I have a 96 CTD, at start up all is fine. The oil pressure gauge swings from 40 to zero as I move along. At stop lights the oil light will come on. I put the truck in neutral and the oil light goes out. At some rpm`s the fuel and oil gauges go nuts. I know that my fuel gauge is bad. I just toop off the tank at 400 miles. But the oil gauge is scareing me. Today I will buy a new oil sending unit. After changing out the oil sending unit what is the fix for the fuel gauge?

 

First off, what oil are you using? I had a few problems a while back when I switched from Rotella mineral oil 15w-40 to Synthetic 5W-40. Showed same symptoms, but only when fully warmed up at idle. Swiched back and it's never come back.

Now to a gauge. On top of your oil filter there is a 1/8" NPT pipe plug. Make yourself a quick pressure checker with a 1/8" fluid-filled 100 psi gauge and the fittings to attach into the port. You may find it's a trick to find 1/8" hydraulic fittings. If you want to check it regurally, install a snap-tite fitting into the port as well as your gauge, and remove it when you're not using it. Now have a friend start the engine and watch the gauge. This will actually give you a demonstration of how inaccurate your "pressure gauge" on the dash really is. Cold idle mine rusn about 65psi, as high as 80 psi cold revving at 2000 rpm. Fully warmed up, it might get down to 20psi at low idle, I think your light comes on below 20 psi. Also fully warmed up it will run about 50psi, so there's no real problem here.

Good luck!

 

96 thanks for getting back to me.

I swapped out the oil sending unit. I now have oil pressure. The idiot lighjt is out, and the gauge has 42# at idle.

I have a problem with my fuel gauge. At fill up, it reads full, at 3/4 of a tank it reads 3/4. Then it drops to empty and stays there until I fill the tank again. For this reason I fill every 400 miles. What do I need to do to get my fuel gauge working again?

 

Drop the tank and replace the sending unit it is on the module in the tank.

 

Is there much dificulty in replacing the tank sending unit? Any pictures?

 

I've not done this, however if you're going to the trouble of dropping the fuel tank, might as well replace the troubled fuel supply & return lines, which tend to corrode and leak air into the system.

 

i replaced 2 of these. there pretty easy make sure your low on fuel. disconnect lines first. i believe there are only 4 bolts holding it on. 2 people makes droping and putting back easy. the top screws off, sometimes its stuck. when its out there are 2 screws holding the float and 2 wires. you wont need anything but a socket set and phillips screw driver. hope this helps. dealer part only, think i paid around 80 good luck

 

Thanks, will get her done next week.

 

BoDiesel,

I am having the same issue with the oil pressure gauge in my truck. How much did the sending unit cost? Easy to replace?

I also had the same problem with my fuel gauge. The guy I bought the truck from told me about it and sure enough once it go to 1/2 to 1/3 of a tank the gauge would drop to Empty. I was just about to replace the sending unit, I went under the truck to see what would be involved. I noticed the bottom of the tank was sucked in like it was under too much pressure. When I would fill up there was always a fair amount of pressure released upon loosening the fuel cap. As it turns out the factory left the plug on the fuel tank vent. I pulled that off and the gauge has worked perfect ever since.

 

first, the oil sending unit is simple to replace. There is a post here with pic`s about replacing the sending unit. Two wires on a clip go to the sending unit. Unclip the wire set up to the sending unit, use a 1-1/16(deepsocket)to remove the sending unit. Do this when the engine is cold. I waited for an hour to let the engine cool. Wait longer, it was still hot. Unscrew the unit, screw the new unit in. BE VERY CAREFUL, do not break the new unit putting it in. I bought mine from the local Dodge dealer for $38.50 or so. Good luck.

My fuel gauge used to work fine. I will pull the tank.