Carburetor is squirting gasoline like it?s a water fountain!!!

[Fishsqueezer]

The Engine: I have a 1984 Mariner 50 hp 4 cyl. electric start outboard, serial # 6542853. It has dual carburetors, an upper and lower, each having an integral fuel pump. The upper crab is stamped WMA 3-1 and the lower is stamped WMA 3-3.

The Problem: When I prime the engine by squeezing the in-line pump bulb, fuel shoots forward out of the upper carburetor. It?s coming from a small brass screw with a hole in the center (see image). I know that the pump bulb should become firm once the engine is adequately primed, but this never happens. Instead, the carburetor squirts out copious amounts of fuel which pool up inside the cowling.


I have the Clymer shop manual for this outboard which lists these possible problems in the troubleshooting section under ?Flooding @ carburetor?

-choke out of adjustment
-high float level
-float stuck
-excessive fuel pump pressure
-float saturated and beyond buoyancy

Unfortunately, the Clymer manual images are not congruent with my carburetor and I?m not even sure what the piece is called which keeps squirting gasoline.


What is the brass screw/hole I?ve pointed at in the photo called? I can?t seem to match it to anything in the Clymer book?s diagrams except that it maybe kind of looks like a jet, but I?m not sure. I removed it, and it?s simply a short brass flat head screw with a hole bored through the center.


Any ideas on why the carb is hemorrhaging gas out of this opening? Any help would be much appreciated.

 

[Daviet]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

The only thing that shuts the fuel flow off in the carb is the needle/seat controlled by the float.
If you have something stuck in the needle/seat holding it open or the float is sunk, the fuel will squirt out the brass air bleed.
I would think you are going to have to remove the carb and check the float, needle/seat.

 

[Scott Danforth]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

the clymer manuals are good as knee pads. check the skickies at the top of the forum page for the proper factory manual

 

[Fishsqueezer]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

@ Daviet
Thank you. That's sort of what I was thinking, but I needed to hear it from someone who knows more than I do about carbs.



@ Scott Danforth:
I felt like the Clymer book was kind of shady after I got it. I've used shop manuals for my automobiles and snowmobile, and this Clymer book sure seems useless compared to the Chilton and Haynes books I've needed to keep the tires and tread turning. I just ordered a SELCO book, so I hope that will be a better option. Thanks.

 

[Daviet]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

I have always found the factory manuals to be the best, they cost a little more, but are worth the money.

 

[Scott Danforth]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

seloc is not much better. just download the factory manual.

 

[ajgraz]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

That brass plug with hole is your carb's fuel bowl vent jet. Agreed that you have a sinking float or a needle that isn't seating properly (most likely the latter).

 

[Fishsqueezer]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

That brass plug with hole is your carb's fuel bowl vent jet. Agreed that you have a sinking float or a needle that isn't seating properly (most likely the latter).

Thanks so much for the good input. I have a few more questions now that you've set me on the right track and educated me a bit. It makes sense now that I look at the carb a bit more and see the anatomy of it that the vent would be located there.

Can a needle/seat or float go bad during storage? Both carbs were rebuilt 3 years ago by my friend who is an automobile mechanic. Shortly after that, an electrical issue was found and I ended up putting the boat into an indoor storage. I seem to recall my friend saying something about the needle not seating when he worked on the upper carb. However, after the rebuild, no fuel was leaking from the fuel bowl vent jet and the prime bulb was rock hard. I also know that both needles and the floats were replaced, along with every part which can be purchased in a Quicksilver rebuild kit for that carb.

I finally had the time and money to address the electrical issue and installed a new stator the other day. I thought I was ready to hit the water but was completely surprised when I primed the engine and it squirted. What surprised me was that the carb had now failed after it was rebuilt and stored.

What can be done to remedy a needle that will not seat properly? Is there any way of fixing the seat if that is what's causing the problem and not the needle? I seem to recall trying to buy just a needle last time I did this but had trouble finding one. Any advice on where to look for carb parts sold individually? I'm really starting to learn why people say the word boat stands for Break Out Another Thousand!


Thanks again for all your advice.

 

[BonairII]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

The needle may be worn and not sealing well in the seat. Or maybe gunk got in there and is holding the needle open. Regardless, needle/seat assemblies are sold by everyone. You'll have no problems finding them.

Go to your favorite boat parts site and plug in your year/model. It will show you an exploded view of your carbs...and the corresponding part numbers.

 

[ajgraz]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

If the needles and seats were replaced within the last few years, chances are extremely good they are the more recent rubber-tipped type (rather than the older all-metal type). Those seal very well at first, but the rubber does swell eventually--some might say, due to crappy fuel ingredients these days--and make the needle stick either open or shut. Sitting a few years would let that happen, definitely. Happens to mine every 12 months like clockwork, and I run my old Merc almost weekly.

On the other hand, as said, could simply be some dirt, gunk, junk left from evaporated crap fuel, etc. sticking it open. Best way to avoid all that is a fuel/water separator filter.

One thing's for sure, if you're going to run an old Mercury, you are going to become very good at cleaning carburetors.

 

[canoemang]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

One thing's for sure, if you're going to run an old Mercury, you are going to become very good at cleaning carburetors.

This made me laugh.. primarily because its true..lol

And yes.. as several has said bad float,sticky needle can cause your issue exactly..

 

[Fishsqueezer]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

Wow, everyone on this site rocks! Thanks!

