Johnson 70hp 1989 carb/fuel problem

Hello, I am new to the forum and am having a few issues with an 1989 Johnson 70hp VRO. I have rebuilt the powerhead as well as the carbs and disconnected the VRO. The problem I am having is that when the engine is running it is spitting fuel out of the throat of the carb as well as when the primer is primed and the motor is tipped. The motor runs very well at all rpm ranges but something is wrong as I am burning a ton of fuel and making a mess of the splash well of the boat. I now have the carbs off again checking float levels but cannot find anything wrong there, and the needle /seats are new as well as clean. Anyone have any ideas? I am setting the float level with the body with the carb upside down and the gasket installed. I am setting the drop at 3/4 of an inch from the body to the part of the float closest to the body, if you follow me there. This is happening on all three of the carbs...any help is appreciated.

Re: Johnson 70hp 1989 carb/fuel problem

Usually if you have fuel spitting out of a carb, you have a reed valve broken/split or something holding it off of the seat. I would think it would be rare that the reeds on all three carbs would be bad. Since you have the carbs off, use a flashlight and look into the intake and look at the reed valves.

Re: Johnson 70hp 1989 carb/fuel problem

Very strange... Running well at all rpms especially at idle while burning tons of fuel and spitting out of all three carbs does not suit together. Spitting a little from the top carb at idle seems to be normal. My own engine does so and I've read it several times here.

You need to determine if you have a carb fuel level problem or an intake/crankcase tightness problem. Unfortunately all carbs are rebuilt and do spit, so you can't swap two of them to find out. Can you borrow a known good 60/70hp carb? Also you may run the engine at idle, pull the fuel line and watch if spitting stops when the fuel levels in the carb bowls drop (prior to stalling of course).

What about the intake manifold gasket?
You rebuilt the powerhead. What about the crankshaft seals, especially the two between the crankcases?

Re: Johnson 70hp 1989 carb/fuel problem

Yes all seals and gaskets were replaced when the powerhead was rebuilt. If you think it could be the intake gasket with the carbs off I can replace that again if it will rule that out. Can't be more than 20 bucks. I don't know if this was a problem before the rebuild because I bought the motor with low compression on the center cylinder and rebuilt/replaced everything I could. I agree it is awful weird how well it runs, one of the reasons I am stumped. I have no problem idling or pulling a 180# skier up and it runs out to full rpm on the upper end. Very confused here I figured with all the extra fuel it would flood or foul plugs. The only thing I noticed is what I think is the low idle jet through the middle of carb leans to one side of the tube it goes through. I have seen pictures of other 70hp carbs and they look similar. Also I have an issue with the fuel primer it will not work with the key switch I have to manually turn the red nob on first start of the day, but after I just turn it backwards and don't have any issues restarting only on the first crank of the day. Do I have the float setting correct or am I off? Sorry for all the questions I am really boggled.

Re: Johnson 70hp 1989 carb/fuel problem

The upright brass tube leading fuel to the idle circuit is not always right in the middle. One of my 60hp carbs looks the same. But it's important that it is fuel tight where the brass tube leads through the upper carb body. In the manual OMC recommends a drop of screw lock to make it tight.
I don't think it's the intake gasket. Even if the manifold was a little warped, a new gasket would at least seal one of the intake paths. We need to look for some more general, influencing all cylinders.
Could it be possible that your primer solenoid is leaking? Have you got the late 1989 carbs with adjustable slow speed needle and all are set way too open during rebuild? A missing gasket in all three carbs? Floats mounted upside down? Is fuel sucked out of the big brass tube at idle?
The float is adjusted just as you described: upper carb body upside down, float parallel to body surface. That's what the instructions say. Some guys here in the forum recommend a little lower fuel level, i.e. the float a little higher at the side opposite from the hinge. The down end is not critical. The float should fall low enough to let fuel in quick enough at wot but should not get stuck in the carb bowl. Have you replaced the floats? For every gramm it gains weight the fuel level rises about 1mm. But my floats did not become heavier over time.

Re: Johnson 70hp 1989 carb/fuel problem

WernerF I think you hit the nail directly on the head with the comment about the loc-tite. That seems to be where the fuel is coming from especially when the motor has a pressure change like from wot down to idle or vise-versa. Do you think loc-tite will seal it well enough to stop the amount of flow I am having or should I maybe use a silicone or anaerobic sealant? Or do the jet and tube come out to be replaced? I can't find any breakdown on Johnson's site. My lovely seloc manual doesn't tell me that little bit of information and I'm grateful you mentioned it. If it works I think I'll save a few hairs on my head. Next problem I broke a nipple on the primer solenoid removing the carbs so I gotta find a cap for it with the nipples. Could the primer be working all the time and injecting extra fuel into the throat? I see the jet for that goes right into the throat. I think its the loc-tite thing but outta curiosity if that doesn't fix the problem I will be looking at the primer solenoid.

Re: Johnson 70hp 1989 carb/fuel problem

Well I stopped at the Johnson dealership on the way home from work and got the nipple thing. Unfortunately the tube and jet are part of the carb assembly. Is there a possibility that I'm missing a gasket in between the tube and the jet?

Re: Johnson 70hp 1989 carb/fuel problem

If you are talking about #18, it has to be there.
http://www.ishopmarine.com/ishop/js...CatFilter=BRP&eCatSupFldr=supplier-100-005-EJ

Re: Johnson 70hp 1989 carb/fuel problem

It's hard to see where exactly the fuel comes from. The fuel spreads easily over the throat wall. In my top carb i used loctite first and a 2-component epoxy glue later. But after a carb swap I found that the brass tube wasn't leaking at all.

A leaking primer solenoid can be checked easily: pull the primer hoses from the carb nipples when the motor is running. No fuel should come out of the hoses. The additional air sucked through the primer nipples is negligible.

Re: Johnson 70hp 1989 carb/fuel problem

Well I tried the loctite. Worked great for my leaking problem, however the boat now only runs at ldle. Doing further research I have found that it was a bad idea to put loctite in that tube. The smaller brass tube is the ldle jet and the the larger brass tube that it runs through is the main jet. The loctite clogged the main solid. Boy am i gonna have a good time trying to get that out. So if anyone is wondering do not put loctite there or anywhere in the 70hp carb it is not recommended. Now anyone got a good carb cleaner that will eat that away?

Re: Johnson 70hp 1989 carb/fuel problem

What color loctite did you use? If blue, a small wire and some brake cleaner will clean it out. If red, then heat is the only think that will loosen it. Do you have any MEK? Good luck.

Re: Johnson 70hp 1989 carb/fuel problem

No I used red...this is getting really fun now.