired.

Incidentally, the pumps are both wired to a common power supply line - either both should run or neither should run. There should never be a time when one runs and the other doesn't.

 

Once again Wally sheds some light on my oh so dark and scary 928 world! I had been told by a 'porsche guy' that the check valve should shut the pump down once the pressure builds in the line...and that some people modify the pumps by taking them out/disabling them for performance reasons??? Didn't make a whole lot of sense to me but what do I know?!? Thanks for saving me some unneccessary work Wally I'll check the wiring first seeing as we replaced the relay with a new one and got the same results. The pump starts up the minute you turn the key on and doesn't stop until you shut it off. I even had someone tell me it was supposed to do that...now I'm blonde but I didn't just fall off the turnip truck ya know?

 

Do the US K-Jet cars have the rev limiter in the rotor or in the fuel pump relay as with the L-Jets?

 

Anne, If blondes fall off turnip trucks, what do redheads fall off of? - Ruf

 

With the ignition off, the only relay contact that should have 12 volts is the #30 pin. You may want to check the other connections to see if you are getting power from the ignition switch (#15) or the ignition control unit. Have you checked the connections behind the fuse panel? If corroded, they would cause high resistance (heat) which could harm your relay.

Dennis

 

Ruf - carrot wagon? <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />