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Yamaha 250SHO dying after long idles

Potomacbassin’ said:
Gotta be somewhere BK - maybe tucked up under somewhere? Not sure how else they primed the engine when they first installed?
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Never noticed it. I'll check when I check on the boat today .....
 
Potomacbassin’ said:
Gotta be somewhere BK - maybe tucked up under somewhere? Not sure how else they primed the engine when they first installed?
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Checked on the boat at the dealership earlier.....Asked the service dept manager if my particular Mercury outboard had a fuel primer bulb. He said the newer Mercs do not come with or need a fuel primer bulb. It has 2 fuel pumps. A lift pump to suck fuel into the vapor seperator tank and a 2nd fuel pump that creates high pressure for the fuel injection system. No primer bulb installed or needed........
 
Well darn of you're not right! Link below states anything over 75hp will have that priming pump. Another reason for Yamaha to step it up!!

Quick Tip: Priming Your Fuel System

Clearing the air from the fuel line is essential for starting your engine. - Clearing the air from the fuel line is essential for starting your engine.
www.mercurymarine.com www.mercurymarine.com
 
I was following this thinking I am certain I don’t have a priming squeeze bulb on our Merc Verado. Now I know why. Good info you two!
 
I suggest posting on the facebook GROUP Yamaha Outboards. There are certified mechanics responding with helpful info. Not knocking the Benny Forum but an answer and a solution is all we seek :)
 
That’s good advice. I may end up with Facebook after all.
 
I did the clear hose diagnostic today. Found air bubbles when I put it between the primer line and the engine. However anywhere before that and no bubbles.

I have all ready put a new primer line and bulb on it but it was a cheap one from Amazon.
Anyone have a good suggestion for a good bulb?
 

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Flysooner9 said:
I did the clear hose diagnostic today. Found air bubbles when I put it between the primer line and the engine. However anywhere before that and no bubbles.

I have all ready put a new primer line and bulb on it but it was a cheap one from Amazon.
Anyone have a good suggestion for a good bulb?
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Original equipment one from Yamaha?!?
 
I had a similar issue - the point where the gas line connects to the fuel tank was loose and letting air in when warm. The connection is friction based, no clamps. (Per Benny Service Dealer Findings) . I concluded our Havasu heat softened up the gas line enough that when going slow the lack of wind accumulated heat and allowed the air to get in. They indicated they have seen this several times, did not ask how fixed.
 
Potomacbassin’ said:
Air leaks should all be eliminated before replacing a bunch of expensive parts. Filter gaskets, fuel lines, incorrectly replaced parts (upside down fuel bulbs, etc.) are all inexpensive albeit time consuming things to check

As others have noted if your bulb is not flat then a blockage or venting issue does not seem to be the cause.

Another thing to check although it's usually a high RPM thing is the VST. A couple filters in that may be dirty/clogged, which even if it doesn't solve the original problem is still a maintenance item that eventually needs to be completed.

Lastly it could be an intermittent electrical issue if the idling is creating heat and expansion somehow works a ground wire loose or solenoid or relay fails. That is on the very low probability end of things but something to add to the list.

Good luck tracking this sucker down!
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Sorry, just following, what is VST? Variable ?? Throttle something.
 
It resides on the engine and from a maintenance standpoint contains the last set of filters before fuel is pumped into the injector rail. It's a fairly fine-meshed screen so any kind of small contamination could crud it up and impact performance.

I haven't had to monkey with mine yet but is probably a 2-3 hr round trip service item for a handy DIY.
 
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