Fuel Pump Fuse/Relay Problem - Dead Engine see Pics

rickster2 · 05-25-2008, 01:47 AM

Was low on fuel and may have run out but did not have any sputtering of motor, just driving down the road and engine dies. Could not restart the engine.

Checked fuses and I see the fuel pump fuse is toast (photos show new fuse but you can see how the solder melted to the fuse holder). Blown violently and the lead wire is cooked with just 2 strands of wire still making the connection.

Installed spare fuse roadside and still no start. Pulled harness on the Mass Air sensor and fuel pumps would not come on. Finally, pulled a red relay from front and put it in rear to replace fuel pump relay (didn't carry a spare) and car started and ran fine.

What caused my fuel pump fuse wire to COOK?

I posted this yesterday but without the photos.

Fritz Peyerl · 05-25-2008, 04:05 AM

if you had to many strands of wire broken, the remaining strands could not handle the fuel pump current and started to heat up and melted the solder.
A good cleaning and replacing the wire properly will work, but the fuse holder will alway give you problems from now on. the corrosion will set in any time there is any humidity.

Jim Sims · 05-25-2008, 08:38 AM

If you ran out of fuel there is a good chance the fuel pump lost its cooling (gasoline) and began to heat up. If the pump motor windings were damaged they can draw excessive current (this can also happen when a pump is nearing the end of it's life).
The excessive current was more than the fuse contacts (they may have been corroded) and likely also the relay contacts could carry. If you open the relay you may find it burned and melted. Check the rubber molded base the relay plugs into for overheating. You can salvage the fuse block by cleaning up the contact surfaces with a fine wire brush/ fine sandpaper. then coat them and the new fuse contact surfaces (including the the surfaces that clamp the wire) with dielectric silicone grease (NAPA "Sil-Glyde" is a readily available type). The dielectric grease can help prevent future corrosion and over heating. If the locking compound was burned off the clamping screws then re-coat the screw threads with light duty Loctite (green?) thread locking compound. If there is slack in the wires, cut off the burned ends, strip back the insulation, tin the end of the wire with solder and re-clamp. If there isn't sufficient wire then you'll have to replace it or splice in a new section. Always use stranded copper wire of equal or greater cross-section. I recommend soldering any splices and using heat shrink tubing for insulation. If this problem re-occurs then you'll want to check fuel pump current draw as the pump may be failing. Good luck.

GothingNC · 05-25-2008, 08:45 AM

You were lucky.

I almost lost the Porsche

rickster2 · 05-26-2008, 02:10 AM

Thanks for the reply on my fuse/relay problem. Your pictures are scary!

What exactly happened to your car to cause such a melt down?

I wonder why only the bottom of my fuse was affected?

My relay in the engine compartment was blown as well as the fuse.

I am wondering how to determine if my fuel pump is failing as the car seems to run fine now.

Thanks

Rick