Hard to start - ignition timing issues?

[mike1864]

My cold starting problem was solved, discussed in another thread, was that I had connected the coil feed wires the wrong way around. In a neg earth car, the white wire should go to the +ive terminal of the coil.

From my readings of various coil polarity threads, I'd expect reversed coil wiring to only marginally affect performance &/or long term component life.
So can the OP check whether now un-reversing those wires really immobilises the engine?
If it doesn't, the real fault lay elsewhere; and - as often happens - it had resolved itself in all the disturbance.

[svenedin]

My cold starting problem was solved, discussed in another thread, was that I had connected the coil feed wires the wrong way around. In a neg earth car, the white wire should go to the +ive terminal of the coil.

My car is still a pig to start, so I've just checked my coil wires and the White goes to +ve and white/black to -ve, so that should be correct.

I did get it to start just now eventually, but it was running roughly with some misfiring. But some days it idles smoothly - it just all seems rather random. I don't understand it.

All in all, I still don't trust it out on the road yet, sadly.

If it isn't fuel delivery related (pump, float chamber, choke) then perhaps it is an ignition problem.

Get a set of these: https://simonbbc.com/sparkrite-spark-pl ... TfZ_DSLhcT

Now you can observe whether you are getting a good spark to all 4 spark plugs. You say the engine sometimes runs well and sometimes misfires, you will now be able to see whether the different behaviours of the engine is related to spark.

It doesn't seem to have been mentioned yet but if the fuel is old you can have exactly the problems you are having. Old being more than a few months. Old fuel is difficult to ignite in the engine. If this is the case, drain out the old fuel from the tank and start with fresh fuel. You can keep the old fuel and add a small percentage back to each fresh tank of fuel just as a means of getting rid of it.

Another way to prove it is a problem with the fuel is to disconnect the fuel pump electrically (remove the wire from the terminal on the cap), remove the lid from the float chamber, mop out all of the fuel in there and re-fill the float chamber with fresh fuel. Then try to start the car. There is enough fuel in the float chamber for the engine to run for several minutes.


Stephen

[KevinB]

Thank you Stephen, I shall work through your suggestions and report back.

[myoldjalopy]

The vast majority of won't start/poor starting/running problems are ignition related. As OP says some days it runs smoothly and others not, it may well be a loose connection in the dizzy, or at the coil, or a failing capacitor. I have had a dodgy rotor arm cause erratic firing in the past. I did suggest checking the dizzy cap - look for cracks/tracking and the operation of its spring loaded carbon bush. Check everything visually first and then, if you are going to replace any part, do it one bit at a time so you can keep track of what has been done.

[svenedin]

The vast majority of won't start/poor starting/running problems are ignition related. As OP says some days it runs smoothly and others not, it may well be a loose connection in the dizzy, or at the coil, or a failing capacitor. I have had a dodgy rotor arm cause erratic firing in the past. I did suggest checking the dizzy cap - look for cracks/tracking and the operation of its spring loaded carbon bush. Check everything visually first and then, if you are going to replace any part, do it one bit at a time so you can keep track of what has been done.

Absolutely. Hence my suggestion to get some of the neon spark plug caps. Then there is a clear visual indication that when the engine misbehaves it is an ignition issue.

Stephen

[KevinB]

I've now got one of the sparkrite indicator lights and the ignition seems okay. It is making HV at least.

But ... the float chamber was full of a sort of sand-like crud. I don't know why it didn't notice this earlier (see photo - dry with sand emptied).

Some people online have suggested this might be to do with E10 petrol.

Now to clean out the carb.

[Bill_qaz]

I wonder how are such large particles getting past your pump filter, is it in place?

[KevinB]

I wonder how are such large particles getting past your pump filter, is it in place?

I can't understand that either. Particularly as there’s also an inline filter between the pump and the carb. I have not yet checked the pump filter.

[mike1864]

I make cleaning my pump filter and float chamber part of the annual service. Plus squirting and wiping the pump points!

