Today I got in my truck and had lost a major amount of power. My truck is a 98 12 valve 5 speed. It has a 0 plate, timing at 16.5, intake, 4" straight pipe, and 3k gsk. It runs perfectly smooth, but it has about half the power it had when stock. I can't get over about 70 mph with it on the floor. It maxes at about 15 psi boost and around 750* when to the floor in 4th gear at about 2800 rpm's. My first thought was a boost leak, but temps are low instead of high and not a sign of smoke. Then I thought the gsk but it idles just the same as before and will free rev (slowly) to over 3000 rpm. It just acts as if it is starved for fuel. I changed the fuel filter about 6000 miles ago. I thought maybe water in the fuel, but I would think it wouldn't be running so smooth if that was the case. Could my timing have slipped that badly or could something in the pump be messed up? Oh and by the way, this happened all at once, it ran perfect last night. Please help. Thanks in advance, Adam.

 

Change the fuel filter again and look at it closely, might have gotten dirty fuel. Lift pump going out? Sounds like it isn't getting fuel.

 

definately sounds like lack of fuel, doubt a dirty filter would change in performance that quick unless someone dumped dirt in your tank, have you made any enemies lately?. maybe check the lift pump pressure. doubt your timing slipped because you would still be dumping fuel in and blowing black smoke at 15psi. good luck my friend.

 

You might check the overflow valve spring.
Is the screen on your fuel heater clean?
I think that BigErksG2 has a point, it the failure was instant, dirty filters is doubtful. Broken spring or faulty lift pump could do it though. Do you have a fuel pressure gauge, that could really help.

 

Thanks for the replies. I am leaning toward lift pump. I do not have a guage, but I am going to check the pressure. I was told that I could tap into the feed line right at the top of the fuel filter canister. Will this work? I was told I could just use a mechanical oil pressure gauge. Also, what pressure numbers should I be seeing? I am not sure about that screen on the fuel heater. Where is it at? Oh and by the way, to the best of my knowledge i have not made any enemies, but the truck is sitting on campus at the University of Tennessee, so who knows.

 

Check pressure before you mess with the LP, could save you a lot of hassle. They are quite strong, not prone to failure often.
Most tap their fuel pressure @ the banjo bolt where the fuel enters the IP. Check threads about it, there is lots of info. I know Infidel has posted some specific information about installation, good read. Fuel pressure 17-22 @ idle, 25-35 @ 2500RPM, no load.
The fuel heater is right next to the lift pump, you can see it from under the truck, although the starter is in the way. There is a 17mm (I think) bolt that removes the bowl, Cummins has a re-build kit for it, cheap. Keep us posted on your progress and what you find.

 

First, check the overflow valve. A broken spring is pretty common.

 

Where is the overflow? On the fuel filter canister?

 

Here is some links with pictures on overflow valve stuff

http://dodgeram.org/tech/dsl/trouble...p.htm#Overflow

http://dodgeram.info/tsb/1996/14-07-96.htm

One more thing that came to mind is check the boost line going to the AFC housing, if the AFC isin't seeing boost it won't let the govner arm onto the fuel plate and would act very similer to this, probably not the problem, but one more thing thats easy to check and rule out.

....Josh

 

Well I worked on the truck this mornin and haven't gotten anywhere. Checked the filter first and it is clean. Then I checked the pressure on the pump. I couldn't find a fitting to adapt it to a guage, but my buddy started the truck up and I couldn't even keep it covered with my finger. Sprayed fuel everywhere. It has to be runnin at least 20 psi. Then I checked the overflow. It looked fine, but just to check I plugged the overflow with my finger and started the truck. It was all I could do to keep it capped off. So there is definately pressure. Also while it was capped the truck ran the same so it is not stuck open. I checked the boost line going to the AFC. It seemed fine but I poured some soapy water on it to check it. I started it up and when I rev it hard I could see just a couple of tiny bubbles where it goes into the intake. It was hardly nothing. Could I be losing enough boost there to throw my pump off? I am going to try and replace that next because it shouldn't be leaking any. I just don't see that being my problem though. The reason I don't think it is my problem is because the truck is very hard to start and has a very weak idle. It has to crank for about 5 seconds where it usually fires up on the first crank. Also, the idle is very weak. I was backing up a small hill today and it would almost die until I gave it some gas. It used to idle up anything in 1st and reverse. I wouldn't think that starting and idling would be related to boost pressure. I am yet to check that screen in the heater but hopefully I can get to that soon. Thanks for all your help and please let me know where to go next. Thanks, Adam.

 

OK, one more thing popped up in my mind, the solenoid switch. If it is not lifting ALL the way, you won't be getting enough fuel. Problems start happening. It is right next to the AFC, you will see small cylinder with wires coming out of it and a rubber boot below it. When you start the truck, the rod inside the boot should go ALL the way up. If it not, then try to push it up by hand and see if it moves. If it is sticking, remove the solenoid, remove the boot if it is still there and clean the barrel where the plunger goes up and down. If the boot has been rotted off, then without question clean the barrel. Then make a new boot from a bicycle inner tube or buy a boot from Foster truck. Hope this helps.

 

OK, one more thing to check is the shut down solonoid, could be the boot tore and the shaft is dirty and not pulling up far enough. Do this, start the truck, then get out and reach under the soilonoid, grab the linkage and pull up on it manually, if it moves up any then I'll bet that your problem. Go drive it then and see if its any better. if that was it, take it off clean it and get another boot.

Or it could be out off adjustment read here for adjustment procedure. http://dodgeram.org/tech/dsl/trouble..._solenoid.html

Could also be worn throttle parts: Symptoms: Low power, engine does not pull well above 2200 RPM
Caused by stretched throttle cable, throttle rod out of adjustment, worn throttle parts
Check by having someone hold the accelerator pedal to the floor while you see if the throttle bellcrank on the rear of the injector pump will move farther by hand.


One last thing go here http://dodgeram.org/support_pgs/diesel_ix.htm and do some reading, there is a wealth of good info there and I bet you can find your problem.

good luck....Josh

 

Fuel shutoff solonoid it is!!! Thanks so much for your help!! Saved me alot of time and money!!

 

awesome, glad you found the problem!!!