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Old 05-06-2019, 02:53 PM
bikerider bikerider is offline
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Default Engine starving for fuel, pulse fuel pump

I have a converted outboard motor that uses a Briggs 6.5hp power head (vertical shaft from a pressure washer). The fuel system I have is a 3 gallon boat fuel tank connected to a primer ball, then a fuel filter then a quick connect and then to a pulse fuel pump to draw fuel from the marine tank to the engine. The original gravity fed fuel system is no longer in play. I have tapped the original intake manifold and added a brass npt fitting for vacuum to operate the pulse fuel pump. The fuel pump is mounted above the carb. I have double checked that I have the lines on the fuel pump in the correct order. I pump the primer ball until it is firm. I can see that the fuel filter is filling with fuel. I can get the motor to run for less than 30 seconds and then it shuts off. I cannot get it to fire again. I have tried starting it with the fuel tank vent open and shut with no difference in performance. Is there something I am missing?

I will take pictures of the setup and post them in a few minutes.
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Old 05-06-2019, 03:08 PM
J.S.@SMS J.S.@SMS is offline
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Try running it without the primer ball. That might be restricting the fuel flow to where there isn't enough flow for the engine. Or try running the pulse pump off the crankcase breather. That might solve the problem.
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Old 05-06-2019, 03:59 PM
bikerider bikerider is offline
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Quote:
Originally Posted by J.S.@SMS View Post
Try running it without the primer ball. That might be restricting the fuel flow to where there isn't enough flow for the engine. Or try running the pulse pump off the crankcase breather. That might solve the problem.
You mean removing the primer ball from the line or just not pumping it? The engine I have is a flathead style engine. Would the breather you are talking about be the one that originally goes from the block to the airbox?
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Old 05-06-2019, 04:12 PM
bikerider bikerider is offline
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Resized_20190503_124523_2151.jpg   Resized_20190506_141720_4723.jpg  

Resized_20190506_141738_3379.jpg   Resized_20190506_141756_3332.jpg  

Resized_20190506_141803_4019.jpg  
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Old 05-06-2019, 05:04 PM
mckutzy mckutzy is offline
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Ya that would be it...
The square little box mid pic of the first pic shown...
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Old 05-06-2019, 06:07 PM
bikerider bikerider is offline
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Quote:
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Ya that would be it...
The square little box mid pic of the first pic shown...
I'm just not seeing it. Could you possibly highlight what you're talking about?
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Old 05-06-2019, 07:11 PM
mckutzy mckutzy is offline
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Right next to the exhaust, I think they usually cover the valve springs...
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Old 05-06-2019, 08:32 PM
bikerider bikerider is offline
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Quote:
Originally Posted by mckutzy View Post


Right next to the exhaust, I think they usually cover the valve springs...
I just went out and took a look. I saw the vent tube that runs to the other side of the motor from that valve cover. That makes much more sense now. Thank you for the picture. As it is I have a small breather filter on the end of that tube. Tomorrow I will route the fuel pump pulse line to that and the breather filter via a T and hope for better results.
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