need new primer bulb what size???

[19bwb67]

Hi, I have a 1985 mercury 75hp ob and the bulb collapses. It sometimes stalls out when starting at low speeds and trying to accelerate. It usually runs fine after i pump it the best i can but the bulb collapses. I checked the inboard tank vent and i can blow into it ok. The bulb seems old and is starting to shows cracks. Does any one know the correct diameter for the fuel lines AND primer bulb. It has grey fuel line/ black bulb on it now. Thanks, Brett. Also I have a portable 6gal and it runs fine without the bulb collapsing.

 

[achris]

Re: need new primer bulb what size???

Same size as the fuel line... And get a genuine one... I've seen the generics last about 6 months... all of them!

Fuel lines for that engine should be a minimum of 5/16"... I would pull it all out and put new 3/8" lines and primer in...

And check the screen on the end of the tank pick up...

Chris.......

 

[19bwb67]

Re: need new primer bulb what size???

"And check the screen on the end of the tank pick up..." How do i do that. isnt it inside my onboard gas tank. I can't get to that unlesss i rip out the tank.???
Also i read an article stating bigger lines actually make the pump work harder due to the increased amount of fuel in the line that needs to be drawn up. What is the correct size line for a 1985 75hp mercury ob

 

[achris]

Re: need new primer bulb what size???

"And check the screen on the end of the tank pick up..." How do i do that. isnt it inside my onboard gas tank. I can't get to that unlesss i rip out the tank.???

You should be able to unscrew the pickup from the tank...

Also i read an article stating bigger lines actually make the pump work harder due to the increased amount of fuel in the line that needs to be drawn up.

Complete rubbish!!! Larger lines create less restriction and allow the fuel pump to deliver the fuel to the carbs, and the engine doesn't run lean... Which will kill the engine quicker than a stick!

What is the correct size line for a 1985 75hp mercury ob

Minimum size for that engine is 5/16", but I would use 3/8".... and the longer the lines, the bigger you should use.

I actually have 1/2" fittings and lines on mine... I could feed twin big blocks with that... That puppy is NEVER going to run lean.

Chris.........

 

[19bwb67]

Re: need new primer bulb what size???

FWIW
http://continuouswave.com/whaler/reference/primer.html

 

[achris]

Re: need new primer bulb what size???

FWIW
http://continuouswave.com/whaler/reference/primer.html

Thanks for this... Is there any particular section you want me to read?