i was having trouble with the fuel pump staying on after i turned the car off. i would tap on or remove the harness that connects to the switch on the oil filter housing and it would stop. i ordered a replacement switch from rock auto and installed it. that solved the fuel pump issue. i notice that when i run the car now the oil pressure gauge needle pegs high. did i get the wrong switch?
i was having trouble with the fuel pump staying on after i turned the car off. i would tap on or remove the harness that connects to the switch on the oil filter housing and it would stop. i ordered a replacement switch from rock auto and installed it. that solved the fuel pump issue. i notice that when i run the car now the oil pressure gauge needle pegs high. did i get the wrong switch?
Tom, I think either you ordered the wrong oil pressure sending unit or they sent you the wrong one. The oil pressure gauge may peg with a cold engine, but once it warms up, it should drop below 80psi at idle. There are different sending units for different applications and a lot of them look the same although they put out different types of signals for the gauge.
I don't know what you are using now but most in your situation would need a stock replacement oil pressure sending unit for a 1988 Fiero GT (2.8L V6).
-ryan
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thanks ryan. i think i ordered a 3.8 sc part. --i think. do those look the same as the correct fiero part?
Could, depending on the year, make, model of car you ordered it for. But most 3800 SC oil pressure senders are short (only about 2" long) whereas the Fiero sending unit is about 4" long or so.
ryan , it's almost 4" . i noticed that when i push on the body of the new assembly the fuel pump comes on until i let go. kinda sensitive ? it seems to work correctly though. i'll check the part# and see what it was i ordered. thanks.
I used the 88 oil pressure sensor and my gauge was always pegged. I added some parallel resistance and now it reads what it should. Phonedawgz recommended using the LS1 oil pressure sender a while ago to accommodate the higher oil pressure of the 3800. Didn't try it yet but it could offer a solution.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
What P# the sender? Could be: Wrong type. Sender for light not gauge. Wrong Value. Fiero uses 0-90Ω later can be 0-120Ω Dash gauge is bad or lying because Wires to gauge or ground(s) have problems.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
this is the part# on the old switch--12555492. it's also the part# referenced for the new "part replaces" in rock auto AIRTEX / WELLS 1S6635 . i'll fiddle with it today. if start the car and pull the harness off the switch should the car keep running? or will the fuel pump stop?
Actually the oil pressure sender/switch I recommend for the 3800 is the one for the 98 SC Bonneville. It is a 0 - 120 PSI sender not the 0 - 80 sender like the Fiero one. 3800s have more oil pressure than the 2.8.
When you use the Bonneville oil pressure sender the top number of your oil pressure gauge would effectively be 120, but the middle number stays at 40.
Note also - when you use the Bonneville sender - it is a 4 wire sender. The 4th pin of the connector needs to be a ground wire. You can remove the pins from your 3 wire connector and install them in a 4 wire connector and then add the needed ground wire.
If anyone needs one hit me up and I can sell you the 4 wire oil pressure sender connector and a ground wire.
[This message has been edited by phonedawgz (edited 07-19-2015).]
L: says to disconnect oil sender connector and set key to run. the correct result should be gauge shows high pressure. if the result is correct then replace sender. then is says FOR DIAGNOSES SEE 1 which says CHECK TAN(31) wire (see schematic) for short to ground. replace oil pressure gauge if wire is ok ,( see section 8C )
M: says to disconnect oil sender connector and connect the A terminal to ground with key to run and the gauge should show low pressure. if the result is correct replace the oil pressure sender. then is says FOR DIAGNOSES SEE 1 which says CHECK TAN(31) wire and gauge cluster printed circuit for an open. then it says if wire and printed circuit are ok the replaced gauge.
when i do the M: test it instantly blows the 10 amp gauge fuse when i turn the key to run. any ideas?
Actually the oil pressure sender/switch I recommend for the 3800 is the one for the 98 SC Bonneville. It is a 0 - 120 PSI sender not the 0 - 80 sender like the Fiero one. 3800s have more oil pressure than the 2.8.
When you use the Bonneville oil pressure sender the top number of your oil pressure gauge would effectively be 120, but the middle number stays at 40.
It may be more compatible with the oil pressures of a 3800SC but the 98SC Bonneville Oil Pressure sender while using a similar connector is a 4 terminal device. The Fiero is three terminal. Can't imagine why 4 terminals are needed but I would guess that the four terminals may be warning light, Fuel pressure switch (2) and oil pressure sense. Is this correct?
