Gas Guage Never Reaches Full

[ktmall07]

Hey All, 

 

My fuel guage never makes it all the way to full after filling up, usually taking a day or two to make it up past halfway, then stopping at around 3/4 of a tank. When it reaches empty, I typically have about 4-6  gallons left before the tank is actually empty. 

 

Wondering if maybe the float keeps getting stuck somewhere, or if the guage is just not getting the right amount of resistance? I have a stock 92 SWB, 18.5 gallon tank.

 

All the threads I've found with similar issues are on Renix systems, so I'm not sure how well they correlate, and none of them really have this same issue.

 

Any ideas?

[jdog]

Sounds like it could be a bad float, when you say it takes a couple days to get halfway, where does on those couple days

[ktmall07]

? Are you asking a question? I'm not sure I understand... Haha it seems like it gets stuck whenever the truck is off, but if the truck is on, the guage will very slowly move up. Usually after about 20-30 minutes of driving, the guage will stay pretty constant, until I stop the truck and restart it, then it moves up a little more.

 

So when I say a couple days, I guess I really mean 4-5 20 minute trips and it reaches about 3/4 of a tank, where it stops.

 

Is there a way to fix the float itself if it's bad, or do I need a new sending unit?

[jdog]

You can attempt to remove and clean it, but best bet is to replace the sending unit. But with that info, I'm wondering if it's not a bad gauge

Sorry on mobile and I can get ahead of myself when typing. Yeah the question is what does the gauge do on those days. Just trying to figure out the symptoms a little better to help get this diagnosed.

If someone else doesn't pipe up and give testing procedures I'll post them up later tonight

[ktmall07]

That would be awesome. When I first fill up and start the car, the needle moves a bit (usually to around 1/8th of a tank), and then on the next few trips the same thing happens, until eventually it stops somewhere between 1/2 and 3/4 of a tank.

 

Seems like most of the initial movement happens when the starter motor cranks, then slows down once the car starts, if that helps at all?

 

Thanks for the help!

[scaleless]

If it only moves slowly while the truck is on, I would expect the guage is sticking a bit. If after sitting for extended periods of time you start the truck and the guage moves, I would expect the float.

 

As in, if you fill up the truck and then immediately park it for a few days, when you start the truck would it be over 1/2 or still read empty?  If empty, the guage is suspect.  If full, the float.

 

Based on your what you're saying, it sounds like the guage to me.  It's fairly trivial to remove the guage faceplate, so if I were you I would try removing the plate and spray the guage internals with an electrical contact cleaner.  It's an easy place to start that doesnt require replacing or tearing anything significant apart. All you have to do is remove the black dash trim and then there are 4 screws holding the clear plastic.

 

Plus, you would prefer not having to replace an HO sending unit, because they're not readily available.

[ktmall07]

The guage only seems to move for the first 20 minutes or so after starting the truck, each time the truck is started, regardless of how long it's sat since filling up. It stops when it gets to ~3/4 of a tank at the most.

 

I'm purchasing a full gage cluster with a tach from a 92 Cherokee, would it be too much work to just replace the fuel gauge and idiot lights with guages from the new cluster? Or should I just replace the whole cluster and then see if the fuel guage is still giving me problems?

[eaglescout526]

Have you done any of the grounds? Cleaning the grounds isnt restricted to us Renix guys, even HO guys should consider making sure their grounds are clean. Behind the drivers side taillamp is the ground for the fuel pump and lamps. The ground for the instrument cluster is on the bottom side of the dash and for whatever reason the dashes bare metal gets rusty just from moisture in the air.

[jdog]

Just replace the cluster,  it will be easier, don't forget to change the oil sender and temp sender. Once the new cluster is in let us know if it fixed the issue

[ktmall07]

I really appreciate the help! 

 

I'll be honest, this truck is my first experience with any kind of electrical work, so all I know about it I've learned from other threads and videos.

 

I know this is a tangent from the original thread, but if I'm going to swap the whole cluster, do I need to do anything special to get the tach itself working? I know the oil pressure and temp senders are easy to replace, but is there anything else to keep an eye out for?

[eaglescout526]

Tach should be plug and play with the ECU on the HO MJ's.

[ktmall07]

Awesome. I'll post updates in this thread when I get the dash swapped!

[Minuit]

Do know that the float could also be bad in addition to any other electrical problem you have. It's happened to me twice.

[ktmall07]

Okay so, 

 

Got the new cluster installed, filled up the tank, and the same exact thing happened. Guage moved from empty (with the light on) to just under halfway, and it's stayed there today.

 

The only time it has moved is when I've started the truck. 

 

It seems likely that even though the guage only moves when the truck has first started, I do indeed have a bad float, or something else wrong with the sender itself. 

 

I know it might not even be worth it right now, since the guage half works, but has anyone repaired their sender/float, or swapped in a new one? What's the process like?