Indmar 5.0 problem

[sunger]

I have a 1973 Bertram 28' sport fisher with twin Indmar 5.0 gas engines. My starboard engine has me completely stumped, and I am hoping for some help.It starts and runs fine, and I can rev it without an issue. My problem comes when I put it in gear and give it throttle. I can not go beyond 2200 RPM,s. I don't have a prop issue, and nothing is dragging under the boat. What is holding the power back?
Thanks for any thoughts.
Steve

 

[Greg Mrozinski]

Re: Indmar 5.0 problem

Sunger,

Welcome to iBoats. There could any number of things causing your issue. Start with the simple things and go from there. Get a service manual to start. You will need it. Check fuel, compression and spark. For fuel, check the condition of the fuel and the fuel tank, fuel filter, fuel pump and pressure and the carb. Check compression on each cylinder. You want to see recommended range and consistancy between all cylinders. Check the batteries to make sure they are in good condition and providing good stable voltage. Check spark using a spark tester to make sure the spark is strong enough. Make sure plugs, wires, rotor, distributer cap, and points are good. Check each plug's condition too see how the cylinder is running. If everything checks out then maybe you need to look at non-engine causes such as the transmission possibly.

 

[sunger]

Re: Indmar 5.0 problem

Sunger,

Welcome to iBoats. There could any number of things causing your issue. Start with the simple things and go from there. Get a service manual to start. You will need it. Check fuel, compression and spark. For fuel, check the condition of the fuel and the fuel tank, fuel filter, fuel pump and pressure and the carb. Check compression on each cylinder. You want to see recommended range and consistancy between all cylinders. Check the batteries to make sure they are in good condition and providing good stable voltage. Check spark using a spark tester to make sure the spark is strong enough. Make sure plugs, wires, rotor, distributer cap, and points are good. Check each plug's condition too see how the cylinder is running. If everything checks out then maybe you need to look at non-engine causes such as the transmission possibly.

Thanks Greg. The fuel is good because the other engine runs fine, and the batteries were new last year. I will put a new distributor cap on incase there is a crack, and I'll have someone check the strength of the spark. I don't know how to do that. Wires are good, and the points are new as well. Anything special to look at tranny wise, or how should I check the transmission? The oil was changed about 2 months ago.
I appreciate your suggestions.

 

[Greg Mrozinski]

Re: Indmar 5.0 problem

I wouldn't worry too much about the tranny just yet becuase typically they either work or they don't. Like I said before start with the easy things and go harder. I recommend runnning through everything I outlined above...especially the compression check. Also helpful would be a vaccum check. Vacuum condition can tell a lot about the condition of an engine. Just suggestions.