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Fuel pump question

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forpoints

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My previous boating experience was in a canoe so when I inherited this old 1975 Fiberform I/O it was a new experience. It didn't have a carburetor on the Mercruiser 165 engine so I purchased a used Rochester off of a similar sized OMC and rebuilt it. After installing it on the engine I set about adapting lines to it and one of those was a vacuum line that comes from the old Carter fuel pump. I haven't ever seen a vacuum line from the bottom of a fuel pump before. Is this line for possible leakage through the diaghram and I want to verify that it does indeed hook into the carb.
 
what you are calling a "vacuum line" is what the merc service literature calls a "sight tube"....it should NOT be black rubber but a length of TYGON tube (mostly transparent. its purpose is to provide a return path (to the carb) in the event the diaphragm in the pump ruptures .... and to let you see the fuel with a quick visual inpection....in other words, the TYGON tube should stay empty when things are 'normal'.

And the port on the carb where the TYGON tube connects should NOT be down on the throttle plate assembly but above the venturi.....
 
look At this picture...the barbed fitting is what Mark is referring to.

The barbed fitting is not a vacuum source but a way for gas to be pushed into the carb at or near the top area above normal vacuum port.

Marine carbs do not have vacuum ports as a rule of thumb
 
makomark said:
what you are calling a "vacuum line" is what the merc service literature calls a "sight tube"....it should NOT be black rubber but a length of TYGON tube (mostly transparent. its purpose is to provide a return path (to the carb) in the event the diaphragm in the pump ruptures .... and to let you see the fuel with a quick visual inpection....in other words, the TYGON tube should stay empty when things are 'normal'.

And the port on the carb where the TYGON tube connects should NOT be down on the throttle plate assembly but above the venturi.....
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Thank you, I had seen the sight tube mentioned in other posts but didn't know that's what it was. The rubber tube was on it when I got it so I will find some clear tygon tubing to replace it. The port on the carb is above the venturri so it should work out OK.
 
2004 - 350 Mag (400 hours)
Engine Model Number: 4-442067RS
Engine S/N: 0W010098
Carburetor P/N: 8M0096994 (EXPartsWeb 90-884717)

KgHost - The Sebago lake boat is covered and I deleted the photo of my carburetor. Do you have a thumbnail of my carburetor? Can you identity the function of the ports (screwed and barb ends)? AND, I guess my real Q is, what preventive service needs to be done to it? Does it have a inlet filter/screen? Replace a diaphragm? The boat is going-in for impeller, Gimbal service in a couple of weeks (Danvers). Its best to try to head-of problems now because repair service takes so long and Sept iis coming
 
Last edited:
sab said:
2004 - 350 Mag (400 hours)
Engine Model Number: 4-442067RS
Engine S/N: 0W010098
Carburetor P/N: 8M0096994 (EXPartsWeb 90-884717)

KgHost - The Sebago lake boat is covered and I deleted the photo of my carburetor. Do you have a thumbnail of my carburetor? Can you identity the function of the ports (screwed and barb ends)? AND, I guess my real Q is, what preventive service needs to be done to it? Does it have a inlet filter/screen? Replace a diaphragm? The boat is going-in for impeller, Gimbal service in a couple of weeks (Danvers). Its best to try to head-of problems now because repair service takes so long and Sept iis coming
Click to expand...

Ayuh,...... What's with the tiny font,..?? Ya come here for free help, then make it extra tough to read yer post,..??..??

Start a thread of yer own, as this will get lost on the end of forpoint's thread,..... show some respect,.....
 
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