I'm experiencing a power loss problem in my 1985 E-350 with a 460. I use it mostly for towing, so the engine works hard nearly all the time. Any power loss is also very noticable. When trying to accelerate on the freeway, or maintain speed up even gradual hills on the freeway, the power falls away, the engine starts sputtering, and backfires will happen both from the exhaust and the carb. While sputtering up a hill, I notice that my oil pressure is much higher than usual.

At idle and around town the engine runs great.

Any suggestions for things to check?

 

Sounds like a fuel delivery issue. Look for partialy plugged fuel filter, low fuel pressure (bad pump), or fuel restriction somewhere (kinked hose, contaminents in carb or fuel line). Deen

 

Mjr,

I had the same problem a few months ago. I have no idea how it happened but after weeks of fretting and watch Chevrolet Chevettes blow me off the road, I found my primary bowl fuel filter was so clogged I could barely blow through it!! I replaced the $1.97 item and now Harrison honkz like a built 460 should.

Just my 2 cents worth...

 

Thanks for the tips. I'll verify fuel delivery, filters, and report back.

 

Also check dist cap-n-rotor. They do weird things. The backfiring sounds more like this to me.

 

As I started working on changing the fuel filter, I noticed that there was quite a bit of oil in the air cleaner housing, so I replaced the PCV valve and grommit. Looking at the spark plugs, which only have around 2K miles on them, most were fouled with large amounts of thick, carbony crap. With a new fuel filter, new PCV value, and new spark plugs, the strange power loss is gone.

Hooray.