intermitant problem
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Senior User
Joined: Dec 2006
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From: upstate central new york
intermitant problem
i have posted on here about the power loss on my v10 while loaded or unloaded well today i took my mechanic with me and drove the truck on one pass on the flats the truck would only rev to 4000 rpm and only get to about 80mph turned around made another pass and the truck reved to 5000-5500 and had all kinds of power got past 90-95 mph tried another run and reved to the 4000 mark if you manipulate the throttle it will shift and may rev higher one time the next no diff like i stated before i has no power while towing and it seems gutless it does not matter if the truck is warmed up or not still acts the same way. also only getting about 6mpg . my mechanic and myself looked at the exhaust as well it was only replace d150 miles ago and it appear to be blue from the cat back only mention this because most exhausts that i have seen seem to still keep there silver metal color and not blue so quikly any help please
Lead Driver
Joined: May 2003
Posts: 9,303
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From: Lyndonville, Vermont
First thing would be to check fuel pressure when it won't run right. That would take having a pressure gauge installed and monitored while you drive. No CEL I take it?
I'm guessing the direction change helped you because of going with the wind?
Dick
I'm guessing the direction change helped you because of going with the wind?
Dick
Lead Driver
Joined: May 2003
Posts: 9,303
Likes: 48
From: Lyndonville, Vermont
No check engine lights? what year truck?
Things that come to mind..
Clogged exhaust. Maf sensor dirty or bad. Messed up air filter. leak in intake plumbing.
clogged fuel filter..
Dick
Things that come to mind..
Clogged exhaust. Maf sensor dirty or bad. Messed up air filter. leak in intake plumbing.
clogged fuel filter..
Dick
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Lead Driver
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If you had a clogged cat ,he would not get anywhere near 90mph !
On this truck you have a fuel pressure regulator ,that is trying to regulate the pressure from your pump. If the pump is failing ,(which in the last few yrs on 99 -2004
there have been quite a few) it can't keep up at rpm under towing load .The pcm increases the pulse width of your injectors but there is not enough pressure to feed all 10 cylinders properly .
Maf
filter
air cleaner
IAC
plugs (proper plugs not off brand)
Is this truck a 4x4 have you chk to see that your front axles are not stuck in 4x
esof hubs will not unlock sometimes and it causes drag also (slight drag but enough to keep fuel mpgs down)Turn front axles by hand to see.
Good luck
Rich
On this truck you have a fuel pressure regulator ,that is trying to regulate the pressure from your pump. If the pump is failing ,(which in the last few yrs on 99 -2004
there have been quite a few) it can't keep up at rpm under towing load .The pcm increases the pulse width of your injectors but there is not enough pressure to feed all 10 cylinders properly .
Maf
filter
air cleaner
IAC
plugs (proper plugs not off brand)
Is this truck a 4x4 have you chk to see that your front axles are not stuck in 4x
esof hubs will not unlock sometimes and it causes drag also (slight drag but enough to keep fuel mpgs down)Turn front axles by hand to see.
Good luck
Rich
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Senior User
Joined: Dec 2006
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From: upstate central new york
truck is a 4x4 and the axles are free spinning. ok so i had my mechanic take the truck again today he put it on the coputer and drove 30 miles here are the findings. no codes ever thing is running perfectly by computer standards no codes coming back the o2 sensor was pulled and he checked for to much back pressure that checked out fine fuel pressure was perfect plug was pulled and it looked like new he said or fairly new. so all checked out but he said it is lacking power as i have stated before he is racking his brain on this one he said at times motor has no power and does not pull then at others pulls like a v10 should no idea rite now so we are going to wait a week or two and try againany other suggestions are welcome you guys have been very helpful so far in where to possibly look keep up the great work
Lead Driver
Joined: May 2003
Posts: 9,303
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From: Lyndonville, Vermont
As I said before you have to check fuel pressure when driving while its screwing up. No way you will know if the fuel system is causing the problem if you don't do this.
Do you think it might be a coil? many times 1 out of ten may be hard to notice
esp if it only does it under power.
Dick
Do you think it might be a coil? many times 1 out of ten may be hard to notice
esp if it only does it under power.
Dick
Last edited by 99f350sd; Jan 19, 2007 at 02:18 PM.
Thread Starter
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Senior User
Joined: Dec 2006
Posts: 166
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From: upstate central new york
how do you check the fuel pressure while under a load is it done by a coputer or what other way do you test it. no the coputer it does not show any misses on any cylinder and both mechanics seem to think they are fine how else would you test the cop's
Last edited by 900rr; Jan 19, 2007 at 07:09 PM.