I run a 97 F-250 7.3l diesel for my work truck. Yesterday, while pulling a trailer up a hill, the truck bogged down, totally lost power, and I pulled over to the side of the road. It started back up, but started roughly.

Pulled into a Ford dealership (I was far from home). They ran the error codes, got only a PO603 which they said indicated the presence of a chip. He checked fuel pressure at idle, and did some more tests, finding nothing. We replaced the fuel filter.

40 miles later the same thing happened, and then after that it happened every 3-5 miles, while we limped to a dielel injection repair place. After the loss of power, we had to shut the truck down for 3 minutes or so before it would have power. It would have power for a few miles and then quit.

The diesel place did another scan, came up with a PO340 and replaced the cam position sensor. No better. He installed a fuel pressure guage and we took it out for ride. It was up around 50psi just idling and then around 30psi while driving very gingerly. It did fluctuate a bit, sometimes going down to 5psi and then jumping back up. Then after a couple of miles, it would go down to 0psi, and the total loss of power would happen, and we would have to wait a few minutes before starting the whole thing over again.

Any help or ideas would be wonderful. The mechanic wanted to replace the fuel regulator and then the lift pump in that order, but he said he didn't really have an idea what the problem is.

I dropped the trailer and was able to limp the truck home for 120 miles, going between 45-55mph the whole way. One time I tried to take it to 70mph, and the power problem acted up again, and we had to shut it off and let it rest.

I really need to get this truck up and running in the next week for a big job. Any ideas?

 

Could be fuel pump, it should have 50psi or higher going down the road.
FPR Fuel pressure regulator may be stuck or the FPR screen is plugged. The FPR is located on the passenger side of the filter housing.
https://www.ford-trucks.com/forums/5...mming-fpr.html

If you have 2 tanks switch to the other one.
If the tank is low on fuel fill it. The fuel pickup tube in the tank may be cracked or broken/

 

Could also be some junk floating in the tank then getting sucked up in the screen. like jim said try switching tanks if one is full. The fuel pressure is low but it could be a restriction. Do what Jim said and give us a yell back.

 

You have to do an idle fuel pressure test. Then a WOT fuel pressure test.
To do the WOT test remove the chip first (may have higher RPM limiter if any). Just hold the pedal to the floor(30 to 60 seconds). If it cannot maintain pressure its the fuel pump. The fuel pump is a 2 stage pump.

Bill

 

Thanks for the replies. I am working long days and just now got back to the computer. I have switched tanks, same problem. One of the mechanics yesterday cleaned out the screen in the fuel pressure regulator.

What does WOT stand for?

Any other ideas besides putting in new fuel pump and/or regulator and seeing if that works?

Thanks,
Jason

 

wide open throttle.
you need to run the test at full engine load while driving, spec is 30- 80 psi, avg is around 40, if it falls low, which i beleive you said it will drop to 0, then check the fuel filter, you said its new, after that make sure the regulator isnt sticking. its the 3\4 bolt just to the right of the filter housing, has 2 10 mm bolts holding the block to the filter housing. remove the 3\4 nut and pull the cap, spring and plunger out. you may need a magnet to get it out. it should move freely in the bore. if that checks out then you need to get a vacum gauge on the fuel line to measure for a restriction. "T" into the larger line on the driver side of the engine near the motor mount, if you have more then 6-7 inches of vaccum you have a restriction before the pump. if its ok then replace the pump.

 

c00n

You can test the high side of the fuel pump under no load. Same as an oil aeration test. I just put it on the rev limiter at WOT.
Just be shure to remove any tunes!
99.9% of the time its the high side of the pump.
50% of the time you can see the failure. When you remove the pump, look in the outet side (banjo bolt) you will sometimes see the seal is torn.

Bill

 

just givin out the official method just incase he doesn fall into the norm, i dont want to confuse anybody. my luck he will fall into the other 50% and be down the wrong track. if i were there with my hands on it, of course i would treat it different, but when dealing with a roadside repair and an owner thats in the dark, i'll go right down the manual to prevent confusion, and if he does get mixed up i can scan the documents on and ship 'em over for clarification

 

Thanks for the replies. I will test things out this weekend when I get back from work (I took my other truck). The mechanic did take out the regulator spring and plunger and said it seemed to work fine.

The mechanic looked for a chip, but didn't find anything. He said it might be with the cpu- if there is one in there, how do I verify or remove it? I recently bought this truck from my old boss, and I know he didn't add a chip, but I am not sure if the previous owner did.

I really appreciate the help here. Thanks!

 

if batts got too low or if you lost a fuse at some pioint the code can be stored,

 

c00n

My thoughts are its safer to go WOT in your driveway than the hwy.

That brings up a question.
Why do we park on driveway's and drive on parkway's?

Bill

 

why does night fall but only day breaks?

 

Bill

 

is my cup half full or half empty

 

just wandering, what is the factory rev limiter set at?

Franklin