Engine stalls in choppy water--help

[mahgnill]

I am having a problem with my 2000 Yamaha SX200 fuel injected motor. I can idle and slow run all day long without a problem. I can even get on a plane with no problems until I hit chop. If i go over another boats wake or just plain hit choppy water the engine kinda stalls (does not shut off completely) and then revs back up until you hit another wake. I took it to one mechanic and he said it was fine at the shop. The engine will start right up without a problem either. Any ideas what to check for? I have already replaced fuel filters, and lines with no luck.

 

[rodbolt]

Re: Engine stalls in choppy water--help

remove the vapor seperator, remove the seperator top, withdraw the top and pump assy, check the high pressure pump inlet screen.
carefully clean the VST tank and replace filters and gaskets as nessasary.
if the cover gasket doesnt swell and isnt nicked or damaged use vasoline to hold it in place and reuse it.
if you cut one of the high pressure clamps it must be replaced with that same style clamp DO NOT use wire ties or worm screw type clamps.
however this job can be done by simply loosening all the screws you can get to then remove the 3 10 mm head screws holding the tank to the block. now remove the last two screws in the cover and slip the tank free of the cover.
now would be a good time to replace the lift pumps as a maint action.
total time for the job without a coffee, 12 hour and 15 minutes.

 

[Mas]

Re: Engine stalls in choppy water--help

Somewhere along the line, some sediments are getting stirred up in the fuwl system...obviously Rodbolt is one the right track.

MAS

 

[mahgnill]

Re: Engine stalls in choppy water--help

Rodbolt, I cannot thank you enough. We pulled the VST tank following the instructions found in this link http://bbcboards.zeroforum.com/zerothread/66928 . The bottom of the tank came right off. I took the screen off the bottom of the pump and it was clogged big time. You probably know I thought about re-using it , and hit it with some carb cleaner, but I figured when im out 30 miles off shore the small price for a new one would be well worth it. Off to the parts store I went. 55.00 for the new screen and about 38.00 for the new gasket. I did not have a chance to test it until yesterday on the water, and what a difference. I picked up about 300 rpm, and the boat did not stall or studder once. It even jumps up from a dead stop like never before. It feels like I have a brand new motor. We hit some fairly good choppy water, and made a few sharp turns, and low and behold no stalling. Once again thank you...thank you. I am sure I saved a few 100.00's on this problem.

 

[rodbolt]

Re: Engine stalls in choppy water--help

had you forum searched here you would have found I have posted screw by screw instructions, however I see a lot of my threads here posted on other boards as well. I recognize my typo's .
takes 40 minutes or less to change that screen, there is a trick to aid in keeping it clean.
remove the VST drain, catch fuel in a suitable container.
use a can of carb cleaner spray, bend the last 1/4" of the red plastic spray tube into a 90*. then work it into the VST and spray off the screen.
helps keep it clean between maint actions.
still needs to be dissasembled cleaned and inspected periodically.