Hey Guys, Correct me if I'm wrong. Didn't all 69 Mach I's have 20 gallon fuel tanks regardless of engine size? Reason I ask is that I've always had a fuel level indication problem and it's either the wrong sender or wrong tank. Most catalogs list senders as for model year, but not tank size. Trying to straighten up one of the last mysterious malfunctions on a restoration.

 

Yep, '69s had 20 gallon tank, '70s had 22 gallon tanks no matter what the engine size.

 

1965-68 were 16 gallon. All 1969 were 20 gallon.

 

make a few adjustments first by bending the float a bit .. worth a shot

 

I've always heard that the 67/68 was interchangable with the 69. You could upgrade your 67/68 to the 69 to get more capacity. Maybe you got the wrong model year tank.

 

It's difinitely a 20 gallon tank, takes that much to fill it when empty and it's been empty a few times. I figure wrong sender as wiring checks out and guage checks out. Here is what it does and makes no sense to me:

Full Tank - fuel guage reads full
Half Tank - fuel guage reads empty

Now if it was the opposite:

full tank - fuel guage half
half tank - fuel guage empty

That would make more sense to me. I just can't get my head around it, old age kicking in, I guess.

What do you guys think?

 

i`d say it`s just worn out then .. if i amember rite the gauge consists of a resistance coil wound to differing rates as the float slides across it .. most cars stay at less than half a tank all their working lives so wear at half and lower is more prevelant .. i sound like i know what i`m talking about .. that rarely ever happens

 

Good theory and a sound one at that. Here's the kicker, sender is no more than 10 years old and has read that way from beginning. Old one didn't work anymore. But, how do I know it's the right sender? You ask for a new sender at the Ford dealer or parts vendor, they bring you out one in a box with only a number and Ford logo. Nothing on the box says what it fits, gallon wise, etc. I wouldn't expect too many mistakes by a Ford dealer, but third party vendor I would. The old one has no part number I can see, neither does the new one. Only thing I see is FoMoCo. Some say, maybe it's upside down. If I remember right, they are keyed to prevent that. Of course, my memory is pretty faded these days. Another thing that makes me think it's in there right is from what I can remember the feed tube is toward ground and the wire connection is at top. Anyone confirm that? I remember testing sender through it's travel range before puttng it in and it worked smoothly full to empty, so what's wrong? The only thing that comes to mind is this theory.

I imagine all Mustang tanks regardless of size have the about the same distance from sender mount to top of tank and the difference is mounting point down or depth, so I'm thinking possibly wrong sender. Could be a 16 gallon and not reaching bottom but half way and fuel guage is reading correctly, just the sender is not right touching bottom, thus reading empty as it should indicate if it bottoms out on travel, just not on bottom of tank.

Does this sound about right? It's only a theory and not hard fact. You could bend it, but it would only be a guess. Besides, it's OEM Ford and could be sold, so I don't want to damage it. If I had a for sure 20 gallon one that works for sure to test, that would be the true test, wouldn't it?

I could also order a repro and hope I get the right one too.

Any wisdom out there on this? Not trying to make a never ending thread, just need some extra minds or thoughts on this. Repro is only $32 anyway, if you get the right one from the vendor.