Frustrating Problem

Nasher · 03 April 2005, 21:31

Hi all

The last couple of times I've put my boat in the water I've had a problem

The engine starts OK using the choke and as always takes about 20 - 30 seconds to come up on all six cylinders then sits ticking over very happily.

To start it I push the key in for choke and as it fires up I raise the revs slightly using the lever. On my surface mounted lever your able to pull it to one side and use just the throttle without engaging gear.
Putting the lever back to neutral after a while it ticks over fine and will rev happily again out of gear.

However as soon as it goes into gear, ie putting the engine under load, the engine struggles to run at all and stalls if the throttle is opened too much.
After doing this 8 - 10 times, all of a sudden it will pick up of its own accord and perform without a fault for the rest of the day.

I was convinced it was the choke sticking on and spent a while today stripping it down to free it off. However I've discovered the solenoid doesn't operate a mechanical choke in the normal way, it just appears to give a single extra shot of fuel to the carbs via a diaphram pump.

I'm convinced its running on all six when the problem occurs and have also checked the advance/retard linkages to the stator plate.

The only thing thats changed is I've swapped to the surface mounted lever, but I've set up the cables etc as per the factory engine manual I have.

Any ideas would be appreciated.

Hightower · 03 April 2005, 21:50

With my Yam 80, I used to stall very easy. What I did was simply raise the tickover a couple of hundred revs. This might help short term!

Nasher · 03 April 2005, 22:09

Thanks Andy

Tried that the first time it did it, but it didn't make and difference, just carried on 'bogging down'.

I wrecked my best prop on the beach Saturday because of it.
Was my mistake, I was trying to get back to the beach after restarting it yet again, was spluttering in towards the shore with the throttle 3/4 open and it was about to stall again when wham it picked up and I couldn't throttle back and power tilt up quick enough. Managed to swerve around away from the shore but took about 1/2 inch of the end of one blade on the bottom.

Nasher.

Paul F · 03 April 2005, 22:13

Sounds as though it needs a good dose of power tune, failing that carb needs cleaning, if that dont solve it then check fuel pump is ok and fuel line.your right choke does inject fuel into reeds.
Paul

Nasher · 03 April 2005, 22:29

Paul

I thought perhaps the carbs/fuel line needed cleaning out, but after the first time it did it (and the second now) it ran fine for the rest of the day and I 'flushed it out' with 50qiuds worth of petrol.
Also it will rev happily when not under load. I also thought that if it was a 'dirty' problem the power would come back in gradualy, this is like flicking a switch.

Nasher.

Richard B · 03 April 2005, 22:45

I'd have a look at the fuel pump - if it's driven from a crankshaft or balancer shaft lobe, check that the crankcase diaphragm is OK and maybe consider overhauling the pump.

I've known fuel pump problems cause similar problems to this - revving happily offload but spluttering under load is fairly typical.

HTH!

Hightower · 04 April 2005, 01:05

Also look at the timing, might be a broken link or something

vortex · 04 April 2005, 22:15

Check the settings of the jets in the carbs. I had the same problem with a Yam 30, it turned out that the carbs needed cleaning and tuning.

Best of luck,
Mark

Richard B · 18 May 2005, 23:52

Did you fix it?

codprawn · 19 May 2005, 02:52

While you are at it check the plugs and make sure the gaps are ok - does sound like mixture too rich though.

Pete7 · 19 May 2005, 09:09

Quote:

Originally Posted by Richard B

Did you fix it?

Must have its now in our for sale section.

Pete

Nasher · 19 May 2005, 23:12

Yep

Got it fixed.

Cleaned the carbs out well, changed the fuel filter, and it ran better than ever.
As Pete says its now for sale as its made way for a 200HP Suzi EFI

Nasher.

Richard B · 20 May 2005, 07:04

Quote:

Originally Posted by Nasher

Yep

Got it fixed.

Cleaned the carbs out well, changed the fuel filter, and it ran better than ever.
As Pete says its now for sale as its made way for a 200HP Suzi EFI

Nasher.

eupa · 20 May 2005, 11:39

Any ideas would be appreciated.

Had same sort of problem with one of the yams.
There is air getting from the tank into the engine fuel filter.
- check fuel filters to see if rubber joints not warped ( Yamaha type)
- check all clips and hoses from tank to carb filter.

when you prime -the ball should go hard and stay hard.Check also quality of fuel ( is there water in the tank?) - if so drain tank
and flush out with Methanol. If it was the plugs it would probaly not fire at all- but you can

jonathan