cmac

my truck lost a bunch of power, it seems to be at stock power levels. it starts and drives fine but here is what it is doing: i get one little puff of smoke if i stomp on it, and it used to smoke quite a bit all the way through the gears. it has the 3k gsk but it now shifts at about 2600 rpm's instead of 3,000-3,100 rpm's. i even took out the arm in the AFC to rule that and an air supply problem with no change in symptoms.

do you think it would be worth changing out the fuel filter even though it isnt due for a change yet? i have a gut feeling that my problem lies within the injection pump.... please let my gut be wrong...

patdaly

You need to check the fuel pressures..........

Could be filter, could be overflow valve.

oliver foster

I think the same as Patdaly.
I have driven a few p-pumped motored trucks that where gutless until I threw a overflow valve at it. A plugged fuel filter would do the same.
I got my last overflow valve off E-bay for $35 I think.
Someone had the info on here at that time, about finding the e-bay guys ad.

infidel

Instructions> http://www.cumminsforum.com/forum/94...-12-valve.html

cmac

thanks i'll try to get to the parts store tomorrow. is it safe to run the gauge into the truck or should i mount it under the hood somewhere?

cmac

also does anyone have a closeup picture of the valve or a part number, the parts stores that i've called dont seem to have a clue what a needle valve is. thanks

infidel

Needle valve> http://www.grainger.com/Grainger/Nee...N31?Pid=search

I've had a fuel pressure gauge in the cab of both my trucks for over 13 years without a problem.

cmac

ok i got the gauge installed and i am getting 10-11 psi at idle, it drops very little when i rev it up to 2500 rpm's like 8-9 psi. when i give the skinny pedal a push down the road the gauge reads a big fat zero. i'm guessing this means i need to change the fuel filter right?

nuttynotty

So what happens when you pinch the return fuel line, if you have no fuel gauge, you need one. The fuel pressure should be around 55~60 PSI, of not I would shoot for the filter, if no change look at the lift pump.

infidel

Change the fuel filter and service the prefilter.
Pinch off the return hose that passes behind the fuel filter with pliers with the engine idling.
You should see at least 60 psi on the gauge.
If you don't the lift pump is bad.
If you do and the fuel pressure is still low replace the overflow valve.

cmac

thanks! i'll try to get to that tomorrow.

cmac

changed the filter and it was black. the pre-filter seems to be where most of my problem came from, there was a bunch of dirt and crap in it, the screen was black and you couldnt see through it. it cleaned up pretty good though. my fuel pressure is up to 17-18 at idle and 20-22 while driving. i havent tried pinching off the return line yet. its crappy outside so i'll do that later. thanks for the help.

brandon mitchel

Maybe it's the driveshaft.

cmac

huh?

oliver foster

I think brandon might have had one too many on a Fri. night.