Low power, low boost
#1
Low power, low boost
Been a bad week here...Just dealt with the ESS for 2 days and got that mess all straightened out. Today, I picked up a load of wood (3000 lbs.) and loaded, the truck felt a bit weak compared to normal (description of truck is in my sig). I picked the load up about an hour away, and the closer to home I got the weaker the truck seemed to get. It seems really "laggy." That is, it seems like it takes the turbo longer than normal to spool up. Under load, if I plant my foot it makes 35+ psi. Today, it would go up to 24 and stay there. The EGT was cooler than normal. Also, at WOT loaded, I could get a haze from the exhaust, today, nothing at all. I noticed too that I had to run it up to a higher RPM in every gear before I upshifted or it would just want to fall on it's face for quite awhile until the boost came up a bit, then it would pull.
So, do I have a fuel delivery issue? Or, since it's not building boost, is it not moving the AFC arm far enough to really fuel the truck? Blown IC boot?
The fuel filter has less than 1000 miles on it. I'm not exactly sure where to go from here. Is there a way I can measure fuel pressure to the IP while driving the truck? Should I just change the IC boots? They might be original, but I don't know for sure. Is there any easy way to pressurize the boost side of the engine to test for leaks?
Any help is appreciated!
So, do I have a fuel delivery issue? Or, since it's not building boost, is it not moving the AFC arm far enough to really fuel the truck? Blown IC boot?
The fuel filter has less than 1000 miles on it. I'm not exactly sure where to go from here. Is there a way I can measure fuel pressure to the IP while driving the truck? Should I just change the IC boots? They might be original, but I don't know for sure. Is there any easy way to pressurize the boost side of the engine to test for leaks?
Any help is appreciated!
#2
Administrator
First off, since you have no smoke, I would lay odds it is a fueling issue. Blown IC boots would smoke like a freight train.
Definitely get a fuel pressure gauge on, could be the lift pump, pre-filter, overflow valve, or something as simple as a binding linkage on the fuel shutoff.
Definitely get a fuel pressure gauge on, could be the lift pump, pre-filter, overflow valve, or something as simple as a binding linkage on the fuel shutoff.
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99farmtruck (08-15-2019)
#4
Administrator
Easiest is to drill and tap the IP pump banjo bolt, but if you are not able to do that, I "think" the early ones like yours had a pressure port on the fuel filter like the 97-99s did. ( sorry, I am primarily a 97 man.)
Source automotive has them pre drilled for 10 bucks..........
http://sourceautomotive.biz/gauges.aspx
Source automotive has them pre drilled for 10 bucks..........
http://sourceautomotive.biz/gauges.aspx
#6
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Thats only if you have a loose AFC. Tight AFC will keep it real clean. My truck was like that when I forgot to tighten a boot clamp once.
Do you have a stiff throttle pedal?. If the solenoid is not allowing the shut off lever to come up fully, you'll feel it in the pedal as the gov arm springs stretch out. It will also cause the engine to try and die and then the governor will catch itself again.
The other thing I'd look at would be the threaded rod in the throttle linkage. It has both left and right hand threads. If the jam nuts are loose, the vibrations will allow the rod to spin and it will extend the linkage, which will lessen your travel. I had this happen on my dually after I did the p-pump conversion. It still had the same power in the lower end, but its like a brick under the pedal. By the time I got to my destination, my max speed was 80 km/h and I was practically idling up the hills in the area.
You might also check the AFC diaphragm. If that is ripped, it would cause low fuel output, which would lessen your power and EGT's.
Do you have a stiff throttle pedal?. If the solenoid is not allowing the shut off lever to come up fully, you'll feel it in the pedal as the gov arm springs stretch out. It will also cause the engine to try and die and then the governor will catch itself again.
The other thing I'd look at would be the threaded rod in the throttle linkage. It has both left and right hand threads. If the jam nuts are loose, the vibrations will allow the rod to spin and it will extend the linkage, which will lessen your travel. I had this happen on my dually after I did the p-pump conversion. It still had the same power in the lower end, but its like a brick under the pedal. By the time I got to my destination, my max speed was 80 km/h and I was practically idling up the hills in the area.
You might also check the AFC diaphragm. If that is ripped, it would cause low fuel output, which would lessen your power and EGT's.
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#9
#10
Thanks for the replies. I was hoping for a silver bullet, but I guess that's not the case. I'll check fuel pressure, throttle linkage, IC boots and the AFC diaphragm. The pedal feels normal so that at least rules out the shut down solenoid. I have to work a million hours this weekend (sucks!!!) but early next week I should be able to deal with it. I'll post up what I find.
#11
Registered User
More reading> http://www.cumminsforum.com/forum/94...-12-valve.html
#12
Well, I feel really stupid. I looked at the truck quick the other day when I got home with it, but it was starting to get dark and I couldn't really see much. I finally had a chance to check the truck over really well today. So, 3 of the 4 AFC bolts were out. 2 were completely gone, and the third one was hanging on by about 2 threads. The shutdown solenoid was only being held on by the bolt dangling from 2 threads. I'll have to go to the hardware store and pick up a couple of bolts. Easy fix, but man do I feel like a moron!
#13
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...Thats ok....I ran my truck hard on the highway today...Ran like a top at 80 MPH...Decided to push it even harder to 90 MPH...Almost 3K on the RPM gauge...Same problem...all of sudden my truck is not fueling up,poor boost and no smoke...Oh well...Got to fix..
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