A few electrical questions - 70 Mach

[Print Dad 58]

Hello ALL,

I hope I can get a little help here on several electrical issues.

I stink at electric for sure.

 

I am having troubles with my gas gauge and temp gauge.

 

I know both work BUT may not be calibrated or something.

 

The fuel situation - - I installed a new tank and sending unit about 2 years ago.

Recently I noticed the car seems to be using too much fuel. The needle read about 1/8 tank. I put in 10 gallons and it read full. This is Ok but I would like to have it right and may be part of another issue.

 

The TEMP - - the needle barely moves when the car is hot. Sunday I broke the fan belt as I was driving and I saw the temp gauge rise about about 3/4 .

I stopped the car - -noticed the belt gone and replaced it. I had only lost about 2 cups of antifreeze out the cap.

Anyway - -I replaced the belt - -drove the car for about 40 minutes and the needle barley moved from cold.

 

I know both coulod be the sending units - -BUT I am thinking it is the Instrument Voltage Regulator.

As a note - -the oil pressure seems to be working.

 

I have the shop manuals and it tells me how to check the IVR using the temp

gauge wire etc.

 

My questions - -

1. - If the test on the temp gauge works correct does that mean the IVR is working??

2. - I see that some places sell only solid state replacements BUT I thought I read that they could be troubles. PLease advise. I don't want to pull that instrument cluster too many times. I would like to do it once and fix things.

So can someone tell me what they used and if the recommendation is to stick with the original style and not solid state - -who sells them?

I looked at MU and a few other places just in case.

 

3. - I recently have an issue with the headlight switch - -I purchased a Motorcraft and plan to replace that in a day or two. I know this switch controls the lights BUT not certain if it could power the cluster.

I STINK at this electrical stuff so I sure need help. My thought and what I can see is that the headlight switch is powered separate from the gauges.

 

4. - If I need to replace the INstrument Voltage Regulator - -can someone offer some tips. I have had the dash pad out MANY time (core last year) and it has been about 30 years since I messed with the instrument side.

Things I should be extra careful of.

 

I thank all that offer ideas and help.

 

Print Dad

[danno 128]

I will see if I can provide some answers.

1. If the temp gauge is working, I would say your IVR is OK. The floats in your fuel level sensor can easily develop a pin hole and leak gas inside. Those cheap aftermarket things do not last, I have replaced them about every 3 years or so. That is probably why your fuel reads low.

2. the original Ford IVR is a very solid design. They last forever, I still have my original installed. It is a very simple and reliable design, go for a Ford replacement. I would not doubt that your local Ford dealer would have them.

3. The headlight switch is powered seperate from the cluster. It only supplies power to the cluster to light the instruments when the headlights are on. No other connection.

4. A couple of tricks on removing the cluster. You have to reach behind the speedometer and release the speedometer cable. It is a trick, see if it is talked about in the manual you have. Also release the wire connector by squeezing the releases at the top and bottom.

 

My guess is your cluster is fine. Another way to check the temp sensor is to remove it, connect a ground wire from the engine to the side of the sensor, and dip it in bioling water. You should see the needle move to about 3/4 up ( I could be wrong on how far it moves). This will tell you it works. The take your fuel sendor out and check for liquid in the float.

 

3

[LoneWolf2U 136]

Pd, your ivr is working if your oil guage is reading.

To test the guage range of both your gas and temp,

Simply unplug the wire at the sending unit and place ground it.

Now flip the ign switch to on and watch the guage, If it goes all the way to the right then the guage is good and the sending unit needs replaced.

 

As for the gas sending unit, it could just need resetting but with the cheap repo stuff they leave alot to be desired.

Had a brand new unit work for 20 mins and had to pull it because the float had a hole in it and sank.

[Print Dad 58]

Hello all,

Thanks for the help.

I really stink at electrical BUT I am learning

 

 

Danno - -thanks for the advice. I am wondering if I could

get a VR at the Ford dealer if I need it and would it be like the original

and not a solid state. If I need to replace the VR I want to do it once.

