Fuel Gauge problem

[LarryM]

Either I'm suddenly getting 50 MPG or the fuel gauge is broke. It is stuck past the full mark and stays there except when ignition is off.

Anybody have a guess how these things work? Does "full" mean an open or a short? I'm hoping it's the sending unit, but with my luck.....

[FirstDiesel]

If it's like any of the other gauges I've fixed it means a short. Unhook the wire from the sender and it should go to empty. Ground the wire and it should go to full. If it doesn't change you definetly have a shorted wire somewhere.

[LarryM]

FirstDiesel, Thanks for the tip. I've tried to disconnect the sending unit, but I can't seem to wiggle my arm far enough over the tank to get at the connector. Any ideas there?

[FirstDiesel]

Sorry, haven't been up in that area yet. Thankfully smile.gif

I guess you could always bite the bullet and trace the wire down to convient place and cut it. Worst case is to have to splice it back together if it doesn't give you the answer you need.

[Idle_Chatter]

LarryM, the sender wire is the light purple one in the large black cable armor running on top of the driver's side frame rail. I'd follow that forward and look for a problem up near the driver's floorboard or up behind the park brake pedal where the whole mess comes through the firewall. Hope this helps.

[LarryM]

Thanks for the info. I still can't get my hand up there far enough to do any good. I'm handicapped by having a busted finger and most of my shop equipment and tools in storage 1500 miles away!

I had a chat with my friendly service advisor. He is pretty sure it's a sending unit problem. His estimate for repair at the dealer is approximately $650! That's over $350 just for the sender.

I can get a bigger tank with a sender and put it in myself for that kind of money. Guess I'll just have to fill up by the odometer and fix it myself after my finger is healed.

[SoMnDMAX]

Larry- are you out of warranty? If not, the sending unit should be covered under the 3/36 bumper to bumper warranty..

I remember a while back someone had fuel gauge problems, and it ended up being the Bosch EDU on the passenger side valve cover... If you are out of warranty, hopefully this is not it... I can only assume the EDU is not a cheap piece..

[LarryM]

SoMnDMAX:

Yup, way out of warranty. Got 52,000 on it now. About 3500 miles every three weeks, nearly all towing.

Can you point me in the right direction to learn more about the Bosch related gauge problem. I don't remember reading about that, but then I'm out driving the truck more than I'm home on the computer. I don't have much luck with searches. I can't seem to figure out the right key words to search on!

If it is an EDU problem that might account for the 350+ bux parts he quoted.

[SoMnDMAX]

No warranty sucks... :(

That post I was refering to was about a year ago. I'll see what I can dig up later tomorrow morning, both in the service manuals and in a search.

Right now I need sleep...

$350 could be one of three things- Gauge cluster, sending unit, or the Bosch EDU. I would assume the Bosch unit would be much more expensive than that. If it is the Bosch EDU, it'd be covered under the 5/100 engine warranty.

[LarryM]

SoMnDMAX:

Thanks. As I think back on my conversation with the service advisor, his actual words were "about $360 for parts". He did not say what those parts were. He did say it would not be the guage cluster based on their experience with the HD's.

I'm leaving tomorrow morning with a loaded trailer for our place in WA. I'll be off line and unable to persue this for the next 3500 miles and two weeks. Sooner or later, I will have to get this fixed, so any info will be helpful.

[LarryM]

Just returned from the latest run with the trailer. Fuel gauge was still stuck on the full peg when I left. Each time I run the tank down, the gauge would drop a bit more. Now after 3500 miles and about 15 fillups, the thing seems to be working correctly.

I don't think I want to trust that gauge at all anymore. Not sure if an expensive repair or fueling every 250 miles is worse......