Outboard issue driving me nuts!

[miket]

2002 Mariner 75hp. Let it sit too long and gas got old. Drained gas, replaced with new fuel. Wouldnt idle, ran bad. Rebuilt carbs. Ran better for a bit, but not great. Then got worse again. Wont idle without hitting the choke ( its not a real chke, it just adds more fuel rather than actually choking airflow ), hesitation on acceleration. Once at high rpm it was good until recently. Now after running hard for a bit it just dies.

Rebuilt fuel pump. No change

Out of the water, wont stay idling. Plug carb with a rag and it runs better. Choking with rag helps. Sounds to me like starving for fuel.

Disconnected fuel hose at carb and pumped bulb. Good full flow. Took off check valve at tank. Not stuck. Bulb pumps up and remains hard. Does not suck down when running. Disconnected fuel line at tank. Sucked on it, fuel comes up easily. Reconnected at tank and disconnected at motor, after bulb, before filter. Sucked, fuel comes up easily. Put pressure on all lines to see if pinhole air leak. No apparent leak.

All indications are that fuel deliver is fine. Dont know what else to do.

Any ideas?

All indications are that it needs more fuel, but that it should be getting it. Choking with the rag makes it run good. If it had a real choke I could make it run fine partially choked

[tx_basser]

have you done a link and synch, as I've found they get a little finiky after you take carbs off for rebuild and put them back on.

[kevin nicholls]

Get a new section of fuel line and run it out of a gas can. Start eliminating things like the fuel system. Ethanol is evil stuff

[Walker]

First thing id do is rebuild the carbs again paying special attention to both lowspeed and highspeed jets. Check float levels. If that doesnt cure it Undo fuel line at the carbs and crank to see if it's pumping gas there. If thats a problem I know you rebuilt it but that doesn't always work. Might need to just buy a new one.

[adam_p]

First thing id do is rebuild the carbs again paying special attention to both lowspeed and highspeed jets. Check float levels. If that doesnt cure it Undo fuel line at the carbs and crank to see if it's pumping gas there. If thats a problem I know you rebuilt it but that doesn't always work. Might need to just buy a new one.

Exactly what I was thinking.

[Crazzy]

If you rebuild the carbs again I would definitely replace fuel line as it could be breaking down due to ethanol and could have caused the carbs to mess up again.

[Drycreek3189]

Don’t overlook the benefits of Mechanic in a Bottle. That’s the best stuff since hot women and cold beer.

[Quackerbox]

It's a mercury, theyre supposed to be a PIA

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[Alderrg]

First thing i would do. Especially if you are running the Blue fuel line that was supposed to be the best out there. It is not! Ive had to replace my blue line with just regular fuel line from auto parts store. That regular fuel line only lasted two years and that was even after treating fuel with stabil.

Get a new section of fuel line and run it out of a gas can. Start eliminating things like the fuel system. Ethanol is evil stuff

[miket]

Unless the carbs got plugged again, I have a hard time believing they need it again. It was a pain getting them off so i was very, very thorough. Soaked in carb cleaner longer than recommended, blew out everything repeatedly. Verified air through the jets. Everything spotless. Not a mechanic but have rebuilt at least 10 in my life. Never had one that didnt work afterwards.

As far as syncing them, the book shows how to align marks and I did that. Didnt use vacuum gage. Will check again.

Also, it has 3 carbs. Seems like at least a couple would still be ok

[EastTexun]

First thing i would do. Especially if you are running the Blue fuel line that was supposed to be the best out there. It is not! Ive had to replace my blue line with just regular fuel line from auto parts store. That regular fuel line only lasted two years and that was even after treating fuel with stabil.

Agree again here. What I have seen repeatedly is even if the fuel line looks fine and is not coming apart, the integrity of the hose is degraded and it basically sucks in on itself from vacuum pressure, which then chokes down the motor.

[darralld]

Do you have an inline fuel filter that might be clogged?

[Txnative78]

Make your life simple. Run the engine on an external fuel tank and see how it runs. That will let you know if it is the boats fuel system messing up or the engines.

[big_smith]

At the bottom of the bowl there should be a drain plug. There is a small pin hole in that plug. Get a torch tip cleaner and run it through. I was on a fishing trip in South Padre and had just had my boat in the shop. It ran fine on the flush cups but put it in water and all it would do was idle. I found an old shade tree mechanic to look at it. Was a 10 second fix.

[miket]

Pulled the carbs and recleaning. Will try some of the other stuff suggested if that doesnt work. I should have tried from another tank, but didnt have a can with any gas actually in it.....son burns it all up.....

High speed jet on the top carb does look clogged and there was a bit of junk i the bowl. Will replace filter. Looks like it aint helping much....