1977 25hp is Bogging Down

[mehoo222]

I have a 1977 25hp tiller steer. This motor idles great. It will run fine when in gear at slow speed, but when you give it a little more gas it sputters, bogs down and dies.

At the same time that I started experiencing this problem, I started having a hard time cranking the motor in the mornings when it is cold. It used to be 1-2-3 pulls and running, but now it is 15-20 pulls and running. It will start on the 1st pull after you shut it off.

I just recently had the intake gasket replaced twice. The first time, the shop did not torque down one of the bolts to the power head and it fell out and busted the new gasket after about 2 hours of running.

The bogging problems started after 30 min. of running from the 2nd gasket replacement.

 

[oldcatamount]

Re: 1977 25hp is Bogging Down

Have you done a spark test for both cylinders? It sounds to me like you may be dropping a cylinder and have an ignition problem. Are you talking about the "intake" manifold that had the gasket replaced?

 

[missotis]

Re: 1977 25hp is Bogging Down

Sounds like similar symptom to what I experienced a few years ago with my 1982 25 hp johnson. It sounds like a blown head gasket. Try doing a compression test. Low compression will make it very hard to start and when you get it started it will bog down due to compression leaking between cylinders. My fix was a $25 gasket and I was back in business.