Air in fuel lines and sputtering at high and now low speeds

[Zed Head]

I don't think that bubbles in the fuel lines and empty filters are much of a problem.  Gases can be absorbed by the fuel and will come out when the fuel is put under the slight vacuum of being drawn to the pump.  The carb float bowls have vents so the fuel will just rise to its proper level and the gases will escape from the vent.

[Zed Head]

4 hours ago, tetert1 said:

 thank you so much for the reply I'm going to check the height of the float and someone said to replace the hose on the bottom of the floats they get old and suck in restricting fuel

The hoses to the carburetor will be under pressure.  Sucking only happens between the pump and the tank.

[tetert1]

Well I just ran a braided fuel line from the tank to electric fuel pump in the engine compartment not as much bubbles as before when the engine gets hot the clear fuel hoses next to the engines start bubbling go to the rail and then to the Su carburetors the clear hoses that go to the carburetors are almost empty barely getting fuel what do you recommend should I set the float bowls. Hoses on top of the float Bowl that go to the air cleaner are sucking air in. when I put my finger on it to stop the air the carburetor wants to die.. gasoline in the clear fuel lines are getting too hot next to the engine and the gas is turning to Vapor I think. I'm going to get a can of gas put the hose in it and see if I get any bubbles in the carburetor fuel lines and see if they fill up like they should

[siteunseen]

The gas can will eliminate any problems you think may be from the tank.  It is almost certainly your floats need adjusting.  Take the tops off and let us see a picture or two.  I'd like to see what the tang looks like.  Some are bent up like a ramp and that's wrong.  Your's should look more like a speed bump.  

There's a way to turn the lids to get them off a lot easier.  You'll need new cork gaskets too.  Nissan still has them or they did a couple of years ago.  I can look through my 240 file and find the P/N tomorrow.

[siteunseen]

Get one of these from amazon.com, about $20 I think.

 

[tetert1]

50 minutes ago, siteunseen said:

The gas can will eliminate any problems you think may be from the tank.  It is almost certainly your floats need adjusting.  Take the tops off and let us see a picture or two.  I'd like to see what the tang looks like.  Some are bent up like a ramp and that's wrong.  Your's should look more like a speed bump.  

There's a way to turn the lids to get them off a lot easier.  You'll need new cork gaskets too.  Nissan still has them or they did a couple of years ago.  I can look through my 240 file and find the P/N tomorrow.

 yes what's the trick to get the floats off and put back on I had a hard time getting them off and a harder time putting them back on I didn't want to damage them. a guy that works on them in the Houston area said to set them at a quarter of an inch from the top? I'm also trying to find a fitting that I can put on the tank drain plug so I can connect the fuel hose. Thanks for all your help

[Zed Head]

14 hours ago, tetert1 said:

 a guy that works on them in the Houston area said to set them at a quarter of an inch from the top? 

Pretty sure that the factory set an official spec.  No need to get your numbers from a guy in the Houston area.  It's probably metric too.

Edited December 29, 2019 by Zed Head

[siteunseen]

On 12/28/2019 at 1:37 PM, Zed Head said:

The hoses to the carburetor will be under pressure.  Sucking only happens between the pump and the tank.

I'd think any pressure would stop at the float valve under the lid. The carb would be sucking fuel from the float chamber through that hose. That's my understanding.

[siteunseen]

17 hours ago, tetert1 said:

 yes what's the trick to get the floats off and put back on I had a hard time getting them off and a harder time putting them back on I didn't want to damage them. a guy that works on them in the Houston area said to set them at a quarter of an inch from the top? I'm also trying to find a fitting that I can put on the tank drain plug so I can connect the fuel hose. Thanks for all your help

I'll get a picture of the lid turned where it'll lift up. Connect the hose for checking fuel level to the nipple on bottom where the small hose is connected that goes to the nozzle. 

Edit: pull the coil wire so it won't try to run off the other carb. You need someone to spin the motor while you watch the fuel level in the clear hose. It should come up to the top of that square boss on the side of the float chamber.

Edited December 29, 2019 by siteunseen

[Zed Head]

I could be wrong.  Let's get a picture.

[Zed Head]

There would be suckage but it looks very slight, I think.  

[siteunseen]

2 minutes ago, Zed Head said:

There would be suckage but it looks very slight, I think.  

I agree.