Mercury carburettor.

[jamie N]

Trying very hard and patiently, to locate a replacement carb for my 2006 Mercury 4HP. Found a new one on Ebay at about £35, and ordered it giving the model number of the engine, and asking if it was the right carb. The retailer told me that although it looked the same, it was incompatible. OK, that's life.
I did then find one with the right part number, which is £200 more expensive, from a different supplier.
WTF?
The carb which came with the engine appears to be a non-standard one from Keihin, with a number of 3CG8AG7, which I've been unable to find any reference for anywhere, which is curious?
As a genuine question, how is it that there seem to be so many different models of carbs, which seem identical, for this engine?
Whilst I continue searching for a 803819A05 compatible carb, or for spares to fit the same, if anyone knows of a Mercury dealer or a Tohatsu agent that can supply this for me, it's worth a virtual bottle of 'The Hearach'.

 

[Beneteau381]

Trying very hard and patiently, to locate a replacement carb for my 2006 Mercury 4HP. Found a new one on Ebay at about £35, and ordered it giving the model number of the engine, and asking if it was the right carb. The retailer told me that although it looked the same, it was incompatible. OK, that's life.
I did then find one with the right part number, which is £200 more expensive, from a different supplier.
WTF?
The carb which came with the engine appears to be a non-standard one from Keihin, with a number of 3CG8AG7, which I've been unable to find any reference for anywhere, which is curious?
As a genuine question, how is it that there seem to be so many different models of carbs, which seem identical, for this engine?
Whilst I continue searching for a 803819A05 compatible carb, or for spares to fit the same, if anyone knows of a Mercury dealer or a Tohatsu agent that can supply this for me, it's worth a virtual bottle of 'The Hearach'.

Why do you need a new carb? All carbs are cleanable if that’s the issue

 

[Steve_N]

I suspect that the Keihin number is a serial number rather than a model no. On mine (Mariner 4hp Sailmate of the same vintage) it was 3CGBVH1 which equally doesn't yield any search results.
I replaced it recently with Ebay item 153586473090 and the motor runs perfectly. For £30 I didn't worry about any detailed compatibility checks.
The Keihin carb was beyond cleaning as it's inner surfaces were corroded (perhaps from the ethanol in E10) releasing particles that obstructed the jets. The float bowl in particular was a right mess.

 

[Beneteau381]

I suspect that the Keihin number is a serial number rather than a model no. On mine (Mariner 4hp Sailmate of the same vintage) it was 3CGBVH1 which equally doesn't yield any search results.
I replaced it recently with Ebay item 153586473090 and the motor runs perfectly. For £30 I didn't worry about any detailed compatibility checks.
The Keihin carb was beyond cleaning as it's inner surfaces were corroded (perhaps from the ethanol in E10) releasing particles that obstructed the jets. The float bowl in particular was a right mess.

The ethanol doesn’t corrode, it absorbs water, we leave it in the bowl, running dry doesn’t work, a small amount is left, the ethanol;petrol evaporates leaving a globule of water which then corrodes the fuel bowl and the bits block jets.
I advise to always drain the bowl, don’t switch off the fuel tap, it doesnt empty the bowl completely
Ive found as you have that cheap Chinese carbs actually work ok and you can actually adjust the pilot jet mixture

 

[jamie N]

Why do you need a new carb? All carbs are cleanable if that’s the issue

Good point and one that I'd thought as well having cleaned quite a number of carb's over the years, but the brass jet is totally corroded into place, and won't turn. I tried soaking in WD and using increasing amounts of force, to the point that I was using an 'easy out' drill which failed also.
@Steve N, thanks for the info, and based on your experience I went onto that Ebay site and:
Happily though, because of their bigotted stupidity in denying the largest area of the UK access to their product, I went to a rival in Wales, and found an equivalent which should arrive in a week.
As a slight aside the present carb is:
I wonder whether the main model/type is the 3CG, and the rest just a more refined ID/version?

 

[jamie N]

My new carb arrived a couple of days ago, in a wee box that looked like it'd been through a hard season of ice hockey.
The choke actuator had been broken off from the choke; the bit to the right has the choke cable attached to it. I didn't want to send it back as I didn't want to wait another 3 weeks, so I ended up using a 1mm drill bit, drilling vertically through the broken off bit, and through into the small hole in the centre of the piece in the carb, then leaving the drill bit in place as an 'internal splint', and super gluing the two pieces back together. I should say that I removed the bit in the carb, which comes out when the choke flap is removed, which was simple. I left it overnight, refitted it in the morning and it works.
Job done.

 

[ProDave]

Could you not use the choke spindle from your old carb? Or are they that different?

 

[jamie N]

I'll admit to swearing Dave! They're identical in nearly every way, but for the choke 'flap' mounting. The new spindle goes through a hole in the top, with the bottom of the spindle in a recess at the bottom. The old one is a complete item, with a press fit cut out at the top, but the same recess at the bottom.
Que Sera, Sera............

 

[jamie N]

Gotta laugh! Today I took the Mercury to the boat, fitted it, connected the fuel line, a few squeezes of the bulb and some pulls on the starter cord.
Zilch, nada & rien.
OK, it isn't the fuel side of it as that's brand new, so it must be the electrical side of it, and the 1st thing to look at is the safety cord onto the emergency stop switch. This was loose as the 'outside bit of the switch had chosen this moment to break.
This is how things happen I know, and that's life. Fortunately though, when I 1st had problems with the engine as I bought the boat, an expert had a quick look and eliminated the issue of the switch being U/S, by disconnecting a brown wire from by the plug. This, he told me, was a common bypass.
Wire off, engine started 1st pull.
Mercury price for new item is £45.00.
Ebay universal £6.00.

 

[jamie N]

By the way, word of warning about ordering online. I want to replace the fuel connectors on this engine, so browsed in the usual way and saw this from a company in Preston.
There's a name to remember.