Solex 4A1 Adjustment - Stalling

[davidvincent]

Hi all

So I previously wondered if the float/needle valve was worn as the engine is stalling once it begins to warm up, now though I don't think it's that, there's no excess fuel running into the carb after stalling.

So, here's the latest, I wondered if you could offer some tips?:

- Starts fine, idles at 1100 for around 3 mins before stalling
- Running without the airfilter, I can see that the flaps are staying open even once a little warmer
- When the engine starts to stall, if I almost close the flaps the engine returns to idle

This all happened a week or so ago, and the problem came on quite suddenly, although prior to this the idle speed had been quite erratic. I'm wondering if adjusting the mixture / idle speed would resolve this? Saying that, I'm the opposite of an expert with carbs - I still can't locate the adjustment screws!.. and my Haynes manual and online scanned Solex docs aren't making it easy for me.

I really wish I knew how to setup a carburettor!! Anyone wanna teach me?!

I do want to keep the Solex setup, just desperate to get driving again!

Let me know what you think folks, here's a little video, note if I had closed the flaps a second earlier the engine would have idled fine again...




Cheers

[Peter V.]

When you are closing the chokeflaps you are making the mixture richer. But i see that it occures when the engine is already at the right temperature to have openflaps.

So you have changed nothing to the carb/engine?

The adjustmentscrews are located next to the electric idlejets. You have two of them. One for the first 3 cylinders and the other for the back 3 cylinders.

[davidvincent]

Hi Peter

Nothing changed on the carb but I did replace a very warn out dizzy cap and rotor, perhaps this makes a difference? Also the car has been off the road for a very long time, putting it back into use after years of being rested may have something to do with it?!

[Peter V.]

Dizzycap and rotor does no sound as an issue i think.

The fact is a have the same carb and rebuild it completly and it has the same stalling but then during warm-up. When there is a little temperature in the engine it runs perfectly.
Normally i would say it is the mixture that is to lean so adjust the mixture screws by turning them a bit out. but because your problem is suddenly i suspect the TN-starter. It is the device that has the coolant run through. After a long period it can be stuck in position.

If you remove it (two screws and leave the coolant hoses on) what is the gap when the engine is cold?

[BertjeConti]

Might be another problem.
When the electric idle jets won't come open the engine runs when cold, but stalls when warming up.
By closing the choke flap you enriche the mixture, that makes the engine still idling with the electric idle jets closed.

Check if the electric idle jets get power, could be a fuse problem. That would explane why your problem appeared suddenly.

Put ignition on and the disconnect /reconnect wires to the electric valves, you should hear a click, like in this video:

[BertjeConti]

Oh yes, i have a manual that explains how the 4A1 works, and adjusted. only it is in Germain.

[davidvincent]

Thanks guys, I'll try and work through these tonight.. Regarding the solenoids, I had listened for the 'click' when turning the ignition on but I haven't checked them individually - a good / easy place to start!

Cheers

[BertjeConti]

And?

Any progress?

[davidvincent]

Hi all

Just tested all three solenoids as per the vid link, all working. Also checked that the choke springs (in the circular housing) were okay,they seem to operate and look fine. Now just going to work though the other suggestion above... Pls keep the ideas coming!!

[davidvincent]

Okay so I've managed to get it idling now by slightly adjusting the two mixture screws - I'l admit that it was purely guess work but I did try to match the changes each side. The best idle I can get is 1000 rpm at the moment, any lower and the tinware that covers the manifold rattles like a goodun! need to see if that can be tightened, or even replaced.

I still, for some reason, can't find the damn throttle speed screw, so i'm back looking at the (not very helpful) haynes diagram in the house now... I feel like I should address the throttle speed too.... back I go.

Having it running as just reminded of how much smoke it's blowing out... one thing at a time I guess!

[davidvincent]

Okay, so some progress... here's what happened:

- Put brain back in, found throttle screw
- Spent an hour or so adjusting the idle using the throttle screw and two mixture screws
- Eventually got the car to a lovely idle, around 900
- Test drive was going very well until I put my foot down, then all of a sudden it seemed that the throttle was stuck open at very high revs (smokey too)
- Pulled over, airbox off, had to blip/punch the accelerator hard a couple of times to get the revs to drop, and then adjusted the carb enough to get me home as it kept on stalling again.

Once home, I then had to start all over again with the idle adjustment to keep it from stalling, somehow whatever that issue was on the test drive, it threw the mix off totally. I've left it for now as I'm already late leaving, but if anyone has some ideas, please post it here!

I'm thinking I should clean (with carb cleaner??) all moving throttle parts and test drive again.... just seems strange that after the sticking throtle I had to adjust the mixture again!

Cheers

[Peter V.]

When hitting the throtle you opened the big flaps. The vacuumbox is there to pull them close and mostly the big flaps are moving bad because of dirt, twisted carbcover, broken vacuumbox etc.

Then it an also be that the big botomflaps are not closing properly so the engine will stall again.

[davidvincent]

So do you think cleaning is the way forward?

[BertjeConti]

No, a common problem with the 4a1 is a warped upper part.
When that is the case you need a new/other part.

[Peter V.]

No, a common problem with the 4a1 is a warped upper part.
When that is the case you need a new/other part.

That's a fact. Because of the twisted cover the big flaps get stuck often. Mostly because the carb is to tightend to the head.