Loss of power going uphill at 50mph

[Doug Long]

Yesterday I was driving home on a road that is uphill at 50mph. The truck would lose power and I pulled off the side of the road and then it was fine. I did this a couple of times. Once I got to a flat road it was fine.
I have an 1976 K20, edelbrock 1406 carb. The fuel filter is about 1/2 full. I was thinking I should replace the fuel filter and mechanical fuel pump. Any thoughts?

 

[CalSgt]

Fuel filter would be a good place to start

 

[mtnmankev]

I have experienced a half full fuel filter many times and the engine ran fine, I never could understand why it didn't just fill all the way up.
That said, I would first do a fuel pump delivery test, disconnect the fuel line (before the filter) and place in a container and crank the engine.
If my memory from way back is correct, you should get about a pint of gas in about 30 seconds.
I'm sure somebody will wander into the thread and provide additional or more specific information.
It can't hurt to replace the fuel filter if it's been on there a long time, it's amazing how much crud gets past the gas pumps and ends up in our tanks.
And a fuel filter doesn't catch everything, lots of tiny crud gets past it and ends up in the carburetor, so you MIGHT end up doing a rebuild/cleanup on the carb.
It's also not impossible the fuel pickup screen in the tank is clogged with crud, so don't be surprised if that ends up being the cause.
I am guessing you don't have catalytic converter on the truck, but if you do, a vacuum gauge test is in order to see if the exhaust system is restricted.
That about covers everything I can think of off the top of my head, hope it helps !!!

 

[Vbb199]

I was wondering about a bowl float misbehaving, as he said it returned back go normal on a flat grade.

 

[Shawn Watson]

A failing ignition system can do that under a load, too. You may want to look at a doing a tune-up there.


Shawn

 

[pnwnvrdn]

Agree, first determine if it is a fuel delivery issue, before throwing parts at it.
I'd also remove distributor rotor and make sure the advance weights move freely.

 

[Doug Long]

I replaced the fuel filter and we are good. Thanks for all the info!