Electrical Gremlin

[neelyrc]

On the drive home from the Indycar event today I downshifted approaching a four way stop where I was turning left. As I turned the engine sputtered and came to a stop. After a few attempts to restart, it occurred to me that I had not heard the fuel pump buzz when I turned the ignition key to restart. It turned out fuse four for the fuel pump had blown. I replaced the fuse and the car started immediately and I drive home without any further problem.  I’m wondering if a fuel pump problem may be developing.  This is the first blown fuse incident I have experienced in many years if ever.

I’ll keep my eyes on it to see if anything further develops. Any comments on possible cause would be appreciated.

[lpeterssen]

Dear Raplh

Keep an eye on your pump, it may be demanding more energy than spec because varnish has formed inside the impeller.

From the wiring harness point of view, check just the terminals at the fuel pump and see if the insulation is jacket is ok and that screws are tight to avoid a false contact that may produce overheating on terminals and as a consequence demand more energy, above fuse capacity.

Also clean to perfection the brass contacts that hold the fuse no.4 at the main fuse box.

Fuel pumps tend to fail after driving a while when they are hot.  Keep your fuel tank full to help it being the coldest possible.

Consider removing your fuel pump to open it, and replace the wearable parts as the carbon brushes.  Deeply clean the turbine (impeller), and rea-seal the pump with a new rubber kit.  Those kits sell for about 100$.

Best regards
Eng.Leonardo Peterssen
Www.wiredoktor.com

[roymil]

Similar thing happened to me.  Just as lpeterssen says, pump was wanting more current due to additional friction and it popped the fuse.  Deep cleaning and polishing the impeller reduced current draw.   Also worth noting that any noise the pump makes pretty much scales with friction and current draw which makes sense.  Originally I could easily hear the pump from inside the car, now after rebuilding it's essentially silent and also runs cooler to the touch.

[mdsalemi]

Ralph, another thing to check (perhaps with battery disconnected!) is the integrity of the wiring to the fuel pump at the rear of the car. In addition to the things inside the pump as Leonardo has mentioned, it's possible that the wiring itself may be compromised. That fuel pump location (especially so if you don't have a cage around it as many do not) is second only to the horns for the worst place for an electromechanical device. It so happened that my wiring was shot there once.

[neelyrc]

Leonardo, Mark, Michael,
Thank you very much for your comments and suggestions.  I’ll follow through on the points you raise and try to put this little item to bed.