Fuel sending unit

FirstMach1 · Mar 30, 2015

Hey guys,

I' ve got a bad fuel reading on my '71. Just bought her recently and getting to know this beast better.

Anyway, I need thoughts on troubleshooting a fuel gauge vs. a sending unit. How is best to determine which is the issue?

Also, assuming it is the sending unit, does the tank need to be removed or can that be done underneath. I haven't gotten up under there to look yet. Just finished putting in a fuel pump so I'm on to the next thing with this.

Thanks,

Eric

midlife · Mar 30, 2015

Unplug the sending unit wires at the plug and briefly ground the yellow wire while the key is in ACC. The gauge should peg. If it doesn't move, the problem is in the wiring or the gauge. If it does peg out, the problem is the sending unit.

rocket366 · Mar 30, 2015

You can change the sending unit without removing the tank.

I wrote a DIY

http://www.7173mustangs.com/thread-fuel-sending-unit-replacement-diy

Paul

FirstMach1 · Mar 30, 2015

Unplug the sending unit wires at the plug and briefly ground the yellow wire while the key is in ACC. The gauge should peg. If it doesn't move, the problem is in the wiring or the gauge. If it does peg out, the problem is the sending unit.

Great tip thanks so much!

You can change the sending unit without removing the tank.

I wrote a DIY

http://www.7173mustangs.com/thread-fuel-sending-unit-replacement-diy

Paul

Glad to hear that. I'll check out your DIY. Just what I needed. Sometime the search doesn't get to what you're after.

Thanks so much!

rutkak · Apr 5, 2015

Replacing a sending unit is pretty straight forward, but expect that it won't read accurately when installed. I've put in three of them on different vintage Fords and it's always the same.

Naturally start with grounding the wire going to the sending unit to verify FULL. If not, you have a wiring issue.

Before you install the gauge check it with an Ohmmeter to verify ~73 on E and ~10 on F. You may have the bend the tabs to get it right. Now fill up with tank with 1/4 tank and check the reading. If it's reading low bend the L shaped float arm down so it reads higher.

I'd try it again at 1/2 as and maybe F as well. At some point you'll get close enough to where you are happy with it.

Oh yeah, if you replace your tank I recommend one with a drain plug...it makes life sooooo much easier.

KR