1996 F350 7.3 low power

[Diablo Blanco]

1996 F350 7.3l 5 speed CC DRW. Build date is 2/96.
Truck came from a farm where it wasn't driven often. Fresh batteries and it started up with little fuss, idled rough for a few minutes then smoothed out. Replaced the fuel filter, cleaned screen, cleaned fuel bowl, replaced fuel hoses, oil change with Rotella and MoCraft filter when I got home.

While driving the truck the accelerator seems to have little effect on engine speed or power output. If I'm cruising and push the pedal all the way down it has the same effect as pushing it 1/8. As i let the pedal up from the floor, the engine seems to surge that last 1/8 of pedal travel. Truck will cruise at 75mph easy but it feels like a 10 minute ordeal to get there. I typically get 8lbs of boost under load but I have seen 11lbs. When driving below 1500rpms I get a shudder that shakes the cab but clears up after 1500 rpms. And cruise control doesnt work.

I have OBD Link MX and my Torque Pro app with some of the OBS PID's. No CEL's, pending or otherwise. I am getting what appears to be appropriate data from the TPS on the accelerator. The EBPV is free and appears to work properly.

 

[79jasper]

A couple things: clean the EBP tube and sensor.
How does the hose to the map sensor look?
Also try unplugging the ICP sensor and look to see if the connection has oil in it. But try driving and see it that makes a difference.
Feel/look around the up pipe connections for soot, which means you have a exhaust leak.
I would put money on the ICP sensor being a highly likely cause.

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[Diablo Blanco]

I will do the EBP tube and check the up pipe

MAP sensor hose looks fresh

I will check the ICP when I go off work tonight.

 

[79jasper]

A bad icp sensor can really act weird. Anything from dead pedal, erratic idle, to anything in between.

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[Diablo Blanco]

ICP sensor was clean and dry. I am also getting good data from it. ~500psi at idle and ~2500psi at WOT

The IPR on the other hand and drench in oil, the plastic connector receptacle is very loose. This sensor is giving erroneous data, the percentage climbs ~.4% every 2 minutes regardless of the what is going on.


Unplugged ICP and it started and ran the same as it has been.
Unplugged IPR and it was a no start

 

[79jasper]

Correct. You have to have the ipr to start.
With it running unplug the ICP and see if there's a change in idle. If no change at all, it's bad. You should get a good difference when you unplug it.
Usually a bad ipr will cause no hot start.

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[Diablo Blanco]

I thought I heard a slight hiccup when I unplugged it but it otherwise idled "normally"

 

[79jasper]

Should be fine then.

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[Diablo Blanco]

Fuel pressure 45psi at idle. When I connect the gauge, the idle stumbled and the CEL came on

 

[79jasper]

Did it bring up any codes?
You are talking about connecting the Bluetooth adapter right?

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[Diablo Blanco]

I used a steam gauge, I didn't check the CEL, it went away a soon as I unplugged the fuel pressure gauge

 

[1995voyagerES]

Last year I unhooked my MAP sensor (took the hose of) just to see what effect it has and it did what you describe.
No power at acceleration.

 

[greenskeeper]

Fuel pressure 45psi at idle. When I connect the gauge, the idle stumbled and the CEL came on

sounds a bit low, what is the fuel pressure under load? Could be a weak fuel pump which on your truck is in the valley powered by the cam.

fuel regulator screen clear?

 

[Diablo Blanco]

Last year I unhooked my MAP sensor (took the hose of) just to see what effect it has and it did what you describe.
No power at acceleration.

I will try that!

 

[Diablo Blanco]

sounds a bit low, what is the fuel pressure under load? Could be a weak fuel pump which on your truck is in the valley powered by the cam.

fuel regulator screen clear?

I didn't check it under load, yet...

Fuel regulator screen was cleaned last week. I bought the oring kit for the fuel bowl so I will tear it down and clean again possibly tommorow

It's starting to look like a fuel pump to me too. My friend wants me to put a vacuum gauge on the supply line from the tank to the pump