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|Ram Fuel Sender
From CJ Johansson
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Here's a fix I devised for the poorly designed fuel sender in the Dodge Ram pickups. This fix took about an hour and maybe 10 cents worth of parts. The big catch is that it requires some machining work - a good lathe (I used a Hardinge), and the skill to use it. If you had someone do this, it'd probably cost $50/hour, and without ready-made plans, more for figuring out exactly what to do.
Just as I was starting to write up this info, another list member, Huey L. Conway, Jr. posted a similar fix, only his doesn't require fancy machining! There's a bit more about this fix later on.
NOTE: Click any photo for the full size image.
|A view of the whole sender assembly. The nuts, washers and spring are modifications which fix the worn out plastic parts of the original assembly.|
|This is a close-up of the sender assembly. The plastic flange which originally holds the whole thing together is visible below the metal arm of the pivot, extending to the left. This flange rides on a flange of the main body and wears such that the contacts get loose. The plastic pivot also wears on pin such that it too gets loose. I suspect that the tolerances on the pivot to pin are fairly loose to begin with.|
The original factory pin does not extend beyond the top of
the plastic pivot. This pin is pressed in from the rear of the main body. Removing
it is as simple as placing the unit on a block of wood with a hole under the
pin, then tapping the pin with a small punch.
The new pin was made from stainless steel on a lathe, to essentially match the original, but longer so that the extension could be threaded. The hole in the plastic pivot was reamed out to a slightly larger diameter to remove wear and make it cylindrical. The pin was then made a few thousandths of an inch smaller than this hole to achieve a close, but free-moving fit.
Originally, the intent was to simply put a nut and washer on the end of the pin. But looking at the pivot and noticing the groove already in it, gave me the idea of adding a spring to help hold the contacts in place as well as putting more of the lateral load near the bottom of the pin/pivot. This way, even if the hole wears larger, the pivot will be held in position better.
I was just about to post info on this fix with pictures when Huey L. Conway, Jr. <firstname.lastname@example.org> posted a note about how he fixed his. His fix is similar, and probably easier for those who don't have access to machine tools. Basically, he cut the upper part of the plastic pivot off and used a Teflon washer and P-Nut (a push-on washer that locks in place). This is much easier to do and will likely work just fine. Me, being an engineer, I had to do it by the total over-kill method...
|This is a view of the improved sender pivot pin showing the spring, washers, and nuts (2 jammed so they wont come loose). The plastic flange which wears out is just visible below the metal bar to the left of the pin/spring assembly.|
|This is an edge-on view to show the spring, nuts, & washers. There is a nut and washer inside the spring holding the top of the plastic pivot in place. This was set with just enough clearance so that everything moves freely. The larger washer and jamb nuts hold the spring in place.|
|This is a close-up view of the nuts, washers, & spring.|
Followup August 2001:
It's still working perfectly a couple of years later and 50K more miles!
When I did the original fix, I kinda went overboard, as I'm often prone to do. The other guy I mentioned had a slightly easier fix (no machining), which sounds like it'd work too.
The whole problem is that the moving part is held in contact by a small plastic flange, which wears away. My original plan was to simply replace the pin with a small bolt (I think 6-32 or maybe 8-32). I was going to just thread the hole in the base plate, screw the bolt in and then put a washer and a nylok nut on the top. I still think this'd work fine. Yeah you need a tap and a drill, but that's real easy in plastic.
But, as usual, I got carried away. I figured that the threads would probably wear the pivot point more than a smooth pin (they would, but probably not much). So I made a new pin like the original, only longer so I could thread it. Then, it still had more slop than I liked, would've been fine, but, Mr. Perfectionist wanted better. That's where the spring came in. Realistically, the contact arm has a spring-type contact, so can take up a fair bit of slop, just not as much as happens when the plastic flange on the original dies.
Last update: September 1, 2000