Hello, Thanks for advice on the fuel pump problem. A new pump solved the problem. Now my new problem is the temperature gauge. It just suddenly died. I checked fuses, but all are O.K. Any ideas where the best place to start looking might be?
Thanks!!
Neb

 

Try replacing the sending unit. There is a 2-wire one thatreports coolant temperature to the computer, you don't need that one. You want the 1-wire sensor since it's for the gauge. Make sure you don't get one for an idiot light by mistake.

 

Hello,
I replaced the temp.sending unit. At first, I had an old one out of an old small block manifold that I had. From a 1974 I think. When I put this one in the temp. gauge went from bottomed-out cold to all the way to the top hot. It just maxed out in the opposite direction. So I went and bought a brand new one and it still just stays maxed out in the hot direction. I guess maybe a gauge check may be in order? Or maybe a wiring issue? Short or something? What do you guys think?
Thanks!!!
Neb

 

It's weird that with the original sender the gauge was dead and now it's maxed out. This leaves me to believe that the gauge is working and the problem lies with the wiring, or you have a bum new sender.

With the engine running, if you pull the wire off the sender does the gauge go down? If so, lightly touch and removethe sender wire to engine ground. Does this cause the gauge to go up and down?

 

Hello alloro, Thanks for responding so quickly!! Yes, when you remove the wire off the sender with the engine running, the gauge drops to dead. Also, when I touched the wire to engine ground and then removed it, it did as you wrote. It went up and down and up and down and so forth.
Neb

 

Then the problem is with your sender unit, the gauge is working as it should.

 

Hello alloro, I will pick up a new sending unit ASAP. Will keep you posted.
Thank you!!
Neb

 

(corrected) Thanks for the information alloro, this clarifies something that the Haynes manual ( p 3-6) shows on a V8 on 8.1b.) but doesn't mention that the gauge sender is a 1 wire device. On the 3.9L on a 94, the 1 wire temperature sender is on the passenger side right behind the alternator. Looks like it will be a little tough to reach, but not nearly as bad as the 2 wire computer sender on the other side of the hose in the center front of the block! Can only see it w/ a mirror. You just saved me a lot of grief.

What messed me up for a minute was that the parts house sold me a 2 wire( computer sensor) & I got confused which was which. Thanks for straightening me out.

 

Take 5 minutes to remove the belt and slide the alternator out of the way. It makes replacing either sender a lot easier.

 

I just took a look at this picture and it appears to be correct. It's showing the 2-wire sensor behind the thermostat housing and the 1-wire sensor over on the passenger side behind where the alternator goes.