Engine Turns But Does not Fire Up

[smudge724]

Hi all wonder if anyone can help me?

A while ago I started up my 850 A engine for the first time in a year. Engine had been turned over by hand during the year. Engine started lovely and sounded sweet. I knew the dynamo was not working due to ignition light staying on. so changed the dynamo, It was a second hand dynamo bought on ebay changed it over, ignition light went off so thought happy days.
However since I put dynamo on I noticed engine was not running well, no power, running rough and losing power continuously. Now starter motor turns over but engine is not firing at all now. Can anyone offer any advice.

All I can think is that the dynamo is caursing the problem, The car is positive earthed could it be that the dynamo is negative earthed and this is caursing the problem? If it is how do I get around this problem.

Any help would be gratefully recieved.

[Spider]

It does sound like it could be lack of charge or could be other things too, however, since you've changed the Dynamo, it does sound like a place to start with.

If you can get it running again (maybe a jump start?) then check that it is charging. Ignore the lamp on the speedo, they are not a reliable indicator of a problem with Dynamos. Use a multimeter and check the battery voltage with the engine running, you'll need to get the revs up around 2200 RPM or more and the battery voltage should then be over 13.2V probably closer to 13.5.

If it's not charging, then check all the wires and connections, especially those on the battery and earths etc, before condemning the Dynamo.

[bmcman.ie]

have you re polarised the dynamo to its proper earth! ian

[smudge724]

Hi all thanks for your help, have not polarised the dynamo how do you do that? also if I have been running engine with the dynamo polarised wrongly would it damage anything?
Smudge

[Spider]

Hi all thanks for your help, have not polarised the dynamo how do you do that? also if I have been running engine with the dynamo polarised wrongly would it damage anything?
Smudge

If the Dynamo came off a Mini, then it's polarity will be correct, however the notion of re-polarising the Dynamo is an old wives tale, they will self polarise when they start working, however then can loose residual magnetism and sometimes if it's been sitting for a long time un-used it may need re-magnetising, pretty rare though.

[smudge724]

If not the dynamo what else could it be?

[zippypinhead]

If not the dynamo what else could it be?

"...A while ago I started up my 850 A engine for the first time in a year..."

First thing that jumps to mind is crap fuel. It doesn't take well to sitting around. After a year all sorts of things could be screwed up.
But, back to the basics... you need air, fuel, compression and spark to run an engine. My procedure for an engine that turns over but won't run is;
1.) Pull a spark plug, reattach the lead and ground the side of the plug against a head stud. Have someone crank the engine. Do we have sparkies???
2.) If we have a nice fat sparky, and as long as the sparkplug is already out, stick yer thumb over the hole & have someone crank the engine. Can you feel that there's compression?
3.) As long as we're at it, pull yer thumb out and give it a sniff. Can you smell fuel?

If you have all of the above, it would pretty much narrow it down to timing. But I doubt that is your problem since it ran once and you haven't messed with timing......