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1972 Evinrude 65 HP triple NO FUEL TO TOP CARB

C

Carterlaker

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I have removed the top carb (clean and dry) the middle carb (blew out all orifices with mild compressed air I have not removed the bottom carb. I am awaiting results from this thread.
The motor runs rough and doesn't take throttle, however if I squirt fuel in the top carb while running rough on the water the motor comes alive and rockets the boat to a plane....it appears all three cylinders are working.
I have a new fuel pump...it is pumping I did a test.
 
Here are some pictures of what I have. I pulled the middle carb "Out Hose" and cranked the engine....yes it squirts fuel Just not going UPwards to top carb.
 

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No replies. Dang. So my theory is that the bottom carb float is either stuck or the needle is bad thus allowing free flow of gas therefore reducing pressure so top carb is not getting any gas and not working. (theory based on when squirting gas in top carb while under way...the motor comes alive)
 
Well I removed the bottom carb. It had clean gas in the bowl. All orifices were blown with mild compressed air and all is fine. What on earth can prevent the top carb from receiving fuel? Too large inner diameter fuel line from pump to middle carb (too big means less pressure??) And what about the little brass knobs that adjust the slow speed? All reeds are perfect and look brand new. Fuel pump is pumping (I removed the 3 way hose and the middle carb is squirting gas out the hole to the "T". (not with great force albeit).
Anyone have any idea? (It seems to me to be a fuel pressure issue as it takes more force to move fuel UP to the top carb). Again if I sit back at the engine with the cowl removed when underway and I squirt fuel directly into the carb intake the motor comes alive and seems to run perfect on all three cylinders.
 
Stuck needle in seat would prevent fuel flow. Disconnect the fuel line to the top carb, route the line into a jar and start the engine to verify that fuel is actually making it to the carb. Other suspects include bad upper crankshaft seal to where that cylinder is not getting enough fuel to fire unless you induce fuel from your spray bottle. Lightly cup your hand over the carb throat while idling and see if the engine speeds up (causing a more rich condition) Do a compression test since you've been running it like this and that cylinder has been running lean and without oil..
 
Thanks Fitz, I did check all needle in seats. Appears nothing stuck and small little retainer wires are present. I will disconnect top carb fuel intake (the three hose "T" and see if fuel comes out the top. If so I will again remove top carb and check N&Seat.
 
One other simple thing to do is remove the high speed jet plug and pump the primer bulb and see if fuel is coming out of the bowl
 
Fitz, by "High Speed Jet Plug" you mean the float bowl drain plug? Otherwise I just checked the schematic at Crowley and didn't see a High Speed Jet Plug. The only other thing I can think of that may be an issue is the Slow Speed Needles? (maybe way off here). And as far as compression goes I do have a compression tester but would low compression in the top cyl cause no gas to fill the bowl? As stated when I squirt Premix while under way the top cylinder screams and brings the entire motor alive boat on plane etc.
 
Yes, the bowl drain plug (The high speed jet is right behind the plug) The slow speed needle static set up is 1 1/2-1 3/4 turns out from lightly seated. Compression is not related to the bowl filling. Don't keep running it that way at high speed, it's not getting oil in that cylinder!
 
Stop running the motor until you find the issue.-----If there is no fuel in the top carburetor , there is no oil going in to top cylinder either.-----Damage to motor will be the result !
 
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