308QV fuel pump blowing fuse

During the 60k service on my 308QV I replaced the fuel pump because it was 1. old, and 2. causing the fuse to run extremely hot. After installing the new pump it keeps blowing the fuse. The previous owner had melted the fuel pump fuse on the fuse block and had an in-line fuse bypassing the fuse block. In the in-line fuse sits a 30amp fuse.

In an effort to eliminate as many variables as I can, I have disconnected the cold start injector and the WUR. Removing these devices has not solved the problem.

The car runs extremely well for about 10 minutes then dies when the fuel pump fuse blows.

Any ideas??

Fuse block:

I will be trying to figure this issue out tonight. Any advice or direction I should take?


JL

My first suspicion would be the non factory wiring itself Jeremey.....examine all those splices..that one short section of oversized wire on the fuseholder isn't "buying you anything", that looks like the ones for audio high power applications.......have your fuse blocks been changed or OEM????

I don't recall without looking but the line side of several of the circuits are interconnected and may not be getting proper voltage. Important to remember TOTAL voltage drop to the pump. Running undervoltage can cause problems...

Maybe you can drop by if you want to survey factory wiring on mine, looks like yours is very simiilar if not identical!

Our buddy Greg328 just put his blocks on ebay...

Any chance there is a restriction on the output side of the pump causing both the new and old pump to be over loaded?

Paul that is a good point. I remember someone on the "other site" having a partially plugged fuel filter that seemed to fix his "hot fuse" problem. But I am certain Jeremy has replaced his filter...but perhaps there is a restriction elsewhere...maybe with the fuel pickup in the tank?

How funny, you guys were thinking the same thing we were. We changed out the fuel filter tonight. The fuel pump fuse did not pop, but it was hot and melting the plastic part of the fuse a little bit. We are getting closer, but not quite there. The fuel pickup in the tank is another good one. We'll check that tomorrow.. What is the procedure for that?

JL

Jeremy,

The fuel pump gets its supply of fuel from a fitting on the alu cross-over tube. You'll see a large screwed in nipple on the cross-over, where the fuel pump input hose is connected. When you remove the nipple (you may have the pull the cross-over tube out of the car to do this)...there's a fine mesh screen there, that acts as a pre-filter to the pump.

This is shown pretty clearly in the Parts Manual.

Regards,
David

Hi David,

I think my setup is a little different than what you are describing. The input hose on the fuel pump goes to a nipple on the fuel tank. Either way, I can see in the parts list that this nipple can be removed. We will check this out tonight..

Sorry about the mis-description...
A little to much BB on the brain...HA!

Per your diagram, Item 48 is where I'd look for obstructions. Also, might want to verify the soundness of the fuel pump connections, particularly the ground.

Regards,
David

Ha ha!! I know how that goes David.

I have been over the FP connections veritying that they are tight and making a good connection. And I have added a second ground wire cleaning up the contact surface there as well. I think we should be good in that department.

It is possible that after sitting for 2-1/2 months that every bit of junk in the tank settled down to the bottom and waited for me to start it up.