Fuel Pump Relay Problem with a twist

[flyin '85]

Hey Guys,
It seems like there are quite a few on here that are having a problem with the fuel pumps not priming when turning the key on. I am having the same problem. I have a 1991 Mustang LX. Original V8 car.
Here's the twist, it has to do with wire colors and relay location. Everyone on here seems to have the Pink/Black wire and Blue orange wires going to thier relay (I know there are two other wires I just can't remember what they are). I don't my fuel pump relay has a Black wire with a yellow stripe and a plain red wire going into it(+2 others). This relay is located up front by my mass air meter. Thats one thing.
The other thing is that there is a relay under the seat and guess what, it has a pink/black wire and a blue orange wire going to it. I think that this is the WOT relay for the A/C though. Here's why I think that, I went and got a new fuel pump relay tonight and it fits on the plug up by the mass air meter with the red and black/yellow wires.
Can anyone PLEASE tell me what the hell is going on here ???? I have literally spent this entire past weekend reading through posts on here and haven't found anything.
I would like to find out what wires are what so I can figure out where to start with trouble shooting.

Thanks in advance guys !!!!

 

[liljoe07]

Fuel Pump relay should have a orange/black wire and a solid red wire also.

The relay plugs are identical, thats why one relay fits both A/C cutoff and Fuel Pump relays.

 

[flyin '85]

Hmm

Hey Joe,
First thanks for the reply, I feel like I am seriously screwed here so I really appreciate the help. Do you have any idea what the relay under my seat might be for then ??? It is smaller than the one I believe to be my fuel pump relay...

 

[ID89GT]

Fuel pump relay should be under seat, and WOT relay should be by MAF. They have the same connector, most the relays on the car do I think.

 

[flyin '85]

OK

Well I can do some more checking for you guys, should the WOT relay click when the key gets turned on as well ??? Because the relay up by the mass-air meter is clicking when I turn the key to KOEO. The relay under the seat does nothing.

 

[liljoe07]

Well I can do some more checking for you guys, should the WOT relay click when the key gets turned on as well ??? Because the relay up by the mass-air meter is clicking when I turn the key to KOEO. The relay under the seat does nothing.

Been a while since i messed with the A/C WOT relay so bare with me here......LOL...... But if Im not mistaken that relay will click and engage, it just shuts done when approaching WOT. As stated the Fuel Pump relay on the Lx should be under the seat.

Try this. Put the relay in the socket under the seat. Use a volt meter and probe the pink/black wire on the relay and a good ground

Use this diagram and and ground the Fuel pump trigger wire.
View attachment 237056

Then turn the key on and see if the pump turns on, or the volt meter registers Battery voltage.

 

[flyin '85]

Thanks liljoe !!!!

I will try this when I get home. For some reason I don't know if the relay that NAPA sold me for the fuel pump relay will fit in this socket but I will try it the minute I get home...
Also is the test port on the 91's still located around the brake booster ??? I have searched thru posts on the location of it I know on the 90's it was there but I am not sure if they have gotten moved.

Thanks Again !!!!

 

[liljoe07]

Same spot.....Over by the brake booster.

 

[flyin '85]

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Hey Guys, here's the deal. I went out to see if I could use the relay from out by my mass air meter and plug it in under my seat.
Just my luck, it will not work !!!! The relays are different. I figured you guys might like to see pics to clarify what is going on here.
The top one is the one I THINK is the fuel pump relay. The relay the parts store gave me when I asked for one matches this one.
The bottom one is the one under the seat. It will not accept the relay from the fender well. I THINK this is the WOT A/C relay only because the plug for it will only accept this relay, NOT the fuel pump relay that I asked for from the parts store
Problem is, the one under the seat is the one that has all the correct wire colors for the Fuel pump relay. So what the hell ??? I need to figure out what I am looking at so I can move on with the trouble shooting. Somebody shoot me !!!! I really need to get this thing squared away.

 

[liljoe07]

Go to the relay under the seat. Make a jumper wire, then jump the Orange/black to the pink/black and see if the pump comes on.

The A/C wot relay is always by the MAF meter on a Fox body car.

 

[flyin '85]

OK just went out there, the relay under the seat has 4 wires, Red, Green/yellow, Pink/Black and Blue/Orange. There is no black orange. I have battery voltage @ the pink/black wire so I tried to jump it to the orange & blue one and no luck. Do I have some sort of bastard car ???
I bought this thing from the original owner and it only has 14000 miles on it so I know that 50 different people haven't screwed with it.

 

[liljoe07]

My bad.....Jump the pink/black to the dark green/yellow. You should also have power to the red wire with the key on also.

 

[flyin '85]

Good NEWS !!!! It worked what might be bad news though is the fact that it didn't "cycle" I don't know if it will with the jumper in though. There is battery voltage @ pink/black all the time and with the key in the KOEO pos. the red wire has power too.
What do ya think ????

 

[liljoe07]

Its not going to cycle with the jumper in place. The ECM cycles the relay ground. With the jumper you have it hot wired and no ECM control. So for it to cylce the relay need to be in place.

Every thing else is fine power wise.

 

[flyin '85]

So not to re-state the obvious but the relay isn't doing its job then correct ??? If that's the case, the drug addict punk @ the parts store gave me the wrong relay too !!!!

 

[liljoe07]

Either that, or the ECM isnt doing its job. Get another relay first.

 

[flyin '85]

I will do that, I will take the relay in for a visual aid, I think I am going to try the ford dealer this time to make sure I get the right relay.
I just hope that I didn't mess up the ECM. I just completed welding up some of the holes in the engine compartment. The weird thing is that I worked in a bodyshop for almost 6 years and never took the computers out when welded.
Thank you so much for the quick replies !!!! I will be sure to keep you posted as soon as I get the new relay.
THANKS A TON !!!!

 

[liljoe07]

Posted via Mobile Device

No problem buddy. Ill send you a bill. LOL

 

[flyin '85]

Well that's not a problem, if this all works out it will be worth it !!!! Thanks again for the help !!!! Hopefully you will be around if I have any other problems once I get the pumps on.
I also did a little re-wiring with this project. All I really did though was take the huge chassis plugs out of the loom and solder the wires together to make the wire bunch smaller. I was VERY careful though and I had buddy look at everything just to make sure that the wires all went to the right wires. I have no problem doing it myself but with that many wires it never hurts to have a second set of eyes to double check everything.

Thanks again !!!!

 

[flyin '85]

update

Well as my luck would have it I got a new relay right from Ford and it didn't do *****. The new relay is a new design and it has one extra pin on top that goes into an empty socket on the relay plug. The guy at the dealer swore that it was the correct one for the application though.
So what's next ??? Ive got power, the pumps come on when I jumper them, I have a new relay and still nothing