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TomEdwards18

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I've got an issue where the motor is sparking fine, idles all good. But when I get revs to the higher end, it'll rev really high for about 2 seconds, then go back to little amount of revs and then cut. I think it could be fuel related - might be carby or fuel pump. Just wanted to get some other opinions. Cheers.
 
Hi,
Have you ever emptied out the fuel chamber?....item #2 in the link below. It is housed inside item #3 that is attached to your engine oil dipstick tube.


That thing can trap water and needs to have all liquid removed every so often. Use WD-40 to help slide it off of of the tube and shake it dry.

If that doesn't make an improvement then yes, it could be a weak fuel pump or a dirty carburetor.

The fuel pumps are pretty hearty and only need to produce about 3 psi so they last a long time.

The carbs though get plugged pretty easily and can be a real pain to get properly clean.

There is a small fuel filter (item #5) but I don't remember ever having one cause a problem. But....you never know.
 
Sorry, I was in a rush when I answered you earlier.

I should have said that a good test to do when an engine loses power and stalls would be to repeatedly squeeze the primer bulb.

If that improves performance and keeps the engine running, then you need to find out why it's starving for fuel.

One other simple test is to loosen the fuel tank cap so that you KNOW the tank is venting.
If that makes an improvement, the you will need to check your tank vent valve. Sometimes they simply vibrate closed and just need to be reopened.

Good luck.
 
jgmo said:
Sorry, I was in a rush when I answered you earlier.

I should have said that a good test to do when an engine loses power and stalls would be to repeatedly squeeze the primer bulb.

If that improves performance and keeps the engine running, then you need to find out why it's starving for fuel.

One other simple test is to loosen the fuel tank cap so that you KNOW the tank is venting.
If that makes an improvement, the you will need to check your tank vent valve. Sometimes they simply vibrate closed and just need to be reopened.

Good luck.
Click to expand...
Yeah mate, when the engine loses power, squeezing the bulb does help. I didn't even think about the tank vent valve, so I'll give that a look at.
A few times that its happened, the primer bulb get completely sucked empty, with absolutely no pressure through it, then the motor needs to sit for a few seconds turned off to be able to squeeze fuel through.
 
Well, that does sound like a venting issue or something maybe inside the tank blocking the pickup.
Let us know what you find.
 
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