Gradual Loss of Power....Help!

[justagoodolboy]

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!!

[flashgordon]

My guess is that you have a boost leak.................................also check at the bottom of the radiator/ intercooler of a bunch of hay that was pull up by our fan. I have seen then stop up Pritty bad.


Flash

[justagoodolboy]

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?

[flashgordon]

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?

YEs and No

if you had blown a turbo hose compeltly off then Yes Probalbly would smoke bad

If you have a leak and the boost level in not high enough to cause the fuel pin to move or move less then before........less fuel less power.

It could be your turbo.................I would start with looking for damaged boots, snuging all the hose clamps and look real close at the boost line going to inj pump

[meby]

Worn injectors could be a source of less power. Also if your VE is like you said, "on its last leg" could be it too. I would certainly have the injectors pop tested if you don't have the equipment. If the injectors are your problem, I would think that you would have some smoke issues especially on a cold start up.

I "doubt" the ULSD has anything to do with your problem. I don't think that the difference is that large from LSD to ULSD.

I think that to flow test your VE, you would have to remove it from the truck to test it or have it tested.

[PToombs]

You should get a boost gauge on there. Then you can see if you are losing boost, or at least keep track of it. My guess is a boost leak that's bad enough to not move the pin.
If you have a fuel problem, it's after where the gauge is plumbed in. If the line from the tank was collapsed, you would lose pressure.

[CumminsPride]

Could the clutch be slipping? Never had a G-Trag so I have no clue what their tell tale signs are.

Wade

[justagoodolboy]

You should get a boost gauge on there. Then you can see if you are losing boost, or at least keep track of it. My guess is a boost leak that's bad enough to not move the pin.
If you have a fuel problem, it's after where the gauge is plumbed in. If the line from the tank was collapsed, you would lose pressure.

Thats what I was thinking too about the fuel supply, but threw that in there incase I was missing something. I will check for boost leaks this evening and report back in.

Thanks for everyone's replies.

[PToombs]

Could the clutch be slipping? Never had a G-Trag so I have no clue what their tell tale signs are.

Wade

Signs? The engine going rrrrrrrrrrrrrrrrrrrrrrrrr

[flashgordon]

Could the clutch be slipping? Never had a G-Trag so I have no clue what their tell tale signs are.

Wade

Signs? The engine going rrrrrrrrrrrrrrrrrrrrrrrrr

[dpuckett]

If you have a boost leak big enough to not move your AFC pin, you would hear it for sure. Big WHHHOOOSSSHHH when you get on it. BTDT.

While we are on the topic of fuel pins, the guide pin that rides on the AFC cone could be stuck in the minimum position, cutting your max fuel by 30-50%, depending on your settings.

Could also be the pot metal AFC hose developed a hairline crack, giving the same effect as the stuck pin.

You got a pyrometer on there? If not, get one, and a boost gauge. It's good you have a FP gauge.

Daniel

[Hot Dawg]

I'm having the same prob with mine! I'm in Korea right now so I can't troubleshoot. Went from making 40+ lbs of boost easy to bearly making 30.
it has been a gradual power loss for me. I think mine is a weak IP. we'll see when I get back to the states in Oct. /:o(

[abledog]

I agree with dpuckett, if the pilot line from the head to the AFC housing is broken or leaking this could be the problen!!!!

Terry

[CumminsPride]

Signs? The engine going rrrrrrrrrrrrrrrrrrrrrrrrr

My NV4500 DD Clutch shuddered and shook the truck when it began to slip. I wasn't sure if those measily little clutches would let slippage by without noticing.

Wade

[justagoodolboy]

Well, I guess it was a major one.

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.