Logo
FULL SITE MENU

Losing prime, 90hp Johnson 2001

S

SuperDave

New member
Ok fellas. I'm losing prime and so far I've tracked it down to one of the carbs. The loss of prime happens fairly quickly. id say id the boat sits for 10 minutes or so i have to give the bait some throttle to get it to crank. There is some fuel coming from the gasket between the carb and bowl. Would it be ok to remove the carb and inspect the gasket? If so, is there anything I should be aware of or watch out for when taking it off? I checked the connections on the fuel lines and everything looked good. Here is a couple pictures. You can see in one of the pictures how its been dripping down onto the other carb. I cleaned this area before I ran the boat and opened up to find this. Any help is appreciated.
 
Pulled the carb and goin to replace the gasket at the bowl and at the manifold.

Does anyone here know how or where to set the float height at?
 
Buy a carb kit At a dealer who WILL DEFINATELY give you the float height & float drop dimensions as part of the sale.

You may have to pull the carb off to set the height & drop CORRECTLY.
 
cyclops2 said:
Buy a carb kit At a dealer who WILL DEFINATELY give you the float height & float drop dimensions as part of the sale.

You may have to pull the carb off to set the height & drop CORRECTLY.
Click to expand...

Ok I'll give a guy a call tomorrow. I just hate going to dealers because of prices. I figured some one would have that info or had a copy of the service manual.

I pulled the carb that was in question but I may also pull the other one below it as well.
 
They didn't carry the carb kits and all he told me was that they set them where the float is parallel to the flange of the carb.

edit. Here is where I have it set currently.



In the picture below the right side of the float hung down further than the left but when I reinstalled it and tightened the screw holding the float I place down the float became parallel to the flange like you see here. I have no idea if this is correct but from what I was told over the phone this sounds like what he was describing.

[FONT=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif][/FONT]
 
Last edited:
SuperDave said:
Pulled the carb and goin to replace the gasket at the bowl and at the manifold. Does anyone here know how or where to set the float height at?
Click to expand...

(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
 
Well.. I replaced the two gaskets on two of the carbs. The manifold gasket and the bowl gasket. Cranked it up on the water hose, shut it down and came back 15 minutes later to try and restart it. It started right up. I'm thinking hell yeah I fixed it. Hooked the boat up yesterday afternoon to take it out but before we left I tried to crank the boat just to see if i would have to prime the bulb... Nope it started right up. Took a 20 minute boat ride and started fishing and about an hour later we decided to head in. Boat wouldn't start. The bulb would never get hard until I turned it to a vertical position. Even then the engine had a hard time starting back up. I had to use the gear selector over ride button to get the engine to stay running.

Any ideas??
 
think about replacing the float. it is not unusual for that style of float to become "heavy", by absorbing gas, and dropping and letting additional fuel in.


....btw.......great pics !!
 
Taken from my database.... The portion in BOLD print would be of interest to you.

(Fuel Anti Siphon Valve)
(J. Reeves)

Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vacuum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.

NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models.

The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.

The above procedure will cure a restriction problem with the anti siphon valve as stated. BUT, it may also allow fuel to drain backwards to the fuel tank when the engine is not running (siphoning backwards) due to the fact that the carburetors/fuel pump etc are higher than the fuel tank. This condition is not an absolute as the valves in the fuel primer bulb usually prevent this backwards siphoning problem. However.... if this does take place, the cure would be to install a new anti siphon valve.

NOTE: There has been cases when the output valve in the fuel primer bulb would come apart, and the inner portion of the valve would actually reverse itself and be drawn back into the primer bulb's output valve body. This in effect would create a shut off valve and result in a fuel restriction. If this is the case, you should be able to feel something laying in the bottom of the primer bulb when held horizontally.
 
Back
Top