Greetings all. I recently picked up a '91 RS with the 3.1 V6 for a father son project for me and my 12 year old son. It doesn't run and we have been trouble shooting and discovered what appears to be a missing fuel pump relay with some rigged up wiring in its place. Here is what the relays look like next to the master cylider



So Im pretty sure this is at least part of our problem I have the repair manual for this car and have search and searched through the forums but cant find a pic of what this set up is supposed to look like. It obvious to me in looking at the wiring and the connections used that this is a rigged up way I think to bypass one of the relays that should be there. I read somewhere that the fuel pump relay will be the one with 5 wires and the others only have 4...is that correct? Can someone either point me to...or post up a pic....of what this set up should look like so I can get an idea of what on here needs to go so I can re-wire it back the way it's supposed to be. Any help is greatly appreciated!

Tim

 

:-)

 

Need a better pic/description of the relay wiring (colors) to know if it is the fuel pump relay or not... Either way, even if the relay isn't working, the oil pressure switch should turn the fuel pump on when there is oil pressure built up in the engine (approximately 15 PSI oil pressure, IIRC).

 

Ok....Ill get a better pic tomorrow when its daylight again and look to see what color wires run into the empty plug. In regards to the oil pressure....I can see where that would work as a fail safe to get you where you were going if the relay went out while you were driving but will the engine build enough oil pressure turning over at startup to get that 15 PSI to kick on the fuel pump?

 

Unless the oil pump is bad or there is a plug in the system somewhere, the oil pump will build almost full pressure when cranking. If the car won't start on the oil pressure switch, it's probably bad.

 

Ok...heres some more pictures and a few details that will hopefully help out and Im thinking I may have talked myself into figuring out what all this is.

This is the connector that appears to be missing the relay. There are 4 wires at the bottom red, black w red stripe, green w white stipe, and brown. In looking through the wiring diagram this appears to be the connector for the Coolant Fan Relay?


Heres the back side of that same connector where a splice has been made on the brown wire


and that splice on the brown wire leads to this


and theres a green wire...which Im assuming is a ground that goes from where all this is taped up and it is connected to the fire wall .. see below...


so...the last two relays that still appeared to be wired up correctly are here...



the one on the left in the picture has five wires...green w white stripe, black w white stripe, red, gray and orange...it appears this is the fuel pump relay? if that's correct how do I test it to see if it's still good? The one on the right has 4 wires and its hard to tell the colors...maybe red, 2 different shades of green and a light blue....and Im not finding anything that matches on the wiring diagram so any help on identifying that would be appreciated. Thanks for all the help.

 

The one with the gray wire is the fuel pump relay. Try swapping it with the other relay and see what happens. The missing one is the coolant fan relay, and the other is the relay for the A/C compressor clutch. The green wires on the fan and fuel pump relays are the signals from the ECM. The gray wire is the power out to the fuel pump... Try jumping this with the orange one in the same connector to see if the pump runs. As for the fan, try jumping the black/red wire with the red wire to see if the fan turns on.

 

OK cool....so is the small box with the "Made in Italy" just some kind of aftermarket relay they wired in to try and take the place of the fan relay?

 

Exactly. I have 2 of them in my harness as the relay connectors were shot for the old relays. And the fact that the newer relays are about $20 a piece for some reason. The one you have there is about $3.

 

Your other mystery OEM relay is AC

 

Awesome! Thanks for the help guys that definately points me in the right direction of what we need to do next!

Tim