f-115 lost power when cold

[L4Rosales]

Hi Guys,
I have a f-115 w/437 hrs and it is currently missing when cold. After coming up to temp, the missing goes away and the boat runs well. Any ideas? on what it could be?

I just got a yds and am planning to test the ignition system. the manual says that I need to install a spark plug gap tester pn# ym-34487/90890-06754. The only place I have seen so far with the tool is on ebay and it is somewhere around $350. Question: will an "adjustable ignition spark tester" that I got at pep boys do the same thing? If so, what is the gap I need to set it at (I don't see it specified in my manual for the engine or for the yds.)

I know I am asking a lot for my first post, but any and all help will be greatly appreciated.

Thanks,
Louis

[rodbolt17]

google
stevens s48.
buy the double and it can test up to 8cyl simultaneously.

[almetelo]

Zenoah PET4000 Ignition Checker Pet 4000 Oppama | eBay

Exactly the same as ym-34487/90890-06754 just don't have a Yamaha BOX which reduce the price... a lot!

[99yam40]

I believe 7/16" is a number I have seen posted before for the gap

[L4Rosales]

Thanks guys.
Louis

[L4Rosales]

Just wanted to write a short note to update and thank.

Boat is now running great...engine is like new. problem was dirty fuel injectors. I also changed the vst filter in case it was related. vst filter was clean (440 hrs). I assume that means my fuel system is in pretty good shape.

Ran the boat yesterday and its quiet, smooth and quick throughout the operating range an back up to an easy 6k. It is so nice to feel that easy, quiet power that it had when new.

I wanted to thank all of you that post on this forum because I read a lot of posts that helped me figure it out, BUT I especially wanted to thank Rodbolt! His responses came quick, were short and to the point, easy to understand and really helped me get it fixed. I know very little about engines and without Rodbolt's assistance, my boat would probably still be sitting while I save enough to get it fixed!


Thank you!
Louis

[rodbolt17]

you cannot and WILL not EVA EVA NEVA, test a waste spark ign system PROPERLY with a SINGLE plug tester.
unless you could figgue out a way to MATCH exactly the resistance of the OTHER secondary path.

the F115,like many other 4 stroke midrange motors, uses a waste spark ign.
means if one lead fire the other lead fires simultaneously.

if you unplug one lead, or foul a plug, its not uncommon to lose spark on BOTH.

can lead to erroneous test results and a tech on a ghost hunt or an easter egg hunt, your choice.

typically what your description was is contamination of the fuel system.
the ign does not care if its 40 below or 140 above.

always break an ign system down to its componets, ign PRODUCING and ign CON*****ING.

can it make spark?
can it control spark.
shortens the heck out of the easter egg hunt.