The needle in the carb does have a rubber tip, as did the one which was taken out during the rebuild a few years back. I use a Napa Gold fuel/water separator between the running tank and engine (although I plan to switch over to using a goldenrod housing since they are transparent and you can visually inspect the filter element). I only run high octane fuel in the engine, and periodically treat my fuel with Seafoam to help clean things up and dry the fuel out if it's got a bit of moisture in it.

Does anyone know of Seafoam causing problems with the rubber tip on a carb needle?

I guess I'll just have to take it apart, clean it, and try to make it seat before I get a new needle/seat. I seem to recall a small gauge which my friend used to test how much air pressure the needle would hold during the rebuild he did while I watched. I'll go bother him to borrow that gauge and begin tinkering.

However, I'm still trying to find the download link for an OEM service manual appropriate for my engine. I can't find it here on Iboats. I did find some Mercury service manuals in the sticky. These appear to be in much better format than the Clymer book, but I don't think any of these pertain to my Mariner. All the Mercury links are for newer (newer than my engine) Merc outboards.

Any ideas where I could find an OEM service manual download for my 50 HP 1984 Mariner?

If I can download it, that's surely what I'd do instead of buying the book, even if the download is not free. I just want the correct book, and there seems to be consensus that the aftermarket books are less than desirable. My Clymer book is on it's way to becoming a knee pad!

Seriously folks, I can't begin to thank you for such prompt support. I hope that someday I can return the favor by sharing info I've learned while working on my engine.

 

[BonairII]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

Btw: If your fuel lines aren't new.....replace ALL of them from fuel tank right to the carb.. Old fuel hose will slowly disintegrate internally and regularly gunk up your carbs. If it clogs your jets, you'll run lean and it'll ruin your motor in no time.

When buying a used motor(with no confirmed maintenance history), I'm a fan of immediately replacing fuel lines, t-stat, impeller,changing gear oil and cleaning the carbs regardless of how well the motor seems to be running. Adding a telltale is good idea also.

 

[Fishsqueezer]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

Btw: If your fuel lines aren't new.....replace ALL of them from fuel tank right to the carb.. Old fuel hose will slowly disintegrate internally and regularly gunk up your carbs. If it clogs your jets, you'll run lean and it'll ruin your motor in no time.

When buying a used motor(with no confirmed maintenance history), I'm a fan of immediately replacing fuel lines, t-stat, impeller,changing gear oil and cleaning the carbs regardless of how well the motor seems to be running. Adding a telltale is good idea also.

Well, I found the problem. The float had a small crack in it and was partially filled with fuel.

I'll replace the float and needle, and all the fuel line too, since this prevention seems like a good way to go. Thermostat is not a bad idea either, and I'll probably replace that as well. When you refer to the impeller, is this part of the cooling system? The only impellers I'm familiar with are ones I've used on the jet outboards I run at work in Alaska. My guess is that you're speaking of another type of impeller, correct? Also, what is a telltale?

When I bought this boat in '99, it was in meticulous condition. The previous owner was obviously a person who kept his equipment in good condition. When I bought it, everything beneath the cowling looked pristine. Noting was dirty or greasy, all wiring was tidy and secured properly, and it ran like a champ. I could tell that the fellow who sold it to me was a little anal about how he kept things, just from the test drive we did, and while looking at the boat inside his shop. I was positive that a well cared for boat is what I got. Shortly after buying the boat, I began working seasonally in Alaska and had no opportunity to use the boat during my off season (winter), so it sat inside a storage for the better part of the past decade. Periodically, I take it out and try to make it work when I have the opportunity. I think that time has taken it's toll from just sitting there for so long. Any other advice on things to look at when an engine sits for so very long?

 

[BonairII]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

The impeller is also called the water pump. This is an example of an impeller: http://scyr.org/stellablue/waterpump.html

I would also check the condition of all wires and the condition of the wires insulation. Lube/grease any zerc fittings, linkages, and any pivot points. Pull the prop and grease splines etc and remove any old fishing line in there. Use very light oil(not WD40 or anything that'll run down into the starter itself) on starter gear.

 

[Fishsqueezer]

Re: Carburetor is squirting gasoline like it?s a water fountain!!!

Now that the carb issue has been exposed, I'm trying to figure out how to enact some of the other quality advice I've been offered.

For starters, I'm wondering what if any gaskets I may end up destroying while trying to get at my water pump. Do these usually deteriorate from sitting in storage for long periods? I know I'll have to drop the lower unit to get at the pump and I'm wondering if it's likely that I'll damage any gaskets or seals while trying to pull the pump. Also, I'm considering an entire pump rebuild kit instead of just the impeller. Is overkill? I feel like it's a good measure to ensure my engine is cooled properly once I get her on the water.

Next, I'm wondering exactly where the thermostat is located on my outboard. I guess I was wrong in thinking that cooling was regulated by pump speed. Since the pump is driven by the drive shaft, I thought cooling would be proportional to RPMs and regulated as such. I really didn't know that my engine had a thermostat. Can anyone describe where it is on my 50 HP Mariner outboard? I can't locate it anywhere on the diagrams which web sites use to sell parts. I would assume the thermostat is plumbed in somewhere near the water jacket or on the block someplace, but I really have no idea how to find it.

Thanks again everyone. You've all been a colossal help to my fledgling repair skills. I'm taking this to a new thread.