Running out of fuel does weird stuff like revving.
Flapper in hose. Your pressure gauge should also read vacuum. I have had these engines "Vapor Lock" pulling against a restriction like clogged tank sock or a softened hose that kinked shut.
Tank lining coming off clogging tank sock.
What rig (pickup looks like) and trailer are your using?
A few of us have attempted this. IDK how many aside of myself still show up. Happy to give out advice.
Warning: Look at the Carnage Thread I Won because hotshotting with a 6.2/6.5L IDI GM Diesel... It can get expensive in parts quick...
Ultimately as the driver YOU are responsible for operating a safe vehicle that is loaded properly and NOT OVERLOADED. Not saying you were, but, you shouldn't be asking this question: you should know before you accept the load! A jury will hold YOU accountable if life is lost from an accident...
Price a new truck : any engine. Your budget should now reflect that for repairs to this one. Hell even drop in a gas engine from a junk yard.
Check for cracks in the block and heads. (just pull the oil pan and check main webs) Low miles (on the 6.2) doesn't mean anything RE: if it's cracked to...
If you can control the brakes enough to try it on gravel roads?! Is this safe to even operate to go out and "test"?
Oil leaking onto rear drums?
Hydroboost pinched return line or filter wrongly put on that line vs. steering box return line. Any restriction on the hydroboost return line and it...
Below 45MPH the torque converter is not locked and you won't feel any engine RPM changes so much.
In addition to @Will L. advice. Check the lift pump fuel pressure. DB2's knock the engine like hell before they run out of fuel. It's a weird sound you will know if a DB2 pulls up to the fuel pump...
You verified you have flow through the heater with a garden hose and the in/out was hot? Stop leak a PO used (or customer) clogging the core?
What exact problems did this engine/vehicle have before you started the repairs? Generally the intake leak is a problem by itself but low coolant could...
Clearly you have a problem in the rear head area or block. Pictures you posted do not help. You need the entire rear head gasket examined both sides. If you don't see where coolant or carbon was tracking, yes, look for cracks. Including cracks past the valve seat into the runners on the head...
Thanks @Big T
Nice to be validated (along with others who worked on the ATT in it's day) starting around 16 min.
21 Min IS the "lag" where you need RPM for the turbo to light off.
23:40 Mr. Banks with a loose converter and Big Turbo. 🤪 Where have we seen this on say a 6.2 IDI Turbo Two...
No. Primitive Artificial Stupidity computer is programmed to ignore intermittent problems to reduce warranty claims and difficult to track down problems.
If you have TWO Volts across the two glow plug terminals when it's on, and you need to check exactly this, then it's a problem: loose...
Guessing 3.1L or 3.8L V6? They are known to leak coolant into the engine from an intake leak and lock the engine up. The reason they have the gasket (pictured) is because of the cast iron and aluminum expansion rate difference: gasket allows some movement.
Have you checked price and...