Evinrude 18 hp starting problem

scimitar858

Seaman Apprentice
Joined
May 16, 2012
Messages
39
Hi All,I have a 1971 18 hp that won't start,it has new plugs and points fitted and there is a big fat blue spark on both plugs,there is 115 compression on both cylinders,however when you remove the plugs after 6 or so pulls,the lower plug and cylinder are wet but the upper ones arn't,they are dry,there is also a pipe that runs from the carb manifold to the bottom section of the plate that has the fuel pump on it,this is full of petrol,should it be?you occasionally also get a back fire when pulling the engine over.Also there are no markings on the hand throttle,where should it be set to start,i've tried it in all positions to no avail.Any help would be much appreciated.
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Evinrude 18 hp starting problem

Howdy, scimitar.

Welcome to iboats. :)

Check the fuel pump diaphragm for rupture. It may be pumping fuel into the crankcase.
 

lindy46

Captain
Joined
Nov 27, 2008
Messages
3,886
Re: Evinrude 18 hp starting problem

Also make sure the plug wires are on the right plugs. The top wire should have a metal band on it if the wires are original.
 

motorhead64

Cadet
Joined
Feb 23, 2012
Messages
13
Re: Evinrude 18 hp starting problem

Sounds like you have great compression and good spark...Backfire could mean timing is off. You never mentioned if you had it running at all. If not, I would seat the needles on the carb, keeping track of how many turns in to the seat. Then back them out 1 1/4 turns from the seat. If she still won't start, spray a little pre-mix into the dry cylinder...if you still aren't getting anywhere, it's time to pull the carb, clean out the carb, and start again.
 

samo_ott

Vice Admiral
Joined
Jun 18, 2006
Messages
5,125
Re: Evinrude 18 hp starting problem

And with the shifter in neutral, you turn the throttle all the way until it hits the neutral stop for it to be in the starting position. Make sure the cam above the carb is actually moving slightly when it moves to that position.
 

scimitar858

Seaman Apprentice
Joined
May 16, 2012
Messages
39
Re: Evinrude 18 hp starting problem

Also make sure the plug wires are on the right plugs. The top wire should have a metal band on it if the wires are original.

Hi Lindy 46,non original wires fitted, although they are new,but i have swapped them over a few times.
 

scimitar858

Seaman Apprentice
Joined
May 16, 2012
Messages
39
Re: Evinrude 18 hp starting problem

And with the shifter in neutral, you turn the throttle all the way until it hits the neutral stop for it to be in the starting position. Make sure the cam above the carb is actually moving slightly when it moves to that position.

Thankyou samo_ott,that's where i had it set,so i know it was in the right place,once again many thanks
 

scimitar858

Seaman Apprentice
Joined
May 16, 2012
Messages
39
Re: Evinrude 18 hp starting problem

Sounds like you have great compression and good spark...Backfire could mean timing is off. You never mentioned if you had it running at all. If not, I would seat the needles on the carb, keeping track of how many turns in to the seat. Then back them out 1 1/4 turns from the seat. If she still won't start, spray a little pre-mix into the dry cylinder...if you still aren't getting anywhere, it's time to pull the carb, clean out the carb, and start again.

Hi Motorhead64,I've never had it running,will check the timing again,i've got the needle out 1 1/4 turns,i've tried the pre-mix spray into the dry cylinder,still no go,i've stripped the carb,and it was remarkably clean,so back to timing.Thankyou for your help.
 

scimitar858

Seaman Apprentice
Joined
May 16, 2012
Messages
39
Re: Evinrude 18 hp starting problem

Howdy, scimitar.

Welcome to iboats. :)

Check the fuel pump diaphragm for rupture. It may be pumping fuel into the crankcase.

Hi,thankyou for your reply,i'll strip it tomorrow and see.
 

lindy46

Captain
Joined
Nov 27, 2008
Messages
3,886
Re: Evinrude 18 hp starting problem

Hmm - have you had the flywheel off and checked the that you don't have a broken flywheel key?
 

64osby

Admiral
Joined
Jul 28, 2009
Messages
6,799
Re: Evinrude 18 hp starting problem

Before you pull the flywheel spray some premix in the carb and see if it wants to run. If she does you have a carb issue, rebuild it.

If not double check points, if they're good, then pull the flywheel and check the key. Also look at the wires to see if they are shorted out or worn.

Good Luck.
 
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