Bedford 214 - Fuel Issues on acceleration

Michael

I think you are messing with the wrong bits.

If you can change the mixture it would require an adjustable main jet. Messing with the idle screw should not make any difference once you are running. It should have no bearing on your current problem which seems to be fuel level in the bowl either running out or now you seem to have over flowing.

Michael, don't take offence as I know you are well past this information but I find it handy to explain a carby. I am not patronizing you.

The float and needle set up have no direct connection to what you are doing with the throttle. If the fuel level in the bowl is correct it is just a reservoir that feeds fuel through the jets into the carby throat at a rate dictated to by the throttle butterfly position.

The throttle is just an air tap and has nothing to do with fuel. The more air flowing through the venturi, the more vacuum and the faster the fuel flows out of the jets mixing with the air in the correct proportions. All this is automatically fixed and set by the size of the jet and the shape of the venturi and design of the butterfly in manufacture.

All the float does is act as an automatic water tap (with the needle the washer on your bathroom tap). As the fuel is used the level drops, the float drops and the needle sitting on top of the float comes away from the hole in the fuel line to allow fuel in to refill the bowl. The float rises and pushes the needle back up into the seat closing the flow. It is like having a little Elf inside the carby turning off and on a bathroom tap as he keeps the fuel between the upper and lower level marks.

The float does not operate instantaneously to throttle settings but just keeps the fuel level in a suitable level range - always a little behind the throttle position.

The accelerator pump is just a one time thing to squirt an extra dose of raw fuel into the throat to overcome a sudden opening. If the butterfly is suddenly opened by planting your foot air flow becomes maximum instantly and because fuel is thicker than air it takes some time for the jets to catch up with the air flow giving a sudden leaning of the mixture. You have probably seen cars with a buggered accelerator pump that cough on sudden acceleration. The pump gives a sudden crude boost squirt of fuel to keep up with the airflow but it is pretty unregulated and wastes heaps of fuel. That is why smooth throttle drivers get much better mileage than rough leadfoots.

Having been through the electrical system. I think there is nothing to be done now but get the carby serviced by a specialist. I know you want to keep it original but I can say without doubt a Stromberg off an old Holden would run better, in smoothness, fuel usage and performance.

Keep at it. It is only an off-pissing minor problem "somewhere" and certainly not an expensive disaster.

Lang

Am I reading what you wrote right?

You indicate (to my reading, anyway) that you have the electric pump feeding the mechanical pump.

Is that correct?

If that is right you are feeding more fuel into the mechanical pump than it would normally see and in turn that will increase the pressure AND flow when it does its job. So the carb will flood as the needle and float can't hold back the pressure

You need one or the other.

I'd by-pass the mechanical pump and give it a try.

I saw the float and said Solex.... the direct acting float needle systems cant handle pressure like the lever float float type ...I think the AC pump must be very low pressure ,as the float system is gravity feed type......I have no experience with regulators ,but lower fuel pressure is needed.

Zuffen

The electric pump is normally quite OK running through the mechanical. If the mechanical is capable of say 4 psi and the electric pump the same it will just be in angel gear as the fuel flows through the valves.

If it is a 2 psi pump and the electric is 4 psi, same thing, the electric flow will just open both valves and flow through.

As John suggested it looks like this has happened to Michael and maybe the 2psi needle can't cope with the 4 psi electric input. With his new needle and seat not the fix it looks like we are back to a crook pump originally not keeping up and while the solution is correct it is overcooked because the electric pump is more than the system can handle.

I will try to find the required pressure for that carby. If, as John says, it is a carry over from the old vacuum pump/gravity feed system it will be very low pressure.

Lang

Michael, slow progress is better than no progress. You know my pump is coming, and that it works okay. While waiting for your mail delivery continue working on your tray . When it arrives, swap your existing pump with mine and try it without the electric pump running (simply disconnect the power to it), see how it performs . . . then with the pump running as well., ditto. We wait breathlessly.

Lang, it is not so easy to change to a stromberg carburettor as the early manifold has the mounting set at about 45 degrees for some obscure reason??? The pictures below are my O type carburettor (the tall bugga) which now is working okay, and my J series (in which the accelerator pump is not! ). Note the angled base.

PDU is it possible to mate the 45 degree base with the normal carby? I know Strombergs had several different bases to drop the standard carby on (bolt patterns etc).

You all know I know nothing, but how come nobody is suggesting a temporary gravity feed to the buggered fuel pump. An old 1 gallon fuel tank mounted above the fuel pump, or even above the carby as well would surely give at least the required pressure, ( also eliminate tank blockages) and would perhaps confirm the many suspicions. But whaddoeyeno.

OK back to the saw bench.

Wishful thinking Lang, but if it was possible I would've probably done it when I was trying to get my engine up and running.

I did look. :lol:

No eBay APP ID and/or Cert ID defined in Kunena configurationMichael

If the problem is too much pressure and you still want to go electric there are plenty on Ebay with shutoff 2-3.5 psi


Just found a little treasure.

1939-40 Carburetors

Operation and adjustment of all makes English and American, on the Australian market.

The detail is minute.

Presume it is a Zenith? What model is your carburetor. More than likely one of those pre-war models or at least a minimal upgrade. I will copy the pages for you.

PS Sarge. Very good thinking is your idea to do a full system check. Direct to carby to eliminate problems there . If OK then to pump to check that and so on back to tank. We need more heads on the job to drive Michael insane but hopefully will have it solved before he tops himself.

Lang

What I found with that style of needle and seat setup was the spring had the ability and did hold the needle either in the open or the closed position for no reason at all. Worked well one minute then next thing it goes wrong. I am guessing now that at some stage maybe the spring got ever so slightly bent and would lock the needle up in what ever position it was in at the time.
My replacement needle and seat had an encapsulated needle, it could not fall out when in position with or without a flaot under it. Then there was a hole drilled either side of the nnedle to allow the fuel in.
By replacing my needle and seat, then following the direction on how to adjust the float level by adding or subtracting a washer under the bodly of the seat housing and looking at the fuel level being at the correct height up the main jet tube. This resolved my flooding and starving problem. If you do have another needle and seat and that it is encapsulated give it a try while you wait for the next fuel pump, I think it is worth a try.
By the time I got through playing with my Solex I was and possible still are the fastest remover and re-fitting of a Solex carby on a David Brown tractor.