Cummins 400 cuts out under heavy throttle

Let's start with the cpl on the engine or what year is it, is it a big cam, small cam, big cam 1 or 2 or 3 ?

 

:/ good call, for some reason I automatically assumed it was an ISX.

 

I have and parked a 350 big cam 1 with cpl 369, But I had oversize injectors with the top stops back off, my fuel pump was pushing over 300 lbs of rail pressure and had a ht4 holset turbo in it.

 

If it's a 400 it has to be a pre electronic motor, and even an pre N14 era motor.

 

Those parts prices are very reasonable. If it needs a cam, it will also need recon cam followers, the gaskets and seals on the front cover and the top of the engine, pan gasket and oil, belts, hoses, misc.
Not trying to burst your bubble but it all adds up pretty quick.

 

Both big cam 3 and big cam 4 were available for the year model (89) so it's possible he has either. Big cam 4 used low flow cooling (small radiator hoses). Engine block will be embossed with designation just above the pan rail.

 

It might be beneficial for you to find out who the previous owner used to service the truck. They may have already priced out a camshaft replacement cost to him and hence his reason for selling the truck.

 

I'm sorry I'm such a Bozo! I'm still a little wet behind the ears! Will you please overlook my shortcomings? Thanks!

 

I'm assuming we're talking about a NTC400 BC I-IV.

Sounds like a fuel starvation issue. Could be a number of things. Filters, water separator, even debris at the bottom of the tank near the feeds can cause it. Rule out the obvious first.

The pump itself could be going bad, but I never saw them fail on a regular basis.

Yes.

You're pretty quick to jump the gun as to regards to camshaft failure. All I have to go on is my good fortune with a seriously overfueled NTC 400 BC I, and I never had problems with cam lobe issues, bearing wear, or the like. Any time it acted like the OP described, it was a lack of supply fuel to the injectors themselves.

If it idles smooth, I can't see it being a toasted cam lobe. If anything, it would be more profound at that point.

Yeah, then he can sink 12 grand into the Kitty down the road. An old Big Cam is pretty cheap to overhaul, providing it needs one to begin with. The old 400's are prone to counter-bore issues, but you are required to cut the blocks to accept the newer style LPF liners anyway, and that alleviates that issue.

Don't get me wrong. I love 3406's. They are great engines. I would just hate to see someone boat anchor a perfectly good Cummins over a simple issue.

I don't think it's an ISX we're talking about.

Yah, especially if you have to mindset to rewire an entire truck because a light bulb burnt out.

Good luck.

Hahaha. I wasn't trying to bag on you, myself. Merry Christmas, Bender.