I know this has been posted several different times on here and I still have not fingered out the solution. I fill up FULL ( fuel at the tip top) and am patient about it. I took a 1400 mile trip, and noticed when the gauge would get down off the full mark, it would go ballistic. That would be roughly 120 miles or so. It would resolve on its accord at @ 180 miles. Would it be a vaccuum lock in the tank from a bad fuel cap? It is a PIA but not a problem.

BTW I decided to drive the speed limit which was 65 ( I drove 67) and got 19-20 mpg! Pix show a bit faster since I was on Interstate.

I have the same problem. It only started acting up when it got below half tank. Now it acts up all the time. It is the fuel sending unit in the fuel tank. I priced it out at $480. I have not replaced mine yet but plan to this month. I have heard a quite a few issues with fuel guages on diesels. ( fuel residue)

If you need to buy a fuel sending unit asembley you can get it cheaper at www.gmpartsdirect.com , I believe they are about $240 plus $45 for shipping, Total about $285

The fuel level sending unit is just a simple float assembley, that rubs on a resistor, looking at it I don't know why there are so many problem's with them. Looks like the same style that's been used for ever.

DD

How hard is it to replace?

Ben

I have not done this on the Dmax but the hardest part is generally dropping the fuel tank. The assembly is mounted in the top of the tank where the fuel hoses and electrical connectors are. There is a picture on John Kennedys web site of the tank removed - did not see any how to's on this site.....

http://www.kennedydiesel.com/docs/liftpump_installation_options.htm

Dealer said it would be @ $350 to repair. Seems a bit steep.

Ben

To change the unit it self is easy just getting access to it is a little tough

Some guy's are taking the bed off the truck instead of dropping the tank.

Or pulling the bolts out of the drivers side of the bed and loosening the bolts on the pass side and then just tilting the bed up to get acess to the top of the tank.

As stated above it is much easier to remove all the bolts (4) on the driver side and loosen the other side. Then you can tip the box and put a block of wood or something to support it while you get in there and swap them out. You will need fuel line disconnect tools to remove the lines. Also getting the locking ring back on can be kinda tricky but you should be fine as long as you tap it around evenly.
:grd:

Dealer said it would be @ $350 to repair. Seems a bit steep.

Ben

If you need to buy a fuel sending unit asembley you can get it cheaper at www.gmpartsdirect.com (http://www.gmpartsdirect.com/) , I believe they are about $240 plus $45 for shipping, Total about $285


you've probably already done the math here but if the dealer will do this for $350 (is that including the part) and it's gonna cost you $285 + fuel line tool (<$15) so say $300. I don't know how you feel but spending half your sat. to save $50......Bill

Hoffz - how much time did it take you raisin the bed up - did that give you plenty of room

$350 was total. Parts and labor. It might not be too bad now that you have educated me. I have noticed yesterday and today and the guage needle bounces around a bit.

Ben

FYI the resistor cards are going bad these days because of all the crazy additives they put in gas. I assumed diesel had less of that sh!t, but maybe not.

They corrode like crazy. Keep your tank full when you don't drive for a while. The fumes are worse than the gas. Again, I'd assume the same would be true with diesel.

Dealer misquoted. The part is $399. Then there is the labor. WOW! What a load of crap. Any pics on this replacement?

Ben

What exactly is the part I need?

Ben

Mine went nuts but it was the inside dash instrument pack.
Under warranty.

I dont have any warranty left. How do I tell?

Ben

The unit in the tank is generally a variable resistance in the groung leg of the circuit. The resistance is changed by the position of the float in the tank which in turn drives the position of the needle on the gauge. When I get home I can check my manual and see if there is a test proceedure to prove whether it is the sending unit or the dash gauge. My experience - not on Dmax - is that with those symtoms it has been the sending unit but as PC said on his it was the gauge cluster.......I'll see what the manual says and/or you can post in ask the techs ......at those prices you want to be sure. Did the dealer diagnose befor the quote or was he just speaking prices......Bill

No diagnosis performed.

Ben