Power issue?

[crashz]

I have a similar problem with my new to me 1 ton dump as Petrella has with his truck. I had to bring the truck over to a welder's place (little problem on the frame) and the truck felt like it had no power. It could top out at about 50-55 mph on the flats, but as soon as it hit a hill, I was down to 35 and at times downshifting to second. This is completely unloaded! The difference is that I could see no noticable smoke.

The truck is an 87, TH400 (replaced by previous owner, may have the wrong gov and converter), 4x4, dually dump, 6.2L. I have not yet replaced the fuel filter, or air filter.

Any thoughts? Could it be a simple filter problem?

[DmaxMaverick]

Filters. One or both. As a general rule when diagnosing driveability/running problems, especially with Diesels, filters should be the first step. Before even asking a question. Not that we mind the questions. Definitely change the fuel filter, and at least check/clean the air filter.

[crashz]

Thanks Dmax!

I appreciate the advice. I actually had a reason as to why I didn't change the filter prior to doign anything else. One of those chicken-egg deals, as I decided to replace the leaking fuel tank prior to changing the fuel filter, which, while draining, found a rust hole in the frame. So rather than go to anymore trouble, I sought the help of a trusted friend who is an expert on frame repair and is fixing the frame now.

For whatever reason, I was thinking that if the filters are plugged, then the truck would smoke. But I guess that would only be true if it was the air filter, and not so with the fuel filter.

Thanks again!

[crashz]

To update - I changed both the air and the fuel filters and found a world of difference. Much better power on the hills and it idles and runs a bit smoother too.

BTW Dmax, I tried the vacuum pump bleeding and it worked like a charm! The truck fired up without a hiccup and the method is really easy. Very good tip! Thanks!