dwindling power 87 300sdl

Lately this car has lost lots of power. It used to fly up the mountains with power to spare, but now downshifts to 3rd & creeps up hills slowing down to below 50 by the time i reach the top. I've run
some diesel purge through it, & i remember an adjustment of the throttle cable i had done on my old 85 sd, but i can't see any play or anything amiss with the throttle. Also, the exhaust out of the tail pipe seems pretty weak.. I think this has had the trap oxydizer taken out.. there is just a length of pipe now..
Unfortunately, i'm driving to san diego tomorrow.. so won't get any help 'till after i get back. But any help anyone has would be greatly appreciated. I will check the group while gone, & take a few hand tools in case i can try something simple.
It idle's fine, & seems to pause briefly before revving up while in neutral. Perhaps a turbo problem?
Thanks in advance. I always enjoy reading this group, even though i don't post much.
Scott Wilcox Sedona, Az
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Sounds like a clogged banjo bolt in the boost sense line.
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Diesels need fuel and air to run. Let's first look at the simple things to ensure it has both.
Check the fuel tank's vent by opening the fuel cap after some driving to determine if there's a vacuum inside the tank due to a clogged tank vent. Fuel starvation is the result.
When was the air filter last changed? If you check it does it look reasonably clean? Or is it oil soaked and restricting the air flow?
Same applies to the fuel filters - when were they last changed? If the air filter is OK then I'd replace both fuel filters, if only to rule them out as possible causes.
The more complicated possibilities should wait until these simple possibilities have been ruled out.
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Thanks for the reply, T.G. .. I'll also check out Richard's suggestion of the banjo bolt.
I did knock out the air filter.. it wasn't that old.. & flushed out the fuel filters.. even ran some diesel purge through the inlet straight.
There is a bit of vacuum when i open up the fuel cap.. this is not normal? Where is the fuel tank vent or the best way to clean it?
Before i left on a trip, i cleaned out the tube running from the manifold to the switch over valve. It was clogged & opening it seemed to help for a while.. the drive out to San Diego was peppier than before.. but the trip back was brutal.. speed dropped down to 40 mph & downshifted to 2nd. It winds up to about 3500 rpm & stabilizes like on a governer.. which makes me suspect the switch over valve/ engine overload protection.
I am planning on ordering new fuel filters on my next order of mb stuff.. perhaps that & the fuel tank vent may solve most of the problem.
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leave the cap off , change the filters
the case, minus a few cans!
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Well, i tinkered with the switch over valve, switch, & tubes yesterday & that seemed to do it. I checked the manual on disk (always a distasteful pursuit) which said some pressure in the fuel tank was normal.. so am ruling out the cap/vent. The fuel filters are ok, too, i guess.
This is the first time i've gotten mostly useless replies on this group, too!
That just goes to show that perseverence & luck can be better than expert advice. :)
But for anyone who is worried about my fuel filters.. i am going to replace them on my next part orders..
Now i can really feel that turbo kick in.. acceleration is back to normal, i can roar up the hills. What a great car. It is strange that a simple little thing could affect it like this.
Scott Wilcox
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