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D24t sometimes seems to be in limp mode

impolvo

Is always busy
Joined
Feb 23, 2006
Location
Chapel Hill NC
Resurrected after may years the 262c with d24t m46 did great
Pulled fine for what it is was getting 8-11 lbs boost
Changed all fluids belts
Fuel filter twice once after 59 miles
Was very old fuel
It’s a little hard to start (under powered battery
Like 550 cca 70ah

But today it finds emwant to jump to life like normal
Needed a jump start and many turns
Took it around the neighborhood but occasionally would not rev over 1k
Even parked in neutral but randomly would decide to work as normal

Any idea?
I know I plan on an in line electric pump to help the injection pump
But no matter how much throttle it wouldn’t muster over a 1000 rpm
Then random moly it’d go away and be boost happy

It’s I thinkable engine from an 85-86 760

Any things that might be restricting it

I swapped glow control module so it’s firing the plugs now
Though I haven’t checked if they are good

No fuel leaks
Just oil from a Ames oil relocation kit
 
There is no limp mode, it's all mechanical. Three things can cause intermittent low power in a diesel like this- Lack of air, lack of fuel, or clogged exhaust. I had a turbodiesel rabbit with a very bad turbo that got terrible mileage. A muffler can fail internally, plugging the exhaust. The air filter can be clogged, causing it to draw enough vacuum to collapse the inlet tube. The lift pump could be failing, starving the injection pump.
When it has these lack of power events, does it smoke?
Also, glow plugs are only used to start the engine. Before cranking, they are heated up to help ignite the fuel. Once the engine is running, the only thing igniting the fuel is the heat of compression.
 
Plugged muffler comes to my mind as well.

But when it chokes the next time, try unbolting return banjo from the pump and see what happens, besides obvious leak of diesel everywhere. Gunk getting into pump, plugging the return *just slightly* and building too much pressure in the pump can make it act like it's starving.

Also, what color smoke?
 
Try doing Lubro moly diesel purge. Do the immediate purge, by having the return and feed fuel lines in the solution.

This. Many times I've turned down the volume in crappy old diesels by running it on Diesel purge. This is one product that is not snake oil. Don't dump it in the tank. Loop supply and return fuel hoses together and run the engine on it.

That said.... No magic juice will solve restricted air intake... Restricted exhaust.... Plugged fuel filter or a lift pump not getting fuel to the injection pump.
 
On these old diesels, its either fuel or air.

given the age of the fuel, I would suspect the fuel pump - either the main pump or the lift pump.

These engines will still run if the lift pump is dead, but not well.

Drain and refill the tank (with some diesel purge in it).
change the fuel filter (again)
Check/change the air filter.
Check that the turbo isn't seized.
Change the oil/filter. You could also run some Archoil in it.
Start the motor and check your fuel pressures.
 
And that one in the injection pump is a centrifugal vane pump that will disintegrate itself if it labors against a blockage over time and send shrapnel thru the rest of the finely machined IP innards.

Where is the OP?
 
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