merc 1150 inline 6 fuel pump issue

[tydog]

hi i just replaced fuel pump diafram on 77 1150hp inline and was wondering if i install the check valves properly as i just put i back together like it was before but may not have been right before as i have low fuel presure. does anyone have a diagram showing the insides of the pump. and the other question is which lines from the block go to which nipples on the pump as i have replaced all the old fuel ines and cant remember.

 

[Chris1956]

Re: merc 1150 inline 6 fuel pump issue

TY, If you can pump fuel thru the fuel pump using the primer bulb, the check valves are installed correctly,

I do not think the hook up of the pulse lines matters which is which. Make sure the fuel tank is not restricting the fuel flow. Check teh filters and antisiphon valve.

 

[tydog]

Re: merc 1150 inline 6 fuel pump issue

ok thanks chris thats what i thought but wasnt sure because both line seem to pump air out and not in so i cant see what diference it would make.

 

[tydog]

Re: merc 1150 inline 6 fuel pump issue

ok so i thought i had it all figured out but whats happening now is that its still not getting fuel to the carbs. to start i pump the ball till hard crank and she starts but about a less than a min later it dies,but if i pump ball it picks up again a continues to run a min or untill it runs out of gas im asuming. the other thing i noticed is that if i pull the line that feeds the fuel pump (line from the fuel tank) it seems to be pumping gas out and not sucking fuel in. now i would think it would be the other way around...

 

[Yepblaze]

Re: merc 1150 inline 6 fuel pump issue

From personal experience I have found that single, stand alone, type pump that sorta screws down to the lower cowl will easily distort while tightening.

Causing very poor performance and a big pain in the butt.

I just finally broke down and disconnected that and stuffed a small electric pump in there.

And haven't looked back.

The loacal auto parts had these in two versions. I found the higher pressure/volume of the two offered worked best.

 

[monk-monk]

Re: merc 1150 inline 6 fuel pump issue

if i understand you correctly, you stated you had the fuel pumps apart to change diaphragms and it sounds as if you removed the disc valves as you say you put it back like it was...what about the gaskets behind the disc valves...did you install new ones? it sounds like your cylinder impulse cycle is messing up, like its not getting the vaccum needed to pull fuel and/or possibly back pressuring your fuel supply line.

 

[tydog]

Re: merc 1150 inline 6 fuel pump issue

yes you are correct i changed all the gaskets in the pump diafram and little ones behind the check valves.

 

[monk-monk]

Re: merc 1150 inline 6 fuel pump issue

are you ABSOLUTELY sure the disc valves seated properly? especially the valve that controls the fuel "out" to the carbs...i just rebuilt my pumps on my '72 1150 and found that the fuel out disc was rather hard to get seated, infact, it took some gentle, and even tapping to get it all the way down and seated...the little clamp and screws should not be used (alone) to "firmly seat" the disc valves. the clamp will apply pressure and keep it seated but it will not "press-in" a tight fitting disc valve.