Misfiring Watermota crossflow.

I have stripped and cleaned the Formoco carb three times because I was having problems with no tickover and needing choke open to run. Ticks over perfectly now and ran well until yesterday when it started to run rough when the throttle is opened. Ticker is fine but what is happening. Do I really need to clean the jets again and again. I fitted a new filter recently.

I would look at the idle mixture.

If it ticks over and throttle up we’ll when out of gear, but sound like it will stall when coming off tickover when the engine is under load, it’s a good indication that the mixture is lean.

Not sure about your carb, but on mine, there is an adjuster screw for this.

Sounds like it could be fuel starvation. Do you have an in-line fuel filter? If you have, and it is one you can open up, have a look to see if it is contaminated. If you don't have one then I'd recommend putting one in, especially f you have a steel tank as it is all too easy for rust particles to get into the fuel system if you let the fuel level run low.

If you do open up the carb again, have a look at the bottom of the float bowl, any contamination will settle here.

Another thought. Have you checked the timing and the points gap?

And another one. Have you got a vacuum advance on your distributor? If you have it might be worth checking it's in place and working before you dismantle anything.

Will check each one soon as. Thanks

If it’s fomoco then it’s probably a Ford copy of the Weber single Venturi.
When you stripped it did you check the small filter behind the float jet needle valve? 
I don’t agree that it’s anything to do with idle mixture since your issue is when throttle butterfly is open so volume control screw no longer in play. 
When it splutters I would switch off and check float level. Also check float is correctly adjusted. If fuel in float down Check fuel pump. Finally this could be ignition so check everything B.B. has indicated... especially timing.
You can’t adjust your carb to make it leaner or richer...but check plugs anyway to see the colour. Tappet clearances are important too. If it is lean then air could be bypassing carb...could be do many things! I say all this having just had similar experience on the car and it was timing adjustment that solved for me..but that was after checking practically everything else!

By the way the original F23 only have 2 filters. One in fuel pump and in line behind needle valve. The fuel pump filters debri from tank and in line only filters anything from pump to float chamber..which in reality only clogs if your diaphragm is deteriorating.
Replacement fuel pumps have no filter in them so folk put one in the fuel line before the pump.
So as B.B. says. Check the in line. If it’s blocked then change your pump diaphragm because it’s a sign it’s deteriorated. It’s 50:50 though whether this is ignition or fuel issue though

Before you start dismantling stuff it's also worth checking the air filter is clean. If this is blocked it would cause the symptoms you describe and you'll also get a strong smell of petrol and smoke as you try to accelerate. Just take the filter off and see if it makes a difference. If it does, clean the filter element and see what happens. If not, tick this off and move on.

NB. Another easy thing to check; is the choke is coming off fully?

OMG! Is there anything else to mention that could be wrong. Propeller size? Stale fuel? In other words by the time you have adjusted and possibly upset perfectly good settings in respect of all the things mentioned and if your engine still won't run smoothly (or at all by now!) you wont have a clue what was wrong in the first place.
I've nothing positive to contribute except to point out that there are so many personal theories that its frightening! Did the distributor cap get mentioned yet or dizzie as it seems to be affectionately known? No offence intended to all those who have taken the trouble to advance a suggestion, though no doubt given.


If, like me to a great extent, you don't really know what you're doing then calling the man from RCR would be my plan.

Ha! that's what makes it interesting! for a simple old engine, its a set of interconnected systems that all rely on each other. Fault finding has never been simple on these simple old engines. That tiny little inlet filter on the carb ruined my summer last year...I broke down 3 times, one of them grounding the boat, trashing my prop...spoiled a weekend with friends on another occasion.... and I didn't even know about that bloody little inlet jet filter that was blocked to the hilt, and deciding to randomly let fuel through thereby completely conning me!!!! (I hate faults like that..). before that I had replaced all the ignition components but not really looked at the carb properly which was still a black box to me. That's when I decided to take more of an interest and learn from the collective expertise on this forum! Same with the Morris, whereby it was running rough, I went through all the steps but the root cause was the garage had unknowingly to me mucked about with the timing. Knowledge of these things is part of the fun, for some...but not all. The good thing about this forum is that engine is only one thread! there's something for everybody on here!

Or get moored near to Jed. A generous man who really does know what to do!

Minerva wrote:I don’t agree that it’s anything to do with idle mixture since your issue is when throttle butterfly is open so volume control screw no longer in play.

Try leaning off your idle mixture and opening the throttle  
You can be as fast or as gentle as you like, when it’s under load and you throttle up, if it’s too lean it will splutter and stall. If it’s really lean it’ll stall as you put it into gear.

The main jet and butterfly valve don’t come into play as soon as you come off tickover

Stephen wrote:If, like me to a great extent, you don't really know what you're doing then calling the man from RCR would be my plan.

