89 OMC Cobra Gas Leak Carburetor

[edisondouglas]

Hello, I am new to the site, and posting about a gas leak in carburetor on 89 OMC cobra. I wanted to see if anyone could provide some insight as to where or what part of the carburetor could be causing this gas leak - picture below with a blue circle showing the area where gas leaks out of carburetor when trying to start up (or when slowly pour some gas into the carburetor). When I pour gas in carburetor, gas trickles out of the area circled in blue at a pretty quick rate (1 drop per second). It will turn on sometimes, but will not stay running. Is this a sign that carburetor needs to be rebuilt? Any feedback is really appreciated, I am unsure of what exactly I’m looking at here or what my next step should be.

I just finished switching out both bellows, gimble bearing, and u joint/drive shaft, only to find this gas leak now.

 

[62Scout]

Other than right were the fuel hose/line connects to a carb, there's no spot that a carb could be leaking fuel externally that doesn't indicate a failed seal, gasket, or bushing somewhere.

I can't ID that carb from the pic alone, though I'm guessing that's right where the throttle butterfly shaft might be passing through? Depending on specific carb model, there could be bushings on the shaft that do wear over time, and if you're pouring gas down the throat, gas could certainly leak past a worn bushing, and could be affecting the vacuum signal enough to affect fuel draw as well.

Some carbs don't employ bushings on the shaft, and just have the shaft ride on the bare metal of the carb body, which then leads to the bore getting wallowed out. Either requires carb service, but the no bushing models requires machine work to open up the bore to install a bushing. At that point it's often cheaper to just buy a rebuilt or new carb than to fix what you've got.

 

[Lou C]

That's a Rochester Quadrajet 4bbl and the place where it's leaking is the primary throttle shaft. While the bushings can wear out, it is not that common, and a leak there can be caused by a leaking needle valve or stuck or mis-adjusted float. Mine did that luckily before I had put it in the water, and a carb rebuild took care of it.

 

[Lou C]

PS
if that's an original Marine Quadrajet, do not trade it for a "remanufactured" carb, these can be "franken carbs" made up of parts from various different carbs, and some never work right. If anyone tries to sell you a "NEW" Quadrajet, there are none and have not been for many years. Just about every part is available, they are not that hard to rebuild once you figure out how to get the air horn off.
If you're not up to doing it yourself I would find a good classic car shop and have them put in a Cliff's Marine Quadrajet rebuild kit.
If your old one is in good shape it is well worth rebuilding the RIGHT way.

 

[edisondouglas]

Thank you @62Scout and @Lou C for the review and recommendations above. I will likely defer this to a mechanic to ensure the carb is rebuilt and adjusted appropriately. This morning, I experienced an issue upon starting (first try it started up fine, but then would not turn over on subsequent turns of the key). I have added a video below showing what is happening - engine tries to turn over, then follows with semi rapid clicking noises. Could this be related to the carb/gas issue? It seems unrelated to me, maybe starter issue? Since the boat started at first attempt, I would think the battery is good, but I’ll test voltage today (I was test starting quite a bit yesterday). Thanks for your time, I really appreciate the knowledgable feedback.

 

[Lou C]

The possibilities:
Weak battery
Corroded battery cables
Rusty starter solenoid
Corroded terminals on both the starter mounted solenoid and the assist solenoid which is mounted on the engine shift bracket with the trim solenoids.
Sometimes water will get under the cover and drip right on that assist solenoid, and you have the V6 batwing exhaust, well the drain is right above the starter and the solenoid terminals! If it leaks water it will leak right on them. When I had those I would cover the starter with a plastic bag when draining the manifolds to keep water out of the starter. I changed mine over to the later 2 piece style manifolds/elbows.
verify battery condition first then check battery cables, if they are old replace with Ancor marine pre-made up cables, worth the money, don't forget the ground cable, DC electricity must travel back to the battery for it to do any work.
If you still have a problem then the starter has to come out
I have done mine several times, not the easiest job but at least your boat has decent access
Sometimes you can get away with just changing the solenoid, but if the starter itself is drawing too much current I would replace it with a new style lightweight PMGR starter, they spin faster and draw much less current
I like ARCO starters and alternators....