Anyone ever have there stock gauge go bad?

stanger8172 · 02-12-2002, 12:59 AM

My oil pressure gauge read low and liked to drop to zero when the oil was hot. Then I put in a new sending unit and the needle read good pressure but it reads zero pressure after the oil is warmed up and rpm's are at 900 or below. Above 900 it'll sit at half which is about 50psi.

Anyone have this happen to them or similiar? My next move when I get the tax return is to get a mechanical gauge and then go from there. Should I or does it sound like I need an overhaul? Thanx

speedytang · 02-12-2002, 08:34 AM

Ford had many factory running problems with the oil pressure gauge from 89-92. The circuit board would over heat and cause false readings. Now how they fixed it on the models that had the problem was to put a resistor between the harness and the sending unit. Does yours have the extra wire with a 2" long resistor attached if so remove that 4" extension and plug the original harness onto the sending unit. The resistor goes bad and the only thing that happens without it is the guage will not move as guick to the pressure reading.

stanger8172 · 02-12-2002, 10:50 AM

Mine appears to have the factory harness plugged into the new sending unit. I did not see a resistor anywhere but there was one wire from the harness that came from under the upper intake and routed down over the timing chain cover and to the sending unit. So you are saying that there SHOULD be a resistor in there? Where is the resistor?

speedytang · 02-12-2002, 11:57 AM

yours may have the fix at the guage circuit board because the resister was attached to the sending unit with the factory wire plugged into it. So either you have a bad guage or your oil pump is going bad

bigredstang · 02-12-2002, 12:54 PM

In my 95 the oil gauge reads all over the place. One time it will be at zero and the next it will be pegged. I have replaced the sender as well.

Also note that on several years I think that the sender is actually a switch that "turns" on at like 4 psi or so that may be why you get zero under 900 rpm and 50 psi later.

(On my 351 with an real guage I have maybe 10 psi at idle and 50 when revving.)

stanger8172 · 02-12-2002, 01:31 PM

Yeah I called the two Ford dealers in my area and they didn't know anything about the sender acting as a switch above and below 4psi. They didn't know anything about the resistor too. I told them that there are no symptoms associated with the falling oil pressure needle. The car sounds and runs just as well as ever, even when the needle falls on it's face.

If no one knows anything more I am going to just install a mechanical oil pressure and water temp gauge in the 2 5/8" a-pillar pod I already have. I just need the gauges and an install.

PKRWUD · 02-15-2002, 04:08 AM

Go with the aftermarket gauges.

Take care,
-Chris

02-12-2002, 12:59 AM	#1
stanger8172 Registered Member Join Date: Nov 2000 Location: Milwaukee,Wisconsin Posts: 380	Anyone ever have there stock gauge go bad? My oil pressure gauge read low and liked to drop to zero when the oil was hot. Then I put in a new sending unit and the needle read good pressure but it reads zero pressure after the oil is warmed up and rpm's are at 900 or below. Above 900 it'll sit at half which is about 50psi. Anyone have this happen to them or similiar? My next move when I get the tax return is to get a mechanical gauge and then go from there. Should I or does it sound like I need an overhaul? Thanx __________________ '91 LX convertible , T-5, Centerforce Dual Friction, MSD Blaster Coil, FR 9MM wires, 13* timing, 1.6rr, ported/polished/milled stock heads, 1.94/1.60 stainless valves, March Performance Pulleys, K&N panel, 1"spacer, BBK shorties, 2 1/2" off road H, Summit 2 1/2" catback

02-12-2002, 10:50 AM	#3
stanger8172 Registered Member Join Date: Nov 2000 Location: Milwaukee,Wisconsin Posts: 380	where around the motor is this resistor? Mine appears to have the factory harness plugged into the new sending unit. I did not see a resistor anywhere but there was one wire from the harness that came from under the upper intake and routed down over the timing chain cover and to the sending unit. So you are saying that there SHOULD be a resistor in there? Where is the resistor? __________________ '91 LX convertible , T-5, Centerforce Dual Friction, MSD Blaster Coil, FR 9MM wires, 13* timing, 1.6rr, ported/polished/milled stock heads, 1.94/1.60 stainless valves, March Performance Pulleys, K&N panel, 1"spacer, BBK shorties, 2 1/2" off road H, Summit 2 1/2" catback

02-12-2002, 01:31 PM	#6
stanger8172 Registered Member Join Date: Nov 2000 Location: Milwaukee,Wisconsin Posts: 380	Yeah I called the two Ford dealers in my area and they didn't know anything about the sender acting as a switch above and below 4psi. They didn't know anything about the resistor too. I told them that there are no symptoms associated with the falling oil pressure needle. The car sounds and runs just as well as ever, even when the needle falls on it's face. If no one knows anything more I am going to just install a mechanical oil pressure and water temp gauge in the 2 5/8" a-pillar pod I already have. I just need the gauges and an install. __________________ '91 LX convertible , T-5, Centerforce Dual Friction, MSD Blaster Coil, FR 9MM wires, 13* timing, 1.6rr, ported/polished/milled stock heads, 1.94/1.60 stainless valves, March Performance Pulleys, K&N panel, 1"spacer, BBK shorties, 2 1/2" off road H, Summit 2 1/2" catback

02-15-2002, 04:08 AM	#7
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Go with the aftermarket gauges. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

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02-12-2002, 08:34 AM	#2
speedytang Registered Member Join Date: Oct 1999 Location: Marengo, Ohio.USA Posts: 135	Ford had many factory running problems with the oil pressure gauge from 89-92. The circuit board would over heat and cause false readings. Now how they fixed it on the models that had the problem was to put a resistor between the harness and the sending unit. Does yours have the extra wire with a 2" long resistor attached if so remove that 4" extension and plug the original harness onto the sending unit. The resistor goes bad and the only thing that happens without it is the guage will not move as guick to the pressure reading.

02-12-2002, 11:57 AM	#4
speedytang Registered Member Join Date: Oct 1999 Location: Marengo, Ohio.USA Posts: 135	yours may have the fix at the guage circuit board because the resister was attached to the sending unit with the factory wire plugged into it. So either you have a bad guage or your oil pump is going bad

02-12-2002, 12:54 PM	#5
bigredstang Registered Member Join Date: Mar 2000 Location: lincoln, NE Posts: 80	In my 95 the oil gauge reads all over the place. One time it will be at zero and the next it will be pegged. I have replaced the sender as well. Also note that on several years I think that the sender is actually a switch that "turns" on at like 4 psi or so that may be why you get zero under 900 rpm and 50 psi later. (On my 351 with an real guage I have maybe 10 psi at idle and 50 when revving.)