LMM: Isolate failing FPR with dual fuelers?

[BLACKMAX1]

Started my truck up after work today and immediately got engine power reduced message followed by a really harsh idle. Code thrown was p0088 for high rail. I reset the code and started the truck multiple times and it would come right back. I left truck off and the key in the run position after I cleared the code the last time and my lift pump was holding solid at 10psi, usually it bounces between 8-10. After about a minute I started the truck and immediately held the throttle to 1000rms, this commanded fuel and lowered the lift pump pressure and the truck ran and drove home just fine. Balance rates are good as well.

This same issue happened two weeks ago and if I unplugged either of the pumps it would idle at full rail. After I disconnected the batteries and pumps let it sit and when I hooked everything back up the problem was gone.

Lift pump is an airdog 150, that I've never had to mess with. Been on the truck since 2012. Dual fueler pump was brand new when I put it on Aug 2014.

So my question is, is there a way to isolate a failing FPR in a dual fueler set up? Or should I take a shot in the dark and change both? Thanks for any insight.

 

[Awenta]

Change the top one. Doesn't work then go for the other.

Sent from my SM-N910V using Tapatalk

 

[Chevy1925]

pull the belt, plug the factory plug back into the valley cp3 and see what happens. if the issue stops, its the top FPR. if it dont, its the valley one

 

[BLACKMAX1]

pull the belt, plug the factory plug back into the valley cp3 and see what happens. if the issue stops, its the top FPR. if it dont, its the valley one

Great idea, didn't even think of that. Hopefully I can get the problem to happen when I'm trouble shooting it. Thanks

 

[BLACKMAX1]

New regulator will be here today. I removed the belt and plugged the factory harness back in as James recommended. Rail pressure is fine and the idle is smooth, so I'll be changing the top one when it shows up. I'll give another update when the new one is on. Thanks for the help

 

[Chevy1925]

New regulator will be here today. I removed the belt and plugged the factory harness back in as James recommended. Rail pressure is fine and the idle is smooth, so I'll be changing the top one when it shows up. I'll give another update when the new one is on. Thanks for the help

sadly, it could be the dual fueler box. i would have swapped the top FPR to the valley and retested to be sure its not the box but when you put the new FPR in, you will know!

 

[BLACKMAX1]

sadly, it could be the dual fueler box. i would have swapped the top FPR to the valley and retested to be sure its not the box but when you put the new FPR in, you will know!

Man I really hope it's not the controller. New FPR just got here so I'll know soon.

 

[DAVe3283]

The fact that it is intermittent actually indicates the controller, IMO. But it could be something simple, like a loose connection. While you are throwing the new regulator on, go over all the connections for the controller and make sure they are all clean/tight.

 

[Chevy1925]

The fact that it is intermittent actually indicates the controller, IMO. But it could be something simple, like a loose connection. While you are throwing the new regulator on, go over all the connections for the controller and make sure they are all clean/tight.

na ive seen bad spots in the coil of FPR's do this too. they get a bit sticky, hit the bad spot and then go back to full open. they can do wacky things thats for sure but i agree, the controller can be just as much at fault

 

[BLACKMAX1]

installed the new FPR and the motor seems to be running fine now. Since the problem was mostly intermittent I'll know in a couple days if it's the controller. If so, anybody know who has the best price on them?

 

[Chevy1925]

i believe fingers has the best price from what i read.

 

[BLACKMAX1]

i believe fingers has the best price from what i read.

Yea definitely, his old thread says $155. I'll give him a call to make sure, a lot better than a PPE one $530-$599.

 

[TowU4Free]

Ill bump this back up, Ive been daily driving my rig lately and recently getting the P0088 code while coming to a stop and the rail does look high on the cts. I have dual PPE pumps, everything is fairly new, im already on my second controller. Will be diagnosing today..

 

[Dan@PPE]

How much lift pump pressure PSI are you running?

 

[TowU4Free]

10-12 psi for the past few years

 

[Dan@PPE]

Have you verified the lift pump pressure recently?

 

[BLACKMAX1]

Ill bump this back up, Ive been daily driving my rig lately and recently getting the P0088 code while coming to a stop and the rail does look high on the cts. I have dual PPE pumps, everything is fairly new, im already on my second controller. Will be diagnosing today..

Make sure the power/ground wires have no play and the battery they are hooked up to is good to go. The battery my leads were hooked up to went out and ultimately I put a new battery in, put fingers controller in and swapped the leads to the passenger side battery. I don't think my FPR had anything to do with it now, and everything is working fine.

 

[TowU4Free]

I have a gauge mounted in cab, sensor mounted at filter head.

 

[TowU4Free]

interesting, my batterys are a year old and very weak when starting, im getting those tested today today here at work. that would be a nice easy fix since im probably replacing them anyway

 

[Rancelot211]

Ill bump this back up, Ive been daily driving my rig lately and recently getting the P0088 code while coming to a stop and the rail does look high on the cts. I have dual PPE pumps, everything is fairly new, im already on my second controller. Will be diagnosing today..

Didnt know you were still around bud.