Series 2 fuel problem

[JOH3648]

Hello

I am a new member and I am hoping for some advice. My Series 2 will not start - it will not even fire unless I squirt fuel directly into the carburettors. The carbs have been cleaned and overhauled and if I remove the section chambers and pistons I can see fuel in the jet. The pump pressure is good but for some reason the fuel is not getting from the jet into the carb and starting the engine. Having replaced the points, plugs and condenser I am getting a good spark. Any ideas would be much appreciated.

Trevor J

[mgcjag]

Hi Trevor welcom to the forum....give us a bit more background.....was the car running and now not......have you just done a rebuild.....etc

[cactusman]

If you are sure there is a spark at the plugs might be worth checking the firing order is correct especially if you have replaced the distributor cap or leads. Check the timing too...

Are you certain the level in the float chambers is correct....assuming you have SU carburettors the floats do leak with age and sink...leads to flooding and makes starting very difficult. Alternatively in the rebuild are the float chamber levels set too low....the fuel should be more or less at the top of the jet......see the workshop manual for details.

Dumb thought but if the exhaust is blocked then the engine will not pull air and hence fuel in.

If it ran fine before the carb rebuild then it is almost certainly an issue with the rebuild or the way the carbs are initially set so work through the workshop manual section on initial set up and then tune...

[JOH3648]

Thank you both for replying. The car had been in longterm storage and needed quite a lot of work to get it roadworthy and running. I had to replace the tank and jets which were seized up. I also had to replace a float which was causing a leak. I also replaced tne su pump with an electronic type. I tuned the carbs to the best of my ability and was pleased when it fired up straight away. I drove it for about 100miles with no problems. After not using it for about a month it was reluctant to start however it did fire up and after allowing it to warm up I went to the petrol station a couple of miles away it started to miss and lose power just before the petrol station but I managed to get there and filled up -I thought it might have run out of fuel. It started but did'nt last long and I returned home on the back of a transporter. I wasn't very happy with the spark so I replaced the points etc. On turning the engine over am getting a good spark but not firing unless I physically introduce fuel into the carbs. The float chambers are full of fuel and as I said if I remove the suction chambers and press gently down on the jets fuel splashes up. The choke seems to operate as per service manual specs. The cause must be something to do with fuel starvation but I am at a loss as to what? Any thoughts?
Trevor

[mgcjag]

Hi Trevor....have you replaced the fuel filter.....the glass bowl may look clear but the filter may be blocked

[cactusman]

If she ran for 100 miles ok after the rebuild then unless something came loose in the carbs I would start to suspect an ignition issue. Cracked distributor cap. Coil failed. The rotor arm has arced to earth. Try fitting a red rotor arm, replace the coil and examine the cap for cracks and the like. If on points replace the condenser too.

[paulsco]

Hi Trevor,

I assume the fibre washers are in the correct positions on the overflow pipes?

The one with the internal cutaways at the bottom.

If not you may get a vapor lock above the the floats and no fuel flow.

Paul

[ralphr1780]

Did you recheck the spark plugs? If it ran some 100miles overly rich, these could be fouled and will not allow the engine to restart, even if you have a good spark checked at coil and distributor and leads.

[Series1 Stu]

Hi Trevor

If you've got fuel at the carburettors and a good spark at the plugs then perhaps the engine isn't creating sufficient vacuum to draw the fuel/air mixture into the chambers. This could be caused by a leaky item somewhere in the vacuum system. It could also be caused by a blockage in the carbs caused by fuel ethanol varnish.

If you can check for manifold depression during cranking then that should give you a good indication to that side of things.

The other thing I can think of is the spark may be breaking down under compression. Perhaps check the spark using a Colourtune plug or similar?

Regards

[JOH3648]

Thanks to all of you for your suggestions - I have plenty of things to work through. Because it starts if I prime it through the carbs I tend to think it is a fuel issue - however time will tell
Regards
Trevor

[Ipace]

Hi
Just joined as given up with garages! I had a similar issue. The Car just ‘stopped’ after running fine and has to be pushed to garage. There is sat for a month ... first a dizzy cap and arm were to blame, then the fuel pump (I have now checked the old pump which works just fine), he finally blamed a dodgy soldered wire to coil. When I picked it up, started fine but when I stopped at home it just stopped, turning over. Not firing. On checking the fuel line between glass bowl & carb feed I can see air bubbles. I tried to loosen banjo and bleed out air but they don’t clear so I suspect sucking air or that’s reason why it won’t fire.
Could it be lack of fuel pressure to carbs?
I have fitted the old fuel pump and want to replace washers on banjos from fuel pump to car and fuel pump feed from tank but don’t know sequence... should I use fibre washers
Any thoughts?

[christopher storey]

Air bubbles ( presumably in the glass bowl ) suggest a leak somewhere. I should take the fuel filter out and see if it makes any difference just with the bowl in place but no filter .The filters are often "blinded" if there has been water in the fuel . I doubt that lack of fuel pressure is the culprit - if there is sufficient output from the fuel pump to fill the bowl , then there is sufficient to fill the float chambers provided there is no blockage. There are ( usually ) thimble type additional filters in each banjo and it is worth checking these , as if blocked they will certainly cause trouble

However, are you sure that all is well in the ignition system ? The old adage that 99% of SU troubles are with the ignition still holds true . It is worth checking both LT and HT out thoroughly particularly as aftermarket rotor arms have been found to become conductive when hot . A red arm from the Distributor Doctor himself ( even these have been faked by other sources ! ) is worthwhile

[madjack4]

Hi before going any further u have put petrol in and not diesel to check drain a small amount of fuel out pour it on the floor and leave it to evaporate if its petrol it will evaporate in a matter of minutes if its diesel it will not just a thought good luck

Regards

[Robbiee]

Hi
Don’t suppose it’s an over tightened Volume Screw that controls the bypass from the fuel float chamber to the far side of the butterfly valve?? Just a thought
Robbie

Otherwise I’ve found that most apparent non firing problems are electrical in origin!