'71 115 fuel pump question

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MercMan82

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How many fuel pumps does this motor have and on what pistons are they located?
 
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mr 88

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Re: '71 115 fuel pump question

Follow fuel line from where it enters cowling,that will take you to pumps.Fuel pumps feeds carbs,which feed cylinders.
 
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Chris1956

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Re: '71 115 fuel pump question

You may look it up on the parts list at crowleymarine.com. Some of those older Mercs had two fuel pumps, some only one.
 
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MercMan82

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Re: '71 115 fuel pump question

thanks for the reply guys. The reason I was asking is because the #3 rings broke on the previous owner. I noticed brand new lines going to the fuel pumps and wasn't sure if he'd taken them off and maybe got them switched or if I was missing one. This particular motor has two and they are mounted on 3 & 4 and 5 & 6 transfer ports. BTW, I also noticed that he used some ac hose connections which look pretty small. Would, say, a 3/16 ID restrict flow on this guy?
 
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MercMan82

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Re: '71 115 fuel pump question

IMG_0376.jpg motor 004.jpg
There is a lot of line the fuel has to travel through, which bothers me also. He also put a T connection and branched off to the middle of the carbs. Is this something that should be corrected, or am I worrying too much? The diagram I see on crowleymarine.com shows the fuel line enter and go to the top fuel pump, then there's a connection between the two pumps and the top pump goes to the top carb and the bottom pump goes to the bottom carb while the 3 carbs are connected together.
 
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mr 88

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Re: '71 115 fuel pump question

This may be a dumb question but what exactly is your issue? Does the engine run badly or lug at certain speeds or are you just not happy with the spaghetti line job.Having said that, I do not like the teflon look of the connectors as the fuel will break any of it exposed in the lines down over time. I would put it back to stock form with the correct length fuel line using the diagram of crowley. If it runs good then the big question is are the A/C hoses ethanol resistant and can I live with the mess under the wrap?
 
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MercMan82

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Re: '71 115 fuel pump question

I bought the motor for cheap as a project motor with the #3 piston rings broke due to several reasons I believe. Fuel related I'm sure because I found the backdraft hose on the top carburetor cracked almost in half. There was also preignition, detonation signs on the top 3 pistons. I'm just going through everything to make sure I fix all issues.
 
Gomer50

Gomer50

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Re: '71 115 fuel pump question

I would feel a little uncomfortable with all that extra fuel line,I personaly would try to keep them as close to original as possible.Nothing worse than having an inline 6 not getting enough gas.
 
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MercMan82

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Re: '71 115 fuel pump question

I believe what I will do is, I will cut out any excess line and I will get rid of the T and have the top pump go to the top carb with an elbow and the bottom pump go to the bottom carb with an elbow just as the diagram shows. I'm completely done boring and honing these cylinders and I've put about 700 in it so far. I'm not gonna take a chance burning it up again. Btw, I was missing 2 bleed restrictors and the other 3 were loose so I did the modification per Faztbullets' instructions. What's the point of having bleed restrictors on the top 2 cylinders if there's no fuel pump up there?
 
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