twin solex Carbs sucking air

[Bilson]

2.0 cu twin solex carbs

I recently replenished all the vacuum hoses, balance pipe elbow and t-piece as they were pretty much all split. My carbs we're leaking fuel beforehand, so I had assumed they might not be too air tight. The van did start and run after replacing the pipes, although it wasn't idling too well. I did change the spark plugs and cleaned up the rotor arm to rule them out, but not much changed.

I went to take it for a little run earlier anyway to see how it drove, and I didn't get too far before I started to hear what sounded like darth vader scuba diving loudly every time I lifted off. It started out with a loud sucking noise as I released the throttle, quietening down again on acceleration. Then it became constant as the engine ran. I left it be for a bit, and I just started it again, and the sound is again more pronounced when the throttle is released, but then becomes more constant. The engine will idle for a period, and then it decides it would rather not, and cuts out.

I've had a look to see if any of the hoses had come loose, but it looks like the noise must be from elsewhere, and I assume it's the carbs. I've already got a gasket set for them, so I will surely be nourishing the forum with more daft questions once I embark on rebuilding them.

For the time being I'm a bit curious about why the loud sucking seems to occur more when the throttle is released, and whether that might be a clue to any other issues I may have with the carbs? The van was sat for a while without being run before last week, so I wouldn't be surprised if old fuel has caused some blockages too.

Any input would be most appreciated

[sarran1955]

Hello,

Here is a short video, where all the leaks etc have been fixed, but the carbs are still not adjusted.

The engine is an early 2 litre CJ.

The rhs carb is 'drowning'..making a noise..

https://www.youtube.com/watch?v=4qayyc9Z4E0&t=3s" onclick="window.open(this.href);return false;

Then the carbs are set up as per spec..

https://www.youtube.com/watch?v=dsfo5ATgBp0" onclick="window.open(this.href);return false;

The other source of 'hiss' is the air control screw on top of the lhs carb..

Hope this helps..

Cordialement,

[Markpc]

sarran1955, great videos!

Just a quick question, where did you connect the two vacuum gauges to, can’t quite see in the videos? Have you drilled a port on each manifold?

Thanks

[sarran1955]

Hello,

sarran1955, great videos!

Just a quick question, where did you connect the two vacuum gauges to, can’t quite see in the videos? Have you drilled a port on each manifold?

Thanks

As I may have pointed out, this is a CJ engine from a bay, so early carbs with a vacuum spigot on both, and an SVDA dizzy (bought for £5 on Ebay)

Slightly different on a CU, more like this:

https://www.youtube.com/watch?v=najLc9GlLJ0" onclick="window.open(this.href);return false;

Hope this helps

Air-Cooled Bliss....

[Bilson]

I have a marvellous update to the situation with my van.

I decided that taking the van to someone who knew more than me to get the carbs cleaned and rebuilt was a good idea.

To be fair, the garage I took it to was located somewhere I really wouldn't want the van left overnight, and they didn't have room inside for it, so I didn't actually care to much about how it was running when I went to pick it up. The van was running though which was good, and the air leaks were no more. It was set to idle quite high though to prevent it from cutting out which wasn't great. I would've been happy to get the van as far as somewhere I could happily break down though, but it did get me home.

Anyway, the next day comes, and the van won't start. I've ruled out a couple of obvious things, like the fuel pump and battery being flat, the starter motor is a couple years old, and sounds like it's playing it's part. The engine cranks, but only occasionally hints at firing

I'm inclined to think I'm going to need to take a look at the carbs.

So after my introduction to my situation. I'd like to ask what problems there may be with the carbs that could stop it form starting?

The top gasket in the kit I bought from Brickwerks is apparently thicker than the original, on their website it states that it is imperative to check/set the float height. Could I be right in assuming that an incorrect float height could perhaps cause the van not to start?

I'm going to try to find and rule out any bad earths when daylight comes, just in case.

[sarran1955]

Hello,

Anyway, the next day comes, and the van won't start. The engine cranks, but only occasionally hints at firing

9/10 of roadside petrol engine breakdowns are due to ignition or electrical problems....

Quoted from RAC 1960's handbook...

If you have the dreaded Hall system, there is a brown earth lead under the dizzy clamp, the terminal should be shiny..

Have you access to a timing light, battery and voltmeter..

Hope this helps..

Cordialement,

[Bilson]

Thanks Sarran, I'd be really grateful for a few pointers

I had hoped it would be something simple like the pump or battery, I'd checked the earth you're referring to, and gave it a clean.

I've run my battery flat twice, had it tested, bought a new one, with no joy.

Currently got my battery back on charge so I can carry on using it, and take new one back to Halfords.

I don't have a timing light, but I've got a voltmeter

I replaced every part known to man on the ignition a few years back until I got to the coil, the idle stabiliser was the only thing I didn't replace, so will connect the cables together and see if that works as soon as battery's done.

