Fuel sending unit and fuel gauge issue.....

[bgreene]

Originally Posted by Blue_Runner

I just replaced mine. There was a calculation on the package. Also had the benefit of holding the new next to the old unit to compare. Old unit still worked perfectly but the design of top round piece (where the screws go) was terrible and allowed fuel to leak around the screw threads.

Mine was a Moeller.

Blue under - I found the same top round piece design so what was different with the new unit you installed ?
Since the tank is plastic, I figured drilling additional holes for added screws wouldn't be able to tighten enough without stripping the plastic top of tank.
Interested in how you corrected this.

[Blue_Runner]

I tried to find a pic of one with the same poor design but I couldn't. Here is how it should be - round plate should be flat all the way around where the rim of the screw heads meet the plate. The old one has notches on the outter edge around the screws making it impossible to seal around screws.

On the new unit I bought the screws have some sort of teflon coating around the rim allowing it to seal around the bolts. I still can't get s few of them real tight but the instructions say they don't have to be very tight. Only tight enough to compress the seal around the screws. I have 1 that is stripped out pretty good, and 1 or 2 more moderately stripped out. Seems ok now but the real test will be upon next fill up.

Stock Interweb photo:

[smokeonthewater]

Two options... One is larger screws and the other is to rotate the sending unit slightly and make new holes.

Don't just leave it with stripped screws as that is likely to start leaking at any time without warning.

[13Echo70271]

Hi Blue, does your tank have brass or metal threaded inserts for the sending unit screws? My plastic Moeller tank has brass inserts for the screws. I had the same issue last year. Once I cleaned out the corrosion using a small pick and WD40, I found the inserts and carefully ran a bottoming (nearly flat bottom) tap thru to chase the threads and clean them. If you need to, you could tap for slightly larger screws. With the new rubber gasket and clean surfaces mine worked out well, no more leaks , no more smell. Good luck, TJ

[bgreene]

Screw holes on tank have metal threads in current position, so rotating would be worse - screws would go into the plastic tank, not the metal threads.

Now with special fuel resistant apoxy applied too, it may be fixed. Will see when I get home.

Still don't like it - should be absolutely secure. It screws down tight - the 5 screws all tight, not stripped, but somehow when pressured at full with fuel, it was weaping out around the rubber gasket.

[smokeonthewater]

Didn't realize it was plastic... Was thinking aluminum

[macojoe]

How about lock tight on the screws, and using a cork gasket??

[Blue_Runner]

You sure it is weeping around the gasket? That is what I thought but it was actually coming from the screw threads

[bgreene]

Originally Posted by Blue_Runner

You sure it is weeping around the gasket? That is what I thought but it was actually coming from the screw threads

Seems fixed now - used the fuel resistant goop and re tightened.
Filled to over flow and it's dry at the sending unit.
Ran a new ground wire, so gauge working too.......got to keep it all good since it's a rare and extremely valuable V21 series :)

[smokeonthewater]

Yeah but how fast will it go?!?!