I have a stock 1984 2.8L with the non-computer controlled 2BBL carb and an automatic. Car ran great all spring and early summer. I parked it (indoors) in July to focus on some other projects and just got back to it now, so it sat for about 2.5 months. Car runs great in town, but as soon as I get on the freeway and try to accelerate at about 50mph it starts to cut out, if I keep my foot in it it'll eventually stall out completely. It only acts up while at speed, at lower speeds I can accelerate hard (wot) and it pulls fine, even up hill. I can rev it easily in the driveway, no issues, no misfiring, etc.

I am not sure if I am dealing with a fuel issue or an ignition issue since the motor seems to rev fine at lower speeds, it's only at high speeds where it just completely falls flat. It does feel like it's running out of fuel, and if I ease up on the throttle it'll recover and run OK again, until I try to accelerate above 50.

The fuel filter was replaced in the spring, so I think we can rule that out. My best guess is that it's not getting enough fuel pressure under load at high speed, so I am thinking about swapping out the mechanical fuel pump for a replacement as my next move.....But I hate to start throwing parts at it.

Thoughts? It's time for winter storage soon and I'd really like to get this addressed before it gets tucked away....

 

Sure sounds like fuel delivery problem. Maybe a new pump needed, or could be drawing some air between the pump and tank. With the age of the car I wouldn't rule out a clogged fuel filter even though it's pretty new. Might try to down shift when on the road at speed when the trouble starts, ease off the throttle and see if the higher rpms will allow the engine to recover and accelerate some.

 

Change fuel filter again and see if it helps. If it does, tank may be rusting out and plugging up filter, which is what was happening to me. You can also cut the filter open and see if it is plugged.

 

Blowing some low pressure air through it backwards will show nastiness coming out if it's clogged easier than having to cut it up, just if your the lazy type.

 

So I got it sorted out. Dlinger was right, changing the fuel filter again resolved the issue. I'll have to monitor it and see if it clogs up again, because yes, it could be rust/dirt in the tank. Since it's a carbureted car, the only fuel filter is the one at the carb inlet, one of those little finger sized paper units. It didn't look too clogged visually, but obviously it was the problem because she's running great now with a fresh one. That filter though, unlike on the V8/4bbl cars, is a real pain to get at on the 2.8L. So I am thinking about adding an in-line filter BEFORE the mechanical pump that I can change out easily if it gets clogged up. Good idea? Or is that going to cause more problems than good?

 

Paper are even easier to cut open.



This is what mine looked like after about a month, probably about 50 miles.

If it was mine, I would leave in the stock location. I am not a fan of external fuel filters. One more thing to leak or go wrong.

 

Oh wow, now I wanna go find mine in the garbage in the garage and cut it open, lol.

 

I'd definately put an external filter on the fuel line and keep a spare handy. The external filter has a much greater capacity too.