66 EVINRUDE LARK 40 HP,FUEL DELIVERY PROBLEM

[glassmaster68]

PUMPED THE PRIMER BULB TIGHT AS USUAL,,,STARTED THE MOTOR,,,,DIED LIKE WAS OUT OF GAS,,,,WENT TO PUMP UP BULB AGAIN AND IT WAS TIGHT,,,FELT LIKE IT HAD NO GAS IN THE BULB,ALMOST LIKE IT BACKFLOWED SOME AIR BACK INTO IT.,,,,,TANK VENTED FINE,GOT A NEW PRIMER BULB LINE,,,SAME THING,,,,,,,SUQEEZED THE BULB HARD,TRIED TO START,,,,, AND ENGINE SEEMED LOCKED UP AND WOULD NOT TURN OVER,LIKE A VAPOR LOCK OR SOMETHING,,,,,TURNED OVER A FEW MINS LATER,BUT SAME THING,SEEMS LIKE BULB IS GETTING PRESSURIZED ,,,,,,,,,,,,,JETS ARE CLEAN,FLOAT WORKING RIGHT,,,,DONT KNOW BOUT FUEL PUMP THO,,,COULD A BAD FUEL PUMP CAUSE THIS?

 

[racerone]

If engine will not turn , you need to investigate that and not the fuel system----" seemed locked up " , are you saying you can not turn the flyweel by hand ??

 

[glassmaster68]

turned flywheel by hand this morning,,,started motor right up,,,,,,cut it off and took the bowl drain screw out,,,fuel pumps into bowl good with primer bulb,,,,,,,[,i always drain the bowl after use,or run the bowl out of fuel,,so no fuel is just sitting in there] ,,,,,if reeds are bad,can that cause back pressure into fuel hose?

 

[glassmaster68]

when i got the boat 5 years ago,i personally replaced,,,coils/cond..points plugs/plug wires,carb kit,,,,,used it for 2 seasons,then it started running on one cyl,,,,,this baffled me due to the coils,cond,points plugs were all good,,,,i kept reading and found that if armature plate doesnt have a good ground this could happen,,,i ran a wire from armature plate to block and have ran flawlessly for 3 more seasons till now,,,,,THE ONLY THING I HAVENT REPLACED WAS THE FUEL PUMP,,,,,,so what i was wondering is if a fuel pump goes bad,can it reverse the pressure back into the fuel hose/primer bulb,,,,,,,,,,

 

[racerone]

Bad reeds would result in a " no pressure in the crankcase " condition.---Then the fuel pump would not work !------But check the fuel pump diaphragm just for fun.

 

[glassmaster68]

ok ,,i like what youre sayin bout the reeds,they are the original ones still in there,,,for fun i did check the diaphragm and im glad you suggested it,,,,,,it was sucked in instead of out and had a bad crease in it,,,it definitely doesnt look as it should,,,,it is the original,i think the ethanol has taken it on out,,,i do use the marine stabil,,,,but im sure the ethanol still does its thing,,,,also the gasket for the screen looks a lil sketchy,,,,i guess if either were not right,,it would be possible for it to pressurize back into the fuel line,,,im gonna get a new pump and see what goes,,,i remember when gasahol was around,,,whiskey gas,,,,in about 1982 i used it in a 79 kx80 [lil 2 stroker bike] and it ate the lining off the inside of the metal gastank,,,,it all got in my carb,,,,,,good octane with bad ju ju,,,,,,,,i will post back if the pump solves my delimna,,,thank you racerone,youre the only one that hit me back on my thread

 

[racerone]

A repair kit for the fuel pump is likely the best option.---Look for one that will fit the pump you have.-----The pump has check valves so this idea of pressurizing the fuel line is a bit of " over thinking " in this case.

 

[glassmaster68]

just for curiosity,i just rebuilt the pump,,,,big spring,small spring,,,,,,took a piece of bicycle tube,made a diaphragm,and a screen gasket,,,,,it was fairly simple,,,,that was the problem,,,,the hole in the diaphragm was letting crankcase pressure go into my fuel line,then when i repumped the bulb till it was hard,i was pumping pressure into my crankcase,,,the equal pressure in my crankcase made it seem locked up,,,,like if you run a truck into the water and suck water in the motor,,locked up with equal pressure on the pistons,,,,in this case,i was doing with air,just on the opposite side of the piston,,,,,runs like a top now,,,bulb loses a lil pressure as it should,,,runs mooth,no leaks,,,,,,still need the right pump or rebuild kit tho,,,i dont know how long the tube rubber will last up against the gas and ethanol,,,,,,i never thought it would do that with the pressure,,,def a new one on me,,had me worried,,,,,but it was the fuel pump diaphragm as you diagnosed,,,,,,,,,,,i shouldve replaced the pump a long time ago,,,,,i saw where i can get a whole newer pump for bout 70 bucks,,its for a smaller motor but is supposed to sufficient,,looked like i would have to run the lines a lil diff,,,,,,cant believe i just fixed that thing cutting out a bicycle tube