[myoldjalopy]

I make cleaning my pump filter and float chamber part of the annual service. Plus squirting and wiping the pump points!

What do you squirt them with?

[kevin s]

I had a issue with ours cutting out running poorly etc, after going through the whole fuel system I found the tube between the float chamber and jet was full of crud which came out when blown backwards , we have a filter king, which is clear, I think this crud has been there for ages and was broken down by ethanol.

[mike1864]

I make cleaning my pump filter and float chamber part of the annual service. Plus squirting and wiping the pump points!

What do you squirt them with?

Electrical contact cleaner, from an aerosol. I do the fuse contacts and the ignition HT and LT connections while I'm at it.
None of these seems to be in the Manual, but these elements are often the cause of breakdowns.

[myoldjalopy]

OK great, thanks. I have dipped a piece of thin card in thinners before and dragged it through the pump points a few times. Then with a clean piece of paper. Seems to work.

[KevinB]

I have now cleaned out the float chamber and the outlet into the jet pipe. The car is now starting and running MUCH better.

I did not however rebuild all of the the carburetor parts. Probably should have, but l just wanted to find out if clearing the obvious problem helped. It did.

Thanks for all the help here.

[KevinB]

The improved starting didn't last long
Soon after, it seemed that petrol had stopped being pumped to the carb. Engine wouldn't fire, and there was no sign of fuel being pumped into the transparent inline fuel filter.

So I have tried to rebuild the fuel pump using the guide Stephen linked to in his thread on this subject.
I have also looked at this SU guide.
https://sucarb.co.uk/technical/technica ... reassembly

I have not touched the points or diaphragm, only the inlet, filter and outlet. See photo.

I put it back on the car and it sounded like the points and the diaphragm pumping was working well, but no fuel came out. So I've done something wrong.

So could you please look at the order of the components in the outlet valve and spot anything that looks incorrect?

Pump components in order

20260411_150700~2.jpg (1.06 MiB) Viewed 62749 times

[svenedin]

It looks OK to me assuming the other valve disc is already fitted.

When you have fitted the valve disc that goes in the valve cage and is secured with the circlip, make sure it rattles when you shake it.

Are you sure that the fuel pipe from the tank isn't blocked with crud? I had no end of problems some years ago and in the end the fuel pump from tank blocked completely. The only solution was a new fuel tank (it was very rusty inside).

Another possibility is that there is an air leak on the inlet side and the pump is pumping air. The inlet and (outlet) spigots need to be rather tight.

Best of luck.

Stephenn

[KevinB]

Thank you Stephen. I will keep going at it.
I am beginning to think the tank/fuel line might be to blame, but then again, it was running so well a couple of days ago once I had cleared the carb crud ...

[Bill_qaz]

You could try putting the pipe to the carb in a container and switch on ign to check flow from pump when you reassemble.

[KevinB]

The pump is dry, it's just not sucking up petrol. So nothing is coming out of the pipe to the carb.

Is the pump really supposed to be self-priming? Maybe I could try to prime it with petrol somehow?

[svenedin]

The pump is dry, it's just not sucking up petrol. So nothing is coming out of the pipe to the carb.

Is the pump really supposed to be self-priming? Maybe I could try to prime it with petrol somehow?

The pump is absolutely self priming, there is no need to prime it with petrol.

Is the pump ticking away rapidly but no petrol coming out of the outlet or is the pump ticking a few times then falling silent? If it ticks rapidly but no petrol comes out then there could be an air leak on the inlet side or perhaps a split in the diaphragm. If it ticks a few times then falls silent then I suspect the pipe from the tank is blocked. You need to ascertain whether the pipe is blocked. Find some suitable rubber or plastic tubing to connect to the metal fuel pipe and try to blow down it. I would not recommend you try to suck up petrol!! Unfortunately, if the inlet to the pump blocks and the pump cannot pump it can overheat and destroy the pump coil. Rarely, the pump can draw in air due to the screws that secure the body of the pump to the base being loose. You could check that too.


Stephen