Carberator problem - looking for help

My boat is only 2 years old but to save some money we decided to go with a carb instead of EFI. Big mistake I know but at the time it sounded good. Truthfully the first year the boat ran awesome but over the winter, the engine was running rough. I took it to the dealer and they said there was some gum build up and it was blocking some of the gas flow in the carb. This repair isn't covered by the warranty.

My options were to pay $550 for a new carb or $200 to rebuild it. But the carb is basically new. Can it be easily cleaned or some additive added to the gas to clean it out?

Go get a can of Gumout from Kragen's and spray it into the chambers as you run the engine. My guess is there is a simple fix short of rebuilding/replacing the carb.

Also, try replacing the fuel filter and make sure it's seated squarely...might just be losing vacuum pressure. Rub a light layer of oil with your finger over the gasket before tightening.

That sounds a little crazy to have build up after 2 years unless you are running PEMEX fuel. Change the fuel filter and get a second opinion. For a carb you could ask an automobile mechanic. I had a 270hp carb'd Merc. and never had a problem with it for 5 years.

I would definitely get a second opinion. We had a carb on our last boat for close to 20 years. The only thing we ever did was change the accelerator pump. Seriously....there is nothing wrong with a carb as long as it is tuned properly. Anyone familiar with carbs (boat or car tech) should be able to square things up quickly and painlessly. Rough running during the winter may have been related to a mis-adjusted choke. A carb that young shouldn't even have any wear issues.

My experience with the fuel additives has been that they will not cure a really sick carburetor. If you used the additives before it got to that stage it might have prevented it, but if a passage is blocked then the additives can't get to it to disolve the blockage.

Some years back I inherited my dad's ski boat that had been sitting around for a few years. The carburetor was having trouble the last time I saw the boat run so I didn't waste any time, I took the carb off and took it right off to a rebuild shop. They fixed it up nice. Unfortunately, the gas in the tank had gone bad so as soon as I tried to start the engine I immediatly messed up the carb again.

I took it off again, back to the rebuild shop and they fixed it again. After I drained and cleaned the gas tank the boat ran great, so that was an example of rebuilding the carb and things were nice.

On the other hand, I am currently experiencing a similar problem but without the happy ending on my houseboat. I have twin 50 Hp Mercury outboards and the gas in the carburetors (four on each engine!) apparently went bad and it destroyed the carburetors! Cleaning them didn't help so I am currently waiting on the arrival of 8 new carburetors at a price of $340 each.

If it was me I would try the rebuild route.
If you are in the San Jose area I can recommend Ace Fuel Systems, they did a super job on my Holley marine carb.

Rod

The shop I took it to was pretty thorough. They disconnected the fuel line and connected the engine to their own shop fuel tank and the problem remained. The idle is rough and will surge. The problem on the water is as soon as I put the engine in gear it starts to die. I have to put a lot of throttle into it to keep the engine from dying. It is a pain to try and dock the boat with a engine that won't idle. Trying to remain slower than 5 mph in the no wake zone is impossible. The only quick solution I found is to crank the idle up to 1000-1100 rpms. I know it is hurting the transmission but it is the only way keep the engine from dying.

The boat shop called Indmar and Indmar said it sounds like bad fuel gummed up the interior of the carb and it needs to be rebuilt. I called a carberator place that rebuilds carbs and they said the same thing. It costs $200 to rebuild it but I would hate to have to do this every couple of years.

I did spray the heck out of the body of the carb with carberator cleaner but the problem remains. Am I doomed and should have the carberator rebuilt or will some readily available fuel additives clear out the gunk.

Also this is the third year I had the boat. Last year (Year 2) the problem developed over the winter. I just decided to deal with it all summer. This year the problem remains and I'm tired of it. Each year when I store my boat for the winter I do put stabilizer in the fuel. That is why I'm confused why this happened.

It is a Holley 650 cfm Marine carb if that helps.

If you stabilized it, it shouldn't be varnishing over that quickly! Next winter you might be better off to get the fuel out of the carb before you put it away for the winter. You might have to get a rebuild "kit" that has the seals you need in it, but at least you won't have to deal with it gumming up everytime. Have you thought about rebuilding it yourself? You can get the kit from skidim.com. They may even be able to supply you with a manual to walk you though the process. Just take pics with a digital camera as you go. I'd give it a try before I bought a new carb. Also, I know people that have gotten lucky by taking a carb off and soaking it in a parts cleaner with degreaser for a couple of days. Get some degreaser and put it in a 5 gallon bucket for a couple days and swish it around from time to time, take it out and let it dry and give it a shot. On my old boat I got lucky and found some gear head at a local shop that rebuilt mine for 25 bucks (I supplied the kit) I just took it off the boat and brought it to him. Adjusting those carbs is cake. There is only one screw on each side and skidim.com has instructions online on how to adjust it.

