4HP 4-stroke in the water - Repair the Yamaha or replace with what?

[sfellows]

A friend dunked our 4hp Yamaha F4 in the (salt) water after a couple of years of no real problems. It kind of worked for a while (it's a tender motor so not used regularly), but required many carburetor removals to clean (well each time we tried to use it actually last year.....). This year, a few weeks ago it refused to start after working rather well the previous weekend (but only after yet another carb clean/replace/new petrol etc etc.).

Taking it to a professional, they have said the Carb is U/S and want £250 for a new one (they said it runs fine with another carb on it, but cannot start it with the original........).

1) Any suggestions what to do with the original carb to get it going? Any cleaning solutions? Would a sonic clean work?

2) What would be a suitable replacement engine? Googling suggests Yamaha carbs are suspect/temperamental? Good reports from Tohatsu? A second hand 2 stroke isn't what we want.

All help gratefully received

Simon

 

[seumask]

IMHO I suspect you need to find the correct bit of the carb that is not working, probably a jet and you may be able to get that bit rather than a whole carb!

 

[Marsupial]

OK so the carb is dirty and suspect but it sounds like the trouble is in the fuel tank. Sort out the fuel tank, fit a cheap inline filter, clean the carb again and run the engine for a couple of hours and it should be fine. If you suspect water contamination in the fuel system treat it with fuel set, it will render the water harmless - but run the thing for a couple of hours at 75% anyway.

 

[Skylark]

.............. a few weeks ago it refused to start after working rather well the previous weekend (but only after yet another carb clean/replace/new petrol etc etc.).

Taking it to a professional, they have said the Carb is U/S

Simon

Are you saying that it runs (or ran) well after the dunking but then stops and requires another clean?

If so, it sounds like it needs a more thorough clean of the entire fuel system. Ultrasonic cleaning of carb parts has worked well for me in the past.

I'd also ask more of the "professional" to define "u/s". Doesn't sound very professional to me.

 

[cryan]

Carb can be easily stripped and cleaned. As above its probably a blocked jet. Most carbs the jets can be easily changed for new. Certainly no need to scrap it! You can buy solvent carb cleaner from motor factors and if you have access to a ultrasonic that would be perfect. If not the kitchen table, a bucket or basin of cleaner and an old toothbrush will do fine. If it has been submerged you should mibbe check the HT leads are ok.

 

[sfellows]

Fuel has been replaced more than once

OK so the carb is dirty and suspect but it sounds like the trouble is in the fuel tank. Sort out the fuel tank, fit a cheap inline filter, clean the carb again and run the engine for a couple of hours and it should be fine. If you suspect water contamination in the fuel system treat it with fuel set, it will render the water harmless - but run the thing for a couple of hours at 75% anyway.

I've replaced the fuel several times and got all the water out. Haven't replaced the fuel filter though.

 

[sfellows]

Exactly

Are you saying that it runs (or ran) well after the dunking but then stops and requires another clean?

If so, it sounds like it needs a more thorough clean of the entire fuel system. Ultrasonic cleaning of carb parts has worked well for me in the past.

I'd also ask more of the "professional" to define "u/s". Doesn't sound very professional to me.

That's exactly what I'm saying - it has run for a weekend, but always appears to need a carb clean every time we use it (after leaving it for a week or 2) before it will start again. Now the professionals are saying after trying to clean it will not start at all (but using another carb from another F4 engine it runs), therefore need a new carb........

 

[Rigger Mortice]

That's exactly what I'm saying - it has run for a weekend, but always appears to need a carb clean every time we use it (after leaving it for a week or 2) before it will start again. Now the professionals are saying after trying to clean it will not start at all (but using another carb from another F4 engine it runs), therefore need a new carb........

I suppose that's a bit better than the "professionals" trying another engine altogether then telling you that the other engine ran fine but yours didn't so the whole thing is U/s.

Have you replaced the gaskets? If you've stripped the thing several times you may have a problem there.

 

[cliff]

Replacement jets are available. The only problem is getting the old ones out - they can be a real ****. broke one while replacing a jet on my own Yam 4t - Carb cleaner and ultrasonic bath did SFA - the jet was BLOCKED. wound up drilling out the jet, using a tap to clean out the threads (carefully), lots of cleaning and air blowing then fitting the new jet - engine started first pull and ran sweet as you like - Sold it and replaced it with a Merc 3.5 2t - much lighter than the Yam and far less hassle.