2T 5hp Mariner OB Flooded

[Mark-1]

Pulled my OB off the rack yesterday and immediately noticed a drip of petrol on my fingers. Fuel tap was off. I think it hasn't been used since August, I may or may not have run it with the tap off to use the fuel in the bowl, I usually do but depends on circumstances.

It wouldn't start and exhibited all the signs of being totally flooded. (There was fuel dripping off the carb.) I dried the plug (electrode was soaked in fuel) and turned the fuel tap off. It ran for a bit and then stopped when I turned the fuel tap back on - again seemingly flooded - plug electrode was soaked when I took it out. (I can't see how an engine can stop with a flooded carb while it's running - wouldn't it just rev higher if it was getting too much fuel?)

I used a different engine and went back to it later. At that point it ran as normal.

So... Would a sticky float explain what happened? Do floats typically stick up or down?

Is there any benefit in spraying carb cleaner into the choke, and perhaps into the carb drain plug without bothering to remove the carb?

What other thoughts do the panel have?

 

[Mark-1]

ChatGPT is incredible, I cut and pasted my post in and it came up with this. It seems to me to be actually reasoning:




It sounds like you’ve encountered a classic case of carburetor flooding, which could indeed be due to a sticky float or an issue with the float valve.

Possible Causes:​

1. Sticky Float/Float Valve:
   • Stuck Down: If the float gets stuck in the down position, it won’t rise with the fuel level to shut off the fuel flow. This would cause excess fuel to enter the carburetor, flooding it, which explains the soaked spark plug and dripping fuel.
   • Stuck Up: If the float gets stuck up, it could cut off fuel prematurely. However, this scenario wouldn’t likely cause flooding. Instead, it would starve the engine of fuel.

In your case, it seems more likely that the float or float valve was stuck down, causing too much fuel to flow into the carburetor, flooding the engine.

1. Running Rich/Flooded Symptoms:
   • When the engine is flooded, it has too much fuel and not enough air. This can lead to hard starting or no starting at all, which you experienced.
   • While running, a flooded carburetor wouldn’t necessarily cause higher revs. Excess fuel actually bogs the engine down by reducing the correct air/fuel mixture, leading to a stall.
   • When you managed to get it running for a short time, turning the fuel tap back on allowed more fuel into an already flooded system, causing the engine to die again.

Solutions:​

1. Sticky Float Diagnosis:
   • A sticky float can often be resolved by tapping the carburetor gently with a screwdriver handle to free the float.
   • If it happens again, removing the carburetor and inspecting/cleaning the float and needle valve would be necessary.
2. Carb Cleaner Use:
   • Through the Choke: Spraying carb cleaner into the choke can help clean up minor deposits on the intake side, but it likely won’t reach deeper components like the float or needle valve.
   • Through the Carb Drain Plug: If you have access to the drain plug, you can spray cleaner inside, which might help dislodge any debris stuck in the float valve. However, it’s more of a temporary fix.
3. Long-Term Fix:
   • Given that it sat for a while, it’s possible some fuel residue or varnish has built up, especially in the float chamber. The best course would be to remove the carburetor, disassemble it, and clean it thoroughly. This would ensure the float moves freely, and the needle valve seats properly.

Summary:​

• Sticky Float: Likely the cause, and they typically stick in the down position, causing flooding.
• Carb Cleaner: Can help, but removing the carb and cleaning it would be a more thorough solution.
• Fuel Shut-Off Practice: It’s good practice to always run the engine dry (using the fuel in the carb) before storing it to avoid future flooding issues. It sounds like you do this, but it might not have happened perfectly last time.

Let me know if you want more details on how to inspect or clean the carburetor!

 

[andsarkit]

It looks like you have just put the forum out of business as all the wise old sailors on here won't be needed any more.

 

[Mark-1]

It looks like you have just put the forum out of business as all the wise old sailors on here won't be needed any more.

I don't think so. I'm hoping some wise old sailors are going to show up with some insights, and what I'm really hoping for is some wise words that give me an excuse not to strip my carb.

I think we can all agree chatgpt did pretty well, though. I find it terrifying that it appears to understand the problem and actually think it through.

 

[Hunterlees]

Ask chatgpt which is the best anchor, and watch it self destruct.

 

[Mark-1]

I'm sure people are hanging on the edge of their seat to find out what I did....

I did nothing. It started again fine today, so I'm not going to tinker, I'll just see what happens.

 

[KevinV]

Ask chatgpt which is the best anchor, and watch it self destruct.

I'm imagining something like WOPR/Joshua playing itself at noughts and crosses

 

[Mark-1]

It would be genuinely brilliant at col regs.

 

[Dellquay13]

I don't think so. I'm hoping some wise old sailors are going to show up with some insights, and what I'm really hoping for is some wise words that give me an excuse not to strip my carb.

I think we can all agree chatgpt did pretty well, though. I find it terrifying that it appears to understand the problem and actually think it through.

It probably did what we should all do before posting our questions; trawl through all the past threads posted by knowledgeable old salts.
Chat GPT works because humans have put the effort in first

 

[MontyMariner]

I think it hasn't been used since August

This not so wise old fart wonders what attitude the engine was stored?
I always store mine upright, and for those who see the funny side, happy and at peace with the world!

