Mechanics

D-21 4CYL. 2X4 PICK-UP SURGING/STUMBLING?

1986 Nissan Truck

The truck has 196,000 miles. (I am the original owner). It starts to surge/stumble upon rapid acceleration.
Gentle acceleration seems not to be a problem. It has stalled once or twice and had difficulty restarting. Two shops have not found the problem. The last shop recommended a scattershot approach (replace the coils and igniters, replace the distributor and the electronic carburetor. As these are not inexpensive parts, I am trying to narrow down the problem area. One of the coils has a very small spark compared to the other. Could this be the issue? This problem started several months ago and has become worse over time. Any ideas?
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Unquity
September 10, 2007.



In my opinion it is a fuel delivery issue, gentle acceleration OK Hard accel NG! Check pump pressure Carb model should be 7-9 psi.

Merlin2021
Sep 10, 2007.
I should explain that the surge/stumble description may not be a good explanation. The symptom seems to be
rhythmic. In other words, during rapid acceleration the
power loss is sort " on" " off" " on" " off" in a pattern so to
speak. Very consistent. I also notice the smell of unburned gas.

Tiny
Unquity
Sep 10, 2007.