So. This is confusing issue to me. Maybe not actually. When towing my fifth wheel, something is happening that won't let me get full throttle travel (I think). I normally run a max boost of around 24psi at 5000 feet elevation. With the trailer, going down the interstate, when I stomp the skinny pedal, I get a...hmmmph...max of about 12-15psi, which just doesn't cut it on the Colorado hills. Sometimes, and I haven't figured out when, I DO get the full boost. When this occurs, the pedal feels much smoother and seems to travel better.

I first thought that maybe my fuel filter was plugging up on me. So I changed it in the campground this weekend, but that made no difference. So now I think it could be 1 of 2 ideas. First, maybe the TV cable or TV spool in the valve body is binding and stopping my throttle travel. I had the transmission rebuilt this spring and haven't put a lot of towing miles on it. So maybe that's the culprit.

Second is an internal injection pump issue. Maybe the governor is running amok? I'm not an IP guru so I really have no idea. When I manipulate the linkages and throttle shaft by hand under the hood everything feels and looks good. I can only make this problem happen when I'm traveling at a pretty good clip with maybe 1/2 to 3/4 throttle.

Ideas?

 

The throttle peddle feel might be an illusion. If so, I'd suspect 1 or more injectors plugging or sticking.

You're basically on to it. Boost is a function of fuel.

 

You may be right j_martin. But I still feel that there is some sort of difference in the pedal feel. Personally I'm leaning toward something with the TV valve in the transmission since this problem started after my transmission rebuild.

 

Maybe the fuel pin is sticking.

 

Could be. That crossed my mind also. But it would not account for my perceived difference of pedal feel. I'll probably take a look at it anyway since it's so easy to get to.