Asking for a friend...

Was talking with and he said he's currently running an edge chip on 5x5, 4in exhaust, K&N intake and an Airdog with no filters and that's it. He did mention he has an inline filter or some sort but didn't really catch it. Has a NV5600, truck has 250k and still running on stock VP44. He's seeing fuel pressure from 20 at idle down to 9 while under load and heavy throttle. He said he would get codes here and there that were VP related but he'd run a bottle of methane through the tank and then the codes could clear and truck would run fine. Not sure how old the airdog is but he seems to think that he's seeing those fuel pressure numbers due to the VP being on it's last leg. I seem to think it's the lift pump is the reason he's seeing those number, but also sounds like he needs a new VP as well.

What do you guys think?

38 minutes ago, notlimah said:

He's seeing fuel pressure from 20 at idle down to 9 while under load and heavy throttle

Lift pump is not keeping up. A wide range of pressure fall is a sign of demand volume being higher than the supply volume. Basically the lift pump can't keep up volume wise so pressure starts to fall.

38 minutes ago, notlimah said:

He said he would get codes here and there that were VP related

As for error codes what codes are being thrown?

38 minutes ago, notlimah said:

but he'd run a bottle of methane through the tank and then the codes could clear and truck would run fine.

Fuel additives tend to mask over the VP44 issues most times and return after the additive is consumed.

I think he said he was getting 216 then he'd put in the methane to 'clean things out' on the longer trips and the code would go away. 

Always makes me chuckle to the comments of using a fuel additive to clean things out. Maybe it would be much better to use a better fuel filter. 3 micron is optimal. Fuel additives typically are like pissing in a pond. a 35 gallon tank is 4,480 ounces of fuel so adding 12-16 ounces of anything going to change the cleaning ability? Very doubtful.

P0216 error code.

I hardly doubt any fuel additive is going to fix a galled up timing piston. Most P0216 codes are caused because the fuel pressure can no longer advance timing properly. The PSG give a small amount of time to reach commanded timing if not reached in that time period the P0216 code is set. It could be a valving issue that maybe the additive ungummed the control valve. Even the valve has a screen to prevent plugging but again shouldn't have anything there if there is a quality fuel filter used.

Oh.. This pump did end it's life as a P0216 code.

Edited March 19, 20169 yr by Mopar1973Man

Sounds like a LP issue I started loosing FP and had a excessive miss under a load and it threw the 216 code but thanks to moparmans help figured out the VP wasn't dead yet but the loss of FP was causing the VP to not advance far enough  so I'd fix the LP first and see what happens after LP repair  if the code still comes back the VP failure is prob the issue 

Thanks for the input guys.

I said he's a friend but he was at the neighbors and saw my two second gens out front of my house and so we started talking. He seemed to be one of those guys that didn't want to consider someone else's input. He kept saying his VP has been on the way out for years, constantly throwing that code. Said the fuel pressure drop was because the VP has a diaphragm that goes bad so that's why he was getting his fuel pressure drops. 

He asked me what EGTs I see when towing. When I told him I stay under 12k he chuckled and said ohh your not even really towing then because I see 14k all the time! At that point I just nodded my head and smiled. He clearly has a different stance on these trucks then I do.

Edited March 20, 20169 yr by notlimah

You run into all kinds. 14k on steady bases and he will need more then a VP. You did the right thing smile and nod.

9 hours ago, notlimah said:

was because the VP has a diaphragm that goes bad

Doesn't exist... That old rubber diaphragm was replaced long time ago with a steel plate. Some people love to use that old diahagm story to sell VP44 pumps.

9 hours ago, notlimah said:

When I told him I stay under 12k he chuckled

After having a long conversation with Idaho State Police Officer about GAWR, GCWR and GVWR numbers. As he told me no matter what its illegal to be over your GVWR on the trailer or vehicle... Period. Take notice I'm only 160 pounds away from my vehicle GVWR and 620 pounds away frm my trailer GVWR. Tight but legal.

Edited March 20, 20169 yr by Mopar1973Man