I just looked at my 93 EVTM and it shows that year the fuel pump relay is controlled by the PCM. Only 2 leeds go from the dist module to the PCM which might be to detect if the engine is running. PIP (profile ignition pickup) & an ignition ground, so looks like PIP is the source for the PCM to determine if the engine is turning sufficent rpm to pull up the fuel pump relay full time. The winding of the fuel pump relay is energized by a gnd from the PCM. 12V is on the other end of the winding. The gnd feed from the PCM is also on the VIP DATA LINK CONNECTOR (where you plug in your reader)

This EVTM is not as clear defining those functions as earlier years were (remember this is on a 93 bronco, dont know if the 91's had a similar PCM or not). I expect they all are the same on FI motors with Electrical fuel pumps.

This EVTM only shows 1 leed (gnd or to be PC, rtn) from the PCM to the winding of the fuel pump relay, and we know its good because you can "drive it down the driveway". I also dont see any designated leeds into the PCM to tell it anything else about KO to the fuel pump/relay. It appears that the problem is with the PCM, not the actual pump or its relay.

I havnt had a chance to to on-line to see if I can find a schematic for the 91. The wiring colors and connectors etc may change a little, but they are basically the same. Safety is the cause of the method of controlling the fuel pump. Hope this helps---at least some LOL

 

Thanks for that info. I guess I will just have to start learning more about the newer stuff. I have just always had the older Cars & Trucks & never had to worry about that many wires and plugs. After X-mass I will dig in and read everyones post's and start reading on-line about all of this new stuff. Again Thanks everyone for your help.

Bill

 

As states a few posts up, when the key is turned to run but engine not started the pump relay should click and you should hear the pump run for a second, then it should stop again. If the pump just stays on then either the relay is stuck closed or you have a bad PCM(computer).

 

Thanks Paul for that info, it sounds like I need a new ECM. Since it will not shift & the fuel pump just keeps running with the key just turned on. I guess I will try the junk yards first, I just want to get it running so I can trade it off. I have a 63 Ranchero with a 302,T-5 & 8" rear-end. The Bronco is in really good shape inside & out for a 91. The only rust I see is on the bottom of the tail gate, & its only on the bottom lip. I am fixing up a 21' Slickcraft Boat, I am making a small cabin on the front so we can take it out in the Gulf. And the Ranchero is just not big enough to pull & stop something with that much weight. So I hope to trade them both off for a nice project, that will pull the boat. Again thanks for all the help & info everyone.