My 86 GT was laid up for 21 yrs (I'm the original owner). I completed the fuel pump install and connected the battery, The pump runs continuously even with the ignition off!!
(No worries I disconnected the battery right away!)
Without doing any testing -I'm assuming the FP Relay is stuck and needs replacing ???
I wont be able to look at it again till sunday. So what do you think??
[This message has been edited by Alex.07.86GT (edited 09-21-2014).]
If my memory serves me, (I've not played with the stock Fiero Wire Harness for quite some time) the Oil Pressure relay provides a ground to close the circuit for the fuel pump. Check that relay - it is on the firewall behind the air cleaner.
[This message has been edited by topcat (edited 09-20-2014).]
There are two "switches", either of which can supply power to the fuel pump. One is the fuel pump relay, located on the firewall, in the engine compartment, behind the drivers seat. There will be more than one relay there, so identify the relay by the colors of the wires. The fuel pump relay has wires that are Orange/Black, Tan/White, Dk. Green/White and Black.
The other "switch' that can turn on power to the fuel pump is the oil pressure sender. Located up by the belts or down by the oil pressure sender. 88 oil pressure senders look different than this one.
The oil pressure sender will have a connector with Tan/White, Orange/Black and Tan wires.
So to determine which one is causing the fuel pump to run, connect the battery and then disconnect one, and then the other and see which is causing the fuel pump to run. Most likely it is the oil pressure sender, which btw, is the one that is easier to disconnect.
With the oil pressure sender disconnected your oil pressure gauge will always show pegged high.
My guess. Pull the connector to the oil pressure sender. If this stops the problem you can do a temporary fix by cutting one pin off that supplies the fuel pump auxiliary path. Your oil pressure gauge will work and the engine will run fine. Then you can order and replace the sender whenever you wish.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, 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 "
The fuel pump relay has wires that are Orange/Black, Tan/White, Dk. Green/White and Black
The other "switch' that can turn on power to the fuel pump is the oil pressure sender. Located up by the belts or down by the oil pressure sender.
The oil pressure sender will have a connector with Tan/White, Orange/Black and Tan wires.
So to determine which one is causing the fuel pump to run, connect the battery and then disconnect one, and then the other and see which is causing the fuel pump to run. Most likely it is the oil pressure sender, which btw, is the one that is easier to disconnect.
Oil Pressure Sender it is!!! Thanks!
Is there a special socket to remove the oil sender?
BTW I only have 2 relays on the firewall. What is the 2nd one for?
On the '85 the left one is the A/C relay, right is the Fuel Pump (looking from the back).
Works great for identifying them assuming no one has ever touched them. If they have been touched in the last 29 years you have a 50/50 chance of identifying them correctly by location.
Identify them by the colors of the wires. It is the only way to accurately identify them.
btw, the A/C relay has wires that are Dk. Green, Black, Dk. Blue and Lt. Blue.
No you can't fix your Oil Pressure Sender switch. You could however do as listed above, break off one of the side connections of the OPS and then run the fuel pump on just the relay alone. Works fine.....until the relay fails. Then you will have to add the cost of a tow truck to the fix.
Is there a special socket to remove the oil sender? Or do I just go at it with Pump Pliers?
The oil pressure sender/sensor removes with a wrench placed at the very bottom fitting. Then you will need another wrench on the oil pressure tube fitting (square piece) to hold that in place so you don't break it. DO NOT remove or replace the sensor by grabbing it by the body and never use a pliers to remove any automotive bolt or fitting. That's what wrenches are designed for. Remember this is a TWO wrench job.. ------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, 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 "
[This message has been edited by Dennis LaGrua (edited 09-22-2014).]
The oil pressure sender/sensor removes with a wrench placed at the very bottom fitting. Then you will need another wrench on the oil pressure tube fitting (square piece) to hold that in place so you don't break it. DO NOT remove or replace the sensor by grabbing it by the body and never use a pliers to remove any automotive bolt or fitting. That's what wrenches are designed for. Remember this is a TWO wrench job..
doesnt look like there is room for tools in there. I guess a lot has to be removed to get to it??
