Boost goes down as load goes up
Thread Starter
|
Cargo Master
Joined: Sep 2007
Posts: 2,470
Likes: 535
From: Chandler, AZ
Boost goes down as load goes up
Still trying to get my 2000 PSD to run properly. All the easy stuff has been checked, probed, cleaned, tightened, cussed at, ect.
I loaded the stock tune and observed some strange behaivor at WOT;
1st gear = 14 psi, 800 dregrees
2nd gear = 12 psi, 850 degrees
3rd gear = 10 psi, 900 degrees
From what I have been told low boost and low temps are a lack of fuel. I probed the ICP sensor to see if the HPOP is dropping pressure as well,
idle = 1 volt
1st WOT= 3.6v
2nd WOT= 3.5v
3rd WOT= 3.4v
With a tune in the truck the numbers are the same in 1st, 2nd & 3rd. The truck runs fine other than lack of power. from what I have read the IPR can be clogged, but the truck should idle and run rough if so. No SES light or DTCs.
Any ideas what would cause this? As far as I know the injector pulse width is the only other thing that directly effects fueling. (temp, MAP, and other things effect pulse width)
My next step it to temperarily hook up a fuel pressure gauge and check out the pressure throught the gears.
--------------------------------------------------------
2000 F-250 PSD Lariat - 60k miles 4" lift, 35s, Superchips, 4" exhaust, gauges, 6637, CCV mod, 1000W stereo, car seat.
I loaded the stock tune and observed some strange behaivor at WOT;
1st gear = 14 psi, 800 dregrees
2nd gear = 12 psi, 850 degrees
3rd gear = 10 psi, 900 degrees
From what I have been told low boost and low temps are a lack of fuel. I probed the ICP sensor to see if the HPOP is dropping pressure as well,
idle = 1 volt
1st WOT= 3.6v
2nd WOT= 3.5v
3rd WOT= 3.4v
With a tune in the truck the numbers are the same in 1st, 2nd & 3rd. The truck runs fine other than lack of power. from what I have read the IPR can be clogged, but the truck should idle and run rough if so. No SES light or DTCs.
Any ideas what would cause this? As far as I know the injector pulse width is the only other thing that directly effects fueling. (temp, MAP, and other things effect pulse width)
My next step it to temperarily hook up a fuel pressure gauge and check out the pressure throught the gears.
--------------------------------------------------------
2000 F-250 PSD Lariat - 60k miles 4" lift, 35s, Superchips, 4" exhaust, gauges, 6637, CCV mod, 1000W stereo, car seat.
Senior User
Joined: Nov 2006
Posts: 160
Likes: 0
I had a similiar problem as you, back over the summer, it ran fine at part throttle & under light accelleration, but under a load I would get almost no boost, maybe 10psi at the most. What I found was the connector on the fuel pump had come off. The only reason I can think that it would run at all was the lift pump I had installed was able to push enough fuel thru the stock pump to keep her runnin.
Thread Starter
|
Cargo Master
Joined: Sep 2007
Posts: 2,470
Likes: 535
From: Chandler, AZ
fuel pressure test results
I plumbed a fuel pressure guage out to the cowl;
idle = 60psi
throttle tip in = 70psi
WOT = 50psi
the WOT number seems suspicious. IF this is a problem, what to do next?
- replace fuel pump
- check return regulator on fuel bowl - free - would a weak spring or debris cause this?
- drop tank and check fuel pickup - free - only 60k miles so probably not to dirty
any thoughts would be appreciated, thanks
idle = 60psi
throttle tip in = 70psi
WOT = 50psi
the WOT number seems suspicious. IF this is a problem, what to do next?
- replace fuel pump
- check return regulator on fuel bowl - free - would a weak spring or debris cause this?
- drop tank and check fuel pickup - free - only 60k miles so probably not to dirty
any thoughts would be appreciated, thanks
