Ox66 issues, cold start runs fine till warm then backfires and stalls

Hi folks,

My friend is having some weird issues with his houseboats power.

They are 2002 250 horse salt water series yammys , and both came of the same boat from a repower. The front engine is fine. Last year the rear engine was fouling plugs like crazy so I cleaned all the oil injection screens like Robolt always sudjets.

After no avail he just put it on blocks for the winter and went to florida lol, So I dug at it this spring and the O2 in the rear motor was solid with carbon. I cleaned it and it fired right away.

New issue is now it will run for 2-5 minutes then the tach shuts off and then the motor backfires then stalls and . Go to restart it runs briefly then shuts off with no tach display. Let it sit for a undetermined ammount of time and tada everything is fine for a few minutes.

Temp alarms and oil levels are good it appears , Cold solder joint in the ecu ?

Thanks Mike

Re: Ox66 issues, cold start runs fine till warm then backfires and stalls

Tinkered with it a little. More this weekend and similar results. Fuel and oil delivery seem to be fine, assuming nobody has ran into a similar large issue. I guess next plan is to get a mobile service to come scan the motor as its impossible to move the boat on land due to height and width. It's 53 foot long and a 15 foot beam

Mike

Re: Ox66 issues, cold start runs fine till warm then backfires and stalls

Sounds like a good plan to have a good Yamaha tech have a look

Re: Ox66 issues, cold start runs fine till warm then backfires and stalls

As I seem to be having one issue with that is finding one around here, Not many people that have good things to say about our local marinas that work on Yammy. Ill keep everyone posted on what we figure out.


Thanks Mike

Re: Ox66 issues, cold start runs fine till warm then backfires and stalls

Backfires & stalls eh?? Cheeez that's a new one, please keep us current with developments.

Re: Ox66 issues, cold start runs fine till warm then backfires and stalls

Its strange for sure , doesn't matter if its under load high idle or anything just pop.