'77 55 hp johnson fuel problems

[Darth Mal]

I have rebuilt the carbs and the fuel pump....new fuel lines and made sure the fuel pumps through the fuel pump...when I first got it it would drop to one cylinder and then cut off, if I pumped the bulb it would pick back up and then run for a few minutes the do it all over again, so I did the above mentioned. I tested for leaks and found none. Then I rebuilt all and checked all, it still does it. If I run it on the hose I get maybe 3-4 minutes before it wants to quit, if I put it in the lake I get about a 15 sec count at 1/4 throttle then it starts to die, pump the bulb and it comes back to life...I also have tried 3-4 other fuel pumps with the same outcome.......any ides?

[Darth Mal]

anyone?

[eavega]

truly sounds like its your fuel pump. The run time seems to correspond to emptying the carb bowls. Check your fuel pump again for proper functioning. put a clear line between the fuel pump and the carb, look to see if you are moving fuel there, or if there is air getting into the system somehow. I tried to rebuild the fuel pump on my '76 70 HP last year, and found that right after the rebuild it worked fine, but after a couple of outings either the diaphragm or something else seemed to slip out of place, and eventually actually found a crack in the plastic part of the pump that would cause it to lose pressure once the motor warmed up. It would start up and run great right off of the trailer, and for the first WOT run. If I shut it down and started it back up, it would have a hard time running. I replaced the fuel pump with a brand new one, and all was well after that.

rgds

[JSGOLD]

probably a stupid question but do you have any issues with the fuel tank vent not being opened properly? Also I just rebuilt my 55' carbs recently and had to open the jets a bit to get it to stay running. You did remove the welch plugs when you did the rebuild too, right? sometimes those will have dirt under them....

[Darth Mal]

vent is open and it has new filter and pump bulb/lines. I was also asked what my turns were on the top jet....I told them it is 1-1/2 from closed. I have tried 3 different fuel pumps with the same results....I will put clear fuel filter in line( should have already done that!) to check for lose of fuel...