More 57 Johnson 18hp Problems

yam350yfm

Petty Officer 3rd Class
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Dec 26, 2007
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79
Okay, after several weeks of overtime, replacing the transom in the boat, etc I finally got the carb rebuilt over the weekend. Now it will start and run for 5 to 10 seconds, then die. It was taking 7 or 8 pulls to start. In the few seconds it runs the water does come out, so the impeller pump change worked.

Here is what has been replaced so far on my 1957 fd-11k 18hp:
1. New coils
2. New condensers
3. New points gap at .024
4. New plugs gapped at .030 (Champion 4 series)
5. Rebuilt pressure tank
6. All new gas hose on pressure tank and engine
7. Carb rebuilt
8. Impeller replaced
9. All throttle linkages lubed (now get full range on tiller throttle twist)

All ignition parts are Sierra and the carb rebuild kit was Mallory, all ordered from iboats. I did check the high and low speed adjusters for wear and they were good. I put them in per the manual (3/4 turn and 1 1/2 turns out). I used the Seloc manual. The carb is the style that does not have the spring between the float arm and the needle, and the Mallory kit did not include the spring and needle as part of the kit, so it is original style.

The best way I can describe it would be an i/o where the timing is off a few degrees. I have good spark and fuel. The fuel is fresh 93 octane Shell with Penzoil synthetic blend and some fuel stabilizer. Compression is still 105 in each cylinder.

Any suggestions, or should I cut my losses and look for something newer?
 

tashasdaddy

Honorary Moderator Emeritus
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Messages
51,019
Re: More 57 Johnson 18hp Problems

according to my OEM manual points should be at .020, rather than .024. that could throw you off, just enough.
 

yam350yfm

Petty Officer 3rd Class
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Dec 26, 2007
Messages
79
Re: More 57 Johnson 18hp Problems

I will change that tonight. I also have a set of Champion 6 series plugs if you think that would make a difference.
 

tmcalavy

Rear Admiral
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Aug 29, 2001
Messages
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Re: More 57 Johnson 18hp Problems

Your carb and magneto may be out of synch. Look at the front of your motor, with the cowl/cover removed. Up under the stator plate is a tapered plate that contacts a roller on the carb linkage. When the throttle is set to Start, that tapered plate should be in contact with the linkage roller. At that point, the rear butterly in the carb should be open just a hair. This is what synchs the magneto/throttle advance to the carb butterfly. Shine a flashlight into the carb throat and make sure the rear butterfly is closed when the throttle is way down at Slow/Stop. Turn the throttle to Start and make sure the rear butterly is just barely open, it should open smoothly as you advance the throttle. You can adjust the linkage to get it in synch. Are you sure the pressure fuel system is tight? Sounds like it maybe out of synch and/or starving for fuel. If you determine that the fuel system is tight/good, and the synch is good, you may have to reclean the carb...the slow-speed/idle circuit has to be spotless for it to idle well. I've had to do more than one carb more than once to get it spotlessly clean. I redid a small 3 hp 58 E-rude recently that drove me nuts, until I figured out that the rubber tip of the needle valve under the float was degraded and some of the rubber was partially clogging the gas inlet. Dropped in a new needle and it runs like Mom's old sewing machine.
 

wilde1j

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Apr 15, 2002
Messages
5,964
Re: More 57 Johnson 18hp Problems

The mixture initial settings are just that. You have to adjust both to get it running right.
 

yam350yfm

Petty Officer 3rd Class
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Dec 26, 2007
Messages
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Re: More 57 Johnson 18hp Problems

Ah...the stuff you can't get from a book.....

The tapered piece that you mention, on my motor has I believe 4 marks that have been scribed and marked (I'll see if I can get a good picture tonight). I assume those are some sort of mark to line up with different throttle positions. The arm and roller you refer to is not always touching that tapered piece. Not sure how that adjusts of if that is how it was supposed to be. The rear butterfly does not open until the motor is placed in gear and the throttle is fully cranked to the "fast" position. The roller is not touching the tapered piece until the throttle is cracked most of the way. I have the silencer off the front of the carb so that I could see what happens with the choke and the butterfly. I do not believe the butterfly opens more than about 20% to 30%. I never could get to where the back butterfly (not the choke) would go horizontal.

I only got the throttle to turn fully from slow,start , fast after the carb rebuild, so the linkage could be off. When I cleaned and lubed the gear at the end of the tiller handle it would then twist all the way. How does the arm adjust?

Like I said, I can try to get some pictures tonight, if I can get some good ones of the roller, linkages, taper, etc.
 

yam350yfm

Petty Officer 3rd Class
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Dec 26, 2007
Messages
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Re: More 57 Johnson 18hp Problems

Adjusted the points to .020 and did the synchronization as best I could. The result was the motor starts and runs at what it thinks is WOT, but will not idle. When the choke is pulled out the roller does not make contact with the cam taper. When the choke is in it does, but I think it still needs adjusting, just not sure how at this point. I adjusted the 2 bolts that hold the taper plate on to get contact with the roller when the choke is off, and that was all the adjustment it had. When the throttle is wide open the butterfly is about 70% open (does not go all the way horizontal, about 2/3's of the way from vertical to horizontal). When the throttle is at slow the roller does not make contact with the taper plate with or without the choke on, and the motor dies (makes sense). In the start position it almost makes contact with the choke off, but no contact with the roller when the choke is on. Had to crank the throttle nearly all the way to fast to get the motor to start.

I will load out some pictures in the morning that will show it better than I can explain it.
 

jbjennings

Captain
Joined
Jul 18, 2007
Messages
3,903
Re: More 57 Johnson 18hp Problems

The roller not making contact on choke is normal. I personally ignore the start, slow, shift on the throttle, and I position the cam so that when the roller hits the scribed line as you turn the throttle handle, the throttle plate JUST begins to open. I've had good luck that way (it's the way I was taught right here on iboats). You should be able to see the scribed line on the throttle cam in the first pic. Also, my roller stays on the cam throughout the throttle range. When you put the shifter in forward, you should get full opening of the throttle plate with full throttle on the shifter. The mechanism won't let it open all the way in neutral to prevent boogers.
Good luck--hope this helps,
JBJ
 

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yam350yfm

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Re: More 57 Johnson 18hp Problems

This is with the throttle in the "slow" position
 

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yam350yfm

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Re: More 57 Johnson 18hp Problems

This is with the throttle in the "start" position
 

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yam350yfm

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Re: More 57 Johnson 18hp Problems

This is with the throttle in the "fast" position
 

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yam350yfm

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Re: More 57 Johnson 18hp Problems

General photos of the motor and the boat it will go on.
 

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yam350yfm

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Joined
Dec 26, 2007
Messages
79
Re: More 57 Johnson 18hp Problems

I forgot to mention that it was running last night in the 1600 to 3000 rpm range and ran well in that range. Just not sure what other adjustments need to be made to get it to idle.....

Thanks for the heads up on the synchronization and the points gap. After making those adjustments the motor ran pretty smooth in the range specified above.
 
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