The usual #30 fuse blowing,but fuel bowl heater has been disconnected for a year??

[Ironworker709]

first off..2000 F250 4x4 extended cab,short bed 7.3 auto..hypertech III programmer,4 inch magnaflow stainless exhaust...around 270k miles..

Ok folks..about a year or so more,this forum really helped me,my fuel bowl heater went bad,kept blowing #30 30 amp fuse,so i unhooked the fuel bowl heater and it has been running flawless ever since,i live in sotuheast Georgia,so cold nights has been no problem...
..........untill this morning...It suddenly died and found the #30 fuse blown..luckily,it only happened about a 1/4 mile from my house so we pulled it home with the My Jeep...

For the past hour or so,i have been under the hood,looking for shorts at plug ends..bowl heater plug,wastegate sensor plug(whatever the right name..lol)...i can see no visible bare wires or shorts anywhere so far,but i haven't got REAL deep into the harness under the hood,just at the plug ends maybe about 5 inches or so....

This thing immediatly pops the #30 fuse with a pretty good LOUD pop blowing the fuse when i put a good one in and turn the ignition key on..I've went through a box of them so far...lol

I also found another plug below the fuel bowl heater plug..at the VERY bottom of the fuel bowl but on the driver's side,when i pulled the plug,,the plug end was totaly soaked in fuel...so i cleaned it well with a contact cleaner and dried to do the best i could and checked for shorts in the wires..,..left it unplugged and still blows the fuse ....i am assuming this plug end has something to do with the water in fuel sensor?..not even sure if this end is in the #30 fuse anyhow?
The oline Manual i downloaded says the #30 fuse supplies --PCM Relay Coil, Ignition Coil (Gasoline

only), Fuel Heater (Diesel only), Wastegate
Solenoid (Diesel only), Injector Driver

Module Relay Coil (Diesel only)---

I've checked all the usual suspects that has been suggested in this site,but still havent really toe into the bigger parts of the wiring harness and checked there....

I remember reading somewhere that there is a harness under the valve cover that is common to rub and short out..could this be the problem too?

Looking for suggections as where to look and some process of elimination suggections to try and pin point the problem...

Someone suggested as a process of elimination is to hook up a 12 volt light in the place of the blown fuse..turn on the ignition and move wires and plugs around untill the light goes off or flickers to help pinpoint the short....i'm kind of leary of doing that for the fact i would think your eliminating safety of a fuse and while searching for the short it could actualy do some serious damage to the harness or other things while the short is grounding out..am i right?....is there a safer way to do this?..maybe with an OHM meter of some sort..i have one..but i am not an electrical wiz....lol

Any help will be appreciated deeply here.......

[Ironworker709]

OK..i "THINK" i found the problem....one of the relays under the hood..when i take the 3 big ones out,no blown fuse..and when i keep all of them out and use the middle one that says it is just the heater relay on either end of that one..the fuse doesn't blow ...closest to the firewall is supposed to be the PCM relay,and the 3rd from from the firewall is the one that controls the Injector Driver Module...both of these i assume runs off the #30 30 amp fuse under the dash.....

I tried the heater relay on both the other ones and no blown fuse..so it seems the relay is the problem........

Soooo..off to the auto store to get new ones,i might as well rerplace all 3 of them,all 3 of them have the same ford parts numbers on them,so i assume they are all the same...

Crossing fingers that it was something so simple...lol

[klhansen]

Yes, the PCM and IDM power relay control circuits are what's fed by Fuse #30. So very likely one of those relays melted down and caused the fuse to pop. It's the control circuit that would have had to short to ground, which seems like a strange failure mode for the relay. If it were me, I'd be breaking the cover off the relay to investigate what went wrong.

They are standard Bosch type relays (rated for 40A load), so they should be readily available.

Good sleuthing.

Hope that fixes it up for you.

[Ironworker709]

I am thinking it may of been sticking or something..because it's running again..took it for a good drive and no problems...
But the store only 2 of them,i was going to go ahead and replace all 3...
So i kept the one that was in the heater motor slot and used the other 2 new ones...

I wanted to see which one was the bad one and keep the other for a spare..funny thing is...when i put them all back in to see which one was bad,they didn't blow a fuse??..maybe it was just stuck and when i pulled it shook it loose?..don't know..i'm baffled now. lol

One other thing that i think could of been wrong..is the one plug i mentioned that is below the fuel bowl heater plug,on the driver's side at the very bottom of the fuel bowl..there used to be a rubber type sealer in the plug where to 2 wires went into the plug from the harness,but the sealer was mostly gone ,and as i said,that plug was SOAKED in fuel(that's another thing i will look at tomorrow,make sure my fuel bowl top is sealed right because i seam to have fuel coming from somewhere in the back at that area and getting things a bit wet)...
Tomorrow i am goin to pull that plug again and put some type of good sealer in it again to seal it off,i am thinking it could of been the culprit and when i pulled the plug and had it standing up in the air,it eventualy dried out and stopped shorting between the 2 wires at the connection......

So i'm not totaly finished with this yet..lol..couple more things to take care of tomorrow that will hopefully stop it from happening again....find and fix fuel leak..and seal of the plug...

By the way..what is that plug?...the truck wouldn't start without it plugged in..just crank but no fire....

I can take pics and post if needed tomorrow..gettin dark now.........

[tinman13kup]

It sounds like you are talking about the IPR plug. No, the truck won't start without it.

[klhansen]

I'd agree that sounds like the IPR plug. I don't remember whether it's on the fuse #30 circuit or not. I'll have to check the wiring diagrams later.

[tinman13kup]

What I'm seeing is that the ipr comes off the switched side of the pcm relay, being fuse 24, which also feeds the iah, gpr, fp relay (coil side), and brake pressure switch.

[Ironworker709]

So in other words,it has nothing to do with the #30 fuse inside the truck?...

I'm still going to seal the plug and investigate the fuel being all over behind the fuel bowl and down inside top of the engine though.

Thanks for all the help guys!..if me not being pretty savvy at process of eliminations and places like this?..i'd be out a bunch of christmas money for the grand kids..lol

[klhansen]

Originally Posted by tinman13kup

What I'm seeing is that the ipr comes off the switched side of the pcm relay, being fuse 24, which also feeds the iah, gpr, fp relay (coil side), and brake pressure switch.

Yep, just checked and found the same thing.

But if it shorted out it would take out Fuse 24 and kill power to the PCM also. Fuse 24 is a maxi-fuse under the hood.

[Ironworker709]

Thanks a bunch klhansen!.....i stink at electrical..lol..but once i get my head into something and bound and determined to find the problem myself,i usualy win ,but sometimes a long journey in the process..lol.

Anytime i've had any problems(the very few in the past 4 years or more i've owned it) i come here and search and if i don't find the answer,i get very reasonable and quick answers here..you guys ROCK!...

I'll finish up tomorrow and take care of the leak and wiring i mentioned...then i can get back to my plans of finishing some work on my Jeep Wrangler to make it road worthy instead of offroad only..and then...a good lil job..new Moog Ball joints on the F250!..lol...fun fun fun........!!

I love my trcuk..wish i would of bought one many years ago,,.,...the most reliable vehicle i've ever owned..just a few minor hiccups thats totaly understandable for a vehicle with 270k+ miles,......

I had a buddy told me a few weeks ago i should trade it in and get a new truck...i asked him how much he pays a month for his....and then told him at worst i MAY have put 1000.00 into mine since i owned it(besides regular maintenance)...he had no more "money saving" ideas for me then...lol