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40 HP Jonhson, when advancing the throttle to full, RPM gose to 3500 no problem, then the engine starts to oscillate back and forth between 3500 and 4500 RPM.

Submitted: 69 days and 2 hours ago.

Category: Boat

Value: $29

Status: CLOSED

Make (of engine): Johnson
Model (of engine): CJ40TTLCEC
Year: NOT SURE
Horsepower: 40

Already Tried:
did a compression check, top cylinder 110 dry - 130 wet
bottom cylinder 120 dry - 150 wet.
Ser# C8245379

Accepted Answer

Your compression does not sound like it is the problem. You likely have a fuel pressure issue.

Does squeezing the primer bulb or hitting the fuel primer help pick up the rpm at all?

Accepts:
Expert:	Master Tech
Pos. Feedback:	100.0 %
Answered:	9/15/2009

Marine Mechanic

Evinrude Master Technician with 27 years of experience.

69 days and 2 hours ago.

Reply

I have not tried what you suggested but I will. If it helps what would you suggest.as the problem?

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Question

40 HP Jonhson, when advancing the throttle to full, RPM gose to 3500 no problem, then the engine starts to oscillate back and forth between 3500 and 4500 RPM.

Optional Information

Make (of engine): Johnson
Model (of engine): CJ40TTLCEC
Year: NOT SURE
Horsepower: 40

Already Tried:
did a compression check, top cylinder 110 dry - 130 wet
bottom cylinder 120 dry - 150 wet.
Ser# C8245379

Accepted Answer

Your compression does not sound like it is the problem. You likely have a fuel pressure issue.

Does squeezing the primer bulb or hitting the fuel primer help pick up the rpm at all?

Reply

I have not tried what you suggested but I will. If it helps what would you suggest.as the problem?

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Question

40 HP Jonhson, when advancing the throttle to full, RPM gose to 3500 no problem, then the engine starts to oscillate back and forth between 3500 and 4500 RPM.

Optional Information

Make (of engine): JohnsonModel (of engine): CJ40TTLCECYear: NOT SUREHorsepower: 40 Already Tried: did a compression check, top cylinder 110 dry - 130 wet bottom cylinder 120 dry - 150 wet. Ser# C8245379

Accepted Answer

Your compression does not sound like it is the problem. You likely have a fuel pressure issue. Does squeezing the primer bulb or hitting the fuel primer help pick up the rpm at all?

Reply

I have not tried what you suggested but I will. If it helps what would you suggest.as the problem?

Related Boat Questions

Make (of engine): Johnson
Model (of engine): CJ40TTLCEC
Year: NOT SURE
Horsepower: 40

Already Tried:
did a compression check, top cylinder 110 dry - 130 wet
bottom cylinder 120 dry - 150 wet.
Ser# C8245379

Your compression does not sound like it is the problem. You likely have a fuel pressure issue.

Does squeezing the primer bulb or hitting the fuel primer help pick up the rpm at all?