My 97 pickup runs pretty good empty. lots of power and acccelerates good even uphill. When I hook up the hard top camper and set out with the wife and kids, things change. Start climbing hills and she slows down and starts blowing black smoke. Not as bad as if the wastegate fails but noticably heavy black smoke. I have manually downshifted to 2cd gear to keep a reasonable speed(auto trans), the revs increase but still suffering up steep climbs.

New IP last year, clean filters and lift pump OK. Is this normal at 180,000 miles. Could it be a timing issue, the truck never started as well after the IP replacement (dealer), but not too bad in summer. I'd hate to tow anything heavier than this and a hardtop isn't very heavy. Any suggestions?

Have you checked the Vacuum from the Vac pump and at the waste gate solenoid? You should have a minimum of 15 inches of vacuum at the wastegate actuator. If not check output at the vacuum pump. Should be 25"+ at the pump.

'S' engine with EGR and MAF sensor right?
There's your problem, poor design.
My advice, reflash to a HD 'F' program in the PCM.

Ideas to check: Cat converter is plugged up. Intake caked with soot.

Everything works okay after you crest the hill?

I've pulled vac line to solenoid, haven't got a tester but there seems to be a fair amount of vacuum there and to wastegate. No cat, but who knows whats in the intake, although it's only been a year since it was off for the IP change. What's involved in reflash and how much does it cost? Truck works fine after hill is crested but coolant temps rise on the way up. Original injectors are probably tired, but seem to work fine, it's just going up steep hills with a moderate load that she smokes and loses power. I guess I expected more from a 400 ci turboed diesel engine.

Maybe intanke air temp sensor is cutting the fuel. IAT temps climb high with warm ambients, under load. I think QM replaced his because of some issues. Maybe he'll chime in here to fill us in, that was over a year ago now.

How high is high with coolant temps? And one last zinger . . . how high in elevation was this hill? Had a guy one time complain about now power at the top of the hill and blowing black smoke. Come to find out, he was a 11,000 ft. You need oxygen tanks if you go a little bit farther.

Where is the IAT located and how would I test? The hills are located in Gros Morne national park and are maybe 1500 feet in elevation max. Coolant temps rise to slightly below 100 C, fan clutch has kicked in occasionally in the past, but not this time. The climbs are steep but short in duration. Any thoughts on timing? Thanks for the replies everyone.