All -

The fuel pump on my '91 RS (orig. a 305TBI) will not start. I have checked the following -

1. Fuse under the hood.
2. Connection block near the battery.

I have not checked

1. Oil Pressure Sending Unit
2. Fuel Pump Relay

My question is this -

WHERE IS THE FUEL PUMP RELAY!?!? ...and what type of relay is it? I'm going to hit the parts store today and want to get all the possible parts, relay, oil pressure sending unit and a new fuel pump. I'll return what I don't need.

Thanks for your help!

 

The fuel pump relay is located behind the drivers side kick panel. Pull the panel and remove the relay. You can remove the cover and inspect the contact points or check it continuity with your ohm test set or take it with you when you seek out the correct replacement part. I'd go to the dealer for it myself, if you can still purchase that part from the general.

Good luck

 

Thank you very much for your help. I'll find it tonight.

 

WRONG WRONG!!!!!

The fuel pump relay is located under the hood, driver side firewall, between the brake booster and the fender. There is a bracket that holds 2 relays. They are both identical. Remove the 2 10mm screws to the firewall that hold the bracket on place, then swap the relays with the connectors. If your fuel pump relay is bad, now the fuel pump will run, but the electric cooling fan will not (test the cooling fan by switching on the A/C with key on - this makes the fan run no matter what the actual temps are).

Now - if you get confused as to which is which - the connector for the electric fan has a very large wire in it - it's black with a red stripe, and much larger (thicker) than any other wire there.

Also - did you check the fuses in the fuse panel under the dash? INJ 1 and INJ 2 - make sure they are good.

If the relay doesn't do the trick - test the pump at the OPSU connector first BEFORE assuming the pump is dead. Remove the fuse by the battery. Disconnect the connector from from the OPSU. There will be 3 wires in the connector - the larger two run the fuel pump, and the small one runs the oil pressure guage. Take a piece of paperclip, and jump the two connections for the two larger wires. Then, reinstall the fuse by the battery and see if the pump runs (this will make it run constantly as long as that fuse is in the connector). This will tell you if the pump is bad.

Good Luck!

 

Well, its been about 6 years since my last post, but Scott (YYZ28) has gotten me back into the 3rd gen addiction by working on his 91. Here's the deal


went to his house, turned the key. Acted like battery was low. switched relays, nothing. took off the OPSU, bridged the wires, heard the fuel pump prime and could smell fuel. with car off, pulled the throttle linkage on the carb and saw fuel drop in. charged it for 20 more minutes, reconnected OPSU, and car fired up. Ran it 4-5 times for 5 minutes a piece and no problem, although the Fuel pressure gauge on the carb would read up to 7-9 PSI, then shudder around, then go to 0, even though car was running fine. Kept it on the charger and fired it up before i left and it ran fine. Rode home on the bike, got a text from Scott when i got home saying it wasn't cranking at all anymore. He's got an Optima Red Top that is under warranty, so we are replacing that tomorrow. Oh, i left out a VERY important piece. Even when the car was running, oil pressure gauge was reading 0, so the OPSU is definitely shot. I'm changing that out tomorrow for him too. Hopefully that will get rid of SOME of the gremlins this car has!


Camaronewbie, your info was so incredibly helpful. Kudos to you! We'll let yall know how it goes tomorrow.

 

Also, OPSU and the harness wire were caked in grease. I'm going to the clean the hell out of the connector when i put in the new one. Thanks again!

 

Glad to be of help. Some other things to know about the OPSU:

1) it can go bad, and not allow the car to run. It may prime and run for a minute or two off that 'prime', but it won't run long. The 'priming' function is a result of the ECM sending a signal to the relay to turn the pump on - 2-3 seconds later the ECM stops sending the signal to the relay, the pump stops, and the only power the pump gets after that is from the OPSU (unless the key is turned off without the car being started, then the ECM will reprime the pump).

2) it can go bad in such a way that it makes the pump run constantly - regardless of where the key is.

3) if you ever go carb, you don't need the fp relay or the ECM anymore - since the carb has fuel bowls that are full enough to start the car, and as soon as pressure is detected the OPSU will run the pump. There's no need for the 'prime' on a carb, since it holds this fuel (unlike injectors that don't hold enough fuel to start)

Good Luck!