Apologies to the forum if this has been drug through the weeds before but it's new to me and yes, I researched the threads.


Losing power on long hills (and a few short, but steep ones).


As long as I stay less than 1/2 throttle I can make it up the hill but, if being chased by traffic and I go WOT, the motor will do okay for a second or two then start to lose power, shuddering like a tire is out of balance.


I can get out of the throttle and the motor recovers - until the next hill.


It does fine on level roads although if I need to pass a car and floor it, the turbo spools up and I accelerate only for about 4 seconds then it loses power again.


I've been through two fuel pumps in the past three years and several filters. When the first pump was replaced I looked at the bottom of the pre-pump filter and noticed a lot of black specks/chips/crud in the bottom of the filter can.


-- 218K miles
-- Oil Pressure is good/full on the stick
-- Fuel pressure gauge jumps erratically between 50 & 70 PSI.
-- Plastic fuel tank (at first I thought I might have a delamination problem)


Going to change filters later today and see if there's a change for the better but I thought I'd bounce this off the group in case you had any troubleshooting ideas.


Thanks in advance.
Greetings from Spicewood, TX!

 

Electric fuel pumps should not be that erratic and might be the issue

 

Have you checked the tinnerman nut on the back of the IPR and made sure it is tight?

 

Wow! I think I just stepped in a pile of stupid! I know what a timmerman nut is....but IPR? <?> Pressure Regulator, perhaps?

 

It's the Injector Pressure Regulator. Here's a little diagram I just found.

 

Got it. Thanks.

 

Sounds like clogged in tank screens. Fuel pressure cannot keep up at higher demand.

 

I have seen that picture before and/but it does not show the correct placement for the IPR on our trucks, is that a pic from a T444E? The IPR sticks straight out the back of the HPOP on the right side of the motor when standing in front of it looking at it. It is tucked down low below some wires and fuel lines. I will look to see if I have a better shot.
And this is what I was thinking, quick short term fix can often be to blow air from the fuel line at the rear of the fuel pump back into the tank to clear the intake. Remove fuel cap before blowing the air through.

 

I was thinking of clogged screens as well. We'll tear down the old pre-pump filter later today and see if there's any debris. Wondering if I've got debris in the tank. Hoping I've not lost another fuel pump.

 

In this picture (courtesy of another member here) you can see the IPR barely stick its head out at about 1:30 to 2:00 off the fuel filter. There should be a nut on it made out of stamped steel, they seem to call it a Tinnerman nut but I don't know what it means yet.

 

I got it from dieseliq.com. I've never read anything on there before, so I don't know how accurate their stuff is- but at first glance out looked like a good diagram. Like you said though, it looks a bit off. Maybe it's from a diesel van? I've heard some of their stuff has different placements, but not sure what exactly. I like that other pic way better. Please forgive my ineptitude

 

A Raymond Tinnerman - Products


aka tinnerman


IPR in that pic is off.

 

That sounds like a clogged filter somewhere.... The OP mentions a pre-pump filter, is he referring to the intank filter or a filter someone installed pre-pump?

 

Maybe a clogged intake, or just a plain 'ol Hutch is needed. Can't yet rule out injector O-rings or a bad ICP sensor, though.

OBDII tools link in my signature is worth a click, and a data log will likely tell us all what's going on.

The IPR has probably been found already, but I'll share this shot of the valley "in-the-raw" - true truck ****:

 

Rich, your picture could be the centerfold for a diesel magazine!

So if the fuel pressure is jumping around, that is one problem, as has been mentioned-some type of restriction in the fuel line/filter/screen, etc. That would cause pumps to go bad prematurely, though. Also, if the fuel intake line to the pump is still stock, air infiltration is a good possibility if the pump is pulling air past those o-rings in the fittings.

But there is no guarantee that that is the cause of loss of power. As others have mentioned, IPR, ICP sensor, injector problems etc could be the cause. If the engine has been starving for fuel, the injector tips could have been damaged by air entrained in the fuel. It acts like sand paper. Poor atomizing because the holes are too large. Damage to the pintle perhaps?