I have read posts about checking resistance and ground but Iam not sure where to test. My gauge does not work for either tank. I have an 83 460 and that has a different selector switch than what is shown in the haynes manual. I unwrapped the wires to the front tank and have a Red, Blue, and Black. Does anyone know what volts or ohms should be coming through these wires. Or up at the tank selector switch I have a 4 wire switch.

 

Inwywind,
Front tank: Red (R)= pump power, Black (BK) = ground, Dark Blue with Yellow stripe (DB/Y) = sending unit. Rear tank: Brown with White stripe (BR/W) = pump power, Black (BK) =ground, Yellow with Light Blue Hash (Y/LB H) =Sending unit.
Quick test: 1. Disconnect DB/Y wire at sending unit, with key "ON" fuel gauge needle should show no deflection. 2. Ground DB/Y wire, with key "ON" gauge needle should deflect to maximum. If it works like this, sending unit is "bad" (or sending unit ground is "bad"). If not, problem is with gauge, tank selector valve/switch or wiring. Repeat test on rear tank Y/LB H sending unit wire. If oil pressure and temperature gauges are also not working properly, suspect instrument panel voltage regulator and/or its ground circuit. A 10 Ohm 10 Watt resistor (available at Radio Shack) from sending unit wire to ground (in place of the sending unit) should make the gauge read at "Full" mark.

 

Thanks for the detailed information Piffery1. I did find the right schematic when I looked at the diesel diagram, another 460 at the junkyard has the same setup as mine, different than the 351 so i think it is an error in the books (haynes and all data). Well any way the gauge is working fine after I unplugged the connector from the selector valve to test from there and plugged it back in. The clip holding them together had been broken off and i think they may have seperated just enough to not make good contact. I hope thats it and all stays working!

 

Ok, I finally got around to putting the J C Whitney universal senders in, the rear required some fabircating, the front tank went well with minimal rework. I unfortunately did not get any pics, but would be happy to answer questions.
The senders are kind of backwards for an easy mount, so I had to get some longer screws to mount them with, so I could reverse the sender, keeping the wire to the bottom. The front sender only needed a hole drilled in the factory sender mount, the rear required welding the sender mounting strap that came with the sender onto the factory pad at an angle. I used the original pivot point as a reference, and then made the sender work to how the original pivoted. I haven't run any full tanks through yet, but at least I will have some idea what is going on in there. T
The floats both were leaking, the reqar had a little fuel inside it, the front float had a lot of fuel in it, so if your guage is such that it steadily reads, but runs out too soon, then I would blame the float. However, i did a resistance test on mine, and there were open spots that would not read.
I don't know how well this modification would work on a 84 and older, as the 85-6 tanks have the bigger opening in the tank, allowing plenty of room for the sender. The rear would not work if it had to have the extra mounting on it as I had to do, because it was a bit of a snug fit for mine.
Both sumps disintegrated while I was working on it, so I had to fabricate new one. Originally, I went to buy replacements, but Ford no longer has it available, and the aftermarket doesn't seem to have it either. I used one of the plasic inline gas filters that you would mount in front of a carb, cut it in half, and notched the bottom for fuel to get in with it all the way to the bottom of the tank. There is no screen, but my rear had no screen in it anymore either. I just measured the depth the original sump set, and made the new one sit the same. So far it all seems to work.

 

So you just mounted the JC Whitney resistor on the factory sender??

DT

 

I removed the factory sender and mounted the whitney sender on the mounting flange of the factory sender. For whatever the reason, the 85-6 senders are $120 each, but I have been able to find replacement senders for the 84 an older for around $40-50, so to do it to one of them, I just don't quite think I would recommend as well, as well as the smaller hole causing problems.
The front tank I just drilled one hole, and it bolted up, the rear I had to work out the location for the mount to go, because it wasn't as easy as just bolting. I might have been able to bend the float arm to match the factory, i just didn't... it seemed to work best having to buil an offset bracket. I did use one of the original holes to help locate the sender, and them welded the mounting bracket based off that. It was about a week ago that I did the rear, so I'm trying to remember why I did things... it just didn't pivot right to have it mount straight onto the pad, making it show empty at the wrong time. I didn't quite figure out a good way to bend the float arm, so I just changed the mounting instead.
The front sender could very well work on the smaller hole size, as it was a direct bolt. If someone would want to attempt to do the rear, I wouldn't say no, but be prepared for the troubles I mentioned.

