OK, I've got a 1998 Ford F150 Flareside with a 6 cyl 4.2L engine. Coming in the driveway the other night, it just stalls out. I turn the key and it cranks, but won't start.

I looked in the Fuse Box in the Engine compartment and Fuse #24 (PCM Power Relay, Engine Fuse Module, Fuse 1) is blown. So I replace the fuse and as soon as I turn the key in the ignition, it blows again.

So, I replaced the EEC Power Relay and the Fuel Pump Relay, stuck another fuse in and get the same result. Any help would be greatly appreciated! Thanks!

Art Plummer
aplummer@comcast.net

 

Hi Art and welcome to the forum
Any luck with it yet?
Fuse 24 sends power from it to the PCM relay and then out to the Engine Fuse Module on a yellow with black wire. The Engine Fuse Module is located right near the Fuse Box. I think that all it has in it is a 5A fuse but I could be wrong. I would have to say that the wire is shorted to ground somewhere between the Fuse Box and the Engine Fuse Module.
Off hand I cant think of anywhere in particular that it would short out so you'll probably just have to follow the wire and see what you find. It could be rubbed through on a bolt or something.
Let us know what you find.

 

OK, I took out Fuse 30 and turned the key and fuse 24 did not blow. Does this help at all? If I put Fuse 30 back in and turn the key, fuse 24 blows.


I need my truck! Thanks for you input.

 

The shop manual doesn't show a fuse 30.
Do you know what the fuse is for?

 

It's not the Power Distribution box fuse, but it's in the Passenger compartment fuse panel. It's fuse 30 and says it's for "Radio Noise Capacitor, Ignition Coil, PCM Power Diode"

 

Ok when you pull fuse 30 the PCM relay wont power up anymore. That would mean the short is on the "out" side of the PCM relay then. From the PCM relay power goes out on the red wire to the PCM, the MAF, the Vapor Management Valve, Canister Vent Solenoid, Fuel Pump Relay, the transmission, the O2 sensors, the injectors etc. Basically anything that the PCM turns on and off and needs 12V to run.
I would look for pinched or rubbed through wires above the transmission, along the frame behind the L/F wheel and at the canister above and behind the rear diff to start.
It might be a hard one to find
Let us know how it goes.

 

It could have had the famous harness dropped on the EGR tube/exhaust manifold on the passenger side just before it runs over the transmission hump back to the TR sensor/O2 sensors and burned thru the harness.

 

So Racerguy, follow that Red wire around ???

Thank HomerWinzlow for that advise, I'll check that first thing in the morning along with Racerguy's advise. I'll let you guys know what I find. Thanks!

 

Guys, I can't find anything. Looks like it has to go in the shop.. yuck!

 

Good luck with it

 

Did you ever figure out what the problem was?My 1997 4.2 F150 is doing the same thing.It only pops the fuse while it is cranking though.It will like fire 2 cylinders and then shut off and the fuse is blown.Only does it sometimes too.2 times in the past month and I have no clue what it is.

 

...Welcome OrangeF150, to Ford Truck Enthusiasts! Please read the Guidelines, it will help you to navigate through and understand this site.

Stick around someone will be by shortly to answer your question.
We are happy you have chosen the best source for Fords!

Enjoy FTE....and
JOIN CLUB FTE -SUPPORT THE FORUMS!
…..See you on the boards.

 

Will start then blows #30 pcm ignition fuse and will then crank but not start.

 

Check your pcm power diode in the power distribution box. It's possible the radio noise capacitor for the coil can short also.

 

someone resurrected a 15 year old thread.