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84 Mercury 18hp Help!

T

Tgc1021

New member
About to give up on an 84 Mercury 18hp tiller I recently picked up for $25. The motor was locked up which is why it was cheap. The motor looks very clean. After several days of soaking oil in cylinders and slowly working the flywheel I got it loose and turning easy. Compression was awesome 135 psi in both cylinders. Cleaned the carbs, fuel filter, fuel pump and put all new lines and fuel connectors. Also new spark plugs. Spark is great and I have clean new fuel flowing all the way to carbs. Choke the motor and it fires up for 2-3 seconds and immediately dies. Also after the first time it fires it takes 10-15 pulls before it fires and dies again. Feels like I’m missing something very simple I just don’t know what it would be. The impeller was shredded so I’m assuming that’s why the motor originally locked up. About to give up on it and pass it along to the next guy to see if he can figure it out. Any ideas let me know. Thanks
 
May have found my issue lol. A few days ago when I checked the carb bowl it didn’t drip much fuel. I assumed is was because I have the motor on a messed up old stand that leans back at an angle. After moving it to a better one the fuel comes out about one drip every 5 seconds. Guess it’s time to rebuild carb. 🤷🏻‍♂️
 
I say rebuild the carbs with OEM parts (preferrably) and make sure the engine in straight up and down when you prime the bulb and try to start it. That's made a big difference in the starting of my 1978 200hp Black max merc. Is the fuel tank new too or, if old, have you checked to see how dirty it is? Debris can still get into your new lines and filter if the tank isn't clean. Good luck, friend!
 
Please take that guys advice on OEM carb kit. I've learned that lesson twice!! On a 115 Yamaha, the carbs are a beast to remove. 2 of the nuts are strictly remove by feel! Anyway, I purchased carb kits from Amazon. Great Price. Less than half the price of OEM stuff. Put them together and put them on. Pumped up the primer bulb and gas went everywhere. Took them off and found that the new float needles are actually 1/8" shorter that the ones I took out. Also, after being on the motor for about 30 minutes, the bowl gaskets were all swollen and out of shape. So, Please don't re-learn this lesson. Buy OEM parts. Even a carb kit.
 
Just clean the carbs do not buy kits until you absolutely have to. You have a motor that was stuck might want to make sure it's healthy first.
 
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