 

[BobnLesley]

...hoping some wise old sailors are going to show up with some insights, and what I'm really hoping for is some wise words that give me an excuse not to strip my carb.

Old but not wise.
However, this was a regular problem on our 3.5hp Mercury and Nissan outboards (I think they're all Tohatsu with different covers/badges) especially in areas where we were obliged to use fuel with high ethanol content (the USA's a bugger):
Pop off the carb, take off the float bowl, swish both the bowl and rest of the carb around in a pot of fresh petrol, refit the float bowl, re-install the carb and Bob is your parents' brother; thirty minutes tops and over half of that will be taken up in getting the plastic covers off and back on again to reach the carb

 

[Mark-1]

Old but not wise.
However, this was a regular problem on our 3.5hp Mercury and Nissan outboards (I think they're all Tohatsu with different covers/badges) especially in areas where we were obliged to use fuel with high ethanol content (the USA's a bugger):
Pop off the carb, take off the float bowl, swish both the bowl and rest of the carb around in a pot of fresh petrol, refit the float bowl, re-install the carb and Bob is your parents' brother; thirty minutes tops and over half of that will be taken up in getting the plastic covers off and back on again to reach the carb

Yeah, you're right. I've even got a spare immaculately clean carb to swap out.

Desptie that sound advice I fear lethargy is going to win verses doing the job right. Maybe I'll find some enthusiasm but I feel like I'll be waiting until it lets me down again.

 

[Mark-1]

This not so wise old fart wonders what attitude the engine was stored?
I always store mine upright, and for those who see the funny side, happy and at peace with the world!

It was upright clamped to a bracket in a shed. (It's not normally left that long but I got into the habit of using the other outboard late in the summer.)

Interesting point though. This episode has made me realise that even when run to a halt with the fuel tap closed there's still fuel in my fuel filter and perhaps in the fuel line. Tilt the OB up and presumably that will end up straight in the carb bowl.

 

[Beneteau381]

Old but not wise.
However, this was a regular problem on our 3.5hp Mercury and Nissan outboards (I think they're all Tohatsu with different covers/badges) especially in areas where we were obliged to use fuel with high ethanol content (the USA's a bugger):
Pop off the carb, take off the float bowl, swish both the bowl and rest of the carb around in a pot of fresh petrol, refit the float bowl, re-install the carb and Bob is your parents' brother; thirty minutes tops and over half of that will be taken up in getting the plastic covers off and back on again to reach the carb

The issue is the e petrol, it does strange things when left in carbs. My 3.5 did the same, the float needle was stuck, a bit of “dried” petrol in the float needle “jet”

A thorough cleaning, not waving a carb cleaner spray at it! did the trick

 

[billskip]

Maybe I'll find some enthusiasm but I feel like I'll be waiting until it lets me down again.

Yep.. right at a time when you need it...you could have had the job done in less time that you spend on here...

 

[Mark-1]

Yep.. right at a time when you need it...you could have had the job done in less time that you spend on here...

Thanks for this much needed virtual kick in the butt.

Directly on the back of it I've cleared my gutters, serviced my chainsaw, changed the PAS belt on the wife's car and, of course, sorted my carb. (I'm serious.)

I swapped my immaculately clean spare in and it seemed to start and run fine. The original carb (which had let me down but was now running as normal) wasn't too bad but there were some noticable grains of black grit in the bottom of the bowl, and the bottom of the bowl was slightly tacky to the touch. Based on little knowledge it didn't look to me like it would obstruct the float but I guess it must have and I was certainly not going to put it back on. I'll clean it thoroughly and check the float height and that will become my new spare carb.

I have no clue where the grit has come from - the air - I guess?

To anyone who finds this thread with Google in years to come, there is no benefit whatsoever in spraying carb cleaner into the choke or into the drain screw. You need to see what's in there - I certainly wasn't expecting grit!

So thanks BillSkip, you got me off the sofa to get a few jobs done that had been nagging on my consicence for yonks.

 

[billskip]

Thanks for this much needed virtual kick in the butt.

Directly on the back of it I've cleared my gutters, serviced my chainsaw, changed the PAS belt on the wife's car and, of course, sorted my carb. (I'm serious.)

I swapped my immaculately clean spare in and it seemed to start and run fine. The original carb (which had let me down but was now running as normal) wasn't too bad but there were some noticable grains of black grit in the bottom of the bowl, and the bottom of the bowl was slightly tacky to the touch. Based on little knowledge it didn't look to me like it would obstruct the float but I guess it must have and I was certainly not going to put it back on. I'll clean it thoroughly and check the float height and that will become my new spare carb.

I have no clue where the grit has come from - the air - I guess?

To anyone who finds this thread with Google in years to come, there is no benefit whatsoever in spraying carb cleaner into the choke or into the drain screw. You need to see what's in there - I certainly wasn't expecting grit!

So thanks BillSkip, you got me off the sofa to get a few jobs done that had been nagging on my consicence for yonks.

Good job I don't practice what I preach....well done..