jsadamson1

Well the cummins is a long term goal. This is a truck that is not a daily driver so I just need it in CA at this point. Dude at aamco said it drives ok with no load so I may just drive it home empty and go fetch the trailer when I can find a vehicle with a gooseneck to do so.

TrkEnvy

Probably a good idea.. That grade through AZ Near the dam is no joke..

taterfarm

If it runs fine empty then no power when loaded do you think it could be the engine not running on all cylinders or weak spark? If the truck slows down to that low a speed on a hill then its loosing speed in all the gears and not just slipping in one gear as if it was burned up, surely all the gears are not going to start slipping at the same time. So if it inst a bad torque converter not passing the power through then maybe its engine just not making power.

What is the engine a 318/360, is it still carb or did they have some type of multiport in 85?

Does it have a catalytic convertor? what for muffler?

I am asuming you already checked plugs, wires, cap/button, coil and all that stuff? Maybe running hot has damaged something there. Any chance a plug wire was burt or unplugged while working under there? Is the coil heat sensitive, does it run strong when the truck is cold?

Any chance its bad gas? Dump some seafoam in her, that stuff fixes just about anything.

I can keep on guessing if its any help for you, if not then just tell me to stop

1992gen1_fan

If everything else checks out good, check the rear diff. The old L/S d70 in my truck throws a heck of a fit most of the time. It makes the truck fell as if it has about 1/2 the hp less. When something is holding back a cummins..
It took me a while to figure out what the problem was, but 99% sure its the rear diff. It makes the truck feel like its got a heavy trailer on behind it when just driving empty sometimes, your's drives fine empty so.. I just thought your problem sounded similar, hope it helps. Good luck.

jsadamson1

Well I got her home. Aamco said the carb needs lots of work but they did what they could for cheap to get me going again.

Funny you mention the rear diff, I have noticed it has oil all around it and before I looked it was fine. It does just what you say, feels like I am towing when she is completely empty.

How can I check that? I am done moving and have my truck so now I can start really trouble shooting the issue!

Thanks for everyone's inputs, very helpful!