Auto Fuel Pump question? Merc. 165 1977 Straight 6

[system-f]

Excuse my post jack in Tiffany's post:

I still wonder if we can run an auto mechanical fuel pump as long as we have another water/fuel seperator on our 250s.

Nope,.. Because a marine mechanical fuel pump is supposed to be vented to the intake....
Automotive fuel pumps would Vent to the Bilge,.... BOOM....

How does the fuel pump vent to the intake? Do you mean if the diaphram breaks it would vent to the crankcase? I guess I don't understand as there is only one hose from my fuel pump to the intake an that is the fuel line otherwise it is on the otherside of the motor and in no way connected to the intake.

I assumed there wouldn't be much different between an OMC Chevy 250 and the Mercruiser Chevy 250...but it looks like there is a difference in the fuel pump????

 

[Bt Doctur]

Re: Auto Fuel Pump question? Merc. 165 1977 Straight 6

I`ll try to explain it. The diaphram needs room to go up and down to pump fuel. The bottom of the fuel pump is open ,on a car it is a vent hole ,so it the diaphram breaks ,fuel dumps to the roadway. You can`t have this in a boat ,so the vent line you referr to is a "tell-tale" .Any fuel from a leaking diaphram gets directed into the carb body and not the bilge.Any visable liquid in this line means a ruptured diaphram.If this vent system is plugged off, the fuel pump wont even work properly.

 

[system-f]

Re: Auto Fuel Pump question? Merc. 165 1977 Straight 6

I just posted a picture. Where is the line on my pump to the carb? or does it jsut drain into the crankcase. According to the mercruiser manual this looks to be the right pump for my boat so I am sure the PO didn't put an auto pump on.

 

[Bt Doctur]

Re: Auto Fuel Pump question? Merc. 165 1977 Straight 6

Check on the bottom of the pump for a pressed in tube or check for a plug where a fitting would go.

 

[Bt Doctur]

Re: Auto Fuel Pump question? Merc. 165 1977 Straight 6

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