Yamaha VMAX Carb 150 - Idle Problems when hot

[Atlanta Boater]

Have an 2002 Yamaha 150 O/B. Just started using 3 weeks ago after sitting over Winter. Experiencing the following problem:<br /><br />Starts fine at launch, runs strong... let boat sit for a while after running for a while, starts up fine again.<br /><br />After running long period, shutting off and trying to re-start right away, hard to turn over, idles really rough and shuts off frequently. <br /><br />Yesterday, couldn't crank at end of day.<br /><br />I'm hearing potential Vapor Lock as mechanics just had in and cleaned carbs, etc... If experts out there agree with this potenial diagnosis, a) how do you confirm it b) how is it fixed?<br /><br />At mechanics now, love to provide them "free" advice, haha..<br /><br />thx

 

[JB]

Re: Yamaha VMAX Carb 150 - Idle Problems when hot

Howdy Boater.<br /><br />Welcome to iboats. <br /><br />Moving this to Yammy Troubles.

 

[rodbolt]

Re: Yamaha VMAX Carb 150 - Idle Problems when hot

hello<br /> talk to me <br /> but we have to talk on the same page<br /> when you say its hard to crank do you mean like maybe a dead battery? is it getting hot? have you tested the alarms?<br />what you described is a case of a bad battery connection someplace. when ya say at the days end it would not crank. do you mean the starter would not turn it over or that the flywheel turned but it would not start.<br /> post back with some concise clear info and we can try to help

 

[Atlanta Boater]

Re: Yamaha VMAX Carb 150 - Idle Problems when hot

Originally posted by rodbolt:<br /> hello<br /> talk to me <br /> but we have to talk on the same page<br /> when you say its hard to crank do you mean like maybe a dead battery? is it getting hot? have you tested the alarms?<br />what you described is a case of a bad battery connection someplace. when ya say at the days end it would not crank. do you mean the starter would not turn it over or that the flywheel turned but it would not start.<br /> post back with some concise clear info and we can try to help

 

[Atlanta Boater]

Re: Yamaha VMAX Carb 150 - Idle Problems when hot

Sorry, clarification...<br /><br />Turning key to start motor results in standard noise of an outboard right before it fires up (believe starter is fine per your question). Battery operation sounds normal, engine will attempt to start but sputter, but never fully start up. If it does, the idle is very slow (compared to when I first launch boat, steady, strong idle) and will sputter out to a dead stop (sorry if I'm not using correct mechanical terms).<br /><br />Timeline on Saturday: top off gas, launch boat, starts right up at launch, idles strong, run for 20+ minutes across lake, shut off for about an hour, starts fine, steady idle... let sit another hour or so, run back across lake 20+ minutes, turn off, throw a skier in the water, try to crank engine, starts, sputters and dies several times. Finally get cranked, go back to dock, put in neutral, engine sputters again and dies, will not restart.<br /><br />This has happened two weekends in a row, normal operation most of day, but idle issues right after running mid-throttle for extended time and then stopping, and trying to re-start.<br /><br />Again, battery new, cranks right up most of time.. did go from a Cranking Battery to a Deep Cycle this summer so I could run Radio more, but both has same MCA's...<br /><br />I see no indication of overheating on dash display, but wouldn't know what other alarms to test.<br /><br />Thx for your help Rodbolt, I was hoping you'd reply.

 

[rfc203]

Re: Yamaha VMAX Carb 150 - Idle Problems when hot

Atlanta,<br />I’m not sure if the problem I had is applicable to your motor, but it might be worth looking into. I have a 2000 VMax 225. It was experiencing the same symptoms you described. There was a recall on the VMax’s for bad fuel pumps. When they fail they leak raw fuel back into the crankcase. If you shutdown after a decent run time and then try to restart after a short time, the motor is flooded because of the leaking pump(s). If you let it sit long enough the fuel dissipates it the motor will start. The way we tested mine was to loosing the bolts that mount the pumps to the block and then squeeze the primer bulb. If the pump is bad it will leak fuel out of the back of it. When I tested mine two of the three were bad. I replaced all three and all the problems disappeared.<br />If your fuel pumps have a white diaphragm, they are the ones that were subject to fail. The new pumps have a black diaphragm.<br /><br />Good Luck <br />Rfc203<br /><br />I just checked the online parts catalog and our motors use the same fuels pumps, so I guess yours could be affected also.

 

[Atlanta Boater]

Re: Yamaha VMAX Carb 150 - Idle Problems when hot

Rfc203, you were dead on my friend! After reading your message, called dealer right away, talked to mechanic, they had just found the exact same problem, small hole in diaphragm. Back out on lake this weekend and crossing my fingers.<br /><br />Thanks again for taking the time to respond, if they hadn't found problem already, they would have due to you.<br /><br />John

 

[rodbolt]

Re: Yamaha VMAX Carb 150 - Idle Problems when hot

hello<br /> go with the pumps. they are cheap. the first sign they are leaking is you will see oily spots on the water at an idle. the second sign is at top speed it wont keep running and the third is when the raw gas washes the oil from the cylinder and ya smoke a piston. a quick test before every outing is to trim the motor down and pump up the primer,with the arrow pointing skyward. when it gets hard just hold it and if it slowly leaks down you have a leak someplace. usually a needle valve or a diaphram<br /> good luck and keep posting