'99 F250 7.3L PSD Issue- Suggestions

[drivadesl]

My truck has about 120K miles on it. I bought as lease trade in with 40K miles. Have performed the normal maintenance split between myself and Ford dealer. Also, use diesel fuel additive every 6 months or so if it matters. Put maybe 10k miles on it annually.

I noticed a little bit different of a sound in the idle in the past few months. Nothing major, but just something different. Normal around town driving truck felt fine, normal power and fuel consumption.

While trailering my tractor yesterday, roughly a 10K lb load, it pulled fine on normal grades, but when I tried going up a pretty steep mountain that I've done many times before with same trailer, it pretty much came to a stop. No power. Had the pedal to the floor going 1mph....in low gear. Engine did sound like it was laboring a bit, but didn't blow smoke or otherwise show any other signs of issues.

After unhooking trailer I was able to drive home 90 miles with no issues. Truck felt normal. Leaves me scratching my head.

Tranny fluid was changed in the spring, and did not smell burned and was at proper level. Same with oil, fuel filter and air filter, all changed within past 5k miles. Trailer was inspected a few weeks back no issues. Tires were inflated to 80lbs, and were not overheated or dragging as far as I can tell.

Did a cursory inspection of the engine, nothing appeared obviously wrong. Turbo hoses showed no obvious cracks or damage.

Any ideas of where to start? Possible fuel injector issue?? Any suggestions on what to check before I take it in? Thanks.

 

[cowski]

change the cps sensor

 

[tcartwri]

Cooling fan relay went on ours, and the cpu put the truck into limp home mode. Would not pull the trailer, and would go no faster than about 50km/h unladen.

 

[Highbeam]

It is not the CPS (that's an all or nothing thing) and there is no coolant fan relay. Did you get any check engine lights? No smoke and no power means you have a fuel supply issue. Change the fuel filter again, it only takes one tank of bad fuel to plug up the filter. The fuel pump is suspect at this mileage as well, it is frame mounted and is supposed to make 70 psi in the system.

 

[PoorPlowboy]

It is not the CPS (that's an all or nothing thing) and there is no coolant fan relay. Did you get any check engine lights? No smoke and no power means you have a fuel supply issue. Change the fuel filter again, it only takes one tank of bad fuel to plug up the filter. The fuel pump is suspect at this mileage as well, it is frame mounted and is supposed to make 70 psi in the system.

Fuel and injector pump are both suspect to me at this mileage. Neither were designed for ULSD. I would highly recommend a lubricity additive at every fill up, rather than every 6 months. I like Power Service,though it is spendy.

 

[Turbys_1700]

Sounds like a fuel delivery problem...
My fuel pump puked out couple years ago...
They can't take that ultra low sulfur diesel...
When mine went out it was like turning off a switch...
Nothing...
I would thing you may have an injector failing...

 

[Ken]

I help drive with a 2000 7.3 and your description could be fuel filter and water in fuel.
Remember filling tank in St. Louis and going west at every hill had to pull over and drain filter. at Springfield unloaded the cattle and returning toward Ill. no problems. Again loaded the trailer with cattle and no problems until hill climbing and engine would just almost stall. got to where changing filters didn't correct . At Ford Service dept they found the filter into the injector pump was also clogged.
Now have 270K and engine still runs good. So my learned skill of draining fuel filter and replacing filter haven't been needed.
Hope this helps.
ken

 

[drivadesl]

Thanks for the great replies. Sounds like fuel filter is easiest place to start. How do you test for fuel pump and/or injector issues??

There were no dash lites on at the time.

It must be a minor issue, since the truck pulled the 10K lb load fine until the big hill, but need to find out what it is....

 

[deerefan]

Throttle position sensor, i think your truck has one. My 97 F150 did the same thing and the tps was the culprit.

 

[Highbeam]

The 7.3 diesel does NOT have an injection pump nor does it have a throttle position sensor. It is a diesel with no throttle plate. There is a throttle pedal location sensor in the cab that is not typically an issue.

Fuel filter is right on top and easy to swap. You can even check it for muck covering the element since it is a naked element and look for muck/water in the bottom of the bowl. There is a fuel bowl drain lever, yellow and on the back of bowl, to just dupm out the fuel bowl and maybe observe water or muck.

