QuiGonJon

Ive had my 81 pickup for just over a month now, do a lot of freeway driving with it. A couple weeks ago it started having this issue. It only does this after driving for about an hour, it hasn’t done it to me sooner than that yet. When I’m going up to freeway speeds, at about 45-55 mph it will start stumbling, especially if I’m flooring it. If I’m very gentle with the throttle I can sometimes avoid it, and sometimes it doesn’t do it at all. It’ll also sometimes do it just cruising at freeway speeds and especially uphill. The other day I almost thought I wouldn’t make it home because it just wouldn’t get up to speed and I kept having to pull to the shoulder. BUT, and I think this is a big clue, while I was on the shoulder I remembered I had some Lucas injector cleaner with me, dumped some in and ran the engine for a while to make sure the Lucas was in there. This definitely helped, not 100% but I was able to make it home just fine. What will also help a little is turning the truck off for a bit, although It didn’t do much this last time. I’ve read a lot and learned it could be a whole host of problems including the distributor/spark plug system. But the Lucas helping makes me really lean toward a fuel problem, maybe fouled injectors. What do you guys think?
Any help is appreciated. I’m definitely not any expert but I know a bit so the more explanation the better.
Thanks guys!

Co_94_PU

iTrader: (-1)

A 22r doesn't have injectors.

Injector cleaner is pretty commonly the same ingredient as octane booster (naphtha)

Are you sure it's not pre-ignition (engine ping, sounds like gravel, robs power)

Punjab

Change your fuel filter. It's cheap and that will rule out a clogged filter being your problem. Your carburetor likely needs a rebuild if it's all factory from '81. That's a long time for old rubber and gaskets to be employed.

How does it idle?

We also need a lot more information about your motor...if you have it.

QuiGonJon

hortonma

I am having this exact same issue and cannot figure it out. I have put in new plugs, wires, cap, rotor, fuel filter, pump and new ignition coil. Any clues what is going on?

akwheeler

I would also try opening the gas cap to see if you are pulling a vacuum and making the fuel pump struggle to fill the carburator float bowl.
Fuel filter first, but I had some similar problems that ended up being from someone siphoning my gas, when they pulled their garden hose back out it left curly green strips in the tank that got sucked into the pickup tube.
They lodged in the fuel line about a foot in front of the fuel tank and choked off enough fuel to make the engine run out of gas if it was revved up. Idle was fine and the problem got worse and worse (repeated fuel theft and more and more bits of hose being sucked up).