V-10 Poor running under load
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V-10 Poor running under load
Hi i have a 1999 6.8 liter. It started running really poor about 2 weeks ago. I changed out the fuel filter, gas filter, air filter, spark plugs, 7 coils, mass airflow sensor. The truck is still running the same. It runs great at an ideal. When you start to drive it runs good for about 10-15 minutes the spitting & sputtering and i can't go over 1500 RPM'S. I shut the engine off for 30 seconds and it's cleared out for 10-15 minutes and back to spitting & sputtering again. Any ideas what what I should do next. Thank You.
Last edited by knberberich; Mar 17, 2013 at 06:18 AM. Reason: v10 poor running under load
New User
Joined: Sep 2006
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From: Calgary Alberta
Fuel pressure numbers you have are too low.Shoud be no less than 32-35psi at running idle and 42-45 under load.Double check those numbers under the conditions listed and verify.
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I did the fuel pressure test again. I have 26 PSI when the truck is in park running and when i put the truck in drive and run it up to 1500 RPM'S the pressure drops to 22 PSI. Could that mean i have a weak fuel pump.??
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Lead Driver
Joined: Dec 2012
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From: Tennessee
Yes that pressure is too low .
More Turbo
Joined: Jul 2010
Posts: 535
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From: California High Desert
Just from what I can remember from reading the V10 forums for the last couple of years it is more likely the fuel pump than the fuel pressure regulator.
You can either do it from below and drop the tank, or you can remove your bed and do it from above without removing the tank. I understand removing the bed is the easier route if you have a couple friends that can help you lift it off, but you will most likely have to cut some bed bolts and replace them since they like to seize.
You can either do it from below and drop the tank, or you can remove your bed and do it from above without removing the tank. I understand removing the bed is the easier route if you have a couple friends that can help you lift it off, but you will most likely have to cut some bed bolts and replace them since they like to seize.
Elder User
Joined: Feb 2006
Posts: 545
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From: FL
Here is a method to test fuel pressure regulator:
(This is from V-10 forum archives posted by the moderator art k.);
"Should be 28-30 at idle, 38-40 with vacuum disconnected at the regulator.
Try that first, disconnect the vacuum at the regulator and watch the gauge. If it doesn't change, and there is vacuum on that hose, the regulator is obviously bad. "
Good luck,
(This is from V-10 forum archives posted by the moderator art k.);
"Should be 28-30 at idle, 38-40 with vacuum disconnected at the regulator.
Try that first, disconnect the vacuum at the regulator and watch the gauge. If it doesn't change, and there is vacuum on that hose, the regulator is obviously bad. "
Good luck,
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Okay I think I found the problem. I dropped the fuel tank and found the 2 pump screens on pump we're so gummed up I can't believe it ran at all. I cleaned out the tank and installed new fuel pump. The truck runs like a raped ape. I think it runs as good as new knock on wood. Thank You
Lead Driver
Joined: Dec 2012
Posts: 7,870
Likes: 47
From: Tennessee
Okay I think I found the problem. I dropped the fuel tank and found the 2 pump screens on pump we're so gummed up I can't believe it ran at all. I cleaned out the tank and installed new fuel pump. The truck runs like a raped ape. I think it runs as good as new knock on wood. Thank You
. Thanks for posting the fix 
.