 

I just have a single tank. 19gal inboard of the frame.

So you were able to use the factory pickup and everything?? I'm not scared of a little fabrication. Just took the old sender on the pickup off and modified it to accept the new one??

DT

 

Yes, I just used the mounting flange that the original sender was on, spliced into the guage wire, used a bare crimp connector and heat shrinked it. You could use a heat shrink crimp connector, I just chose to do it this way is all. The original setup on the Whitney sender was to bolt it through a slide with 2 bolts. Since the float arm rotation was wrong for simple bolt up, I had to get two longer machine screws, put a nut against the replacement sender, and another to hold a little distance, and then two more on the other side of the factory mounting plate to hold it tight. The float length from the factory was approximately 5", so I cut the Whitney float to match that. On the factory mount, there is a hole for a locating pin on the plastic sender cover, I drilled it out to accept the machine screw, and then used one of the square holes for the factory sender to put the other bolt through. I was able to work it out such that the replacement sender was able to be straight up and down with the sump, I just bent the float arm a little to keep it off the bottom of the tank. I had to fabricate a new sump, as the original failed, and disintegrated. I fully understand now how the tank will read 1/4 and run out of fuel, the sump on our trucks is cheap garbage that doesn't last. I took an plastic filter and cut it down to the width the original sump was on the floor, and then notched it to let fuel flow in. There is no screen, but I got 2 sumps for the price of $3, along with hose and clamps. When you get yours out, I think you will see it isn't too hard to duplicate what I did. Just to warn you, be sure the sender wire comes out the BOTTOM of the sender... I didn't do that on the rear tank, and had to rework it a bit to make it work, as that made the guage read backwards...I tested it by hooking up and checking the guage readings before I put it all back together, so it wasn't a terrible big deal, that was when I devised the "pedastal" style mount with the machine screws. I'll try to draw up a schematic so you can visually see what I mean, so there is no confusion.

 

I see what you are saying. You put a nut as a spacer between the resistor and the float right?

I'll probally know what your talking about once i pull the sender.
If i get under the truck i can see the sender. Is there enough room to pull it without taking the tank down??

A diagram would be nice, Thanks

DT

I guess i'll have to order one.

 

Yes, I got the sender out, but it was a devil, due to having been rusted in place in almost 20 years... but I didn't much like the idea of fighting with the skid plate to get it down, and as it turns out I had quite a bit of fuel in it, now that I have a working guage I can see that... but there is room to get it out. I was able to get the lock ring off, but not without a bit of frustration and choice words... I pryed gently on the tabs that hold the lockring down to loosen them a shade, and break the rust I also had to pry the ring sideways a bit to loosen it. It got a little deformed, but not so much that I couldn't fix it. If you are careful, you should be able to do the same. If you want to, I know bronco graveyard has some replacement lock rings, at least I think that was where I went, one of the FTE sponsors has them for a fairly good price. Same on the pre 84 senders, for those who have them.

 

I guess i'll spray it down with some WD40 or PB blaster a couple days before i do it.

This is next on the list after the Rear main next week.

I drive it very little since school let out.

I've made driven 60 miles and my guage says i have 1/2 tank which isn't right. And i'm doing a tune up to get better milage.

Thanks

DT

 

i got a problem with my gas gauge. when it goes down below 3/8ths, it reads great, but fulle than that, i goes straigth for the full line

 

sounds like the variable resistor has failed, which is generally the reason for changing the sender.

Here is the schematics for how I mounted the universal sender on the front tank pickup/sump. schematics