1996 Fisher DLX 240 with 115Hp mariner, trying to identify engine and prop

[jabroni1m]

I have read many posts on props and know it is determined by RPM's, size of boat, weight of boat, particular motor. The boat is a 24 footer by 8 foot wide I believe. Its a bi toon. It has a 115hp mariner. I'm assuming the motor is a 1996 as well but do not know how to tell, anyone know where the information plate is or does it have one? I am not sure on the weight but it says 2900 pounds max for passengers and engine. So I'm assuming 2700 or so is how loaded I would have it. I have a lot of family. RPM's are a problem because it seems to start fine and at idle says like 2k, but when I give it just slight gas the rps skyrocket to 4 or 5k and at full throttle 9k or more. Not sure on exact because it maxes the RPM gauge. I don't think it could be this high or am I wrong? I'm assuming the tach is messed up. It currently has a 3 blade prop made by solas, I believe its a myth model and numbers say D3X13.75X13R. So does this sound like the correct prop or would a 4 blade pontoon prop be better suited? I know without correct RPM its hard to determine but is there any guideline for a 115HP mariner on a 24ft pontoon? Thanks for any help and if all else fails I could have the boat shop check rpm for me and then have you guys tell me the prop cause my boat shop don't know much.

 

[steelespike]

Re: 1996 Fisher DLX 240 with 115Hp mariner, trying to identify engine and prop

The tach probably has a selector on the back.It may be set wrong or sometimes it gets corroded.Make note of the setting and rotate the selector a few times to clean the contacts.The prop is about right. rpm range is 4750-5250.Should be propped to the high end.

 

[jabroni1m]

Re: 1996 Fisher DLX 240 with 115Hp mariner, trying to identify engine and prop

This will probably sound stupid but where is the tach usually located on the engine? Down by the prop somewhere or up by the flywheel type thing? Thanks for any help. So a three blade should be fine? Don't need to go with 4 blade?

 

[jabroni1m]

Re: 1996 Fisher DLX 240 with 115Hp mariner, trying to identify engine and prop

Does anyone know where to get engine schematics with these older engines? I want to be able to replace some of the smaller things if it goes wrong.

 

[Hoss007]

Re: 1996 Fisher DLX 240 with 115Hp mariner, trying to identify engine and prop

If you have not yet corrected the problem with your boat, contact Fisher. Go to Fisherboats.com and find the contact number. I talked to a representative who has worked for the company for years. Give the representative your hull identification number. This number is on your boat documents and usually on the back of a pontoon. They can tell you which propeller was used on your boat when it left the factory. Mercury does not put the propeller on the boats. Fisher lake tests the boats to determine propeller size. It is my belief that you need a 13.75X15. Also, your rpm at idle sounds high.

Stay away from the four blade propeller. They vent with the slightest tilt at full speed.