Well, my truck among other problems has gradually started losing power over the past several months, and I cannot seem to locate the problem.

My 1st obvious answer was to change my BHAF that was about 6 months old, and the fuel filter. That helped a little, but not much.

My fuel pressure remains in the 12 to 15 PSI range depending on the situation and age of the filter, but it has never stayed at 15.5 even with a new filter (I obviously have the Piston Lift Pump).

I have not checked for boost leaks, and I don't have a gauge.

My truck used to run very strong and pull very good. Last night I pulled my 16ft bumper pull trailer with my AC Prowler and I would lose speed on the hills that I used to be able to gain speed on with triple the weight. That said, my FP gauge never pulled below 12 PSI.

Thinking out loud:

- Could this be a result of the new ULSD? It seems my power loss started back at the end of the summer once my local station switched over - and yes I use power service as an additive. I have thought about filling up with off-road diesel to see how it reacted to that (I have a tank at the house).

- Could I have a collapsing fuel supply line/stopped up pickup hose in the tank? I would think 12PSI would not cause that much loss of power, but who knows. Also, my gauge is post filter.

- Do I have a boost leak?

- Is my VE on its last leg, and if so, is there a sure-fire way of knowing - IE, can a local pump shop hook up a pressure gauge of sorts to tell what the output is.

The truck cranks good, idles smoothe, and goes through the gears without any hessitation, but I can tell its no where near the truck it was back in the summer during hay season, and last night was surely a kick square in the groin.

Please Help!!

 

No way of knowing 4 sure, but when my IP was going out it sounded like the same symptoms. Midwest fuel injection was the best deal I found on a stock IP. Its a very nice pump, IMO. Hope you find the prob to be elsewhere or a cheeper location. Good luck!

 

Thanks for the reply. Anybody else have any ideas?

 

I would say IP get it rebuilt and keep a healthy dose of Power Service in the tank. I got my IP rebuilt ran very good no problems very slowly I started to see more smoke.

 

Before we jump the gun here and send the pump off to get rebuilt lets look at this a little deeper and look at the simple things.

Obviously you have a fuel pressure gauge, I see you don't have any other gauges, I would get a pyro and a boost gauge soon. Especially when working a turned up truck. 12psi is pretty good, I can make mine 0 with a good tromp.

1. Are you getting full throttle travel?

2. Boost leaks, yes you can check for them, but I would look closely at the line that goes to the top of the pump for leaks, cracks, etc.

3. After you check for boost leaks or before, I really don't care which order you do these in. Check the AFC diaphram to see if its leaking or torn. While your in there make sure the pin that comes out of the pump and rides on the AFC pin is moving freely.

 

1 - yes, I am for sure getting full throttle travel. Checked that last night.

2 - the line you refer to, is that the one that goes from the back of the AFC housing over to the side of the motor (I think) that is a hard line?

3 - How do I "check" the diaphram? I take it you are referring to the round rubber seal that sits atop the fuel pin? It looked good with no obvious cracks or dry rotting. The small pin that rides on the AFC pin is for sure functional, and will come out with a cycle of the throttle.

I know I need a boost and pyro but to be honest, $$ is tight right now due to Christmas and my wife thinking we have to buy EVERYONE in our family a gift.

 

Another thing I noticed as it does not seem to smoke as much as it used too. I was under the impression boost leaks would create more smoke. Am I correct?

 

If the boost leaks are big enough, you won't get enough boost to push the AFC down enough for full power. I would take a close look at the diaphram, it only takes a few minutes just to be sure and blow out the AFC tubing just for kicks.

Maybe the fuel shudown solenoid has left some rubber in the port???? The tip off of the SD plunger may be hanging up in there...??

 

It was what I would consider a big boost leak.

I used that 4 in Rubber coupler from the hardware store with a PVC cap and put a air attachment on it. Then I pressurized the system to 10 PSI. I could hear the air, but not find any bubbles with my soap/water spray bottle. I then started feeling for air and found it. The bolt holding the fuel lines thats behind the intake horn was completely missing. I ended up finding it against one of the valve covers. I replaced it and its like having a new truck!

Funny thing is, I was thinking my truck was running good and acting normal. It performs and sounds like a completely different truck now.

Appreciate everyone's advice.