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Heddman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
The 98 SC Bonneville oil pressure sender is definitely 4 wire. I have one here and can send a photo if you like. You can also look on Rock Auto for a confirmation picture. Phonedawgz recommended it as it is more compatble with the oil pressures of the 3800SC engine and will keep oil gauge readings on the Fiero gauge in a user friendly range.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
"It sounds like one of the coils in the gage has shorted. The gage fuse should not blow when performing this test."
i'll pull the gauge and have a looksee. thanks people sorry, i don't know how to the quote thing.
Click on QUOTE in the upper right hand corner of the reply you want to use, a window will open with the quote. After the [/QUOTE] at the end of the copied text, space down and type your reply and hit REPLY.
i didn't order the 98 sc bonniville as suggested. put the it on and the fuel pump went off the first time. after that i had to wiggle the body of the pressure switch to make it work. the pressure gage pegs also. i'll try the bonneville version.
I don't think it has been asked yet, but It could have been I forget most things as soon as I read them.
What weight and kind of oil are you using? It does make a difference on how the oil pressure gauge will read, especially at startup. And is the pressure constant or does it go down as the car warms up?
Steve
------------------ Technology is great when it works, and one big pain in the ass when it doesn't
still fooling with this. disconnected the wiring harness from the oil / alt cluster.
tested the gauge cluster wiring harness the pink/blk wire has 12 volts to ground when the key is on. it's the power supply to the oil / alt gauge.----good according to the fiero service manual.
tested the tan wire at the gauge cluster harness which should be oil gauge out to the sender variable resister has 12 volts to ground when the key is on with the gauge cluster disconnected and the oil sensor disconnected there should be no voltage or ground on that wire. i pulled the gauge fuse and the voltage went away at the pink/blk and the tan.
for some reason with the gauge fuse in theres power being applied to the tan wire. the only time that tan wire should have power on it is when the gauge harness is plugged in, and pink/ blk is providing some voltage through the gauge winding.
any ideas where the tan could be picking up voltage from the gauge power supply? does anyone know the path that harness takes from the gauge area? thanks
The fuel pump fuse supplies power to the pressure switch in the oil pressure sender. An internal problem with the sending unit could supply voltage on the tan wire.
The fuel pump fuse supplies power to the pressure switch in the oil pressure sender. An internal problem with the sending unit could supply voltage on the tan wire.
the oil sender connector is disconnected at the sender. voltage exists on the tan only when the key is on and the gauge fuse is in ,even when the oil / alt gauge harness connector and sender harness is disconnected whether the fuel pump fuse is in or not.
the oil sender connector is disconnected at the sender. voltage exists on the tan only when the key is on and the gauge fuse is in ,even when the oil / alt gauge harness connector and sender harness is disconnected whether the fuel pump fuse is in or not.
Thank you for the clarification.
Check C3 connector on the dash (vertical 18 pin plug on backside, closest to console) and verify that the tabs for positions 17 (OPS) and 18 (TACH) are not touching each other. It's not uncommon for the circuit traces on the flexible printed circuit to come loose and touch....
[This message has been edited by olejoedad (edited 04-17-2016).]
Check C3 connector on the dash (vertical 18 pin plug on backside, closest to console) and verify that the tabs for positions 17 (OPS) and 18 (TACH) are not touching each other. It's not uncommon for the circuit traces on the flexible printed circuit to come loose and touch....
what do i need to do to get to that 18 pin c3 connector? is it in the upright radio console area? or in the center armrest console area?
what do i need to do to get to that 18 pin c3 connector? is it in the upright radio console area? or in the center armrest console area?
The C3 connector is one of the plugs on the instrument cluster. Remove the top and bottom trim pieces, the trim plate overlaying the clear plastic instrument cover and the four 10mm head screws holding the instrument pod to the dashboard support structure to provide access to the plugs. The C3 is the large plug on the right side of the instrument pod.
Originally posted by olejoedad: The C3 connector is one of the plugs on the instrument cluster. Remove the top and bottom trim pieces, the trim plate overlaying the clear plastic instrument cover and the four 10mm head screws holding the instrument pod to the dashboard support structure to provide access to the plugs. The C3 is the large plug on the right side of the instrument pod.
finally i found it. about 9 years ago. i removed the instrument cluster to install led replacement bulbs. when i reconnected the c3 connector i then clipped in the harness with that rectangular retaining clip. well, i pinched the black ground and tan wires. i took this long for them to short out.
the c 3 connector did have some delamination on that flexable printed circuit thing on the dash.
well i thought i found it... i put everything back together and the problem is there again. i rechecked the tan sensor wire with the sensor harness disconnected and the oil/volt meter connector disconnected. i get a short on the sensor wire to ground. i remove the right side connector from the instrument cluster and the short goes away. i checked the tabs where the cluster harness plugs in and they're all in place. help , while i still have hair.
