86 175 mercury fuel starving

M

mnfishingfool

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Aug 22, 2010
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I have rebuilt the fuel pump one week ago and have replaced the primer bulb and fuel/water separator. What happens is if I pump the bulb solid and run down the lake runs fine. When start back up will run short distance and starve for fuel. The primer bulb will need to be pumped up again. The primer bulb will have some fuel in it but not much. I was wondering what the fuel pressure should be out of the pump. I removed the discharge fuel line and started the motor to watch the amount of fuel coming out and it seemed low. Any help would be greatly appreciated.
 
j_martin

j_martin

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Sep 22, 2006
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7,474
Re: 86 175 mercury fuel starving

With all due respect, yer barking up the wrong tree.

If you put a piece of clear fuel line between the primer bulb and the engine, you'll see bubbles where you shouldn't.

Probably air leak in pickup tube, fuel line to primer, or the primer bulb itself.

Fuel pressure should be over 1 and less than 7 over the range.

hope it helps
John
 
M

mnfishingfool

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Re: 86 175 mercury fuel starving

Thanks I will try that this weekend. Work interferes unfortunately. Will let you know.
 
M

mnfishingfool

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Messages
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Re: 86 175 mercury fuel starving

ok I got a chance to try clear fuel line today. There are a few very very small. Smaller than the period in this sentence. I changed the fuel lines between the tank pickup and the fuel/water separator and the separator and the fitting for the primer bulb. The primer bulb pumps up better now, quicker and seems to stay full. Ran motor for 5 min. on muffs. Will try on lake this weekend. Also changed the fuel line connector to the motor. Will let you know. Are these bubbles normal?
 
j_martin

j_martin

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Joined
Sep 22, 2006
Messages
7,474
Re: 86 175 mercury fuel starving

Shouldn't be any bubbles.

If you replaced the bayonet fittings with aftermarket (plastic) ones, you are adding to the problem.

You can pull in air anywhere before the fuel pump, including the bayonet fittings, and the oil injection mixer T.

hope it helps
John
 
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