3.0 Mercruiser help...fuel issues?

[mizestang]

Hello Iboat! I am a new member here, but been boating since 2006. I have a 2002 Bayliner 175 capri with a 3.0 Mercruiser. I live in MN, and every Spring the boat starts up with no issues. This year, it fired right away ran for 30 seconds at 2000 rpm and when I went to throttle down, it shut off and will not start again. I had only a 1/4 tank gas, but did put stablizer in it, so I thought it might be the gas. So, I bought new fuel filter, changed oil, changed plugs, sprayed the **** out of the carb, filled tank with new gas. Still no start. Bought some starter fluid. Turned it over and it started, then died. The only other thing left is fuel pump or people tell me anti-siphon valve. Not a big carb guy, but if I give the throttle gas, should it spray into the carb? When I do that, it is bone dry, I see no fuel.
Sorry for the long post, but before I throw money into a fuel pump, is there anything else I should check? And, I checked run switch is on. Any help is appreciated before I have to bring it in. Thanks!

 

[TurtleTamer]

If it starts with fluid and doesn't otherwise, you have a fuel problem. Pumping the throttle without resulting twin streams of fuel also means you have a fuel problem. You can tell if it's your fuel pump by disconnecting the hard line from the carb end and cranking it a few times. You should see fuel squirt out, and in fact I'd have rag in place to catch it. At this point you can also access the filter at the inlet to the carb.

 

[TurtleTamer]

Should have asked: is there any fuel present in the clear line coming from the pump to the carb? That would indicate a ruptured diaphragm (bad pump).

 

[ThomW]

Agreed. If no fuel is squirting into carb, you are not getting gas. Start at the carb and work back. Pull fuel line from carb (the one coming from fuel pump) and crank motor a few times to see if gas squirts out. If not, something is up with fuel pump. They can stick after sitting idle for a few months. If you don't get gas after cranking motor, pull off fuel pump. Not sure on model of fuel pump, but when you pull it off, you can try moving the arm (the one that would be pushed by crank in motor) by hand. This may unstick the pump and get gas pumping through again.

 

[hoowahfun]

Disconnect the fuel line near the carb and crank the engine for a couple of seconds to see if any fuel comes out. Make sure to catch it in a jar. If you have fuel from the pump then you probably just need to rebuild your carb. Rebuild kits are pretty cheap.

 

[mizestang]

Awesome advice guys! Thanks much!

 

[imjb]

It is also possible that the carb float needle is 'sticking' from sitting etc... you can also try ( as a test), gently - GENTLY banging on the bottom of the carb with a rubber or wood mallet. Then crank... if this gets you going, it is best to have your carbs rebuilt. It sure does sound like you are not getting any fuel...

 

[mizestang]

Update! Unhooked the fuel link and cranked it. Fuel came gushing out the line. Guess I can rule out FP. I don't understand why there wouldnt be fuel going into the carb?? WHere is the fuel going?

 

[mizestang]

It is also possible that the carb float needle is 'sticking' from sitting etc... you can also try ( as a test), gently - GENTLY banging on the bottom of the carb with a rubber or wood mallet. Then crank... if this gets you going, it is best to have your carbs rebuilt. It sure does sound like you are not getting any fuel...

Verified fuel is pumping up through lines, but I don't see it entering the carb. What would prevent fuel from entering the carb?

 

[TurtleTamer]

It's not going anywhere, haha. It's stopping at the fuel strainer in the carb, or the needle is stuck, or less likely, all circuits are completely clogged. I suspect it's the filter or needle. More likely the needle. If you're any level of tinkerer it's not too bad of a fix.

 

[mizestang]

It's not going anywhere, haha. It's stopping at the fuel strainer in the carb, or the needle is stuck, or less likely, all circuits are completely clogged. I suspect it's the filter or needle. More likely the needle. If you're any level of tinkerer it's not too bad of a fix.

Guess Im about to venture into new territory. LOL. At least I know what it is now. I hope.

 

[mizestang]

Should have asked: is there any fuel present in the clear line coming from the pump to the carb? That would indicate a ruptured diaphragm (bad pump).

There is no fuel in the yellow line, but yesterday, I removed the line from carb and cranked it and fuel came shooting out. This would indicate its not the pump?

 

[ThomW]

Sounds like its not your fuel pump. Pull off the carb and clean it! Its not too tough if you have any mechanical ability. Just take your time. Have a clean area to lay everything out. And watch where things go as you remove them. Take pictures if you need to! An air compressor and can of carb cleaner, and you should be able to get her good as new. A quick youtube search and you can find many videos walking you through a carb rebuild. You will probably wanna get a carb rebuild kit before you dig in, as the gaskets will probably rip. Can find those fro around $40 onlne.

 

[Scott06]

Unless your fuel inlet filter is clogged (where fuel line threads into carb) it is likely the needle and seat is stuck closed. This is what let's fuel into the float bowl. As mentioned above wrap on the carb with the handle of a screw driver to see if you can unseat it. Otherwise rebuild the carb and replace as well as clean all passages. If this works after cranking the engine for 20 sec the carb should be full of gas and shoot fuel out of accelerator pump nozzles when the throttle is opened.

 

[mizestang]

UPDATE** Had the carb professionally rebuilt. Still having the same dam issues, but I do see fuel in the barrels now, so it probably needed to be done. People are telling me to check the distributor cap/rotor. Any thoughts on this?

 

[hoowahfun]

Maybe check your anti-siphon valve and the inlet screen on the pickup tube from the tank. You could be getting gas, just not enough, and something is restricting the line.

Also if you left your tank half empty over the winter you could have condensation that formed and you now have water in your tank. Maybe collect some of the gas from the fuel filter and let it sit in a jar a bit and see if it has any water in it.

 

[Lightwin 3]

Easier just to check if you're getting spark. Spark checkers are cheap at auto parts stores.

If you've never tuned it, it may be time. It's simple on that engine.

 

[mizestang]

New distributor and rotor, starts now, but then dies of after 10 seconds. I'm almost ready to get rid of it. WHere is the anti-siphon valve located??

 

[hoowahfun]

On top of the gas tank usually. It'll be between the tank and the fuel pump. If you have a fuel/water separator it will be before that as well.

 

[mizestang]

Shop said the carb wasnt properly done and that is the problem. The tech could keep it running if he constantly gased the throttle. WTF? Paid 200 for professional job.