Mechanics

CAN A VACUUME LEAK CAUSE OCCASIONAL ROUGH RUNNING

1994 Ford Ranger • 16,000 miles

Runs smooth and then runs very rough on what seems to be on 3 cylinders. When given full power, it will jerk and act like it is trying to clear itself and run normal and usually will. First, I changed the fuel filter, no change. Nexted, I pulled the plugs and the exaust plug on the number 1 cylinder was black, all others looked normal. Both coils tested in spec, replaced all plugs and wires. Drove for 10 miles and then same problem occured. Sometimes it runs smooth and sometimes rough.
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21smack
May 19, 2012.



I would start with a compression test to verify the cylinders are ok.

If you did the secondary side as you said, I would suspect an injector issue. They may ned to be professionally cleaned, not an additive to the fuel.

Roy

ASEMaster6371
May 19, 2012.