t5 still wont start

[rodmca]

My mk1 t5 saga goes on. Ive just replaced the ignition unit after being told by a mechanic that was the problem but it has made no difference!!! There is plenty of fuel getting to the carb, with a good spark and good compression. When i try to kickstart it and remove the air filter it blows petrol back through the carb. Any ideas whats wrong or how to solve it? Thanks for any help!!!

[bryno]

Could be any of a number of things, so to narrow it down..

What happened to suspect the ignition unit was faulty? how was it running prior to that? has the motor been stripped/rebuilt? what else have you tried?

Blowback through the carb could mean timing is out (but not likely unless it's been in pieces), snapped woodruff key/flywheel slipped on crank..

[rodmca]

Thanks for the help Bryno.

it has had trouble starting for a few weeks now ( i havent been out much over the winter but i always had it ticking over in the garage a couple of nights a week and a few miles done at the weekend and everything seemed ok) , there was no life in the engine most of the time, its maybe started twice in the last few weeks and ive been trying to start it nearly everyday to try and get to the bottom of it. There was a bit of a spark from the old ignition unit but i thought it might be on its last leags and as there was no problem with the fuel getting to the carb i thought this might be the problem. I have tried different spark plugs but nothing.The carb was then taken out and cleaned and all the gaskets look fine so everything was put back together but still it wont start. As you say timing might be the problem, ive sort of ran out of ideas so if you can shed any light on what may be wrong it would be much appreciated.

[joey]

First thing I'd be checking is whether your HT lead is earthing out on the motor, you'll get a decent spark with the plug out but put it back in and nothing. Check for it by kicking it over in the dark, if it's earthing out you'll see tiny blue sparks along the length of the lead.
Next thing....... how long has it been sat still???
If it's not been used for a while there's a chance that the slow running and choke circuits may be blocked. The only way you're going to find that out is by thoroughly cleaning the one you've got or trying someone elses that you know works.

[rodmca]

Thanks Joey will check the HT lead tonight.
There shouldnt be any problem caused by it sitting still as even though i havent done loads of miles over the winter i have been out most weekends just to keep things ticking over and everything seemed ok.

[bryno]

I'd also try draining the fuel and sticking some fresh in there if it's been standing for many months...

[dave1967]

Hi
If you have fuel blowing back through the carb then you must have either a timing problem or a crank problem. To blow back through the carb without igniting first the timing is either a long way out or your crank is slipping causing the fuel to be dumped in the chamber on the wrong part of the stroke. Be careful as there is a possibility it could ignite as it blows back.

In your descriptions above you dont say whats states the plugs in after you treid to start it ??

[rodmca]

Hi Dave

There is no noticeable problem with the plugs they seem ok

[dave1967]

Try starting it and then remove the plug , is it wet, oily, clean, or coked up.If you can work out whats going on inside the chamber then you are half way to sorting the problem. email me at [e-mail] your number.

[rodmca]

Hi dave

Thanks very much for the offer to help but ive admitted defeat and had it picked up last week by a localish vespa dealer to sort out. Im hoping to hear from him before the weekend so i can finally get back on the road and have things ticking over properly before the mot next month.

[skrappey]

I bet he'll be changing the piston rings for you.

Best of luck.

[rodmca]

Thanks for all the help and advice. It is finally all sorted out and it turned out the pick up coil was knackered and the timing was out. So anyone with similar symtoms check your coils!!! It passed the mot last saturday and we are back on the road just in time for our glorious summer!!! Happy scooting.