Good luck

Hmmm...something fishy.
First off is it running rich or lean? How does it run when you open the throttle up while moving? Does it lean pop? Has it backfired through the carb recently? When it dies is it a gradual RPM decline or a sharp cut?

First off you can just clean out the bowls and jets if it is varnish. No need for complete disassembly. If you do disassemble anything use new gaskets then check over and over for fuel leaks. Holleys are also known for blowing their power valves that will cause exactly what you described but it is a rich running condition not a lean condition.

Using propane (or carb cleaner, but not prefered) induced into the carb with engine running, does it idle fine?

One thing you can also do is take the needle valves for the idle adjustment out and inspect them. These are the flat head screws on the side of the carb. First turn them in until gently seated counting how many turns and write it down. Put them back when finished. If it is a lean condition you can also turn these screws out and it should affect the way it runs.

That's the wired thing. As soon as you give it throttle (over 1000 rpms) it runs fine. No backfire, no hesitation,no lean pop, nothing. Give it some gas and the engine runs great. Drop it down to neutral and the problems begin. I have used carb cleaner and when I spray it down into the carb the engine runs ok until the carb cleaner is used up and then it goes back to the rough idle.

I adjusted the needle valves and still no improvement. When it dies I see the RPM's start to fluctuate between 400-600 and then justs cuts out.

One more key to the puzzle. Even after the boat is at the optimum temperature, it will not start without a shot of gas. If I turn the key the engine will turn over but will not turn on. I have to prime it with a shot of gas (like a cold start) to get the engine to fire.

I like to think I can fix the problem myself but I'm not sure what exactly needs to be cleaned. Also my dealer told me Indmar had been notified and now they (Indmar)is requiring proof that the carberator was rebuilt in order to honor the final year of the engine warranty.

I have been through this many times. I had a boat from 1970-2003 and got very good at carbs. First, prevention:
Run Chevron Techron through every 3-4 tankfuls.
Clean the carb before winter layup.
Use Stabil during layup and run the engine at least 15 minutes.

Correcting:
Rebuild yourself. It is not hard, just follow directions.
Get a dip tank from the auto store.
Make sure the small channels for the acellerator pump are free and clear - use compressed air. This is likely the cause of your problem along with some build-up in other small passages. When you put the boat away hot or store it for the winter, that is when the problems occur.

I bought a EFI MPI boat, but still use the Techron.

First off no dip tanks if they even sell them in Cali. They are considered a hazardous waste and very toxic.

A.P first thing to try would be to remove the mixture adjusting screws and spray carb cleaner through them then some air (Safety glasses). This can be done in the boat, and might just solve the problem. If it is just at idle it is the idle jets that are plugged. Other thing to do is to remove the front bowl and clean everything out removing the jets. Not sure if you can do this in the boat and will require a new bowl gasket. If you need to remove the carb from the boat you can easily do it but will also need a base gasket.

Now as for fuel additives, they can be good when run directly into your injectors, but FYI you do not want to run them through an electric fuel pump, as it will destroy it. Secondly they remove all the deposits in the fuel tank and bring them forward into the fuel filter and injectors.

Thanks for the info. I'll give it a shot and see if the problem is fixed. Somehow I think I may just have to get the carb rebuilt professionally in order to get the warranty validated.

Second question I have is do I have to worry about the gas that is in the tank right now. This problem occured last year and we ran it all summer with rough idle. When I put my boat away this year I did put stabilizer in the fuel tank. We took it out last weekend and the boat ran fine - except in idle. How do you know if the gas you have in your tank is bad. I would hate to rebuild the carb only to have the gas foul it up again.

The fuel will loose its potency shall we say. Personally I would not worry about the fuel in the tank. Carbs are less susceptable to damage vs fuel injectors.

One of the best things to do for a boat is to always store the fuel tank full even if it is going to be stored for just a week. This works well for keeping water vapor from getting in the tank, and fuel vapors leaving the tank.

There is nothing wrong with having a professional rebuild the carb. The warranty thing?? Well they could try to pull something with it but why isn't it covered under warranty now? They can not tell you who has to service or work on your boat as long as it gets done. They can not insist on "you" spending money to fix something a certain way or else!

Hey Peter,

I thought the same thing with keeping the gas tank fuel. Everytime I take the boat out I always fill the tank when I'm done using the boat. I worried about condensation. However the tech at the dealer told me that isn't true and it is better to leave the tank empty. He claimed condensation doesn't build up on the new fiberglass tanks.

fork out the 200 and see what it does.... if it does not work then take it back... If you have enough money to buy a boat that new, 200 should not mean much to make it work correctly. I spent the money on mine and it works like a champ... that carb can make all the difference in the world!!