Mercruiser 300 Rough Idle

[matthew colgate]

Hey guys need some more advice ....... After installing the new Impeller while running to test water circulation .....

I noticed a little bit of a rough idle not bad but enough that i notice it ........

The fuel pump looks brand new so where do i start on figuring this out .....

Also i noticed on my steel fuel line there is a section on rubber hose kind of in the middle ........ I am assuming this is not the right way for it to be any help and or advice is appreciated ........... Thanks Guys

 

[Don S]

Re: Mercruiser 300 Rough Idle

What's a Mercruiser 300 ???????

 

[matthew colgate]

Re: Mercruiser 3.0 Rough Idle

Re: Mercruiser 3.0 Rough Idle

sorry its got the gm 3.0 4cyl engine

 

[Bondo]

Re: Mercruiser 300 Rough Idle

Hey guys need some more advice ....... After installing the new Impeller while running to test water circulation .....

I noticed a little bit of a rough idle not bad but enough that i notice it ........

The fuel pump looks brand new so where do i start on figuring this out .....

Also i noticed on my steel fuel line there is a section on rubber hose kind of in the middle ........ I am assuming this is not the right way for it to be any help and or advice is appreciated ........... Thanks Guys

Ayuh,... It could be nothing more than it wasn't warmed up, 'n still running on the choke,...
Or, maybe some crud in the carb,...
Who knows...

The rubber hose in the fuel line is probably a repair...
It should be steel from the pump to the carb...
Rubber line is Ok, if marine rated...

 

[ziggy]

Re: Mercruiser 300 Rough Idle

After installing the new Impeller while running to test water circulation .....

I noticed a little bit of a rough idle not bad but enough that i notice it ........

whatever the rough idle is, i wouldn't think R&Ring the impeller would have much to do with it.

The fuel pump looks brand new so where do i start on figuring this out .....

fuel pumps can be diagnoised some. at least pressure and volume can be specified. the oem service manual for your rig would have this info in it as to how to test + specifications.
have ya done your spring tune up on it? (imho, a good place to start)http://forums.iboats.com/showthread.php?t=192804

Also i noticed on my steel fuel line there is a section on rubber hose kind of in the middle ........ I am assuming this is not the right way for it to be any help and or advice is appreciated

there are specifications that need to be complied with for that too. http://www.uscgboating.org/regulations/boat_builders_handbook_and_regulations.aspx check out sub part j. all about fuel lines and connections. more than you want to know even. i doubt a splice in your fuel line between the fuel pump and carb is acceptable. either marine rated fuel hose to comply or metal, but a solid length of either or, no splices.

 

[matthew colgate]

Re: Mercruiser 300 Rough Idle

whatever the rough idle is, i wouldn't think R&Ring the impeller would have much to do with it.

I didnt think the Impeller replacement had anything to do with the rough idle thats just when I noticed it.......

The fuel pump looks brand new so where do i start on figuring this out .....
fuel pumps can be diagnoised some. at least pressure and volume can be specified. the oem service manual for your rig would have this info in it as to how to test + specifications.
have ya done your spring tune up on it? (imho, a good place to start)http://forums.iboats.com/showthread.php?t=192804


Also i noticed on my steel fuel line there is a section on rubber hose kind of in the middle ........ I am assuming this is not the right way for it to be any help and or advice is appreciated
there are specifications that need to be complied with for that too. http://www.uscgboating.org/regulatio...gulations.aspx check out sub part j. all about fuel lines and connections. more than you want to know even. i doubt a splice in your fuel line between the fuel pump and carb is acceptable. either marine rated fuel hose to comply or metal, but a solid length of either or, no splices.

Thanks for thode sites with all the info very helpful stuff there