87 Suzuki samurai, engine "misses" throughout driving speed range and hesitates/stumbles during acceleration. Stumbles even while trying to rev it in neutral.
-engine timing is correct, tho idle is high probably due to a weak return spring on the throttle
-engine was fully rebuilt in March 2016 so do not suspect anything internal
-I have replaced all vacuum lines
-replaced fuel filter
-checked fuel delivery to carb from pump, appears adequate
-all spark plugs are clean
-replaced all plug wires and coil wire
-replaced gasket between carburetor and manifold, ensured a nice tight seal
-checked function of the mixture control valve by following directions in my manual. passes the test. (Disconnecting the small hose from the valve, reconnecting it while simultaneously holding a piece of paper close to the under side of the valve. The paper was drawn up to the valve like the book indicated and the motor ran rough while performing the check as the book indicated.)
-checked the EGR valve by touching the diaphragm while motor was cool and then while it was warmed up, revving it slightly at both temps, diaphragm didn't appear to move during either check. Book indicates it should at warm temps, but I don't think mine did. A mechanic told me these rarely get stuck open, so I ruled out the EGR by disconnecting it and performance was still bad. Unless it truly is stuck open...?
- I do have a crack in my exhaust pipe in the last 1/3 of the pipe. I feel this crack is far enough back that it couldn't be the culprit. Please correct me if I'm wrong!
At this point I have troubleshot everything I know to do and am stumped. Where else might my problem lie? Do I need to rebuild my carburetor?
Any insight would be greatly appreciated!! Thanks a lot!
Katie, zukchik
