250hp OX66 Problem - The Hull Truth

John_Madison CT · 06-05-2007, 03:08 PM

Andy: Weird problem I just developed. The engine seemed sluggish the other day. Needed more throttle to keep the same RPM's. Then I noticed that the fuel burn, via the NAVMAN was much higher than normal (up 50%).

It almost felt like something was being towed behind the boat. At one point the engine seemed to "break free", go up in RPM's, I panicked, threw it into neutral, and she stalled.

She restarted and I came home under similar conditions, sluggish, very high fuel burn rate.

I checked plugs, all OK. Took out O2 sensor and found it not too dirty. Transfer tube was clear. I will clean well and put back.

The VST filter and low pressure pumps are overdue. (300 hours on engine and they are original as far as I know)

Can you think of anything else?

Thanks,

John

SIM · 06-05-2007, 06:26 PM

John,

What do you have for diagnosing tools for the engine? Do you have any ofthe test harness's, DVM and diagnostic indicator tool (winky blinky tool)? Fuel pressure gauge?

Andy

John_Madison CT · 06-05-2007, 10:59 PM

Andy: I put in another 02 sensor I had kicking around and it seemed to fix it !! I'll need a few trips to trust it 100%, but after about 20 minutes of run time, all is well. Perhaps the old original O2 sensor went bad.

Thanks for your help, I really appreciate it !

John

SIM · 06-06-2007, 01:08 PM

We have several ofthose test harness's and Winky blinky indicators that we sell and will loan out to parts customers if needed. We had another THT (Striper Tom I think) that we sent them to. He had no runningissues but wanted to get himself familar with how to test components and use of the indicator toolon a known good engine so if he had trouble, he would be familar with it.

Hope that 02 sensor took care of it for you.[img]../images/emoticons/thumbsup.gif[/img]

Andy

John_Madison CT · 06-06-2007, 09:13 PM

Andy: I put another couple of hours on the engine today. All is AOK, so far.

John