If the engine idles smooth (for a diesel), starts well, and runs well then your injectors are fine. You aren't likely to loose all injectors at once. You have a fuel system failure so the big single parts are the culprit.

 

[foreman Etexas]

change the cps sensor

When mine was bad the truck(97model) would die every now and then,but doesnt sound like hes having that issue yet but would be something to go ahead a change its a really easy change out. Now my 99 I had problems with my injection cups but you would see the antifreeze getting back into the fuel filter it didnt smoke or anything at first just didnt pull that well just lacked power,I just thought the loads were heavy but then after a fill up made it about 15miles and water in fuel light came on and truck is now in the shop needs everything should have cought it earlier my fault,leason learned.

 

[Soundguy]

If it's not making smoke, and seems to drive fine, I'd take it ut on the interstate and see if it will open up with the turbo like it should. by now you should be familiar with how the truck handles when you put a foot in it.

see if it still does that.

any time i even think I get water in my fuel, in goes a container of seafoam.

Of course.. I alternate between adding PS white bottle, silver bottle and water dispersant at each fill up.. i have also treated my tanks with biocide .

the extra treatment is if I suspect water did make it in.. etc.

soundguy

 

[PoorPlowboy]

The 7.3 diesel does NOT have an injection pump nor does it have a throttle position sensor.

Please pardon my error in calling the high pressure fuel pump that feeds the injectors an "injection pump." My point remains that it was not designed to handle ULSD without lubricity additives.

 

[Ryan03]

Please pardon my error in calling the high pressure fuel pump that feeds the injectors an "injection pump." My point remains that it was not designed to handle ULSD without lubricity additives.

The "pump" on a 7.3 is a high pressure oil pump. Fuel never enters the pump, just engine oil. Not sure if you were talking about the hpop pump or the electric fuel pump on the frame. Improper or contaminated engine oil can cause all sorts of driveabilty issues an 7.3's. I would suggest spending $75.00 and finding a diesel tech with a good scanner that knows how to use it to diagnose your truck. Otherwise you are playing pin the tail on the donkey.

 

[pilot-werx]

It is not the cps. The last time one of my trucks acted like that it was a short in the injector wiring harness...

 

[Soundguy]

i see there are a few here not familiar with the PSD...

soundguy

 

[Ken]

The 7.3 diesel does NOT have an injection pump nor does it have a throttle position sensor. It is a diesel with no throttle plate. There is a throttle pedal location sensor in the cab that is not typically an issue.

Fuel filter is right on top and easy to swap. You can even check it for muck covering the element since it is a naked element and look for muck/water in the bottom of the bowl. There is a fuel bowl drain lever, yellow and on the back of bowl, to just dupm out the fuel bowl and maybe observe water or muck.

If the engine idles smooth (for a diesel), starts well, and runs well then your injectors are fine. You aren't likely to loose all injectors at once. You have a fuel system failure so the big single parts are the culprit.

O'k missed named the "thingy" that receives the fuel after the fuel filter. This is where the Ford mech. removed the fuel blockage after I had stopped about every 15 miles and drained the filter when the water in fuel light came on. And purchased filters at anyplace that had one for the engine.New filter could get maybe 30 miles. Yes the filter is easy to reach and drain. under normal conditions.
ken

 

[deerefan]

i see there are a few here not familiar with the PSD...

soundguy

I am one. I was wrong about the tps, thought it had one but was quickly corrected.

 

[tcartwri]

and there is no coolant fan relay..

You're right it was introduced in 2003. My error.

 

[firefighter9208]

What is your build date??? Pre- December 1998 or January-June 1999. The January 1998-Dec 1998's were titles as 99 models, but had a few different features. The Jan. 1999 thru June were unofficially called 99.5 models by a lot of people.

Do you hear the turbo whistle???

Do you hear a loud "air escaping" noise??? Could be the turbo boots are leaking and not building boost.

There is a TPS, actually two, on the throttle pedal. They are not serviceable, you have to replace the pedal assembly. Usually you get a "dead pedal" when they go out though. The truck will idle, but that is it.

I would go over to Diesel Forum - TheDieselStop.com and post your questions there in this 7.3L Power Stroke Engine and Drivetrain - Diesel Forum - TheDieselStop.com forum. There are some real knowledgable guys there that can help you.


You will have to create a username and password. I suggest that you use the same one you use here, I do, and you'll probably recognize a couple guys from TBN over there.

Chris
Chris