1993 70 TLRR power loss (updated with videos)

[grouper sandwich]

I was able to get to the coast this past weekend and run the boat. I didn't have any of my test equipment but did shoot a couple of videos. If anyone cares to watch them and sees ANYTHING they think I could use, please do. I appreciate all of the help this place provides to us novice wannabe boat mechanics.

Cowl on, power loss occurring after running at 4700 RPM for about a mile:

1993 Yamaha 70 HP power loss - YouTube


Cowl off immediately after initial power loss then trying to plane up again:

1993 Yamaha 70 HP power loss cowl off - YouTube

Cowl off after idling at about 1200 RPM for 10 minutes, running at 4700 RPM:

1993 Yamaha 70 HP cowl off underway - YouTube


Thanks in advance!

[99yam40]

it would help a lot if you would not start new threads, just add to your old one if the problems have not been resolved.
That way all the info would be in one thread

[grouper sandwich]

Original thread updated...

[dorf]

How about a sticking. Anti siphon vale in the fuel tank that was re-used when you switched fuel tanks

[grouper sandwich]

How about a sticking. Anti siphon vale in the fuel tank that was re-used when you switched fuel tanks

I don't think I re-used anything. I replaced the old tank with a 12 gallon above deck tank from Moeller with Moeller fuel line and bulb. I threw everything else out. Is there something I could've missed? Are there any other anti-siphon valves I could be missing? That would certainly be an easy and CHEAP fix! LOL

[mackwrench]

While I cannot explain the "runs great wtih cowling off" It surely sounds fuel related......I'm also in Tallahassee (go noles).... I'm not a "master marine yamaha tech" like some here, but I'm local and perhaps take a look at with you....PM sent