Thoughts on our crappy sending units.

[Diesel JD]

Hey all...happy Easter! Well, what I have been rolling over in my head for the last week or two is this. I wonder if the problem with most of our bad sending units is that the bronze float that Ford put in there was not designed for diesel, let alone biodiesel, veggie oil, and fuel cocktails, but worked pretty alright with gasoline. I had a fairly new sender from fordparts.com and within less than two years it already wasn' working right. I had gotten a nice working unit from gonecrayzi, and was all set to put that in, when I was examining the sending unit that came out, I found that when you moved the wiper arm it still followed the correct ohm range, but when I filled the tank the reading did not change. So my question is two fold...do you guys think the innacuracy could be mostly a float problem as opposed to a true electrical problem...and if yes, could we fix it by finding a plastic, diesel resistant, modern float instead of having to try to source these obsolete units or do something really difficult like the Fellro86 universal sender adaptation? Just tossing it out there for your thoughts. Thanks
JD

 

[hayisforhorses]

Just went through this issue. found 4 units in junk trucks took them out all had brass floats that were ok but the electical rehostat was bad on them.Bought a new referbished unit for 150.00 and going to install this week. I think the issue is the electrical components short out in the tank when summersed in diesel. just my thoughts
for what they are worth.

 

[smolkin]

I used to wonder about why mine don't work, then I dropped the front tank for WVO reasons and saw that the the rheostat strip contacts had a groove worn right through them from 26 years of float arm movement. Question answered. Well, mine, at least.

I'm sure that the occasional water-in-fuel situations we diesels have also don't help, esp. if these senders were designed for gassers, which prob don't have that issue as much.

 

[jim_22]

Well, it could be either an electrical or float issue. For JD, he has evidence that in his case it is a float issue. He could prove (or disprove) that by checking resistance while submerged in diesel. BUT since so many people have reported electrical issues (presumably they diagnosed them correctly...) it seems not a good bet to spend money on a new float for a weak system. I have one tank that is intermittent in its readings now, due to an electrical issue. I wish the fill tube was not baffled. I love the stick method.

 

[Dirtleg]

My thoughts would be that if you always filled up both tanks and then used both of them before filling up again you will see the longest life from the sending units.

Here's my thoery on why. When a tank is full the fuel is not surging as much while you are driving. Same with an empty tank. By filling and then using both tanks you are minimizing the amount of time that the wipers are subjected to the violent surging of say a half empty tank. This will reduce the number of higher velocity swipes of the blade over the rheostat coil over the life time of the truck.

No real answers here just an idea and opinion. Just got me thinking is all.

 

[Jake S.]

I just fixed my front tank by using a gasser sending unit. First I cut the pump off, then used a piece of hose to replace the pump to get to the bottom of the tank. The only other thing was that I had to use the wire connector from the gas truck because they have a four wire connector. The reason I did this was that there are a lot of gassers out there for parts, and they are cheap or free if I find a truck to part out/scrap.

 

[Diesel JD]

Okay, I wasn't saying I knew anything. Obviously the electronics suck, I just wondered if anyone had taken the time to check why the senders fail, I did and in this case t was the float. I'm not even sure I know what a rheostat is...not very good at electronic stuff, I just figured I'd throw it out there, and with this community of talented individuals, maybe somebody will even come up with a solution. Moose Pumps and Moose Misters, Typ4's intake hats, freebird's reinforcement plates...if yo offer a service and I'm leaving you out, don't feel bad....anyway, maybe somebody figures out a drop in fix for this and they can earn bragging rights, help the brotherhood and maybe earn a few bucks too savvy?

 

[jwalterus]

I'm not even sure I know what a rheostat is...?

quick explanation: it's the same as the dimmer switch in your living room

 

[franklin2]

There are some threads(I thought they were on this board) that show links to where a guy retro fitted a JCWhitney unit to repair the original rheostat. I haven't had to take mine out yet, but if I remember a picture someone had, they built the rheostat(which is just a variable resistance) by "painting" carbon onto a piece of plastic or fiberglass. You can imagine something rubbing constantly on something that is painted on, will eventually rub through. Throttle position sensors are made the same way.

Ok, here's the "comments" section of my post. Why do they fail? Because they are cheap junk, just like many parts of the these trucks. I consider the 80's thru the mid 90's as the low point of American quality in car making. I work on and restore many older cars, and many have their original heater cores and original rebuilt radiators, as well as their original sending units. Their frames are not flaked with rust and falling apart, they do not have as many cheap plastic pieces on them in critical areas, like a clutch pedal retainer/bushing. Their metal is thick enough where a firewall re-enforcement plate is not needed. They certainly had their problems, as well as the newer vehicles, but these era vehicles have more than most. I just wish the pickups the 6.9 and 7.3 where installed in, had the quality these engines had in them.

 

[jim x 3]

With my '88, the fuel sender problem was electrical. The brass float was just fine.

See http://www.oilburners.net/forums/showthread.php?t=36318 post #21 for a photo.

Regards,

 

[CDX825]

When I got my truck both tanks would not read.

After dropping both I found the brass floats had cracked and filled with fuel. I drained and re soldered them but ended up having the front one crack again. Drained it re soldered it and it been good since.

Before I even tempted to mess with them though I was checking the auto parts stores for replacements. I seem to recall the non fuel injected gas engines of that era having mechanical pumps on the side of the engines. I figured the sender from one of them would work but I was not able to locate any for non fuel injected vehicles.

Seems all the ones I could find were in tank pump units and the diesel ones don't exist.

 

[plywood]

Just went through this issue. found 4 units in junk trucks took them out all had brass floats that were ok but the electical rehostat was bad on them.Bought a new referbished unit for 150.00 and going to install this week. I think the issue is the electrical components short out in the tank when summersed in diesel. just my thoughts
for what they are worth.

Where was that from if you don't mind me asking?

 

[THECACKLER]

First my front tank float went bad, I fixed it ... then six or seven months later the sender crapped. I couldn't find one for a reasonable price, so I copped one off of an '89 at Pick-a-Part for ~$20. I un-clipped the sending unit electrics and transplanted it onto my pick-up tube, soldered the wire to the terminal at the tank mount plate and stuffed it back in the tank. The '89 float arm was very different from my '90, but I left it on as opposed to trying to coax 20 year old plastic any more than necessary. It works great. I need a new tank to sender o-ring seal since I folded mine when I reinstalled it. Something like $2 at Ford.

 

[LCAM-01XA]

My solution to the brass float is a small plastic medicine bottle, seal the ca[ threads with Permatex #2 and clip the thing through the neck right in place of the factory float. Seems to work good for me...

 

[plywood]

Blow up a Trojan and tie off the end, it ought to last at least a month.

Reduce, Reuse, Recycle.