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Catalina/Capri 25/250 Sailor's Forums

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Finally! I think my OB is running properly again.

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Initially Posted - 04/01/2012 : 20:05:38

I went down to the boat today to see if I could get my Tohatsu running. It was exhibiting the exact same symptoms as last year when I had so many problems after my gas can went through phase separation, rusted, and I ran rusty water through my carb. I'd rebuilt the carb, replaced all the filters, added a Racor water/gasoline separator, and it would still only run either above 2k RPM, or about full choke. I figured I'd take the carb apart one more time, replace the spark plugs, and see what happened.

I decided to drain the Racor, and then run some gas out of the feed line into a clear plastic bottle to see what it looked like. I put the feed tube into the mouth of the bottle and pumped the ball. Nothing happened. Hmmm...maybe it can't get past the fuel pump, so I decided to back up the line a bit, so I took apart the fuel connector at the Racor and tried the same thing. Nothing. Huh? So I took apart the fittings at the feed side of the Racor...nothing. So I took apart the hose itself at the bulb, and all I got was a dribble.

I had another bulb & feed line, so I swapped it out for the other, reattached the carburetor, and pumped up the bulb. A satisfying rush of fuel into the see-through in-line filter.

I started up the engine, and once I got fuel into the carb, it started right up, at full choke again. I let it run choked for a bit, then slid the choke in. Every other time in recent memory, doing this caused the engine to die at about half choke. Not any more!

I still need to adjust the idle speed (it's too high), but the engine will happily idle down to about 800 RPM now. Before it wouldn't run below about 2k.

I think the engine was simply starved for gasoline the whole time, and the reason it'd run at full choke was that was the only way it could get the mixture rich enough to actually run.

David
C-250 Mainsheet Editor

Sirius Lepak
1997 C-250 WK TR #271 --Seattle area Port Captain --

Edited by - on

JimGo
Admiral

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USA
962 Posts

Response Posted - 04/01/2012 : 21:11:13

WOW! Too bad it took this long to find the problem, but I'm glad to see that it's solved, and by a simple solution.

BTW, Defender is closing out some of the bulbes and tubes ($7 for a complete set, with fittings), in case you need a spare.

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Joe Diver
Master Marine Consultant

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USA
1218 Posts

Response Posted - 04/02/2012 : 06:56:47

Nice...congrats on finally getting it fixed....look at all the other stuff you did as a "major tune up" that needed to be done anyway.....why not.....

Edited by - Joe Diver on 04/02/2012 06:57:12

OLarryR
Master Marine Consultant

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USA
3466 Posts

Response Posted - 04/02/2012 : 09:10:25

David,

Thanks for the Heads Up regarding the fix ! I am going to try and save that nugget in one of my brain cells.

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 04/02/2012 : 11:27:56

I wonder if something lodged in the one way valves that's kept them closed? Judging by the rust I found in the filters, it was just tiny particles, not enough to wedge the valves I'd think. Maybe they simply rusted mostly closed? I'll probably cut the bulb open at some point just to find out. It was too cold to mess around with it yesterday. The temp was in the mid-40's with a stiff south wind making it unpleasant to be out there for very long. Getting even little bits of gas on your hands was like encasing them in ice.

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redeye
Master Marine Consultant

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3476 Posts

Response Posted - 04/02/2012 : 11:39:06

I've had several bad bulbs, and we would keep a backup bulb onboard on the powerboat. I would search around for one that is well made cause everything I saw for some time was CFC ( Crap From China )

Buy one brand new and had to replace the clamps. Another had bad valves.

Edited by - on

redeye
Master Marine Consultant

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3476 Posts

Response Posted - 04/02/2012 : 11:40:23

That's the reason they sell them in the plastic cases so hard to get into... so you can't find the defect till you get it home.

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 04/08/2012 : 21:42:39

So I tinkered with the throttle linkage today to reduce the idle speed. The adjustment isn't as straight forward as it would seem, you can't just run the linkage all the way out like you'd think, it has to be somewhat centered up in the range of the cable's throw. It took more tinkering than I expected, but it took less than half an hour to get it dialed in. It's idling around 700 RPM now, which is still a bit low according to the specs. It's supposed to idle at 900 after it's warm, but it seems happy at 700. I also replaced the inline fuel filter since it still had the one that particular line went through the phase separation episode with.

Now the engine will quite happily start (when warm) with no choke, and zero throttle, and run at idle with no issues.

I might actually have a sailing season this year!

Edited by - on

TakeFive
Master Marine Consultant

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2272 Posts

Response Posted - 04/09/2012 : 05:04:55

FWIW, I've had a long history of priming bulbs going bad on my Trophy boat (50 hp outboard with 9 gal external tank). The check valves in the bulb tend to go bad and get stuck in the open position. Thus when you squeeze the bulb, you push the gas in both directions, and when you release the bulb, you suck the gas back from both directions. The end result is no net flow, and the system never gets primed.

If you ever find yourself in this situation, there is a simple temporary workaround that will get you going for the day. Pull the gas tank out of the locker so you can reach it. Close the vent cap and sit on the tank (or press hard with your foot), then open the vent cap and release the weight, close the vent and press again, open vent and release pressure, repeat... You're basically using the flex in the plastic tank to pump the gas through the system, priming the lines. Once it's primed, open the vent cap and use as normal.

This procedure has saved me from embarrassment on the boat ramp a few times over the years.

Edited by - on

islander
Master Marine Consultant

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USA
4024 Posts

Response Posted - 04/09/2012 : 14:02:58

Now aren't you glad you had a pull choke?

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GaryB
Master Marine Consultant

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USA
4304 Posts

Response Posted - 04/12/2012 : 18:50:23

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by RhythmDoctor
 FWIW, I've had a long history of priming bulbs going bad on my Trophy boat (50 hp outboard with 9 gal external tank). The check valves in the bulb tend to go bad and get stuck in the open position. Thus when you squeeze the bulb, you push the gas in both directions, and when you release the bulb, you suck the gas back from both directions. The end result is no net flow, and the system never gets primed.

If you ever find yourself in this situation, there is a simple temporary workaround that will get you going for the day. Pull the gas tank out of the locker so you can reach it. Close the vent cap and sit on the tank (or press hard with your foot), then open the vent cap and release the weight, close the vent and press again, open vent and release pressure, repeat... You're basically using the flex in the plastic tank to pump the gas through the system, priming the lines. Once it's primed, open the vent cap and use as normal.

This procedure has saved me from embarrassment on the boat ramp a few times over the years.
<hr height="1" noshade id="quote"></blockquote id="quote">
You could use a pair of pliers on the gas tank side of the bulb. Squeeze the line closed with the pliers when you squeeze the bulb (forcing fuel into the engine only) then release the pliers after you un-squeeze the bulb (refilling the bulb).

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