#4 cyl no fuel

[Lee Potter]

I have a 1977 Chrysler 105 HP 4 cyl outboard. The problem is low power, it has good compression 120 psi on all cylinders, spark is fine, new fuel, drained tank and refilled, Reed valves look fine, no vacuum leaks, but #4 cyl plug is completely clean, no fuel or water residue, looks exactly like when it was installed, other 3 cylinders plugs have evidence of fuel burning. I've checked intake and exhaust, both look fine. Any ideas.

 

[pnwboat]

I would suspect that there is a problem with the ignition system for #4 spark plug. Check the distributor cap, rotor, wires etc.

 

[Lee Potter]

I would suspect that there is a problem with the ignition system for #4 spark plug. Check the distributor cap, rotor, wires etc.

 

[racerone]

Does fuel pump run off PRESSURE from #4 crankcase ?-----Ruptured diaphragm perhaps ?----Did this problem develop suddenly ?----Lower crankcase seal ?-----How did it run for you last season ?

 

[jerryjerry05]

I don't think any Chryslers except the 50hp or lower used the #4 or bottom piston to run the fuel pump.
Usually #2 on a 3cyl. or #3 on a 4cyl.
Some bigger 140/150 could have 2 pumps utilizing #2 #3 cyl.