intake manifold gasket causing carb to blow?

[pudlejumper]

sorry for all the rambling posts but everytime i think i figured it out its not what i thought at all.<br />so my v4 140 evinrude is misfiring under a load then clears and runs perfect after 3000 rpm.<br />i THOUGHT it was the reed valves because air is blowing out of my top left carb. i took off the carbs and throttle body to get a closer look before attempting to take off the intake manifold,during inspection i noticed that the reeds look fine and seated however a 1/2 inch piece of the gasket is gone. i plan on replacing it anyway but i have a few questions.<br />1: would i be getting blow back from that piece missing?<br />2: would that be causing my misfire?<br />and 3: i bought a horrible manual where can i find one for MY motor.i bought the one that covers pretty much every evinrude motor known to man and doesnt even TOUCH on the intake manifold removal.

 

[mikeyzx2]

Re: intake manifold gasket causing carb to blow?

1: you shouldn't get blowback at all if the reeds are sealing properly, which gasket are you referring to?<br />2: misfire, blowback are related<br />3: don't the manifold just unbolt from the crankcase? it did on my 8HP with only four bolts, the reeds are mounted on a "reed block"<br /><br />I'm no mechanic, but I did stay at a Holiday Inn Express last night...

 

[R.Johnson]

Re: intake manifold gasket causing carb to blow?

If you have a piece of gasket missing under the reed box, that would cause a lean condition spitback, that would also be rare. What year is your 140?

 

[pudlejumper]

Re: intake manifold gasket causing carb to blow?

its a 91. its the gasket between the mainfold and the reed block. and mikey i WISH it were four bolts.lol.

 

[paul5]

Re: intake manifold gasket causing carb to blow?

hi pudlejumper . i have only just found this forum . i also have a 91 140 v4 loop charge . mine is having the same problems as yours . i stripped mine out today and found on my bottom left carb was blowing air out . (big thud huh). when i got to my reed valves i found it had blown the gasket out of the mating surface area , although the gasket was intact, just not in the right place .did changing the gasket repair yours or did the blowback damage your gasket . thanks , paul in the uk

 

[Walker]

Re: intake manifold gasket causing carb to blow?

My guess is you faound the problem. What do your sparkplugs look like. Do they all look the same.

 

[paul5]

Re: intake manifold gasket causing carb to blow?

the spark plugs are all the same color and the spark is strong . although it is backfiring through the exhaust (prop) and spitting violantly through the bottom left hand carb . i was concerned as to weather the back firing blew out the gasket or the gasket is the cause of the back firing thanks for such a speedy responce . cheers . paul uk