02 Fuel system help

BRE

BRE

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May 19, 2010
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Alright, truck started to get the funky idle I've always put together with the fuel pressure regulator. Dad swapped a new one in, made the idle way worse.
He's been so busy at the shop he hasn't had time to swap another back in. He gets home the other day, truck won't start. He pumps the filter housing back up, starts. Don't remember the reason but he went back under the hood to pump the filter while running, said you can just continue to pump it no problem. Only thing, it starts getting injector rattle. Goes inside, rail pressure gauge is at 20 some thousand (don't remember exact number) wouldn't go down till he shut it off.
He showed me the same thing but didn't pump the filter up as much. Idle gets smoother, rail pressure climbs, gets more rattle obviously.... Then slowly drops rail pressure and idle goes to screwing up.

Filter housing cracked? Bad pressure regulator?
We have had a problem with this truck holding rail pressure under heavy throttle input before but he just drives it normal and it does just fine. He's looking to fix this problem ASAP though.

Truck is an 02 with nothing really done to it. Banks six gun, cold air intake, piddly bolt on crap that doesn't matter.

Any body have any pointers?
 
I feel like if youre dropping rail pressure with a banks six gun you probably have a larger problem than just a fpr. If you have a way to check the demanded vs actual pressure I definitely would start there, that should identify a bad fpr or something else. If you had to prime the system again to get the truck to start again it seems like air is getting in somewhere. I have changed a couple fpr's on various duramax trucks and have never put one in that has been bad right off the bat.
 
I told him to put a pump on it when it started that crap anyhow. You leave it turned up and gag on it and it will drop down to like 17k or something like that. I took video and put it on you tube. I'll see if I can't find it.
 
Check the filter housing and id double check the fpr. The bottom bolt especially on the lb7 those are a little tricky. I have never heard of a truck idling at 17k.. mine idles about 4200-4400.

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LlyDMax said:
Check the filter housing and id double check the fpr. The bottom bolt especially on the lb7 those are a little tricky. I have never heard of a truck idling at 17k.. mine idles about 4200-4400.

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No it doesn't idle at 17k, under hard throttle it will drop to 17k
 
Might be a bad cp3 then

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LlyDMax said:
Might be a bad cp3 then

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That's what I'm worried about. However, he ordered a housing rebuild kit yesterday. We will start there and see if we can diagnose any further after that gets taken care of.
 
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