yamaha malta

[Maurice55]

Hi, as I did not winterise my old malta, I decided to give it a good clean up for the season, so I took the thermostat out and cleaned it in acid, took fuel tank and carburator to bits, cleaned everything with a spray-on carb cteaner and put everything back together.
Amazingly enough I used up all the bits and did not end up with a single "spare" bit, wondering where the hell it should be.
Even more amazingly, after putting brand new petrol mix and pulling a few times on the cord, it started !!!!! I was real proud. So I thought I'd go for a spin and it run fine untill I put full throttle and it just stopped dead after a few seconds.
I rowed back, re-cleaned everything and it did the same thing. If I pull the thottle when it starts to conk out, it goes on a bit longer so my conclusion is that somehow it is starved of petrol, but if I unplug the petrol hose from the carb, petrol flows very easily.
So to my eyes everything points to the membrane pump. The whole set of membranes and seals was renewed last year and a part from looking a bit floppy to me the whole thing looks fine.
So there I am, stuck.
Any ideas, anybody ?

 

[steve28]

if you pull it over for a bit with the choke out, is the plug wet. if so then i doubt its the pump. more likley to be plug or electrics,check the stop button/killcord

steve

 

[davidej]

I had very similar problems on my Malta and, over a period, a number of "professionals" charged me large sums of money but were unable to sort it out.

Finally I discovered that there is a small fuel filter hidden in the on/off tap. I removed this and replaced it with a proper in-line filter. Hey presto, no more starvation problems.
You have to screw a self tapper down the fuel's 'entrance' to the tap, then pull it out , removing the tiny filter

 

[maxi77]

I suffered fron this sort of problem with an out board, the carbureter seemed to block with great regularity (I became able to clean and reset it in minutes) until I discovered that the pipe from the tank was slowly disintegrating on the inside. New pipe with an added disposable filter and the problem went away never to return.

 

[Maurice55]

Thank you all for the help and I will check all these points when I get back to the boat.
I should say I will check them again because on the electric level, I ran the engine with the on/off button disconnected, and as for the petrol line, as I said in the post, the petrol runs very freely if I disconnect it from the pump.
But I will check again, perhaps a little rest will have sort it out.

 

[davidej]

Thank you all for the help and I will check all these points when I get back to the boat.
I should say I will check them again because on the electric level, I ran the engine with the on/off button disconnected, and as for the petrol line, as I said in the post, the petrol runs very freely if I disconnect it from the pump.
But I will check again, perhaps a little rest will have sort it out.

Yes but so did mine. I replaced the petrol cap in case it was the vent , all the piping, stripped and ultrasound cleaned the carb several times, put new parts in the carb pump etc etc -£100's spent. Petrol still seemed to flow fine - but after a few minutes running - fuel starvation.

A simple removal of this tiny hidden filter sorted it

 

[maxi77]

Thank you all for the help and I will check all these points when I get back to the boat.
I should say I will check them again because on the electric level, I ran the engine with the on/off button disconnected, and as for the petrol line, as I said in the post, the petrol runs very freely if I disconnect it from the pump.
But I will check again, perhaps a little rest will have sort it out.

Yes with mine the fuel flowed very freely through the pipe, it was the little bits of pipe coming of the inside wall that were blocking the jets.