Engine won't start, carburettor problem?

[MDP]

I have recently got my Traveller running after being off the road for many years. The ignition system is working ok, it has a new coil and a good spark. I had a plastic fuel can hooked up to the carburettor and it started fine every time.

Once I flushed the fuel tank and fuel pump and connected the fuel pump up to the carburettor the car wouldn't start. I suspected dirt had got in the carburettor so removed it, cleaned it out and replaced it. The engine still wouldn't start.

I have changed the carburettor for another one that I was told worked well and it still won't start, when connected to the fuel pump or the plastic can.

Fuel is going into the float chamber, I can't see it going through the jet into the carburettor though. The jet doesn't seem to be blocked and I can manually draw fuel through it. I have tried holding the carburettor piston up when turning it over and it makes no difference. It moves freely but doesn't go up and down on its own accord when I'm trying to start the car.

When turning over, it sounds like it is not getting fuel as it makes no attempt to start. If I pour petrol into the carburettor while turning it over, it will start and run briefly until that small amount of fuel has run out.

The engine sounds like it is turning over too fast. I have checked the vacuum hose to the brake servo which looks ok, I have tried disconnecting it and blocking it off, this makes no difference.

A compression test gives PSI readings of cylinder 1: 130, cylinder 2: 150, cylinder 3: 140, cylinder 4: 150.

I've cleaned the spark plugs, they were really black and sooty.

I am not sure what to check next. Has anyone had this issue and has any ideas?

[kennatt]

if it starts when you pour petrol into the carb then it is a petrol supply problem,don't mess about with any other setting,because you may add a problem.I would suspect you have got grit under the needle valve in the top of the carb,Its held in the cap on the top of the carb fuel bowl three screws on top,when you take it off there should be a full bowl of fuel,if not then that is an indication that either the needle valve is clogged or the pump is not supplying fuel to the carb,

[MDP]

Thanks Kennatt, I've taken the top off the float chamber this evening and it was half full of fuel which seems about right? I've tested the fuel pump and it is delivering fuel to the carburettor.

[beero]

If you add fuel to the carb and it starts then maybe you should check the choke operation.

[MDP]

I've checked the choke operation and it's working ok.

[kennatt]

Try ...... screw the big nut under the carb fully in,then unscrew counting twelve flats see what happens and report back.

[Myrtles Man]

I don't know if this is particularly relevant to this particular query but, as a 'quick and dirty' test, whenever an engine is refusing to show any signs of wanting to fire/start after churning over on the starter motor, a brief sniff round the end of the exhaust pipe will soon tell you whether it's a lack of sparks or a lack of petrol that's the problem. Obviously, if there's a stink of petrol, you've got an absence of sparkage on your hands and you can then proceed in that direction. I merely throw in this observation for what it may be worth.

[MDP]

I've done the big nut under the carb up and undone it 12 flats and it is still not trying to start. It does seem there is some problem with the fuel getting through though.

I can't smell petrol when turning the engine over, and have a spark plug tester connected that shows there is spark. It is also starting when I pour petrol directly into the carb.

[oliver90owner]

Just read through this thread.

Good spark, no fuel has been observed.

Changing one carb for another good one seems to rule out the carb as the fault.

That leaves the fuel supply, prior to the carb.

There are only a few items involved in the fuel supply. Pipe from pump to carb, fuel pump, electrical connections to pump, pipe to tank and tank (with fuel pick-up).

Concentrate your efforts in this area, is my suggestion. Stop fiddling with the carburettor until these parts have been proven to be operational. Then check the fuel flow into the carb.

Only then, suspect the carb internals.

[kennatt]

You say you have checked ,fuel in bowl and pump is supplying petrol to carb,that you have check the choke operation that on tipping petrol into carb it runs for a while. So it must be getting a petrol supply.Adjusted carb(12 flats).
Is it fresh petrol in tank,or did you return old petrol when you cleaned the tank out.

[Trickydicky]

On Tuesday you said the plugs were dark and sooty, if fuel was getting to the cylinders then I would expect them to be wet? Sounds like a blockage to me in the carb.

[MDP]

I've had another look at the carb and fuel supply:

The fuel pump is pumping fuel ok.

With the ignition on I've sucked fuel through the jet in the carb through a hose and it comes out, the fuel pump ticks to supply more fuel, although there was a lot of air coming out as well. Having checked the fuel hose connections, the one coming from the fuel pump appeared to be leaking a bit so I have refitted that.
Still air coming out though.

Have checked the float chamber and still staying at half full.

I put fresh fuel in the tank, and have tried with a plastic can as well bypassing the fuel pump with fresh fuel, so I think it is either carb or pressure.

The petrol comes through ok so I can't see why the petrol isn't coming through when the engine turns over, except if there is no pressure to draw it out when the engine is turning.

[StillGotMy1stCar]

Has it got a servo fitted.
If so, has the hose from it to the inlet manifold become disconnected or perished, letting in too much air and therefore low suction at the carb.

Regards John.

[kennatt]

Its unlikely to be anything mechanical,timing,, pressure,air leak electical . because.....when you tipped petrol into the carb it started and ran till that petrol was used up,it starts and runs when you used a petrol supply from a can (is that with the replacement carb as well) Have you tried feeding carb again from external can.,or was that just the original carb. put that one back on if so.If it starts and runs from an external supply then as previous post has to be the supply from tank to pump to carb,