 

Mach1Rider - Thanks. I knew how to test the fuel gauge by grounding

the wire and it should read full - - I DID NOT know that this same thing

will work on the temp sending unit wire. THANKS.

I have a temp sending unit and plan to install it Wednesday after work.

I have bought a lot of parts from "Rock" when they have sales so I have

some sending units etc already.

 

I can live with the fuel gauge for now - -BUT the temp is something

I like to keep an eye on. That and the oil pressure.

 

I was thinking about the temp gauge not going up and then I was thinking

perhaps the thermostat stuck open when it slightly overheated. I can check that out pretty easy and will tomorrow.

 

I would like all the gauges working and I kinda hope I don't need to replace the IVR. I am thinking I amy not have to and that would be good.

I have had the dash out quite a few times this year and it is easy but time consuming.

 

Thanks people for the GREAT help.

 

as a side note - -tonight I went to install the hood on my friends 61 Lark.

We installed a 350 with a 700R4. My friend is about 73 and still likes a little

umph when he steps on the gas. The car is headed to an exhaust shop in the morning and I think my work is done on it. I can wrench a bit BUT when it comes to electric boy am I bad.

The Lark is a 61 Vert and it is in real good shape. There were some issues replacing the original 6 cyl BUT nothing too bad. His other car is a 65 Falcon - 289 small blower under the hood. He likes speed I guess. LOL

 

Thanks so much for the ideas and advice and I am going to follow up on this.

 

Be well - -work safe - -Print Dad

[Print Dad 58]

Well the headlight switch is finally in. They sent me the wrong one and I had to strip parts

from the old switch (stupid I know) I should have sent it back. The switch they sent had the same wires BUT it didn't have the cone shaped mounting piece on the part that sits

against the dash.

I took the old cone from the old switch and welded it to the new switch. Should be OK

 

I checked and grounded the wire to the temp sending unit and the gauge went up to hot.

 

Got late so tomorrow I will put in the new sending unit.

 

Becuase I stink at electrical - -I am wondering if I should install it with Plumbers tape on the threads or RTV or should I use nothing.

 

I am thinking the tape may hurt the ground of the unit BUT not certain. My normal plan would be to use the tape on areas with water and use RTV on others.

 

I was just wanting to do this right - -so any advice on the RTV, tape or dry

 

Thanks all - -Print Dad

[Big Secz 26]

Well the headlight switch is finally in. They sent me the wrong one and I had to strip parts

from the old switch (stupid I know) I should have sent it back. The switch they sent had the same wires BUT it didn't have the cone shaped mounting piece on the part that sits

against the dash.

I took the old cone from the old switch and welded it to the new switch. Should be OK

 

I checked and grounded the wire to the temp sending unit and the gauge went up to hot.

 

Got late so tomorrow I will put in the new sending unit.

 

Becuase I stink at electrical - -I am wondering if I should install it with Plumbers tape on the threads or RTV or should I use nothing.

 

I am thinking the tape may hurt the ground of the unit BUT not certain. My normal plan would be to use the tape on areas with water and use RTV on others.

 

I was just wanting to do this right - -so any advice on the RTV, tape or dry

 

Thanks all - -Print Dad

 

 

PD, just use teflon tape on the sending unit and you'll be fine.

[buening 63]

I typically use a plumbers paste on the upper threads. You want some of the threads bare so it grounds good to the intake. If you coat the bottom threads, as you thread it in the rest of the threads get coated....thus the recommendation to coat the upper threads. I believe these fittings are pipe thread, meaning the diameter of the fitting gets larger as you go up the threads. This essentially means the threads are self sealing (unlike a bolt), but a little bit of plumbers dope helps with the upper seal.

[LoneWolf2U 136]

I also use the plummers paste, the teflon type avail in small squeeze tubes from the local hardware.

A small amount on the upper part of the threads for sealing is all that is required.

The tape just rolls out and rtv may leak later.