No Power Over 45 mph

[spaceboy]

Howdy all, just bought my first 50 this week('89, 2L, 4cl, 2WD), so I'm new to these trucks and the engines. She does well in first gear, but has very little power generally(0-40 takes about a minute), and can't go over 50mph unless it's downhill. Brand new Carburetor, brand new vacuum pump. Throttle opens fully and has good tension. I'm thinking it's the distributor, but again I don't know these trucks yet. Any ideas?

[geezer101]

Hi and welcome to mightyram. If the vacuum advance on the distributor is shot, it will nerf acceleration badly. Normally no top end power is a carb related issue as the stock Mikuni carb is prone to secondary solenoid/servo failure (the diaphragms in them split, not only preventing the secondary throat from opening but creating a vacuum leak in the process) If the original coil is still fitted, it is worth considering replacing it. A weak spark will also cause loss of power and fuel economy. This issue could also could be something as simple as a bad engine tune.
Start by testing the vac advance and work your way from there. :thumbup:

[Swansburg]

I have a G63b dist. for sale if that ends up being your problem, only 6 months old

[Can1991Ram]

Replacing my coil, pulling a few litres of water through the engine through a vaccum hose brought my truck back to life.

I would also suggest a good tune up including replacing the O2 sensor.