I have a 98 Ford Ranger that won't start. It has a new fuel pump. The relay is not energizing the fuel pump at all. It seems to be getting power to the relay but not reaching the pump circuit. I have checked the inertia switch and it seems to be okay. I have switched relays around of the same value to no avail. Also have check a number of things but can't seem to get an indication of where the problem is. The scanner I have won't communicate with the computer in Generic mode for some reason. It is programmed up to 97 models but has the generic OBD II feature. Thanks for any help or suggestions. e-mail address is portcroz@msn.com

 

check pcm power relay, the fuel pump won't run without it, it can also keep the pcm from talking to your scanner.

check f9 on the fuse panel under the hood the 20 amp mini fuel system fuse.

Pull the connector off of the fuel cutoff switch. With key in on position, look for 12v on the dark green/yellow wire. If it is there, the relay and wiring is ok, it goes to the pink/black to the fuel pump.

If Not, pull the relay and look for 12v on the Light blue/orange pin 1. that comes from the fuse.
look for 12v on pin 2 of the relay, it should be ok from the buss. look for a ground on the light blue/orange wire. that comes from pin 80 on the PCM.

also look on dark green/yellow pin 5 of the relay 12v, that comes from the pcm for inital start then opens when fuel pressure is up.

 

Thanks Dave257 for your help on the fuel pump problem. I still haven't found the problem. I have checked all you said to check. The inertia switch has the 12 volt plus going in on a gray with stripe color wire, but nothing is coming out of the dark green yellow stripe or the pink with black stripe wire. Any other suggestions. Thanks again. I have went as far as I can go in knowing what to check.

 

The gray wire goes to the dash, don't worry about it for now. The pink/black wire goes to the fuel pump after it comes through the inertia cutoff switch. The green/yellow wire is the problem.
You need to pull The fuel pump relay and check for 12 volts on pin 3 of the socket. the light blue/orange wire. (with key on)
The relay should have the pin numbers on it somewhere.
Dave

ps; Did you check the fuse's and check to see if you have 12 on the fuse, with key on.

 

All fuses check out. The blue/orange wire has no voltage or minimal, coming from the fuel pump relay. So, I really don't know what is next. Thanks for the help, I am not sure what to check next.

 

Well the lightblue/orange wire is feed 12v from the 20 amp fuse. pull the fuse and check on both sides with you light/meter. One side should have 12 volts and the other will not have anything. IF there is no voltage at that fuse, alot of things would not be working.
Dave

 

The fuse checks out right on spec like you said. This thing is getting real interesting.
I used a multimeter so I know the voltage is there.

 

OK, the wire runs from there to the pin 3 on the relay. If 12 isn't on the relay the wire may be open.
Measure the resistance between the fuse side with no voltage on it and pin 3 on the relay. if it measures 0 then the wire is ok, if it measures high or open the wire is bad between the fuse and the relay.
Dave

 

Okay, I am getting a reading of 1880 ohms, and I suppose it should be infinity.
I checked the wire from the fuse no voltage and the relay wire light blue with stripe.
Again, I have to say in this instance I don't what the next step unless the wire is bad or shorted.

 

It shouldn't be more then a couple of ohms. looks like the wire/connectors are loose/bad. you will have to give it a good visual inspection.
good luck
Dave (i got to go to work)

 

Thanks for your help Dave257, I really appreciate it.

 

wincher, do you have a copy of the wiring diagram? Maybe I should post a drawing to make it clearer.
Dave

 

Dave257, I don't have a copy of the wiring diagram on anything related to that. I have a Haynes Manual, but the diagram shows a 94 Ford Ranger which is different. The inertia in their diagram shows 2 wires, this vehicle has 3 wires going to that switch. Those manuals are not for professional and serious tech work, my opinion. Only one wire is hot with the switch on at the inertia switch and that is the light blue with stripe. The green wire coming off the relay is not hot with the switch on. Thanks.

 

Wincher,
Open your email and I will send you diagram.
Dave

 

Dave257, I have my e-mail open, so what do I need to do?