1957 Johnson 18 hp. FDE-11

[twheels*]

Motor runs out of fuel. I have cleaned carb, set float level, replaced fuel line & air line to the fuel connector on handle from the motor. Sprayed all fuel connections when pressurized with soapy water and can't see anything leaking ( fuel or air ).However if i manually pump fuel tank button on fuel tank motor runs fine. Note I'm using the original two line fuel tank. Running out of ideas. The only other thing I can think of would be crank seals which I doubt.

 

[Crosbyman]

does the tank go psssst if you pop open the cap when theengine is running ?

NO ??? possible flaw in the the 2 small check valves behind the carb plate used to build up pressure in the tank.


motor obviously not self feeding itself or the fuel needs help to find it's way back into the carb bowl (dirty filtering somewhere ???)

crank seals should be OK since hand pumping fills the carb and..... & fuel is sucked into the crankkcase properly (engine runs ok)

if the engine gets to run lift the tank above the carb for a while and if OK
air pressure issue to the tank

 

[racerone]

Agreed with above.-----Sounds like not enough pressure in the tank.-----Cap on tank has to be closed.

 

[twheels*]

does the tank go psssst if you pop open the cap when theengine is running ?

NO ??? possible flaw in the the 2 small check valves behind the carb plate used to build up pressure in the tank.


motor obviously not self feeding itself or the fuel needs help to find it's way back into the carb bowl (dirty filtering somewhere ???)

crank seals should be OK since hand pumping fills the carb and..... & fuel is sucked into the crankkcase properly (engine runs ok)

if the engine gets to run lift the tank above the carb for a while and if OK
air pressure issue to the tank

Thanks for the suggestions will give try.

 

[jimmbo]

Am exploded diagram typical of those tank

 

[oldboat1]

Might check the glass bowl and sintered filter assembly. Make sure the top of the bowl is secured by an undamaged gasket on top. Check for leaks/adjust fit/tighten.

 

[twheels*]

Might check the glass bowl and sintered filter assembly. Make sure the top of the bowl is secured by an undamaged gasket on top. Check for leaks/adjust fit/tighten.

Thanks

 

[twheels*]

Thanks for the suggestions will give try.

Replaced the check valve, spring and spacers and new gasket behind the intake assembly. Still having problems with tank holding pressure. Tried switching fuel tanks but no sucess. O rings on fuel connector seem fine.This motor is kicking my ___.Any more suggestions? Note: motor runs fine if the fuel tank is elevated.

 

[Crosbyman]

if you have air pressure loss use soapy water spray bottle and find the leak .

check for bubbles ...... like checking a inner tube flat on a bike

vacum loss may be stopped with a temporary coating of grease on suspect junctions
or tightly wrap in cellophane wrap on easy access points

 

[flyingscott]

Here is a dumb question, are you using a 2 line pressure tank?

 

[cc67]

Here is a dumb question, are you using a 2 line pressure tank?

Read post #1

 

[racerone]

Agreed---Post #1 seems to indicate it has a pressure tank.-----Is tank cap closed with a good gasket ?----If motor runs it must be producing crankcase pressure for the tank.-----There is a blockage or leak somewhere.----Checked fuel filter and strainer inside the tank ?----The pump on the tank pumps fuel only.----When motor starts crankcase pressure puts air into the tank.------This should be simple to figure out.----When motor stops wait 5 minutes to open the tank cap.-----It should hiss from the pressure.-----I suspect there may be a pin hole leak in the pick up tube inside the tank.

 

[Crosbyman]

"Sprayed all fuel connections when pressurized with soapy water and can't see anything leaking"

assumption or fact... is is really pressurized ???

ok so you had tried the soapy water ...(post#1) but we still do not know if you have pressure build up in the tank.....does it or not go Psssst when you open the cap ???

if you dont have a psssst.... you have no pressure build up ( and no soapy bubbles) only 2 options..

1- leak of pressure...try soapy water ..again
2- no pressure build up from the crankcase ....check the flapper valves behind the carb plate, check channels for obstruction check airway to the nipple etc... everything to do with the pressure system feeding the air nipple.

no pressure to fuel tank => no fuel from tank to the carb !!

 

[racerone]

He says that flappers were replaced.-----The manual pump on the tank does NOT pressurize the tank.----It pumps fuel only.

 

[Crosbyman]

"Replaced the check valve, spring and spacers and new gasket behind the intake assembly"

yep did not see that comment :-(

yet ... basic question remains... does enough air end up in the tank to push fuel back up ? answers are elusive....

pin hole would be tricky one yet 2 tanks were used ??? Murphy issue ?

 

[racerone]

This should be easy to figure out.----But for some it appears to all be " black magic " and simple trouble shooting is going out of favor I think.

 

[jimmbo]

"simple trouble shooting is going out of favor I think."

There's no App for that

 

[twheels*]

Read post #1

Yes.I have tried using a second 2 line tank with without any positive results. I do however have pressure in the fuel tank when I release cap after sitting without engine running.

 

[twheels*]

Might check the glass bowl and sintered filter assembly. Make sure the top of the bowl is secured by an undamaged gasket on top. Check for leaks/adjust fit/tighten.

I checked the gasket on the filter bowl / no leaks,

 

[twheels*]

"Sprayed all fuel connections when pressurized with soapy water and can't see anything leaking"

assumption or fact... is is really pressurized ???

ok so you had tried the soapy water ...(post#1) but we still do not know if you have pressure build up in the tank.....does it or not go Psssst when you open the cap ???

if you dont have a psssst.... you have no pressure build up ( and no soapy bubbles) only 2 options..

1- leak of pressure...try soapy water ..again
2- no pressure build up from the crankcase ....check the flapper valves behind the carb plate, check channels for obstruction check airway to the nipple etc... everything to do with the pressure system feeding the air nipple.

no pressure to fuel tank => no fuel from tank to the carb !!

Tank itself seems to hold pressure while sitting without motor running and the tank will psssst when fill cap is opened. Once the motor is running there is no psssst when cap is released. I guess I can go back and check the installation of new check valves.