1993 Power Loss

[boomer]

On my way to Califonia from Oregon I had to go over the passs.
On the way up...my truck had an unusual loss of Power.
It got worse over time....down to 30 mph on the climbs. Dropped into 3rd....kept it at 30.
Once on open road....no problems...
Tranny is not slipping....engine feels like it has far less power uphill.
When I got to the next mountain range after 8 hours...I started up new mountains.
It was FAR worse....and I had to drop into 2nd...to keep 20mph.
After about 20 minutes...I was down to 10mph in 1st gear.

I stopped...no over heating....and thought it may be turbo...but it seems fine...very little shaft play.spin freely
Then maybe filter on fuel...changed it....no change

Lift pump? Perhaps....
Then!! What about AIR FILTER???
Oh my...it was PACKED with dust...about 1/4 pound!!!

I know...stupid me...
So I got a new airfilter...and it helped NOTICEABLY.

But it still lacks power uphill....and I can seem to get the jump it once had when I go WOT.
In fact it seems to dog even more at WOT.

so now I am wondering about just what happened to my power....over the course of a day...and why I can't seem to get it back

If I had a list of checks....and knowing I have no guages as extras...where would you start?

I've been told I should check lift pump..even though its new. Injector pump also new.

What psi do I need?
could be valve adjust? I've never done it....and I have 300k on my engine.
If I should....what are the clearances I need on valve adjust.
And finally...how do I check boost..I don't know what that means.

Thanks guys...still learning about my truck
Take care
John

[Hansen01]

sure it wasnt just high elevation? or are you home now and it still doesnt run right?

[oldestof11]

How much fuel was in the tank when going up this pass?

[skilletky]

Check your AFC tube. May have failed and is not supplying boost to your fuel pin thus not giving you more fuel with increase of boost. Also check for boost leaks elsewhere. Also check your fuel system on the suction side of the lift pump for possible bad spots were air could get sucked into.

[m880cummins]

My dad's truck has a 1991 fuel tank and the tank sender is held with a big plastic nut. If yours is like that, there is a big pancake paper filter on the bottom of the sender. Just take it off. Don't bother replacing it because the new ones are crap and as long as you are not dumping sand in the tank there is no reason for a tank filter.

My dad's truck would be no good below a 1/2 tank because after that the fuel would not spill over top of the sender. When we removed the filter it floated in diesel because it was so clogged. It was replaced 50000 earlier and we couldn't see any dirt in it but the paper lost it's porosity.

Charlie