Some of us have an idea of what we’re at

Minerva - "Replacement fuel pumps have no filter in them so folk put one in the fuel line before the pump" you said. I've been struggling to find why my pump doesn't look like all others mentioned in that it doesn't look as it can be dismantled - so is mine perhaps the replacement type you mention? Does it have a name (and not a rude one!)?


And if you could more fully describe where/how/what it looks like - the inlet jet filter you mention. I'm suddenly (after running fuel low in my steel tank and the boat suddenly behaving like a car does when running out of petrol but despite full tank now), spluttering and cutting all the time. You may have found me the solution!

I don't know if you can make it out because it's in the bag and if I open the bag I can't refund it...but this is a SM replacement pump. You can see the top bowl is not the type you can remove. There is no filter in this one. It's my spare. However if I were to fit it then I would need to fit an in line bowl shape filter in the fuel line between the pump and the tank.

Also this pump has no priming handle underneath like the originals ....where you literally could hand operate the diaphragm on the old ones.
Regarding your spluttering, Andrew on this forum has an in line filter and managed to get an air lock in it. Obviously check your filter situation...I don't know if your carb has a micro filter in the inlet valve like the Fomoco but need to check that. If no filter at all see if rust in the float chamber....and whilst off if you got the old pump with the handle operate it and check flow out of depressed needle valve...if dirt has gone from tank to pump in a filterless setup, then you may have compromised the diaphragm...lot to check here.

Mine is like that I think. And I have a, small metal detachable-bowl, in-line sediment trap between there and tank. Can't see it could fit a filter. 
And if you could kindly remind me where the inlet filter is on the carb? My symptoms were as you yourself described. My arrival on the (fully renewed at last) staging outside the Swan at Staines was more of a crash landing (though I try to pass it off with style) and at my home mooring I hit the pontoon-end for sudden want of an engine - look, no brakes! No damage and no-one watching! One has one's pride!

OK - thanks for all that. I'll go through it all again. In neither the trap or in the float chamber, yesterday, were more than grains of muck and no water and yet the intermittency continued. Fine in all respects for two or three minutes and then almost violent hesitation, an attempt at recovery, and then stoppage. Instant restart, and so on and so on. You're so kind to share your info.

Stephen wrote:Mine is like that I think. And I have a, small metal detachable-bowl, in-line sediment trap between there and tank. Can't see it could fit a filter. 

Hang on...that sounds like a filter....maybe you have air trapped in it as a result of running out of fuel.  Fuel filters can be simple metal gauzes. Take that bowl apart, clean it and prime it with fresh fuel and see where that takes you. We can worry about the needle valve filter another time.

I had a similar problem and traced the fault to a sticking needle valve. It was sticking shut stopping fuel refilling the float chamber so that once the float chamber emptied the engine stalled. The vibration shook the needle free and allowed the float chamber to refill and an easy restart. An annoying little problem easily cured with a service kit. Your can clean the needle valve filter while you're at it.

Good shout BB, if Stephen ran the tank dry, I guess dirt could have gone that way.... really he needs to look along the line as it were!
If it's a solex it may not even have an inlet filter....
When my engine cut out I was staight into the float chamber to see if starvation was the problem.... sometimes if you wait and try to restart it fills up again and you run round in circles...with me it was blocked inlet filter that decided to let fuel through now and again just to trick me.

The picture (you've all been waiting) of my apparently non-standard fuel pump, with no lid to lift. Perhaps it could be dismantled, and it might indeed have a filter, but I'm loathe to attempt it, make a new problem, drop bits in the bilge, and so on. Will try everything else suggested, first! That tube is the sump case breather that vents to the transom but tends to fill itself with condensate. I thought I'd read that some members channel theirs back to the air cleaner to exhaust through the engine. Best idea?

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That fuel pump is replacement part and contains no filter. Do not disassemble. Check the in line bowl thing u described earlier which is probably the filter. Do u have photo of that?

In-line metal bowl. Very small. Petite, even! Opened it again today - no sediment, neither in the float chamber. All jets clear. Restarted and still hesitant. After a while it settled down, just as I was thinking it was like hunting but reluctant to touch the settings and create new variables! So, so far so good at last.
However now I see its not charging and the ignition warning lamp is never coming on. Perhaps alternators don't need a voltage regulator or its inbuilt? I don't now know what to be looking for. Probably when I was desperate to return to base with the engine repeatedly stopping two days ago I got quite aggressive with the repeated restarts and now wondering if the fluctuating loads on the alternator blew it? Guidance please if anyone familiar with no-charge, no red light.

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Confused...ignition warning light should come on at first key switch position and then extinguish once alternator or Dynamo output hits 12v. It’s extinguishing does not necessarily indicate alternator output is 14v...just that it’s at least 12.
Do u have alternator or dynamo? 
With alternator the voltage regulator is incorporated. With dynamo it’s a separate control box. It’s designed to stop battery overcharging. 
Do you have voltmeter? 
Your thread should be renamed “bar of soap”!