DavisIslander Posted November 25, 2020 Report Share Posted November 25, 2020 Been driving this wonderful vessel like a "scalded dog" (old timers will know this term) and recently (as in the last three times out), I've started to get vapor lock on my 2004 115 4-stroke Yamaha. 354 hours on the motor and it runs beautiful. (usually) After a few starts and stops, I get the dreaded rar-rar-rar-rar and it won't start. After waiting a decent timeframe (30-60 minutes) it cranks right up. So...are there any remedies or work-around that I can employ to remove this new annoyance. BTW, can't wait for trout to open back up here in Tampa Bay, (May 2021)..been slaying 25-30 inchers. Artificials. Thanks everyone. Quote Link to comment Share on other sites More sharing options...
Coto Posted November 26, 2020 Report Share Posted November 26, 2020 Fuel bulb maybe? 2 Quote Link to comment Share on other sites More sharing options...
wthree3 Posted November 26, 2020 Report Share Posted November 26, 2020 A friend has a similar issue with a smaller yamaha. There is a heat exchanger under the cowl that has a fuel line and a water line running thru it. It's about 6 or 8 inches long and 1 inch wide, metallic, and located just before the telltale (water pressure indicater). Disconnect the water hose and run a piece of string trimmer cord or wire thru the water passage to determine if it's clear. Clogged passage can cause vapor lock. 1 Quote Link to comment Share on other sites More sharing options...
SCFD rtrd. Posted November 26, 2020 Report Share Posted November 26, 2020 I'm not a mechanic, but the first place I'd look is the fuel delivery system. Bulb, fuel lines, connections and anti-siphon valve. 2 Quote Link to comment Share on other sites More sharing options...
polliwog Posted November 28, 2020 Report Share Posted November 28, 2020 I had a problem with my gas tank's vent being clogged,once i solved that all was well. 2 Quote Link to comment Share on other sites More sharing options...
polliwog Posted November 30, 2020 Report Share Posted November 30, 2020 I am no sure about this ,but I don't think the older models,early 2000's had anti siphon devices installed. All the new ones do. If the fuel bulb is collapsed that would be the problem, the fact that the boat started up after you left it for a while makes me think there is an air lock in the tank that prevents the fuel from being drawn as it should. 1 Quote Link to comment Share on other sites More sharing options...
jh141 Posted December 1, 2020 Report Share Posted December 1, 2020 On 11/25/2020 at 5:26 PM, DavisIslander said: Been driving this wonderful vessel like a "scalded dog" (old timers will know this term) and recently (as in the last three times out), I've started to get vapor lock on my 2004 115 4-stroke Yamaha. 354 hours on the motor and it runs beautiful. (usually) After a few starts and stops, I get the dreaded rar-rar-rar-rar and it won't start. After waiting a decent timeframe (30-60 minutes) it cranks right up. So...are there any remedies or work-around that I can employ to remove this new annoyance. BTW, can't wait for trout to open back up here in Tampa Bay, (May 2021)..been slaying 25-30 inchers. Artificials. Thanks everyone. Not Sure if this applies to your boat but my 2012 TRS had the anti siphon valve in the pickup of the fuel tank. Caused a few issue's like that on my 4 stroke. I changed primer balls twice and checked and tested the entire fuel system. Since I removed the anti siphon valve all the problems disappeared. It was a bit of a pain but wow what a difference. Keep in mind, the valve was now stuck closed or anything, and my boat was only six or so years when this was occurring. It has been perfect ever since. 2 Quote Link to comment Share on other sites More sharing options...
Wanaflatsfish Posted December 1, 2020 Report Share Posted December 1, 2020 I agree with above...check your antisiphon....easy peasy fix.... I took mine off the MA17....when I bought the MA17, the antisiphon was full of gunk.... dc Quote Link to comment Share on other sites More sharing options...
SCFD rtrd. Posted December 1, 2020 Report Share Posted December 1, 2020 Yep, the anti-siphon valves do cause occasional problems, but they are installed for a reason. I would not remove it without installing a new replacement. Just saying. 1 Quote Link to comment Share on other sites More sharing options...
jh141 Posted December 1, 2020 Report Share Posted December 1, 2020 I hear ya....Just not convinced....What the experts say, "The anti siphon valve is not needed to run your boat properly, but is required by law so that if you capsize fuel will no leak out of the boat".Aug 25, 2004 If I capsize that would be my almost last concern.....I can think of at least a couple other ways to keep the fuel in the tank after a sinking or capsize that would not malfunction and strand me. OR "The anti-siphon valve is for safety. On many boats, if the fuel line between the engine and the fuel tank breaks, the gas could be siphoned into the bilge. To prevent this, an automatic spring-loaded valve is in the fitting that leaves the fuel tank."Oct 3, 199 Again, I would know pretty quickly if fuel was leaking into my bilge and if I had a line failure I would have the same type engine problems caused by a stuck open or closed anti siphon valve that would send me trouble shooting. I do not disagree that these should be installed in all new boats being sold. I just do not "want" one in my boat due to it causing problems. Quote Link to comment Share on other sites More sharing options...
polliwog Posted December 3, 2020 Report Share Posted December 3, 2020 If you have access to a 5 gal separate tank,hook it up and see if the problems continue,at least you can eliminate the main fuel source as your problem I did that when I had a problem with my BW whaler Montauk with a 90HP 2 stroke Yamaha. Quote Link to comment Share on other sites More sharing options...
FooFoo502 Posted December 4, 2020 Report Share Posted December 4, 2020 may seem small, but had similar starting issues, bulb would get full but wouldn't stay that way. Found tiny little cracks in my fuel hose where it connects to the actual tank..took it off, cut back about 3/4 of an inch and put it back along with a new SS clamp. Checked the fuel line into and from the actual bulb and had same tiny cracks. Couldn't tell as they were so small that they didn't leak but just enough to allow air in keeping me from getting fully primed. Cut those back to clean hose and reclamped them...fixed it like a charm. I'd do the simpler things first...not a bad idea to take apart you carbs and clean them...I had to do this recently on my old Yamaha 130 Saltwater and it is really easier than you think. Quote Link to comment Share on other sites More sharing options...
jason p Posted December 15, 2020 Report Share Posted December 15, 2020 On 12/1/2020 at 4:19 PM, jh141 said: "The anti siphon valve is not needed to run your boat properly, but is required by law so that if you capsize fuel will no leak out of the boat".Aug 25, 2004 "The anti-siphon valve is for safety. On many boats, if the fuel line between the engine and the fuel tank breaks, the gas could be siphoned into the bilge. To prevent this, an automatic spring-loaded valve is in the fitting that leaves the fuel tank.” Neither one of these statements are true concerning outboard powered boats where the tank top is below the lines and engines fuel inlet, from the USCG Boatbuilders handbook: § 183.568 Anti-siphon protection. Each fuel line from the fuel tank to the fuel inlet connection on the carburetor must: (a) Be above the level of the tank top; or (b) Have an anti-siphon device or an electrically operated fuel stop valve: Quote Link to comment Share on other sites More sharing options...
Captron904 Posted March 9, 2023 Report Share Posted March 9, 2023 I'm having the same issue. Did you find the problem? Quote Link to comment Share on other sites More sharing options...
SouthernWake Posted March 10, 2023 Report Share Posted March 10, 2023 On 12/3/2020 at 11:54 AM, polliwog said: If you have access to a 5 gal separate tank,hook it up and see if the problems continue,at least you can eliminate the main fuel source as your problem When chasing a perceived fuel problem this should always be step 1. Quote Link to comment Share on other sites More sharing options...
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