Temp and Fuel Guage

[ddm156]

After a few weeks away I am looking to get back to some troubleshooting. I'm having guage issues (still). Here is what I can tell you:

I am running a Centech Harness

Oil Pressure seems to be functioning as expected. Moves around 40-70 while driving, hangs at 40 when idling.

Temp - I have an issue here....When the truck warms up it will read about 120, maybe just a touch beyond. That is it. So, here is what I did about it: I replaced the thermostat with a new 180. I tested this on my stove and it was working and accurate. I also replaced my temp sender (with the one for guages and not for light). My old temp sender had t-tape around the threads in the manifold. I put the new one in with nothing on threads. I did these things and started the truck. No change. I start the truck and it moves slightly right and as it warms up it moves a bit more right but then never goes beyond 120. Here is the odd thing - When I shut the truck off for a minute or two and then turn the key to accessory power it will read 170. If I restart the truck after warmed up the guage will read 170 immediately, but then creep back down to 120 pretty quick as the truck is running. Why would that happen? Like a mixed signal when the truck is actually running?

Fuel - Moves from far low position to E at startup. That is it. No matter how much fuel is actually in the tank, I show E. I did the basic test of grounding out the sender wire at the tank and I did have a full sweep to Full. That would tell me that I have good wiring, right? I have another fuel sender float on hand but have not run the truck dry yet, so that replacement is on standby.

I thought maybe I had two seperate issues. Now I'm not so sure. Is there a common denominator between just fuel and temp guages?? Seems like if I had an electrical issue to the cluster I would be lacking an oil reading??

I have two young ladies that are expecting to go get some ice cream cones in dads Bronco when the weather turns. Just looking to get things operational as they should be. Not really interested in aftermarket guage clusters.

 

[Wild horse 75]

Sounds like the fuel sender needs replacing. As far as the temp gauge, do you actually know what temperature your engine is running at? And where is the sender located? You should be able to find the resistance for the sender online and check with a multimeter and infrared temp gun.

 

[ddm156]

Sounds like the fuel sender needs replacing. As far as the temp gauge, do you actually know what temperature your engine is running at? And where is the sender located? You should be able to find the resistance for the sender online and check with a multimeter and infrared temp gun.

Was getting 160-170 at the thermostat with temp gun when I checked that a few weeks back. I want to try that again just to make sure.

 

[Wild horse 75]

So it sounds like the gauge and sender aren’t matched then. I’d be leaning towards a bad gauge since you’ve replaced the sender but before you go replacing it it wouldn’t be a bad idea to check the sender with a multimeter.

 

[DirtDonk]

Here is the odd thing - When I shut the truck off for a minute or two and then turn the key to accessory power it will read 170. If I restart the truck after warmed up the guage will read 170 immediately, but then creep back down to 120 pretty quick as the truck is running. Why would that happen? Like a mixed signal when the truck is actually running?

Not odd at all. Completely normal occurence known as "heat soak" by most.
Modern vehicles tune that out of their gauges, but it's still going on inside the engine.

What's happening is that, stored heat, for lack of a better term, is heating the engine coolant after you turn the engine off. Only now, the coolant is no longer circulating. And, since the sender is at the top of the engine, that's where the coolant gets the most heat while sitting.
Some engines may only gain 10 or 20 degrees at the sender, while others may gain 40, 50, or even more degrees before stabilizing and then cooling down.

I always liked it myself, because it was letting me know just what was going on inside a particular engine. Even when it wasn't running.

Paul

 

[m_m70]

Not odd at all. Completely normal occurence known as "heat soak" by most.

Exactly!