1958 18hp Johnson fuel problem

I have read many helpful posts on this forum, and have decided to join now that I have a question of my own. I have a 1958 18hp Johnson that has been sleeping for close to 10 years. After bringing it home, I removed the carb, disassembled it and let it soak overnight. I dried it with compressed air, then reassembled it with new gaskets. The glass bulb was also removed and cleaned. Both spark plugs were replaced, along with all the fuel lines. I now have a problem getting it to start. It has good compression and spark, and I get fuel to both the bulb and the bowl. I do not get gas to the cylinders. After puling it many times, both plugs are barely damp. Spraying gas into the cylinders does not seem to help. It sounds like it wants to run, but so far I have had no luck. Any help would be greatly appreciated.

Re: 1958 18hp Johnson fuel problem

set your carbs like this.

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle va /lve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, wating for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

are you pumping the button on the fuel tank until it is really hard to push? this get fuel to the carbs.

Re: 1958 18hp Johnson fuel problem

I set both high and low speed needles again today. I also made sure to press the button on the tank more than usual. The motor still would not fire.

Re: 1958 18hp Johnson fuel problem

if is sat for that long it could has a nest in the reed valves or some rust. Could also be the gasket at the bottom of the high speed jet.

Re: 1958 18hp Johnson fuel problem

Where would I find the high speed jet gasket? Is that the gasket that goes between the body of the carb and the high speed needle?

Re: 1958 18hp Johnson fuel problem

I believe the gasket in question is not where you are asking, but you need to remove the needle itself; then you will see a rubber gasket inside the carb. I have your same outboard and have the same problem: the gasket has decomposed and I get a fuel leak through it. If yours doesn't leak, its probably in good condition. I'm hoping to find someone that'l still sell carb kits for these vintage outboards. Any suggestions out there?

noelfm58

Re: 1958 18hp Johnson fuel problem

Try iBoats first, if you have the Part# for the kit.
Try here also: http://www.maxrules.com/fixomctunekits.html