Fuel not pumping through

[Tommac]

Hello all I have a conundrum: my Morris Convertible (1962) has been laid up in my garage for a while. The problem I have is getting fuel through to the engine. The SU pump is new. When all the pipes are connected, the pump will tick at a decent rate but quickly slow down then stop and only tick occasionally. If I remove all the pipes then it ticks away at a high rate but when I connect either the inlet fuel pipe it’ll tick then slow down then stop. If I connect only the outlet then it will do the same but take longer. Any suggestions anyone?

[svenedin]

How long has the car been standing unused? It’s possible that there is a lot of rust in the fuel tank. The fuel line from tank to pump may be blocked. Try connecting the inlet pipe to the pump and directing the outlet pipe into a suitable container. Is any fuel being delivered? Even though the pump is new it may have sucked in a lot of muck. Have a look at the pump filter and clean as necessary.

If the fuel in the tank is old it is now useless anyway. Remove the drain plug underneath the tank and drain away any stale fuel. This will hopefully take rusty particles out too.

Stephen

[simmitc]

You can blow backwards down the pipe towards the tank. You should hear bubbles in the tank. If you have an old fuel pipe, you cut the end off, can fit that to the pump and then connect the stub to some hose which goes into a fuel can. The outlet hose can feed back into the same can. This will allow you to check that the pump is actually pumping.

With fuel flowing through the pump, connect the outlet to the carb. Remove the top of the float chamber and check the operation of the float and needle valve.

Remember the risk of fire and explosion. Always use suitable containers, work in a well ventilated space, and avoid naked flames, sparks, and any other source of ignition.

[oliver90owner]

Ticking, slowing and stopping (only to tick occasionally) is normal for the pump. Are you sure it is not delivering fuel to the carburettor?

[geoberni]

Hello all I have a conundrum: my Morris Convertible (1962) has been laid up in my garage for a while. The problem I have is getting fuel through to the engine. The SU pump is new. When all the pipes are connected, the pump will tick at a decent rate but quickly slow down then stop and only tick occasionally. If I remove all the pipes then it ticks away at a high rate but when I connect either the inlet fuel pipe it’ll tick then slow down then stop. If I connect only the outlet then it will do the same but take longer. Any suggestions anyone?

Have you actually tried starting the car, because all you seem to be describing is an SU Pump working normally
You've not actually mention any fuel coming out of the pump.

When all the pipes are connected, the pump will tick at a decent rate but quickly slow down then stop and only tick occasionally.

That'll be the pump filling the Float Chamber and then cutting off...

If I remove all the pipes then it ticks away at a high rate

Well if there's no back pressure from the Carb, it's going to try and pump like crazy...

when I connect either the inlet fuel pipe it’ll tick then slow down then stop. If I connect only the outlet then it will do the same but take longer.

I admit I'm not quite following that, your use of 'either'... If only the inlet is connected, it should be pumping fuel all over the floor...

[Tommac]

Yes if everything is connected I can start the car but since the pump is not supplying enough fuel quickly enough the engine will stop after (about) 20 seconds. Then I wait (about) 10 seconds and I can restart and so on. I took the cover off the float chamber and it was full and the float valve was working normally. I think at least one problem is a blockage in the inlet pipe. I used a bicycle pump to blow it out in reverse but that made no difference. I have plenty of fuel in the tank.

[KeithL]

I have plenty of fuel in the tank.

Is that fresh fuel?

[svenedin]

Yes if everything is connected I can start the car but since the pump is not supplying enough fuel quickly enough the engine will stop after (about) 20 seconds. Then I wait (about) 10 seconds and I can restart and so on. I took the cover off the float chamber and it was full and the float valve was working normally. I think at least one problem is a blockage in the inlet pipe. I used a bicycle pump to blow it out in reverse but that made no difference. I have plenty of fuel in the tank.

