Evinrude 18 hp won't start, update from may16th post.

scimitar858

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Hi All,The engine will run for a few seconds,but only if i remove the carb and spray premix directly into the inlet manifold, when i replace the carb it won't run,not even if i spray premix into the carb venturi,i've stripped the carb, blown all the airways and gallerys out,and it still won't start,i also have a spare carb, of which i've done the same to,and get the same result,is there something i'm over looking,it's as if there isn't enough vacumm to drag the fuel out of the carb.
There is also a pipe which runs from the bottom of the inlet manifold, to the bottom plate beneath the plate which the fuel pump mounts too,this appears to be a vacuum pipe,but fuel comes out of the outlet to it in the inlet manifold,is this normal.Many Thanks in anticipation Phil
 

boobie

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Re: Evinrude 18 hp won't start, update from may16th post.

Got a model # ??
 

scimitar858

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Re: Evinrude 18 hp won't start, update from may16th post.

Hi,it's a 1971,number18103.Thanks
 

Cap'n Chaos

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Re: Evinrude 18 hp won't start, update from may16th post.

Hmm... if your carb is clean and set properly I would suspect the fuel pump or ignition.

Disconnect the fuel line that supplies the carb and start (pull the rope or activate the starter) fuel should pulse from the line.

Have you checked spark and compression?
 

omcnut

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Re: Evinrude 18 hp won't start, update from may16th post.

is there suction at the carb thooat when you crank it ? if not mabey reed valves or crank seals are bad either of wich could cause a no fuel draw problem
 

scimitar858

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Re: Evinrude 18 hp won't start, update from may16th post.

Hi Again,Yes the engine has good compression 115 on both,a good spark fat and blue,fuel pump pumping fuel well,after a few pulls it runs out the choke aparture,so i think there is some draw there,i'll check tomorrow if there's any suction on the throat,i had a niggleing feeling it might be a full rebuild,just hopeing it might be an easier fix.
 

scimitar858

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Re: Evinrude 18 hp won't start, update from may16th post.

It now appears the pipe that runs from the inlet manifold to the cylinder block is an overflow pipe for excess fuel,i presume it enters the lower cylinder to burn off.
 

boobie

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Re: Evinrude 18 hp won't start, update from may16th post.

Yes, that "pipe" is part of the oil recuit system on the mtr. How did you check your spark ??
 

scimitar858

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Re: Evinrude 18 hp won't start, update from may16th post.

Hi,i checked by earthing the plug on the head,and then with an in line sealey spark tester,both showed a good big blue spark,like i said in earlier post if you take the carb of and spray pre mix directly into the manifold it will run for a few seconds,but not when the carbs back on,there must be some suction from the engine as fuel will leaak out of the choke throat after a few pulls,but it doesn't seem to reach the cylinders,with the carb removed,how far should the reeds open when pulling over,these appear to hardly move.It won't run if you spray premix into plug holes though.Phil
 

boobie

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Re: Evinrude 18 hp won't start, update from may16th post.

Is there an open air gap in the sealey spark tester or just a neon lite ?? I'm not familiar with it. I always use an open air gap tester.
 

nwcove

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Re: Evinrude 18 hp won't start, update from may16th post.

does it make a kick...snort ..or backfire when you put premix directly into the plug holes??? what plugs are in it?
 

Cap'n Chaos

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Re: Evinrude 18 hp won't start, update from may16th post.

You said fuel runs out of the carb throat after a couple of pulls? Your float may not be set properly.

The float should be level with the carb body when upside down. (Somewhere on this site *in the top secret files* there is a good picture of a proper setting.)
 

scimitar858

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Re: Evinrude 18 hp won't start, update from may16th post.

Hi,float sits dead level when carb body is inverted.
 

scimitar858

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Re: Evinrude 18 hp won't start, update from may16th post.

does it make a kick...snort ..or backfire when you put premix directly into the plug holes??? what plugs are in it?
Hi,none of the above,plugs are new j6 champions,,,
 

omcnut

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Re: Evinrude 18 hp won't start, update from may16th post.

im still not shure if you have checked your reeds...if you hold your hand over the carb mouth and pull it over do you feel suction? and if you hold your hand aprox 2 cm in front of carb mouth wiyh throttle wide open do you feel any air blowing out against your hand?... air blowing against your hand would indicate reeds not sealing and nu suction would be a symptom of bad crank seals either of wich would cause no intake charge to be drawn into the cyl preventing ignition.....
 

kfa4303

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scimitar858

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Re: Evinrude 18 hp won't start, update from may16th post.

Thankyou to all who replied with advice,the engine is now running,i still don't know what was wrong,but it suddenly started and has done so ever since,one of lifes big mysteries i suppose,once again many thanks to you all.Phil
 
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