Mercury 350 on my houseboat starts but wont stay running ...sometimes please help

[mikethepike]

Ok, I bought a 1971 Gibson houseboat from my dock mate who didn't have time for it anymore (he completely gutted it, and redid the interior..its really nice!!!! It has a 1971 350 (Mercury???) and a new carburetor. I've had it running on the Detroit River and it just stalled. Once I got it started again I promptly took it back to the well for inspection.

It will run at all different rpms and then just die. I can start it up and then it will die again.

So here is what I did.

-It had 5 year old gas in it so I dumped a "cocktail" of water dryer, lucas fuel treatment and some gas stabilizer (biospur?) for the fuel phase separation. and 20 gallons of fresh fuel in each tank.

-replaced the fuel filter in the carb and put in line fuel filters at both tanks and at the water fuel separator

-blew out all the lines with an air compressor to the fuel tank , out the vent, out the water fuel separator and out the 1 way fuel valve and out the fuel line back into the tank

-We poured gas down the carb to get it going and finally it was primed. It ran great with excellent throttle response . I just let it run for an hour and 20 minutes. I shut it off thinking it was fixed

I go and run some errands for a few hours and went to go and start it up. It will start and die after a 2 seconds. This is where i'm stumped. After wrenching on it for 4 hours , i'm frustrated and thinking I just wasted my time and $$$

Any thoughts of what to try next ??? It has to be something simple

The new carb is a quadrajet that was installed previously before my ownership if the helps

 

[alldodge]

Re: Mercury 350 on my houseboat starts but wont stay running ...sometimes please help

If gas ever goes bad you cannot put anything in it to make it better. That being said, running the engine for over an hour and it does fine with no load says the engine is fine but we still have a fuel issue. You probably still have bad gas but try this. Get a gas can and put your fuel line in it, prime it if you need to and get it running. Once going let it run for a while and then let it sit. Later try firing it up again from the gas can and see if the problem went away. If problem went away need to have the gas pumped out.

Would like you to get it going and run it on the water for a bit to really put a test on it but a house boat will need a big gas can.

If this didn't help, let us know.

 

[Bondo]

Re: Mercury 350 on my houseboat starts but wont stay running ...sometimes please help

Ayuh,.... I'm with AllDodge,.... Ya went through All that work, 'n then pumped Rotten fuel through it,....

Yer now back to square 1,.... 'n another 19 gallons to pump out,...

Clean up the motor end again, 'n run it on a remote tank,... for Testin' purposes,...

 

[spdracr39]

Re: Mercury 350 on my houseboat starts but wont stay running ...sometimes please help

So many people want save a few dollars worth of gas, waste a bunch of money trying to make it run then have to pump it out anyway. If you have 5 year old gas DO NOT TRY TO USE IT!! If that small expense is a concern you don't need a boat.

 

[mikethepike]

Re: Mercury 350 on my houseboat starts but wont stay running ...sometimes please help

1st of all thank you for the quick and process driven thoughts....I really appreciate it--GREAT FORUM!!!!!

ok, so I put the in line filters in so I wouldn't have to go thru all this again. I guess a 1st line of defense. I do have 3 other boats so I'm used to the "expense" at all costs . That's not the problem.


ok, so this coming wknd i'll choose a tank, shut the valve off the other and run it off my dinghy motor tank and see what happens.

Could it be a worn 40yr old fuel pump where the fuel falls out of the carb and once primed its fine or a quadrajunk sticky/filled floats?

If I have to pump the tanks , what do you do with the old gas ?? We're talking 50+ gallons

I do want to take it out and load er up w/ 10 peeps so I can see whats what. I'll get unlimited towing 1st from Boat U.S. . The Detroit river isn't a place you want to break down at

 

[alldodge]

Re: Mercury 350 on my houseboat starts but wont stay running ...sometimes please help

ok, so this coming wknd i'll choose a tank, shut the valve off the other and run it off my dinghy motor tank and see what happens.

Could it be a worn 40yr old fuel pump where the fuel falls out of the carb and once primed its fine or a quadrajunk sticky/filled floats?

If I have to pump the tanks , what do you do with the old gas ?? We're talking 50+ gallons

Sounds like a good plan on the tank
The fuel pump may be causing a bit of an issue but the odds are not there since it does run when you do get it running.
Carb may be part of the issue but it's not sounding like it at this point
Contact a company which takes used oils and other chemicals from auto industry. I think Safety Clean is a national company

 

[mikethepike]

Re: Mercury 350 on my houseboat starts but wont stay running ...sometimes please help

What keeps fuel pressure to the carb?? I assume the fuel pump...that's why i'm targeting that

 

[Bondo]

Re: Mercury 350 on my houseboat starts but wont stay running ...sometimes please help

Could it be a worn 40yr old fuel pump where the fuel falls out of the carb and once primed its fine or a quadrajunk sticky/filled floats?

What keeps fuel pressure to the carb?? I assume the fuel pump...that's why i'm targeting that

Ayuh,... It could be Either, but Gravity holds the fuel in the carb,...
Gas Can't jump up through the air, 'n out through the needle valve at the carb's entry port,...