[sarran1955]

Hello,

In order to get the motor running properly both the carburation and ignition must be 'on song'...

It should start instantly from hot or cold using the correct procedure.
You should never have to flatten the battery.

If you can see a squirt of fuel into each carb when the throttle is opened then the pump and carbs are ok'ish

If you still have the Hall ign system it is nearly 40 years old.

Here is a simple low cost fix:

https://www.ebay.co.uk/itm/034-VW-Beetl ... 1644163600" onclick="window.open(this.href);return false;

Like this:
https://www.youtube.com/watch?v=KkyBAMMHpa4" onclick="window.open(this.href);return false;

Reading your posts, I suspect that the carbs are badly set up still, and the mechanic has altered the timing setting to
get it to run hot at idle....

But then it won't start the next morning from cold...because the timing is out....

All is not lost, even poorly regulated carbs will not prevent you from starting the engine.

Buy a strobe lamp..

https://www.ebay.co.uk/itm/Powerspark-T ... :rk:2:pf:1" onclick="window.open(this.href);return false;

We will get there....

Cordialement,

[Bilson]

Thanks, when I picked it up, he told me that the timing was spot on when he checked it, I was more concerned about making sure the van wouldn't be left outside overnight, so I didn't question the high idle.

Either way, the first thing I did was disconnect the main fuel line from the t-piece, and there's a good flow of fuel to that point. I'll check the carbs now and see what happens when I open the throttle. I do recall the choke plates looking dry when I last looked, but I wasn't sure if fuel was supposed to be present. Is it supposed to come out from the pipe above the choke plates?

I've got a feeling it has more to do with fuel than ignition, as while the starter makes it's noise, it hasn't made many sounds like it's close to firing, only subtle hints which are far and few between.

As a side note, the accelerator had been adjusted when I went to drive it, so that it had very little feedback, and was hardly off the floor. The mechanic told me that this was how it should be, but having never known it to be any different than it was beforehand, I thought it was a bit strange, so I put it back as it was. Just thought I'd mention that in case it could be relevant in any way.

Regarding the ignition, I replaced the hall sender around 5 years ago. I'm going to check to see what kind of spark I'm getting if I can find someone to turn the key for me in a bit

[Bilson]

Right, when I operate the throttle, the right hand carb seems to be producing a decent squirt of fuel. Nothing at all from the left carb.

I've done this without fuel pump running though, as the battery is still on charge.

I can also hear the right hand carb spraying the fuel, can't hear anything going on over on left hand side. Could there be a blockage perhaps?

[sarran1955]

Hello,

Right, when I operate the throttle, the right hand carb seems to be producing a decent squirt of fuel. Nothing at all from the left carb.

I've done this without fuel pump running though, as the battery is still on charge.

I can also hear the right hand carb spraying the fuel, can't hear anything going on over on left hand side. Could there be a blockage perhaps?

The 2 carbs are identical, just the air horn on the LHS.

When you operate the throttle, the accelerator pushrod and actuator diaphragm squeeze fuel in, that you can see, for accelerating.

The diaphragm is the triangular one in the service kit..

Make sure that all the wires to the carbs are in good condition, you can unscrew the cut off solenoids to make sure no one has cut the foot off, no really..
Test the solenoids by putting 12volts across the terminal and the case, should jump..

Run the pump to be sure that the lhs bowl has not drained down. Otherwise ignition off and use your volt meter .

Even if the accelerator pump is u/s, it is unlikely that the main jet is blocked since the engine ran recently.

Carb overhaul and setting here:

https://www.youtube.com/watch?v=najLc9GlLJ0" onclick="window.open(this.href);return false;

So, it will be timing and electrics next..

Cordialement,

[Bilson]

I tried the throttle with the fuel pump running, still no fuel coming through, and no sound of the pump working either on lhs.

[Bilson]

This is where I am at the moment



Looking at this picture, I have nothing really to reference it to, but I'm assuming that the diaphragm must interact with some part of these workings, in order to work properly, and I can't currently see how it could do so.

From looking at your video Sarran, I can't see enough of your choke mechanism to compare it but it looks like the bar that drives the diaphragm is perhaps not positioned correctly, or perhaps the cam inside has been bent so that it doesn't interact with the bar (assuming it's supposed to).

I could of course be barking up the wrong tree?

[Bilson]

Better view of mechanism. I can't know for sure but it looks like the part that has a cross head has been bent? Causing it not to align with the bar that drives diaphragm?

[paperhouselad]

Yes I'm sure thats been bent somehow, should be square to the face of the carb, to engage in the slot of the diapragm spindle, did you bend it back getting the spindle out? Looks like it will bend back though ok, try some bent nosed pliers if you can get some in, good luck.