vapor lock ... first time out for the - stalling

[Yankee Clipper]

Vapor lock may not be the correct term. But my last three times out on Lake O; the boat starts just fine, idles great then when I give it the throttle to get up on plane it bogs and stalls. I go into the bilge area and pump the primer ball which is soft … the engine fires again – then bogs and stalls. Usually the third time the ball finally hardens as I pump it and it stays firm and I know I’m good to go. It fires, gets up on plane, trolls all day beautifully and then screams into the marina when I’m done. To complicate things, I knew I could not make it up to the big lake today so I put it back into my slip on Oneida, and went out this am just to check it out and it fired it up and ran perfectly. I seem to only ahve two conditions are common when it acts up like and it may not ahve anyhting to do whith the problem – it’s been trailered and it’s rather cool out - mid 40’s one morning.

200 horse Yamaha 4 stroke with 180 hours on it - well maintaned and I treat the gas with Staybil evry fill up. I thought air was getting into the system so I’ve checked the connections and hose clamps throughout the fuel system and they seem tight enough and I’m not smelling or seeing and gas leaks??

Any suggestions on where to look??

[lil' troller]

I have had two primer's go bad, and last week my dad was getting his boat ready for it's maiden trip and the same thing. Sometimes the check valve in them starts to go bad and it leaks pressure back into the tank, or sometimes it sucks air through the outside of the primer. it could just be gummed up too. It's a cheap place to start, or if you have another primer that you know works try switching them out. Just something to check out.

[Yankee Clipper]

thanks for the idea ... I hope it turns out to be somthing this simple.

[times two]

I used to have a 70hp Evinrude that litterally went thru a primer bulb every other

year. IT was the lowest point in the fuel flow and the ethanol ate it up. Shake the

bulb. It should not rattle.

John

[Yankee Clipper]

X2 thanks .. Im heading out of town but with yor and lil troller comments it will be the first thing I look at when I get back

Each time its happend the ball was soft and as I squeeze it you can hear the gas going thru it but the ball won't harden at the first or second attempt so I can predict she will fire up but then bog and stall. It takes about three attempts and when I feel the ball firm up and I dont ehar the gas anylonger I can predict Im good for the day. One it should not be happneing but I am worried that one of these days, if I dont figure it out soon, I will be getting a tow back into the dock

thanks for the opinion ..

[ERABBIT]

If the above doesn't fix it , it could be the diaphram in the fuel pump. I had the same problem you talk about , started fine ran good at idle and would open up fine with no load. Put it in the water and open her up and she would bog down. Last time out before I changed the fuel pump diapharm we had to have someone pump the bulb all the way in.....................good luck..............Oh also if you have a inline canister before th bulb it would not hurt to change that out also could be plugging up and you have to help get the gas thru to the fuel pump.

[Yankee Clipper]

ER thanks .. my brother in law had this problem and mentioned it to me ...

[huskyjerk]

Hey do I have a story for you. On my yearly Canada trip to Bob's Lake I could not accomplish my usual extended slow trolling activity due to vapor lock. I found if I took off the cowling it would troll fine. Ambient temp was the problem. My 2009 EFI 150 at idle trolling just got too hot under the collar so to speak. Mercury Inc suggested adding lots on Quickleen to my 82gal tnk. One of my ideas was to run the gas line thru a sytraform box filled w/ice {like we did when we had a drag car. the other was to have a custom car body shop fashion an air scoop or louvered area on the front of the cowling neither suggestion has been accomplished yet since im away on a non fishing vac to Gettysburg Pa. I WAS PISSED AT THE VAPOR LOCK ON A 'NEW' 10K+ ENGINE

[Yankee Clipper]

Huskyjerk, since posting this we found a bad fuel line filter with a cracked O ring. My assumption is that it was introducing air into the system. Anyway once this was replaced I have not had a problem since. We wenmt ther last sicne it was a pretty new filter .

Good luck with your problem ... I would like to think that there has to be an easier solution