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Wits end with this JW18 3 hp engine

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paul85

New member
I bought this complete engine at an estate sale and found the ignition coils to be cracked and bad. I replaced them a couple years ago and rebuilt the carb at that time, cleaned out the fuel tank, petcock, etc, and put a new water pump in it at that time as well. I could never get it to start, so i shelved it. I took it out of storage last week and replaced the points and condensers and have spark. I cannot get it to start, even by spraying 2 stroke oil/fuel mix into the carb at all. It will only backfire. The low speed screw is set to 1.5 turns out, but i have tried it just about everywhere. I have compression and new plugs that are gapped correctly. Points are gapped correctly as well. I am posting some photos of the timing setup to see if anything stands out that I've incorrectly reassembled. I had it all reassembled and it still did not start. It just pops through the exhaust like I have the timing incorrect. I've even sprayed fuel directly into the cylinders and it will not run even for a little bit.

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I hope you can all see these.
 
/facepalm. I've been dinking with this thing for years and think it was simply a case of having the plug wires reversed.....i just switched them and got it to fire for a few seconds. time to put it all back together and see what happens.
 
That I exactly what I was going to post.
if you have a clean carb, good compression, strong spark…it has to bark if you squirt fuel into the carb.
The top cylinder goes with the points/coil/condenser closest to the carb. Look closely at the ignition wires.
 
It runs. Need to dunk the lower unit in water and see if it idles and revs up and pumps water now. I'm surprised I had all the parts still after having it sitting in the corner of my garage. I was so close to throwing it away...
 
Back to this engine. It starts, it runs about 10 seconds, and then dies out. Sounds fuel related, sure. Anything specific I should look at? Carb has been gone through, soaked, ultrasonic, etc, and a kit put in it, but it sure seems like its running out of fuel, but it restarts easily, runs for another 10 seconds or so, then dies.
 
It might have been an ebay kit, i don't remember. Do you have a recommendation on where to get a better one? It's 100% carb related.
 
Your local boat shop may have wonderful factory parts.----That carburetor / carb kit was common for many years up to the late 1970's-----evinrudeparts.ca----might help you.
 
HA. I thought it would be simple, but I might be better off just buying another carb. I've rebuilt tons of carbs, from weed eaters to lawn mowers to jetskis, boats, trucks, but this one I just can't get right for some reason. I think the previous owner overtightened the adjustment screw and mushroomed it too much so i might just need to get a full kit with everything, not just gaskets, o rings, etc. so frustrating because you need to take off a lot of the metal surround if I remember correctly just to get to the carb.
 
Have you verified that when you open the fuel tank petcock that fuel is actually flowing and not just dripping out into the carb? I have seen those completely plugged with old fuel varnish. They can be disassembled and cleaned, also depending on the model, some had a screen or a porus stone to filter the fuel which can get plugged. How is the engine compression? The cylinder head on that engine is notorious for warping and leaking and needs to be surfaced on a flat plate or a piece of glass and figure 8 lap on 220 grit sandpaper until it cleans up and use the new syle head gasket that has larger water holes to help it run cooler. That engine runs hot at 175deg F on the exhaust plate and about 150deg F on the cylinder head. These are wonderful, simple engines and the fixes are usually simple.
 
fitz73222 said:
Have you verified that when you open the fuel tank petcock that fuel is actually flowing and not just dripping out into the carb? I have seen those completely plugged with old fuel varnish. They can be disassembled and cleaned, also depending on the model, some had a screen or a porus stone to filter the fuel which can get plugged. How is the engine compression? The cylinder head on that engine is notorious for warping and leaking and needs to be surfaced on a flat plate or a piece of glass and figure 8 lap on 220 grit sandpaper until it cleans up and use the new syle head gasket that has larger water holes to help it run cooler. That engine runs hot at 175deg F on the exhaust plate and about 150deg F on the cylinder head. These are wonderful, simple engines and the fixes are usually simple.
Click to expand...

Yes, fuel flows well from the brass petcock tube with the cap on and vent open. Delivery seems good. It starts easily and runs well also for 10 seconds and then dies out. It sounds to me like its running through the fuel in the float bowl and now filling up fast enough which is what I think you are alluding to, but in testing, the flow looked very adequate. It sat all winter. I will recheck, maybe a piece of gunk got stuck in the tube or something. It comes off easily enough and I can blow some compressed air through it to check. Thanks for the tips. I will invest in a new head gasket as well and do what you said, lap it on a flat piece of glass and check high spots. Thank you and to everyone who posted.
 
I always have to choke it. It does restart easy. I do not have to wait other than the normal 1-3 seconds after it dies to reposition myself and pull the cord. I used the settings for the adjustment screw that are in the documentation, however, I've tried several turns of leaner or richer and it didn't seem to make much of a difference.
 
Have you pulled out the choke momentarily to see if it wants to run longer when it starts to stall? I have to believe it is still a fueling issue like float height/sticking or pluggled high speed jet. I see that the JW-18 had a fixed high speed jet.
 
Do you have new fuel ( do not use any with ethanol). It will gum up float valve needle, carbs ,fuel filters,etc. When it dies if you pull the plug out is it brown and dry or wet or wet and oily ?
 
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