Yamaha 40H 2T 1994 lost

[nw04jen]

Hi
Can anyone help b4 try and get dealer ?

https://drive.google.com/file/d/11UC...ew?usp=sharing

Have cleaned fuel tank and brand new fuel
New plugs
Cleaned carbs and checked all jets and reset floats to horizontal
New pump and filter
Set mixture to factory and have played with
Synced carbs so fully closed on idle and fully open WOT
About to do coils next but after that at a complete loss - runs smoothly idling then if increase revs coughs squeals and cuts out

[tinker]

Originally Posted by nw04jen

Hi
Can anyone help b4 try and get dealer ?

https://drive.google.com/file/d/11UC...ew?usp=sharing

Have cleaned fuel tank and brand new fuel
New plugs
Cleaned carbs and checked all jets and reset floats to horizontal
New pump and filter
Set mixture to factory and have played with
Synced carbs so fully closed on idle and fully open WOT
About to do coils next but after that at a complete loss - runs smoothly idling then if increase revs coughs squeals and cuts out

Just had a similar problem with mine, 6H4. Found an earth cable had been trapped, continuity lost, behind the cover at the side of the coil packs. I haven't tested mine in anger yet but it now starts fine, runs at tickover and revs in neutral.

Some of the process I followed....

Does using the choke stop it cutting out?

Does pumping the primer bulb help?

Remove the spark plug plugs one at a time, does the engine tone change for each one.

Increase the mixture on each carb one at a time until the revs change then back off a bit.

Removed the fuel connection on the outboard and gravity fed fuel into the filter.

Check the CDI timing is set correctly, think its 7 degrees. On mine there 3 marks close together at tickover the pointer has to be between those marks after selecting fwd/reverse and putting back into neutral, the play in the linkage makes this an awkward adjustment.

I eventually found the cable, after the carb clean, filter change and following the above and a bit more , spark plug clean/gaps.......Some great videos online with this outboard and others of the same family .

[nw04jen]

Firstly, thanks for coming back

SO there is no noticeable change in engine sound when I remove boot from second plug - 1 & 3 yes there is a drop off - 2 no sound change so will change that coil as plug is brand new and see if makes a difference
Not sure if that being the fault would make the engine 'cough' 'squeal' and cut out as it is...?

[tinker]

I doubt it would, sounds like fuel starvation. Have you got a choke switch, if you have it will enrich the fuel and should indicate, if it doesn't stall, that you have a fuel mixture issue

You can swap the coil from 1 or 3 to 2 and see if that changes where the issue is. If it does you know you.have a faulty coil. If it doesn't then it's the power supply to the coil or a fuel issue, more likely imo

[nw04jen]

Have checked fuel and all good ie new pump, filter flowing - when I choke it after a while still cuts out.
There is definitely no change to engine when I remove plug 2, as though it isnt doing anything. Plug 1 removed and engine cuts out immediately which I assume.is correct and plug 3 causes a change in sound.
Will replace coils and then take to dealer as everything else that a DIYer can do will be done. Have looked at pretty much every video I can find hence cleaned carbs, altered mix screws, replaced filter, replaced pump, replaced plugs, set idle speed, synced linkage and checked carb plates shut / open at correct points.

[A1an]

that squeak is a "lean sneeze", I'd say there's not enough fuel on idle circuit.

[tinker]

Change coil number 1 for coil number 2 and see if 2 still doesn't do anything when disconnected. Let us know what the dealer finds, maybe useful in the future.

[nw04jen]

Will do - at a total loss - even swapped fuel tanks and hose / bulb today but staying primed, fuel pump new ...have opened mixture screws more than suggested and increased idle screw slightly which seems to have got rid of the squeal (just) but minute i press down on linkage she cuts out - would think because not enough fuel but theres nothing left to test on fuel delivery side - and I do not know whether a faulty coil could cause this outcome?

[A1an]

How many turns out do you have the mixture screws?

Were the carbs ultrasonically cleaned?

[nw04jen]

Not ultrasonic but done as per all the youtube videos - power tune carb cleaner, all holes cleaned with carb cleaner rods etc and compressed air b4 back on - long soak ...i can remove again and take another look but the main jets were all completely clear

[beamishken]

If you have a cylinder off & swapping the coils over doesnt see the fault follow the coils then I'd suspect one of the trigger coils under the flywheel may be faulty, it's a fairly common issue on those engines

[tinker]

You can use engine start spray when it starts to stall, start with carb 2 and see if that brings it back to life, if it does its on the fuel side....

If you your prime (choke ) doesn't have an affect then it maybe down to that, apparently the membrane can fail..

On mine manually pushing the throttle linkage.....I'm not sure it advances the timing linkage correctly/ in the same way the remote throttle does.

[Roflhat]

As these guys have said, I'd start with fuel. Worth getting the carbs ultrasonically cleaned, I've cleaned carbs many times and the engine not run right, then get them ultrasonically cleaned and it goes perfect.

Try priming the fuel bulb as you go along, just in case it is the fuel pump drawing in air even though it's been changed.

Taking boots off the plugs on the 3 cyl Yam doesn't always give obvious results sometimes they seem to run no different on 2 at least in neutral. You can link all the coil earths together with short wires, saves a lot of grief I did it on mine years ago haven't had to touch them since.

Trigger coils beneath the flywheel can go, check the resistance should be around 160 ohms. If they all seem ok try gently heat them up with a hairdyer or heat gun and check resistance again

[Fenlander]

>>Trigger coils beneath the flywheel can go, check the resistance should be around 160 ohms. If they all seem ok try gently heat them up with a hairdyer or heat gun and check resistance again

A really good tip. I once had a car with a frustrating running issue once warm, turned out an ign component was situated touching a cooling hose. Only connecting a test meter and watching the results through the heat cycle identified the problem.

[nw04jen]

Really appreciate all the help. Will try easy start on the carb to see if helps and will strip again and get ultra sonically cleaned, will switch coils but after that I think its going to be a 'bridge too far' for my ability so will book into shop and come back when / if they find answer,

[nw04jen]

so can get her to increase RPMS spraying easy start into carb 2 - what does this tell me?
main jet issue, gasket not seated correctly, faulty coil, blocked fuel tube?
or all of above

[spartacus]

I'd be inclined to remove carbs again and get them ultrasonically cleaned. Like everything, you need a base point to refer back to with the exception of new parts of course. Maybe overlooked, check the fuel connection from tank to engine to make sure its good. Had a pattern part Tohatsu 'o' ring dislodge cutting fuel.

[User name]

Sounds ok on idle so it seems like fuel starvation when the throttle is opened. Likely main jet, or it could be a restriction in how much fuel can get into the carbs. I'd go with the cleaning again. Compressed air, some wire run through all the ports etc.

[tinker]

It's telling you it's fuel related, so coil should be OK. Strip and clean again, I have rebuilt carbs more than once in an attempt to get them working correctly, with carb cleaner it's an uphill struggle. Ultrasonic cleaner is the way to go but buying one is quite expensive if you want to fit the whole carb body in, £150 off Aliexpress.

Maybe a local garage has one, you could ask them to give it a clean for you?

[nw04jen]

Bought the ulktrasonic as clearly fuel issue carb 2 it seems so will go again