Thread: Fuel problems

G'day Paul,

Yes 0.75Ltrs per Km is very excessive. (60Km on 45ltrs of fuel).OMG
Only can give you some information about excessive fuel consumption with the Solex40PA10.
-Check the Float chamber needle and seat is tight and not leaking.
-Check the float chamber is not flooding and float does float.
-Check the main jet threads are good and not leaking.
-Check the accelerator pump diaphragm is not leaking.
-Check the air correction jet is tight. This jet hold down the Emulsion Tube on it taper.
-Check the Starter (choke) is not jammed open
-Check the castings for leaks into the throat of the Carburetor.

I would check the Starter is not jammed open FIRST. Maybe the cable is not opening and closing the Starter properly or fully closing.

These carburetors are over 50 years old and the castings are getting soft due to the reaction with petrol and is getting harder to stop them leaking.

A good replacement is the Weber Carburetor available from UK parts suppliers.

Other Forum members may have info on other things you can check.

Chris

Many thanks, I will try all that this weekend

G'day Paul,

Following on from your question about jet size, the most critical is the main jet.
The main jet screws into the end on the main jet holder. For the Landrover 2.25Ltr it will be size 120 or 125 and sometimes 135. The number mean the diameter of the hole is 1.20mm or 1.25mm or 1.35mm. The size number will be stamped on the jet.
( The reason why there are 3 main jet sizes is a bit more complicated but depends mainly on the size of the choke tube.)

However, it maybe drilled out to a different size. So you have to measure it.
I use precision metric drill shanks to measure it. I buy my precision drills from aircraft maintenance suppliers or maybe you know someone who maintains aircraft. Also carburetor repairers may have these drills which you can borrow.

If the jet is oversize you can fill it with solder and re drill to the correct size.

Good luck and let us know what you find wrong.
Chris

http://www.oldengine.org/members/die...enithSP173.htm

http://www.aulro.com/afvb/series-ii-...or-thread.html

http://www.oldengine.org/members/die.../SolexCarb.htm

whitehillbilly

Thanks guys, I will take a look next saturday, and I will change the main jets for new ones and continue testing

Ok, this is the update:

I did a dismantle all the carb and put in ultrasound machine
Buy some main jets 125 127 130 132 and 135, new gaskets and accelerator pump diaphragm
So start some test, I put 125 and the engine can't start or start and stop again, with 127 start but a lot of engine stalls.
With 130 engine run "normal" small fails in the carb but still a lot of fuel consumption and a lot of fuel comes out in the emulsion tube.
More testing I screw all the mixture control screw and the engine never stop, or drop RPM, this was strange to me. So I put off the screw, the engine continue working with some difficult and cover the hole with my finger, strangely the engine starts to work perfect I can put 600 RPM with the butterfly screw engine works really well.
I'm not mechanic, i'm autodidact, I like read manuals, look in forums and do testing, this is very strange but now the engine works really smooth.
So now I have and small tube with a screw in the mixture control hole (I know in not correct but it works) and a main jet of 127, no more fuel from the emulsion tube in ralenti, looks normal fuel consumption, and steady and smooth 600 RPM and 18 lbs in the vacuometer. I'm happy now.
A little slow top speed only 70 km/h witg 7,5x16 tyres, but continue testing
This is my update thanks for read



p.s. Can anyone please give my a photo of the mixture control screw and measure the diameter in the cone, I think my screw in not correct
Many Thanks

G'day Paul,
Good to hear from you. You have been very busy and your almost there!!!.
Nice clean engine and Solex as well.!!!!
127 main jet is in the ball park. What are the last 2 digits on the choke tube number?.

From the picture I see a few problems.

The outer choke cable wire covering is not secured onto the carby. The choke cable action is not going to operate properly and open and close off the starter. Also the starter fuel jet is either 145 or 130. For the 5a it should be 145. You need to measure it at 1.45mm. If the starter is not closing properly it will effect the idle circuit. Also if the starter is not opening properly say to the half way position the engine will not run for more than a few seconds as you have experienced.

I also see the vacuum advance steel tubing from the distributor and hopefully connected properly to that rubber tubing and banjo on the carby.

Now a few more things to check.
The height of the fuel in the float bowl is critical for fuel consumption. The height of a new needle above the body of the seat is 0.155" ( inches). Probably yours is very worn and should be replaced with a new one. Size is 2.0mm. You can fine tune the fuel height by making different sized aluminum washers under the needle and seat.

Now for the idle problem.
If the starter is not closing off properly the idle screw will not have much effect as this is your symptoms.
Because you effectively modified the volume screw control circuit to flow full fuel at idle, it indicates there is fuel starvation in this circuit. The Pilot jet is 75mm above the volume control screw so maybe this path is partially blocked. Also the gasket joining the top half of the carby to the throttle body has a hole for this path. Check gasket orientation and blockage.
The idle circuit consists of the pilot jet, the air bleed and the volume control screw:
The pilot jet is next to the choke tube fixing screw. It should be marked 55 or 60 and sometimes 65 and maybe partially blocked. This jet is an unusual design and you need to measure the size as well. Above it is the pilot air bleed.(Check this is not blocked).
The volume control screw (idle screw) is a complicated tapered profile.
The overall length to the shoulder is 8.66mm. The taper starts from the end for 5.75mm to a diameter of 2.20mm approx. Then a slight bevel to the diameter of 2.92mm.
Have not got a digital camera to take a photo for you.

From the symptoms I would still be looking at the starter control and cable because it appears it is not closing fully and also the needle seat height for fuel consumption and a blockage in the idle fuel circuit.

Also if no success maybe take some more photos of the Solex and in particular the starter cable and back of the Solex.

Others may have more ideas and a photo of the idle screw for you.

Chris

Many thanks for your observation Chris, well the chocke cable is perfect working was loose in the photo because I was doing many testings, the choke also work perfect and close very well.
I can't see any number is the choke tube, starter fuel jet or ascelerator jet.
The fuel level is at 0,6 inches
The air bleed on the top of the carb for the idle circuit is clear
I'm sure that my idle screw is not for this carb, I will chech the meansure you give me.
Many thanks