Today my car was at 30psi and when I disconected one pump module it would still run and it was running 30psi, then when I plugged it back in and disconnected the other one the car would stall.
So I thought my module was bad, then I switched connectors between the modules and did the same thing, but this time it was opposite, when I unplugged the module that stalled the car the first time, it stayed the same and idled. However when I disconnected the one that kept the pressure the same the first time,it stalled the car.
It's almost like my connector is no good, but I took a multi meter to it and it showed 12v on both...

Can someone do me a favor.
Turn your car on, note the fuel pressure at idle, and pull the connector out of one of your modules. Then see what your fuel pressure is. Plug it back in and do the same to the other one.

 

Wow thats interesting.....seems like it is still a wiring problem regardless because the pumps work when wires are alternated from the working side to the non working side....maybe moose will run that test for you....hope its not the pump itself?[&:]

 

I'm a little confused about what you switched? I'll have to look at my fpdms and see what exactly switching connectors does. One of your pumps isn't run for some reason and I guess your test can rule out the fpdms. If I pull one fpdm at a time i'd expect my fuel pressure at idle to remain the same. You only need one pump to maintain fuel pressure at idle/cruise, but at WOT the one pump won't be able to keep up.

 

Did you remove the two sending wires from the stock connector and plug them into the gt500 harness? Make sure you removed the right wires and have the correctly colored wires going to each other. Make sure they are seated correctly in the connector. someone else had this problem.

 

http://www.users.qwest.net/~cookpaging/whipple.pdf

Go to page 57 and double check your fuel sender wires. I bet one is not seated correctly or possibly you have them backwards.

You said that both pumps were getting 12v, so this is the only thing that makes sense.

 

Moose, I don't think that's the problem. I'm pretty sure those wires only send a signal to the fuel level gauge. I don't think they have any bearing on the functionality of the pump itself. When I first installed the whipple, one of those two wires was not fully seated in my wiring harness. My fuel pressure and air/fuel were fine, but my gas gauge read empty. I'm thinking that the problem may be one of the actual pumps.

 

Yeah those wires are connected correctly.

 

+1 At this point, the pump has got to come out. You can still have voltage present with a broken or loose wire somewhere. You've checked everything else, if it were me I'd pull the pump.

 

Ah problem fixed!!!!!!
I e-mailed whipple and sent them this thread to look at and he came back with my problem!!
There is a yellow wire that goes from one FPDM to the second FPDM and that wire is like a data wire that tells the second pump to come on. Well the pin was not seated correctly in the connector, so he had me pull the connector apart and put the yellow pin in correctly and BAM the car is a frickin beast!!!

 

glad you got it fixed!

now we can all relax and enjoy the
holiday weekend

here's a pretty cool diagram for future
reference



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