North American Turbocoupe Organization



Fuel gauge not working ....88 TC
ianbfromct Offline
Senior Member
#1
I know some guys can live without it but I need mine working lol. Just to give a heads up..my car has a wired in voltage regulator from the previous owner for the dash. He felt that it was a better fix than just replacing the whole cluster. My gas gauge worked fine up until a few days ago. The last thing I did was I had it on a lift fixing a small oil leak on the turbo (I pulled the coil wire and tried cranking it over to see if I can spot the leak), bolted up a sway bar mount, and washed it. I doubt any of this stuff caused it and its unrelated.

I did put in a walbro 255 high pressure pump in like 3 months ago and the gauge worked fine after that. How can I start troubleshooting this? Are there any fuses or relays I can check or is it all in the tank ?
88 5 speed TC
-3" DP,lowered, 255 Walbro, Gillis valve, Cobra R's, bondo/rust, Stinger's PIMP Ecu
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Pete D Offline
Administrator
#2
If it is the sending unit that is bad, there are no new ones.
See this whole thread: http://natomessageboard.com/ubbthreads.p...Post133796

Jeff can probably give you some diagnostic tips before dropping the tank
Pete Dunham


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Jeff K Offline
Administrator
#3
I assume the temp and oil press gauges work? If so the problem isnt the aftermarket IVR. The actual thermal / bimetal gauges (oil, temp, fuel) gauges virtually never fail.

Several possibilities: 1) Cluster connector has come loose and the terminal for the fuel sender is no longer making contact. 2) sender connector on top of the tank isnt making contact. 3) sender has failed. 4) Harness problem between sender and cluster.

Best way to check gauge / harness without dropping tank is to find the sender wires coming off the top of the tank and pierce each one with a pin. With key in run and a friend watching the gauge, short the 2 wires using the pins pushed thru the wires. Gauge should very quickly pin on full. Dont leave the short there for more than a few seconds. If it does, harness from tank to gauge is good. Be sure to put some RTV over the pin pricks in the wires when done.

If gauge doesnt move using the above test, its time to drop the tank. Check the connector on top of the tank for looseness, corrosion, etc, and try the "short it out" test on the connector to absolutely verify no harness problems.

Also measure sender resistance with a DMM. Empty tank = 75 ohms or so, full tank 10 ohms or so, 1/2 tank, 22 ohms or so.

If sender is bad, hunt up a replacement variable resistor as noted in the post Pete linked or pull the sender and have it repaired. there are a few companies that rebuild obsolete senders (google is your friend), but the repair isnt cheap, I think around $100 or so.

High sulfur fuels are known to coat the sender resistance wire coil and cause the gauge to read empty. If this is the case, running a tank or 2 thru with a high concentration of Techron fuel system cleaner MAY get the gauge working again.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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ianbfromct Offline
Senior Member
#4
Jeff thanks for the detailed response..

My oil pressure has been disconnected for a while now because it never seemed accurate and I ran a aftermarket one. My cooling temp one is working its strangely fluctuating all over which might be a another problem in itself but it does work.

I was told I could ground out the black wire on the connector in the trunk coming from the sender to the gauge with a 8-12 ohm resistor and that wont do any harm to the gauge. You ever heard of this? I did run it pretty low a few days ago not if that could have done anything. I put in around 4-5 gallons since then.

Ill pick up some of that techtron anyways for the hell of it.
88 5 speed TC
-3" DP,lowered, 255 Walbro, Gillis valve, Cobra R's, bondo/rust, Stinger's PIMP Ecu
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Jeff K Offline
Administrator
#5
Ian, I don't remember for sure where the sender wires enter the car interior or trunk. I do know the pump wires come into the trunk, but not sure on the sender. Whenever you access the sender wires, a ten or so ohm resistor will make the gauge read full or close to it if the harness, I've, etc are ok. If your temp gauge and op gauge we're acting up, it sounds like you have problems with whatever kind of aftermarket ivr the op put on, but that's another problem.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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ianbfromct Offline
Senior Member
#6
My oil pressure always ran dangerously low on the dash and after I got my AEM gauge in I was happy to see normal readings so theres that. And my temp sensor normally reads on the lower side I wasnt sure if it my car actually running hotter than normal or the gauge/IVR was on the fritz. Ill have to see where I can get a replacement IVR and what kind I need? I wanna make sure I run the right one.
88 5 speed TC
-3" DP,lowered, 255 Walbro, Gillis valve, Cobra R's, bondo/rust, Stinger's PIMP Ecu
Reply

Jeff K Offline
Administrator
#7
The stock mechanical / thermal IVRs are junk, and date back to the 1960s or maybe even earlier.... Some 60s Fords I owned had the exact same IVR as the TC. As far as a decent replacement, I dont know... I built my own solid state ones for my 2 Tbirds.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
Reply

ianbfromct Offline
Senior Member
#8
Jeff K Wrote:The stock mechanical / thermal IVRs are junk, and date back to the 1960s or maybe even earlier.... Some 60s Fords I owned had the exact same IVR as the TC. As far as a decent replacement, I dont know... I built my own solid state ones for my 2 Tbirds.


Jeff I just checked out my piece mealed IVR and took a few pictures. Its kinda a terrible rats nest and he spliced in the head unit into it somehow. Im extremely intimidated by electrical stuff so I never cleaned it up lol.

[Image: IMAGE_407.jpg]

[Image: IMAGE_408.jpg]

Theres no type of marking or serial numbers on this thing to even replace it. I would replace it with a good one if I can figured out where the wires go.
88 5 speed TC
-3" DP,lowered, 255 Walbro, Gillis valve, Cobra R's, bondo/rust, Stinger's PIMP Ecu
Reply

ianbfromct Offline
Senior Member
#9
Jeff K Wrote:The stock mechanical / thermal IVRs are junk, and date back to the 1960s or maybe even earlier.... Some 60s Fords I owned had the exact same IVR as the TC. As far as a decent replacement, I dont know... I built my own solid state ones for my 2 Tbirds.

Feel like making a 3rd and selling it to me lol??
88 5 speed TC
-3" DP,lowered, 255 Walbro, Gillis valve, Cobra R's, bondo/rust, Stinger's PIMP Ecu
Reply

ianbfromct Offline
Senior Member
#10
Well I ended finding the post that the previous owner used to build this solid state IVR lol turns out he built from this
http://www.centroidproducts.com/mustang.pdf

Good thing is it tells you what voltage should be on what terminal so I can easily check out that and see what its putting out. Im still kinda thinking its the fuel tank float but who knows. Ill check it over the holiday or weekend. I cant drive to carlise guessing how much gas I have lol.
88 5 speed TC
-3" DP,lowered, 255 Walbro, Gillis valve, Cobra R's, bondo/rust, Stinger's PIMP Ecu
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