Problem starting / running

[pjh56]

I have not had the opportunity to start my car since last October, when I did I found the battery flat, now fully charged.

Today I thought I would reconnect the battery and see if it would start, it did but not very well. After some coaxing the engine fired but sounded rough and would not respond to the accelerator or choke, this got worse as time went on and now will not start.

I have replaced the spark plugs and checked for a spark on all leads.
I have checked the fuel delivery into the float chamber.
I have checked for blockages in the air filter.
I have checked to see if the piston inside the carburretor gets stuck and it doesn't, there is also oil in the dashpot.

Tomorrow I was going to check that fuel is getting from the float chamber to the carb, should have done it today really.

While the air filter was off I tried squirting fuel directly into the carb and this did nothing. I did notice that nothing in the carb moved when either the choke or accelerator were engaged. It might be a stupid question but is the piston (see gif) supposed to rise and fall when the accelerator is engaged?[frame][/frame]

[MarkyB]

It raises and falls with the air flow not the accelerator.

I suggest you check the points gap.

[pjh56]

Thanks Marky,

Did you recognise the car from a wet 'n' windy Sheppey?

It might well be the points as I tried cleaning them just before it got worse, maybe I have messed up the gap.
I also read that it might be something to do with the vacuum pipe having a leak or something but that wouldn't explain why the problem has worsened. Something for me to check tomorrow if it's dry.

thanks again

Peter

[alex_holden]

Perhaps the old petrol in the tank has gone a bit 'off' (lost its more volatile ingredients). Try filling up the float chamber with some fresh stuff.

[bmcecosse]

If you added petrol directly and it still didn't run - the problem IS with the electrics. Check for sparks.

[pjh56]

Hi Roy,

There are definitely sparks from each plug as I tried them all individually against the engine block.
The petrol I used was from a petrol can I use for the lawn mower and I must admit it has been in there as long as the petrol in the car. I will buy some new tomorrow and maybe try Alex's suggestion . Can I just check that I was squirting the petrol in the right place. I removed the air filter, raised the piston and squirted a syringe full directly toward the engine, is that correct?

Peter

[bmcecosse]

Yes! If in a sealed can it should have been ok. HT leads on correct order? maybe it's just flooded. A squirt of 'carb cleaner' (toluene!) invariably gets them going - IF - there are sparks at the right time.

[mike.perry]

Running but misfiring could be the wires in the distributor not in the correct positions and shorting out. Just had this one when I changed the base plate.

[beero]

If it has not been run for a few months then one or two of the valves may be stuck down. Had this on mine but it had been stood a bit longer (25 years)

[MarkyB]

Now you mention it, I do remember the car from windswept Sheppy.
The nature of the misfire can be revealing, if it's regular then one or maybe two pots aren't firing.
If it's pretty random then I'd be looking at the cap, points or even the coil.

If it wont start at all today then take the plugs out and warm the tips on the gas cooker.

If you can get it to run, then run it for a few minutes then turn off and see which plugs are hot, these are the running cylinders.
beware! they get VERY hot.

[pjh56]

I managed to get the car started this morning after putting the old spark plugs back in and spraying the electrics with wet start but it was still sounding rough. I emptied the float chamber of fuel and replaced it with fuel from a can. I did notice that when I refilled the chamber it stirred up a lot of sediment which had been stuck to the bottom of the float chamber

All plugs were hot so I presume that all cylinders are fine, the only conclusion I can come up with is that the carb is dirty. Looking in the manual I thought it was beyond my abilities to try to dismantle and clean, I will have to try and get a mobile mechanic to come and have a look.

[bmcecosse]

The only thing that can really go wrong is if the piston doesn't rise/fall nicely in the bell. Try with finger - does it lift up quite easily and fall back with a nice clunk ? Nothing much else can wrong with an SU!

[mike.perry]

Dirt in the float chamber is normally trapped at the bottom with a well surrounding the fuel outlet so it does not get sucked into the engine. Clean the float chamber by disconnecting the fuel pump electrics and running the engine until the fuel in the float chamber is used. Dry the residue fuel with a clean tissue and suck any remaining dirt out with a vacuum cleaner.
I still think that the distributor wires are a more likely cause.

[pjh56]

Thank you to everyone for their help.
Well the Hometune chap came and fitted new points,plugs and condenser did a diagnostic and tune up. it now goes at 180mph in fourth (only joking). It runs sweet as a nut. One thing he did point out was that the hole in the brass connector at the end of the wire on the condensor was not big enough to accommodate the plastic insulator, he had to file it slightly bigger. Just a tip for the future.

Thanks again
Peter