Engine does not start (fixed...for now)

paydase · Post by **paydase** » Sun Jun 21, 2015 7:19 pm

I have had ignition/carburation problems since some time, in particular when engine revs above 3000 rpm at full throttle, with occasional apparent fuel starvation and detonations.
Bizzarely, the issue does not appear on every run and it turns out that sometimes the engine responds nicely up to 5000 rpm.

Today, when I cranked the engine (using full choke) it painfully started on second attempt then collapsed. More attempts with or without choke did not succeed.
I then noticed that I had not heard the usual ticking of the fuel pump when turning the key for ignition.
I verified that the 5 amps fuse for the fuel pump is not grilled.
What puzzles me is that the fuel filter bowl however remains full of gas and I am wondering how cranking the engine would not empty it because of the carbs maybe sucking the fuel. But maybe I'm wrong, the pump should push the fuel and without it, no fuel move...

I suspect therefore a dying fuel pump (it seems to be an original submersible Lucas pump, positive earth) but am not sure...
Do you think that could be the culprit?
I have one spare fuel pump.

I imagine that the first check to do would be to measure voltage across the wires in the boot to verify that the pump is correctly powered.
To do so, how should I proceed to remove/open the small block covering the electical wires (is it cliped)?

Then, if voltage is there and if the pump does not work, how to proceed to remove the pump and make the change safely?

Obviously I should first disconnect the battery.
Then I should probably empty sufficiently the fuel tank (right now it's full and I fear that if I remove the flange on the tank, fuel will flow out). Is it possible to suck up some fuel through the reservoir cap or should I empty the tank through the drain plug (difficult if seized)?
Any other useful advices (verify that the pump does not touch the bottom of the tank, specific care on mounting, orientation, etc. change the seal or not...)?

Help appreciated, please indulge my questions, it's my first mechanical repair on this car...

abowie · Post by **abowie** » Mon Jun 22, 2015 3:15 am

Disconnect the fuel pipe at the fuel filter. Put it into a suitably sized container and turn on the ignition. Fuel should come out quite quickly.
If it doesn't then you can work back from there.
Could be the pump, could be kinked or squashed hoses or pipes, could be a problem with the fuel uptake pipe and filter in the tank.

Post by **Heuer** » Mon Jun 22, 2015 10:18 am

The early submersible pump does not tick, it whirs as it uses an electric motor to constantly pump the fuel. If it is the original (notoriously unreliable) Lucas item you may want to consider replacing it with one of the SNGB modern submersibles to avoid future problems. Other things to check are:

1. the correct fuel filler cap is fitted - it should have a breather hole. Try running without the cap
2. the fuel tank sump filter is clear. Remove the sump and check for debris

paydase · Post by **paydase** » Wed Jun 24, 2015 7:58 pm

Thank you, Andrew and David, for your advices.

I could not make a new try before tonight.
So I started by opening the fuel cap, listening for any whistle in case there would still be some depression in the tank. Nothing.

Then I turned the key for ignition and, this time, I heard very distinctly the noise of the pump, a whirring indeed (although in the past I also heard some sort of slowing ticks after some time, as if the pump had reached its top pressure...).
Put the choke and pushed the button for cranking and the engine roared!

Afterwards, I made several other trials of re-igniting (with and without fuel cap, which btw seems not to be correct as it does not have the ventilating hose) and each time I got the noise of the pump.
So my pump still works but...not sure it will be reliable. Could be a sticking relay or bad electrical contacts or worn electrical motor....
I better take with me a spare for each trip or I should consider replacing it!

Btw, when inspecting the engine bay for kinked or squashed hoses at idle, I noticed a fuel leak ( a drip every 5 seconds!) on the feeding line of one of the carburetors. Apparently a worn seal (the small black one in the centre of the pic):

Difficult to notice when driving (apart from maybe some smell), as the fuel evaporates quickly within the hot engine bay and the leak seems to happpen only under pressure, so stops when engine is stopped...
Scaring! Needs a quick fix...

ralphr1780 · Post by **ralphr1780** » Thu Jun 25, 2015 7:46 am

Serge, glad the engine is running again.
There is no relay for the fuel pump (cost cutting). The external SU pump is the one that ticks.
What you have now experienced are the symptoms of a quitting pump, it would work perfect for some time and randomly cease leaving you stranded.
As for the fuel leak on the carb banjo, there are 2 fibre washers one on each side of the banjo. Be cautious in dosing your torque when undoing/tightening, as you could easily ruin the float chamber lid.

Post by **Heuer** » Thu Jun 25, 2015 9:09 am

A new SNGB submersible pump costs ?135 and you should buy one without hesitation. Driving along playing Russian Roulette with the original Lucas pump will ruin your love of of the car and the cost of recovery will be significantly more than the cost of the pump. Put the original pump in a box and hand it over to the next generation of owner when the time comes.

paydase · Post by **paydase** » Thu Jun 25, 2015 4:17 pm

I agree with both of you. Changing the pump is needed and that's on my workprogramme.

Thanks also Ralph for the advice concerning the banjo.

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Engine does not start (fixed...for now)

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