I'm having problems with the 1250cc A series in my Coupe. It starts ok, runs smoothly with no choke, the mixture seems ok, but when I floor the accelerator it dies. The dizzy cap, leads and points were changed less than 500 miles ago so I think that should be ok. If I accelerate slowly it revs freely as well. It did run out of fuel, but there is an inline filter before the carb with plenty of fuel in.
All advice will be gratefully received, if I can't sort it soon there will be no time to get it MOT'd before Stoneleigh
Thanks
Griff

Is the inline filter one of those clear plastic ones with a paper element, as I have had one of those cloapse looked fine but it broke up and got stuck in the Jet, I had flames coming out the exhaust and intake when that happened back in the days of A series and SU carbs, car would start fine and drive fine until you tried to put any load on it then it would hit a wall and back fire and fart about., double check the points and the new plugs etc, as you may have a rogue faulty one,

Any air leaks? altho that should make idling a pain.

WEST

West

Yup, it is one of those clear plastic ones with a paper element - I also had flames coming out the back !

I'll bypass it tomorrow night. I thought I'd cracked it when I found the vacuum advance tube melted through.

Plugs and points were changed at the same time as the dizzy cap.

It has been standing at my friend's place for about 10 month's since the MOT ran out, until then it was fine. I wondered if the vacuum advance is sticking.

Griff

worth a check if its been standing that the vac and mechanical advance is working, also if it has been standing the fuel will have evaporated in the carb, and you would be surprised at the sludge left when fuel evaporates so give the float bowl/fuel jet a cleran out/check too while your their. Dashpot oil ok too and moves as it should?

WEST

Also check that the piston rises and falls freely in the carb and that's there's oil in the dashpot.

Sorry West, I obviously don't type fast enough!

West

Dashpot oil ok, it was a bit low though. I think I'll check the vacuum advance first. Would you expect to see much movement ?
I think you're right though - it's a fueling problem

Griff

Dino

I have checked and it seems ok to me, I found the dashpot oil was low by accident - by removing the filter and watching the the "thing " that the needle goes into ( sorry forgot what it's called - I'm an electrical engineer ) shoot up as I blipped the throttle, by slowing it down with slight finger pressure helped a bit with the problem.

Griff

Hi Griff, the 'thing' is usually referred to as a piston.
Lack of oil classically causes flat spots on acceleration. But as West said you need to clean out the carb really to eliminate any muck.
Also unleaded fuel seems to go off very quickly, if the fuel's been in there for 10 months that could easily be an issue!

Check the mechanical advance is working as well, not just the vacuum.

Also don't forget 90% of all fueling problems are caused by ignition faults and vice-versa

If it's run out of fuel recently it will have sucked up muck and sediment from the botom of the tank. It may also be worth blowing the line from the tank to the fuel pump clear with a foot pump. Stick an airbed type nozzle on the foot pump, remove the fuel filler cap and blow air down the pipe from the fuel pump end.
I had to do this regularly on an old Bond I had. The fuel gauge broke so I used to run out fairly regularly and the line blocked up frequently.

I had the very same problem when I got my 1275GT running after a very long lay up.
I would suspect the fuel has gone off.
To make life easier in the future I would suggest cleaning the complete full system out.
I had to renew most of the fuel lines and clean both my tanks out properly, oh and new fuel pump,carb rebuild, fuel lines etc etc.
I still have to change the filters(all 3 of them) on a regular basis.
Stale fuel is horrible stuff.

Thanks to everyone for your good advice, on closer inspection the filter was quite mucky, I've got the carb off for a clean and I'll be flushing the fuel pipes and tank as well. Trouble is can't work on the car until Good Friday which is cutting it fine for Stoneleigh

Griff

It's cutting it even closer for Detling

Did you enter the Drive it day tour????

I didn't enter in the end as I couldn't afford it (my wife was laid off ) - definately next year.
Didn't get to the Coupe on Good Friday as the weather was bad, but managed to work on it on last saturday.
I took the carb off and cleaned it, bypassed the clogged fuel filter. Fault still remains but this time it backfired quite
a few times, so I guess the fuel must be getting there .
Tried altering the timing to avoid backfire but couldn't turn the dizzy much. Turns out I was loosening the clamp bracket
Took the dizzy off and checked vacuum advance working - seems ok, but not sure how mechanical advance works.
Refitted dizzy (much swearing involved, I used to moan about mini's but a coupe is worse.)
Next weekend I'm going to check all the ignition system. I've given up getting it ready for Stoneleigh
, if I MOT at the end of May at least it'll be current for next year's Drive it day tour and Stoneleigh 2010

this is probably a curve ball, but worth a look maybe...

When I first had my Coupe tuned it was popping and banging, especially under load. Took ages to find but the HT lead was shorting on the chassis (it burned a very small hole through the insulation on the HT lead). Cured by changing the dizzy cap type, increasing the clearance from the HT lead to the chassis (and chucking / replacing the failed lead).