lack of power?

[ruff price]

i just bought a yamaha made mariner 40 E twin carb that idles rough but cranks easy, and will barely push a 14 ft AL boat (low rpms), but when in neutral the rpm will go all the way up and will surge at top. bought new plugs i just cleaned the carbs and there was some gum in the bowl and the slow jet on the upper carb was stoped up. i took out the needle, main and slow jet on both carbs. could the slow jet being stopped up cause power loss when full throttle? and what are the signs of the coil going out?

 

[crem1]

Re: lack of power?

If you cleaned your carbs well, then check the fuel pump next.(cheap to replace)

 

[Doug57]

Re: lack of power?

Check fuel lines for weak areas that could collapse, kinks, or anywhere the system could be sucking air. When under a load will require more fuel. Also you shouldn't run the RPM's up when in neutral, can cause problems you don't want.

 

[ruff price]

Re: lack of power?

i recleaned the carbs again and seemed to help but went right back to the way it was. i'll replace the fuel lines next, is there a special grade hose? or will automotive fuel line work? on the fuel pump do i need to get a diaphram kit?

tell me about getting the carbs set and how much should this cost me?

 

[shadowcrest5]

Re: lack of power?

Hey Ruff Price,
You did not say if this is a old motor or new?Either way BE SURE ....ALL GAS LINES that are replaced are rated for......ALCOHOL RESITANT!!!
Unless you have found a gas station that sells JUST non-reformulated gas.(No ETHANOL, or METHANOL). Most newer engines are supposed to have this type of fuel line.If not SURE call the tech dept. of the motor manufacturer.NOT A MARINE MECHANIC. If you read these posts like I have been doing for months you WILL find that MANY simply may not know FOR SURE.And WILL tell you what THEY think you want to here.
Good luck.....Shadowcrest5

 

[Doug57]

Re: lack of power?

You might as well put a fuel pump kit in. When cleaning the carbs you need to boil them out with carb cleaning solution. Some automotive gas lines will not deliver the flow that a OEM type fuel line will. You said the last time you cleaned carbs it seemed to help. How much help? If the engine ran like it should then check your fuel tank for varnish. You need to get it clean or this problem could be like the movie ground hog day. That varnish will just keep heading for the carbs. and you'll be doing this whole thing over and over.

 

[Droll]

Re: lack of power?

Does it have the right propeller for the boat ??, almost any propeller should work since it's a small 14 ft boat... but if the engine was used on a even smaller boat before it could have to big a prop .... or maybe some sort of high pitch "racing" prop ??


Arne Kjetil

 

[ruff price]

Re: lack of power?

Hey Ruff Price,
You did not say if this is a old motor or new?Either way BE SURE ....ALL GAS LINES that are replaced are rated for......ALCOHOL RESITANT!!!

it is an 85...so i need to get line from a marine dealer?

You might as well put a fuel pump kit in. When cleaning the carbs you need to boil them out with carb cleaning solution. Some automotive gas lines will not deliver the flow that a OEM type fuel line will. You said the last time you cleaned carbs it seemed to help. How much help? If the engine ran like it should then check your fuel tank for varnish.

i called a mechanic and he told me how to reset the carbs after i completely disassembled the carbs. i cleaned them good and got it ildeing alot better. i have a brand new tank that is for my johnson so ill prolly just buy a new yamaha end for a new bulb and hose that will fit that tank should solve`two possible problems at once.

Does it have the right propeller for the boat ??, almost any propeller should work since it's a small 14 ft boat... but if the engine was used on a even smaller boat before it could have to big a prop .... or maybe some sort of high pitch "racing" prop ??


Arne Kjetil

it is a 15p if that sounds right. the motor was on a 15 foot glastron fiberglass boat...