Yamaha 99' Salt series II Stalling at idle

[mrom1234567]

My Yamaha motor seems to idles rough at idle and then stalls. If I give it gas in neutral lock it will run. It also runs fine at higher cruising speed.<br />Where should i start trouble shooting.<br />Can this be a fuel line issue or fuel pump?<br />Can it be an idle adjustment?<br />If so how can i diagnose the problem before I pull the boat.<br />Previously, my primer bulb was not getting hard.<br />However I tighened clams on all hoses, and it seemed to solve the problem.<br /><br />The only out of the ordinary thing I recently noticed is that the problem engine started to idle at a slightly lower RPM. Only about 1 RPM lower though.<br />Please help.<br /><br />Michael

 

[mrom1234567]

Re: Yamaha 99' Salt series II Stalling at idle

This is a 1999 Saltwater series II Carbed motor.<br />Sorry.<br />Michael

 

[rodbolt]

Re: Yamaha 99' Salt series II Stalling at idle

test your fuel pumps.<br /> a leaking diaphram will do what you describe.<br />also test the spark plug caps for 5K ohms resistance plus or minus 20%.

 

[mrom1234567]

Re: Yamaha 99' Salt series II Stalling at idle

Stupid question.<br />Can I check the fuel pump or change it without special tools?<br />I am mechanical, but not an expert mechanic.<br />Can it be checked visually? Will it be obvious?<br /><br />Michael

 

[bigbrownbuku]

Re: Yamaha 99' Salt series II Stalling at idle

when you pull the fuel pump/s from the side of the motor they will split fairly easily with the tap of a screwdriver handle. if you are not comfortable replacing the gaskets and diaphragms you can just change the pump/s wholesale.<br />the spark plug caps unscrew from the ends of the leads.<br />whats the service history on the engine?

 

[mrom1234567]

Re: Yamaha 99' Salt series II Stalling at idle

The history in unclear.<br />Last year I purchased the boat.<br />I had the water pumps changed and told the Yamaha mechanic to check the motors over.<br />I am usually liberal with what needs to be done.<br />I am perplexed that the Yamaha mechanics wouldn't tell me to change my fuel pumps and rebuild the carbs. I guess their attitude is wait until it fails to replace. Not my motto though.<br />I would repair replace anything for maintenance sake. No matter the cost.<br />This site is a great source of knowledge.<br />I will keep everyone posted as to the outcome.<br /><br />michael

 

[mrom1234567]

Re: Yamaha 99' Salt series II Stalling at idle

When I put my throttle in neutral lock, and tap it forward to get the motor to idle at 7000 rpm like the other motor, it idles perfect.<br />If I snap it back to the idle position the motor idles at 5 then 4 then stalls.<br />Am I fooling myself to think that I can just adjust the set throttle screw?<br />Should I adjust the throttle cable linkage set screw?<br />If everyone here agrees it is probably the fuel pumps, I will definitely change them.<br />The fuel pumps are probably original to the 1999 motor. How often are these usually changed?<br />Thanks for everyones help in advance.<br />Michael

 

[mrom1234567]

Re: Yamaha 99' Salt series II Stalling at idle

well, here is the update.<br />My carbs were all gunked up.<br />I had the mechanic rebuild all carbs and change the fuel pumps.(I had to twist his arm to change them-the pumps that is.)<br />The motors run beautifuly now.<br /><br />Michael