Yamaha F15 won't start after replacing head gasket

Joined
May 26, 2012
Messages
18
Hi all,

Ok, so i replaced the head gasket on my 2000 Yamaha F15 (F15ESHY) after noticing "milky" engine oil and power loss. I put it back together and got nothing. Engine turns over, has good compression and good spark. I just cleaned the carb and replaced all my fuel lines, filters, and fuel pump. The fuel pump is strong but it feels like strong bursts of air are blowing back out of the carb when I'm trying to get the motor to start. I tried squirting gas down the carb throat and still got nothing. Any suggestions?
 

Ldavidgrover

Petty Officer 2nd Class
Joined
Feb 22, 2012
Messages
197
Re: Yamaha F15 won't start after replacing head gasket

recheck the timimg. Since you have air, spark, fuel
 
Joined
May 26, 2012
Messages
18
Re: Yamaha F15 won't start after replacing head gasket

Hey man,

I just did, or at least I think I did. I aligned the two arrows on the small wheel that controls the valves but didn't see any arrows on the big wheel, just a pink stripe in the middle of the nut that matched the color that was used to mark the arrows on the small wheel. So I just aligned the two arrows and made sure the stripe was in line with them. Did I miss a step? Thanks!
 
Joined
May 26, 2012
Messages
18
Re: Yamaha F15 won't start after replacing head gasket

UPDATE: So I found the other set of timing alignment marks under the flywheel, so everything is aligned. Now, when I turn the motor over, it will occassionally pop like it wants to start but it won't actually turn over. Still lost.....
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
Re: Yamaha F15 won't start after replacing head gasket

recheck compression and give us the numbers or use a leak down test
Check spark with a spark tester and then use a timing light to see if and when it is sparking(timing)
Hope you are working with a service manual
 
Joined
May 26, 2012
Messages
18
Re: Yamaha F15 won't start after replacing head gasket

Thanks 99yam40. I'm at work now so I'll recheck the compression in the a.m. Doesn't look like I'm going to be able to hit the water anyway with this storm off the coast. I'm also going to pick up a spark tester (the test I did was basically just grounding it against the block and looking for a spark). What gap should I set the tester to?
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
Re: Yamaha F15 won't start after replacing head gasket

I have seen 7/16" listed for gap on spark testers.
Hard to believe the compression was good when you had the valve timing off.
Hope that is one of the motors that the piston will clear valves with the cam timing off
 
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