Ok. Try the test of disconnecting the fuel pipe from the carburettor and directing the hose into a petrol can. Does the fuel flow freely? The pump is capable of pumping way more fuel than the engine actually needs if everything is working properly. Also please confirm the fuel is fresh? Fuel goes off really quickly these days. A few months is all it takes.

[paul 300358]

Have you considered that the problem could be electrical?

[Tommac]

Thanks for suggestion - I tried this and it will tick very slowly with or without the outlet connected or disconnected. The fuel is fresh. The engine starts freely but soon runs out of fuel.

[svenedin]

Ok so the pump runs fast (normal) with nothing connected to it. This suggests there is no electrical issue.

With the inlet connected the pump only pumps slowly regardless of whether the outlet hose is connected to the carb or not. Have I got that right?

I still think there is a partial obstruction of the fuel line from the tank or that the fuel pump filter is blocked. Please check both. It is very easy to check the pump filter.

Stephen

[paul 300358]

Have you considered that the problem could be electrical?

Are you sure the problem is with the pump, have you got a spark when the engine dies?

If you run the engine then turn off the ignition as soon as the engine stops, is there fuel in the float chamber?

[Tommac]

Stephen I think you’re right it is likely to be a blockage in the fuel line from the tank.

Paul yes I still have spark when the engine stops and there is fuel in the float chamber but at the point of dying there is no fuel showing in the transparent fuel filter. I checked the filter in the pump and this was fine. I’m sure that when it all works correctly the transparent filter should be full.

[simmitc]

Transparent fuel filter? Get rid of it, completely unnecessary, and could even be causing your problem. My main thought at the moment is that the hose from the pump to the carb might be breaking down and has formed a valve from a flap of rubber. I suggest removing the existing hose (and clear filter) and fitting a new length of ethanol compatible hose.

With the new hose initially in a suitable container, switch on the pump and see how much fuel it delivers in a minute - it should be easily a pint and maybe 2. Also leave the pump running and check that it does not stop after a short period. If all OK, then connect to the carb and run as usual to test that.

[svenedin]

Transparent fuel filter? Get rid of it, completely unnecessary, and could even be causing your problem. My main thought at the moment is that the hose from the pump to the carb might be breaking down and has formed a valve from a flap of rubber. I suggest removing the existing hose (and clear filter) and fitting a new length of ethanol compatible hose.

With the new hose initially in a suitable container, switch on the pump and see how much fuel it delivers in a minute - it should be easily a pint and maybe 2. Also leave the pump running and check that it does not stop after a short period. If all OK, then connect to the carb and run as usual to test that.

I’m glad to see that old BMCEcosse’s loathing of the in-line fuel filter is alive and well . I totally agree that they are trouble. The low pressure pumps are not designed to work with such filters which is why the filter is on the inlet.

[geoberni]

Ahh, the classic additional information comes out. An old transparent Fuel Filter.
My car has one, because it came with one and I haven't got around to doing anything about it, but they are transparent for a reason, to let you see how grubby it's got....

Right at the beginning, I'd have taken the line from the Carb and pumped fuel into a clean container to see how well it pumps. It should be a little over 1pint/500ml a minute. Literally a check that takes a couple of minutes.....

[myoldjalopy]

Take the fuel line off the carb float so that you can do geobernie's pumping check with the filter in situ, stop and then de-couple it, so that the pump is then pumping without going through the transparent filter. If it is markedly slower through the filter then there's your problem, unless the line downstream of the filter is compromised in some way. As always, address any fire risks first (it seems obvious, but I did know one poor soul who was checking for a fuel leak under his car with a cigarette lighter and managed to burn himself quite badly in the ensuing fire! )

[simmitc]

I suggested checking the flow in the second response to the OP

[geoberni]

I suggested checking the flow in the second response to the OP

I was just being subtle and saying it again

[svenedin]

I suggested checking the flow in the second response to the OP

Yes and I suggested it in the very first response