Slow moving fuel gauge

Automotive
#1

Drive back from Vegas is in-progress, and something odd happened with my fuel gauge. After one of the fill ups completed (and not the first one since the return drive started), the guage was where it originally was prior to filling, and took a few minutes of running to actually read a full tank. Computer calculations for range etc all kept adjusting as the gauge went up.
Next fill did the same thing, but the last one did not.

Thoughts I have having looked at systems but never really debugged them:

  • foreign object messing with float (really hope not, as I’d wonder how it got there)
  • coils on float sensor worn / loose connection /high voltage drop upstream.
  • something I may not even think about.

Anyone debug such a problem? Do we have the right tools to do this? I’ve never taken a fuel tank apart before.

Cheers,
-Jim

1 Like
#3

I’ll second the suggestion to start with narrowing the fault down to a sensing problem versus an indicator problem. We do have the tools to diagnose it in one way or another. Someone may also recognize it as a common problem and have key experience to share which could bypass the initial steps you’d otherwise take to diagnose it.

If you’re lucky, gaining access to and tapping into the wire that carries the fuel level signal from the fuel tank may be fairly easy. Your biggest enemy is that it’s an intermittent problem. If this were happening to me I’d tap in to the fuel level signal under my rear seat with a temporary extension wire and then wait for the problem to reoccur so I can hook up a meter and observe the signal. Been there, done that. Actually I’m still waiting for the fault to reoccur. Yours sounds much more repeatable though and therefore much easier to diagnose. This is actually a good thing.