L18 Carb problem

[RockFord_]

Hello. I know nothing about carbs other than that they mix air and fuel.

 

 

The problem i have is that the engine wont run properly, i have to use almost full choke all the time or it stops.

Had it at a shop to adjust it but he said it had a internal leak he can not fix

 

We took care of the small things first, like bad hoses and other small things.

Adjusted idle and got it to the point where it passed emissions so that he can approve it for the road.

 

The readings on the exhaust said it was way low on the co. 

Adjusted this screw

 

 

That is where the problem is at first it was stuck, got it loose and the screw does nothing and we can not get the car to run properly.

 

Do you guys know what it is and if that is fixable. Can it be as easy as to swap over the needle or the lower part of the carb from a donor?

 

i met up with a datsun guy who gave me 2 carbs for free but they are newer and have auto choke.

 

 

 

 

 

Also if these carbs will work ?

And what do i need to make the auto choke and idler work on my engine?

 

I know a new carb is the easy way out of this but i am on a low budget right now and i need the car running.

[datzenmike]

 

Connect the Blue wire (electric choke) to a switched electrical source run from the ignition switch. If the idle cut solenoid pictured below is working just use it.

 

 

 

 

 

 

The screw in the picture is the idle mixture screw. It only adjusts the idle richer or leaner. So you must have an idle around 800? or so.  Can't see if these carbs have the idle cut solenoid, if they do that also needs to be powered like the auto choke. Where does that second wire go to?

[ggzilla]

If you have to run near full choke, then its not an air leak- its a fuel blockage.

 

If it will run at 1600 rpm or higher without the choke, the idle circuit is blocked

[That4doorKiD]

run the carb with your hand over the intake mouth. If it runs its an air leak? right,

[ggzilla]

Nope. Hand acts like choke is all.

 

When engine is warmed, if it requires choke, it nearly always means not getting enough fuel

 

Engine will run with air leaks. Make sure all the visible jets on top of carb are not loose

[RockFord_]

The screw in the picture is the idle mixture screw. It only adjusts the idle richer or leaner. So you must have an idle around 800? or so.  Can't see if these carbs have the idle cut solenoid, if they do that also needs to be powered like the auto choke. Where does that second wire go to?

 

If you have to run near full choke, then its not an air leak- its a fuel blockage.

Yes. this sounds about right

 

Nope. Hand acts like choke is all.

 

When engine is warmed, if it requires choke, it nearly always means not getting enough fuel

 

Engine will run with air leaks. Make sure all the visible jets on top of carb are not loose

Where are the jets? i need to check that out.

 

Thanks for your comments guys. 

[RockFord_]

oh. and what we call the co screw is the mixture screw as pointed out here. It was low on fuel, so i am looking for some kind of blockage. 

[ggzilla]

On the top of the carb may be two brass things each with a screwdriver slot. Make sure they are not loose. In other words try to lightly unscrew them. If they are loose, tighten then a little.

[datzenmike]

The jets are behind two hex shaped plugs just below the glass window on the front of the carb. The jets are up inside the carb screwed into the floor of the float chamber behind the glass. You will need a slender screwdriver to fit up inside once the plugs are removed. The blade must be wide enough to grip the slot in the brass jet without damaging it. Every time I have removed a jet I had to grind down an old screwdriver to fit properly.

 

The primary jet is to the valve cover side. Take care, as the jets can be interchanged, this is to be avoided. The primary jet will always have the smaller number stamped on it. A small blockage of the jet will reduce the fuel mixture making it lean and possibly why the choke is needed to keep the engine running.

 

Probably best to remove the carb to get at the jets, it's much easier. Sediment on the floor of the float chamber is likely in or covering the jets. Might be a good idea to take the glass front off and clean it out. When done replace the fuel filter if you find sediment.

[RockFord_]

thanks guys. i will get to work :)

[banzai510(hainz)]

adjust the mixture first then ck if the idle jet is plugged. anytime you have to run the choke. Or main barrel is plugged also.

 

make sure the fuel level in glass is OK also

 

 

If all fail get a Weber DGV with manual choke

 

 

the 1st photo shows a carb with a fuel cu off selinoid. Other carbs on table looks like they dont

[RockFord_]

Mixture screw does nothing. 

Fuel level in glass is OK

1st photo shows the carb on the car. the one that has the problem.

Fuel cu off selinoid goes on the main jet? I have to check if that works aswell :)

Thanks!

[banzai510(hainz)]

selinoid is for the idle jet.

If selinoid dont work you wont be able to set the mixture as its blocked.

 

You can take out ans see if it moves when you turn the key ON . But the case has to be grounded so you seee the needle move. Its blocks( When Key OFF )the hole so NO gas will flow .. When Key is ON the needle will move so gas will flow to the idle circut of the carb. the mixture should work when this is clear. Alot of time Rust will plug up the idle jet.

 

If truck runs above idle say 1200 rpm of more then I saw the main jet is OK. But I had a manin jet plugged with a tiney rock. I could idle but once I get above idleit felt like it ran out of gas. So I put the choke ON and drove home. What I did is bypass the main jet and got the 2nd jet to work by using the choke to create a vacuum.

 

if you have a bad fuel filter that is full of rust then check to see if idle just has rust or dirt in there..

 

 

motor should run if you pump the pedal( or use your hand to cycle the carb linkake) and you should see gas squirt in the main barrel of the carb.

[ggzilla]

In addition to all that, check to see if the VISIBLE jet covers are loose. They are on top of the carb, in plain sight

[RockFord_]

I did not get anything done on the car today :(

-Checked the selinoid and it works.

-Fuel level in glass is now high.

sadly that is all i had time to do.

 

By the way. what carb do you guys recomend i buy when i get the money?

[ggzilla]

Two common choices:

* remanufactured stock carb

* Weber 32/36

[banzai510(hainz)]

How high is the level? if not too much where its FLOODING out and smelling like gas and wont start.

 

a Weber 32/36 5A is a manual choke type which is the most simple.

 

 

also one other thing I forgot to mention you should have looked at first , Make sure the second butterfly or flap on the driver side is all the way shut. If still open you will not be able to idle very good as your loosing to much vacuum in the main circut of the carb.

 

the second flap should be closed. This only works when you are going very fast and then it will open only enough what it needs.

 

A person who knows old Volks wagons will know carbs and how to help you out. Also know Weber DGV carbs

[RockFord_]

it is just a bit over OK.

 

The second flap is closed.

[jhw1980]

Hi I was wondering if anybody can tell me what might make a hitachi carb automatically redline upon starting it