Low speed, 25hp bucks like mule

[mayorj1227]

86 25hp evinrude with Manuel primer pump. ( What frigging genuis come up with ditch the choke). Problem is full speed fine, mid range to idle it bucks and kicks like on one cylinder then goes dead...Suggestions anyone...

 

[tphoyt]

Contaminated fuel, tank vent closed or not working properly has the carb been cleaned? Is this motor new to you?

 

[F_R]

Low or no fuel through carburetor idle circuit.

Slow speed mixture needle set too lean.

Throttle synchronization out of adjustment.

Air getting into crankcase.

Loosing ignition at slow speed

Checked compression??

 

[mayorj1227]

Contaminated fuel, tank vent closed or not working properly has the carb been cleaned? Is this motor new to you?

New fuel, vented, just bought it. Says to pump twice to fuel the head. Pump 4 times to get fuel to the primer. Also pulled low speed screw, was bent about 30 degrees

 

[mayorj1227]

Low or no fuel through carburetor idle circuit.

Slow speed mixture needle set too lean.

Throttle synchronization out of adjustment.

Air getting into crankcase.

Loosing ignition at slow speed

Checked compression??

Cold start compression 110psi both

 

[racerone]

How did this motor run for you last season ?-----If throttle plate opens too early the motor will be very unhappy.-----The primer is better than choke plate in my opinion.

 

[mayorj1227]

How did this motor run for you last season ?-----If throttle plate opens too early the motor will be very unhappy.-----The primer is better than choke plate in my opinion.

Just bought it

 

[racerone]

No surprise to me that a motor with issues is put up for sale.-----Look into the procedure for synchronizing throttle opening with spark advance.----Check gear oil too.

 

[tphoyt]

If it were me I would start with rebuilding the carb, check for good clean spark, water pump service and check or replace gear case oil.

 

[mayorj1227]

If it were me I would start with rebuilding the carb, check for good clean spark, water pump service and check or replace gear case oil.

Carb rebuilt, spark good, bottom end good, power head problem

 

[racerone]

Any chance for a refund ?

 

[mayorj1227]

Any chance for a refund ?

Yeah Right

 

[oldboat1]

Keep it simple until it ain't. See post #3.

Measure spark at idle with an open air tester. Might need to set throttle idle a bit higher (throttle setting, in addition to proper carb air/fuel mix).