Engine/Transmission (1994 - 1998) possible fuel problem

[b.ferrara]

started loosing power on wurtsboro mtn, had to downshift to 4th. Got home changed fuel filter, n/g. Changed all the boots for intercooler, n/g.

Sprayed turbo with seafoam, n/g. Going to do lift pump, is there anything that might help? Flat ground can only get 72mph, I think normal was 80mph. Hills have to downshift to 4th, if towing trailer I'm down to 3rd. Any help greatly appreciated.

 

[Missouri Mule]

I do a fuel pressure test before you start replacing parts. Minimum 20 psi (25 or over better) at idle rev engine to 2000 rpm should be 30 psi or over. If pressure is low squeeze retun Line (rubber) with pliers. If pressure goes up its your overflow valve if pressure doesn't go up or goes up slowly lift pump.



Any smoke? If yes, what color?

 

[b.ferrara]

I do a fuel pressure test before you start replacing parts. Minimum 20 psi (25 or over better) at idle rev engine to 2000 rpm should be 30 psi or over. If pressure is low squeeze retun Line (rubber) with pliers. If pressure goes up its your overflow valve if pressure doesn't go up or goes up slowly lift pump.



Any smoke? If yes, what color?

I get black smoke if sitting still and punch it but not as much as I use to, I use to get good amount of smoke when climbing hills or heavy excelaration now nothing. I can hear the turbo so I know it's a fuel problem.

 

[KRStone]

I have a 96 12v, if yours is like mine, you want to check:

1) fuel heater failures can leak to the heater element sucking air

2) fuel bypass hose cracks can lead to air being sucked into the fuel system

 

[b.ferrara]

thanks, I ordered a fuel pressure gauge, while waiting for that to come I will check bypass hose

 

[hsmith]

Might want to look at the pre filter screen also. I've seen some in pretty sad shape.

 

[b.ferrara]

I didn't even know there was a pre-filter screen, thanks I will check it out

 

[hsmith]

Do you know where it is? May as well delete the fuel heater while you are there. Known source for fuel-air leaks.

 

[BigPapa]

Check the shut-off solenoid for full travel.

Start the truck and then try to pull the shut-off lever up some more. If it's not all the way up I'd say that could very well be your problem.

 

[b.ferrara]

I know where it is now(pre-filter) will pull it out after my coffee. Don't want to delete it as it can get cold here in Jan/Feb. Big Papa I took out the fuel shut off solenoid about 10yrs ago, I did check for full travel on the lever though. Thanks

 

[b.ferrara]

pulled the pre-filter wasn't bad at all considering I never cleaned in 10 years. As soon as the gauge package gets here I will work on fuel pressure, overflow valve and bypass hose. thanks again

 

[b.ferrara]

after cleaning pre-filter I pumped lift pump about 10 times, she started and ran fine. That was about 2pm, I went out 7pm and she wouldn't start, I pumped lift pump about 20 times. It was real hard to start ran for about 30 seconds to a minute and she ran herself out of fuel. Hopefully lift pump and not the p pump?

 

[b.ferrara]

ok so I got her running today, I have to hold pedal to floor and it barely idles, second i let off pedal she stalls. Lift pump? probably not, something else that probably costs alot of money.

 

[GAmes]

Prior to the low power problem were you having difficulty starting the engine? If not, you have introduced a problem, specifically an air leak prior to the lift pump. Either the gasket for the prefilter or the elbow hose from the prefilter to the pump is the first things I'd look at. Ditch the heater, it isn't needed at the north pole and just causes problems. A fuel pressure gauge is worthless if the engine won't run.



More info from an old member.



http://www.cumminsforum.com/forum/94-98-engine/58777-joe-gs-fuel-system-writeup.html

 

[b.ferrara]

I was thinking about that pre heater, 2 things come to mind one is maybe i put in upside down. 2nd is if i pull it just bolt pre heater or is there something to put in the space

 

[GAmes]

I don't think it can be installed upside down. Just discard it and the bolt that holds it in. The threaded part of the prefilter base fits perfectly. It is all described in the link I sent.

 

[b.ferrara]

ok pulled pre-heater, got truck running again. But still have original problem! won't climb hills? I took for test ride and climbed wurtsboro mtn, I hit bottom at 67mph and instantly started losing speed, I climbed last 1/2 mile at 50mph. i aslo noticed 2 things (1) that there is no exhaust showing out of the stacks. idling at a stop give it a blast blows black smoke and should be blowing black everytime I switch gears especially on hills. (2) she doesn't have the get up and go she normally does when putting pedal to floor. Thanks for all the help

 

[Berrigan]

Do you know what your boost pressure is under load? My 98 did the same thing. I found an air leak on the black plastic tubing (at a fitting) that supplies the boost signal to the AFC. The AFC thinks there is no or low boost so it holds back the fuel under load.

 

[GAmes]

Did you get the fuel pressure gauge installed? Did you check the fuel shutoff solenoid for full travel? If it isn't full up it will cause a power loss. You might have to remove it and the deteriorated boot, then clean the piston and bore and reassemble. Genos carries the boot, about $10.

 

[BigPapa]

Did you get the fuel pressure gauge installed? Did you check the fuel shutoff solenoid for full travel? If it isn't full up it will cause a power loss. You might have to remove it and the deteriorated boot, then clean the piston and bore and reassemble. Genos carries the boot, about $10.

This was my suggestion, also, Gary. I asked him about the solenoid earlier, post #9. He replaced it with a cable a long time ago and he said he'd checked, and it has full travel.

For what it's worth, I've been running my solenoid without a boot now for over 300K miles. Never had an issue with it.