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Old 05 October 2016, 01:27   #21
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still sounds like a fuel restriction of some sort could you rig up a temp fuel supply above the height of the engine and try that to separate fuel ignition faults i usually give an engine a whiff of brake cleaner to see what the prob is
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Old 05 October 2016, 01:53   #22
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Soz to go over the symptoms again!!!



The engine starts easily?

Does it idle cleanly when on the muffs?

If you do nothing how long will it idle for?

Does the idle revs die suddenly or over a period of say 10 secs , 30 secs to what?

By pumping the bulb will it continue to idle? That is very significant?

Will it restart normally or must you use the choke?

Do you need to pump the bulb to get it to start?



My thoughts are about raising the fuel tank to atleast the height of the carbs and as a tempory measure i'd replace the fuel tubing by clear transparent stuff just to watch the fuel flow.

I don't know the engine how many carbs and how many cylinders? Pull or electric?

regards Nic

Hi Nic!

Engine runs smooth in idle for around 1minute.

Dies in less than 5secs sometimes longer but no more than 10.

If I keep priming slightly it will continue to run.

It will restart straight away by either choke, no priming, or no choke with priming.

It's got an inline fuel filter that I can see is always full of fuel.

It's a tohatsu m50d2, 3 cylinder with 3 carbs and its pull start

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Old 05 October 2016, 02:40   #23
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If the motor keeps on running while priming the bulb it is clearly a fuel starvation problem. The fuel pump might still not in good order.
I do not reckon it to be an air leak, on the engine side, otherwise rpms should go up. scream of death.
Look at the fuel lines and search for an air leak into the fuel lines. Might be a vapor lock.
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Old 05 October 2016, 05:33   #24
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How about raising the fuel tank and line and bypass the fuel pump so that the carbs are fed by gravity. Disconnect the fuel line from the pump to the carbs and with the engine running under the gravity fed fuel see if fuel is been pumped by the fuel pump into a safe vessel. I think it is fuel starvation. It's just a matter of finding where the restriction is. Can you get a hold of a separate fuel line/tank/bulb and try it. Is there an air lock in the inline fuel filter?? Nik Keep me posted
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Old 05 October 2016, 15:43   #25
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How about raising the fuel tank and line and bypass the fuel pump so that the carbs are fed by gravity. Disconnect the fuel line from the pump to the carbs and with the engine running under the gravity fed fuel see if fuel is been pumped by the fuel pump into a safe vessel. I think it is fuel starvation. It's just a matter of finding where the restriction is. Can you get a hold of a separate fuel line/tank/bulb and try it. Is there an air lock in the inline fuel filter?? Nik Keep me posted

I'll give raising the tank ago & bypassing the pump. It's a whole new fuel pump so should be good to go but I'll try anyway!

I've got my old bladder tank but no line and the tanks full of dirt, so that's a no go.

My main suspicions are with the fuel line I think so will try get hold of a new/borrowed one.

Cheers for the help, much Appreciated
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Old 05 October 2016, 16:05   #26
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Check for small cuts in the fuel line. I had a very similar problem. Turned out to be a barely detectable cut in the fuel line hidden by a circlip (I think the circlip created the cut at some point). Cut out that bit less than a fingernail width and all was well
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Old 09 December 2016, 11:26   #27
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Finally found the fault today...

Turned out to be a stuck diaphragm plate in the pump only letting fuel through when the bulb was primed

Finally fixed and ready for a water test!

Cheers for the advice everyone
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Old 09 December 2016, 13:19   #28
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Hi Luke, thx sharing. good luck with the test
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