Code P0087?

C

chevyota84

New member
Working on a stock 2003 duramax that keeps throwing a P0087 (low rail pressure). the truck suddenly loses power and can barely maintain 25 MPH followed by the CEL light coming on. The fuel filter was changed and the problem still exists. I looked a little further and noticed that someone had previously added a small carter electric lift pump on the framerail. The rubber hose connections there seem to be seeping fuel. I cleaned the area very well and tightened the clamps but with the engine off and key on wih the pump running, fuel leaks at a rate of about 1 drop per minute. I also checked to see if any other flexible hose areas of the fuel line was collapsing but no luck. I hooked up my cheapo scanner with live data capabiltiy and took it for a few test drives after clearing the code. I can maintain about 23k of rail pressure at full throttle with no CEL light coming on. I also tried chopping the throttle quickly to spike the rail pressure and the CEL light will not come back on. Any ideas? This problem comes and goes intermittently and has been around for a few months now.
 
It could be the FCA going bad and it sticks occasionally. Have you had a scanner on it when it throws the code? Can you read the injector balance rates? If so what are those numbers?
 
It could also be a faulty rail pressure sensor showing low pressure when it is really fine.
 
Probably either the ECM dropping desired rail pressure when the code sets or the rail pressure relief valve is popping open prematurely.

The frp and rail sensor could cause this issue but are long shots at best. I have seen only 1or 2 pressure sensors fail on a dmax and have never seen the frp cause a p0087, the first symptom is a surge at idle.
 
Never got it to throw the code again so no I never got to watch what happens on the scanner when the code comes on. I drove the truck around again today for about 15 minutes after it got warmed up doing a bunch of WOT runs with rail pressure getting alittle above 23k and maintaining. Was hoping it would drop off and throw a code letting me see if the releif valve was opening. My scanner cannot read balance rates or so I dont thinkit can. What do those numbers show up as on the scanner? And no surging at idle. Also, changed the small segments of rubber line today that was seeping fuel so now its leak free.
 
I was thinking something along those lines. Any way to unstick it? Does adding a lubiricity additive such as the diesel concentrate from Amzoil which I put in the tank tend to mask or bandaid these types of problems? Thanks
 
My guess is the carter lift pump. Most likely that is acting up causing issues. I ran a Carter many years ago and had to have a by-pass around it when it would quit. Not made for diesel anyway.
 
I was thinking that the pump might be a restriction as well. But its hard to tell if it shutting off or not. I was thinking of taking it off but the owner of the truck told me that years ago the truck quit running one day and couldnt start. He took it to a shop and they told him the truck had bad fuel pressure and the only way they got it to start was by adding that pump. Makes no sense to me but Im afraid to take it out then the truck not run. I dunno I guess its easy enough to bypass and give it a shot if the problem returns.
 
I agree the pump may well be an issue.

One thing you can try is watch desired vs actual rail pressure while making a hard pull and see if the actual drops very far off desired.

I think the sudden power loss is the code setting and the ECM dropping rail pressure.
 
Yeah my scanner is too low tech to show desired pressure. Just shows actual. Maybe Ill pull this crappy pump off and put like a Air Dog or something if it still persists.
 
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