CU engine not starting

[Choppski]

Hi guys,

Decided to do a service on my CU Aircooled engine as the camping season is about to hit full swing and i thoughts i'd change the spark plugs, dizzy cap, coil. I'm using WR7CC bosch plugs which i gapped to 0.7mm (it said 0.8mm on the box but the Haynes said 0.6 to 0.7mm, hence the regap). I didn;t replace the HT leads.

The old plugs looked brown with some black sooty deposits - a little rich on the fuel i think, but now where near the extremes you see on the plug condition guides.

I made careful note of the connections to the coil before removing and did a straight replacement.

i also gave the carbs a quick blast of cleaner for good health.

When i turned the engine over, it turns quick but would not fire. bugger. so decided to retrace my steps and put the old coil back on. The engine then struggled to start, but start it did. It ran for about a minute then cut out and would not start. BTW the smoke out the exhaust was a little blue on start up then went a little white. Its normally very clear and doesn't normally burn oil.

so i then changed the dizzy (bosch), no joy. Changed to an older (but was working) rotor, no joy.

went back and took the plugs out and checked gaps - still at 0.7mm

I got my wife to turn over the engine while i disconnected the coil plug to the dizzy and held it close to the engine - blue spark - but only one? Not the rapid fire Haynes suggested i'd see.

Very frustrating - any ideas tips etc?? i suspect its the coil connection/ HT leads but don;t know where to go from here...

Help

[dapple]

Have you checked the in line petrol filter, that's what was stopping mine starting up

[edoh]

sure the leads were put back on the right way?
https://club8090.co.uk/wiki/Pe ... ring_order" onclick="window.open(this.href);return false;
leads fully in (including the one to coil)?
rotor arm in nice n snug?
coil connections ok?
petrol in tank?
what happens when you turn engine over?

have a lookski n let us know -

reluctant starting file on the wiki - always worth a look -

[sarran1955]

Hello,

Some pictures of the engine bay would help.

Did the engine run ok last time out.

What sort of ignition do you have.

Standard Solex carbs

Does the dizzy have one or two spigots on the vacuum canister .

What coil did you buy....if you have mechanical ignition ( points and condenser) you need a coil with resistance
( say between 1,5 and 3 ohms). If you have an electronic,(transistorised) ignition then the coil is zero resistance.

Are all the vacuum hoses in good condition.

With the engine hatch open have your faithful assistant switch the ignition on.. do you hear a click.

Use a voltmeter to be sure that you are getting 12 volts to all the terminals.

Did you remove the dizzy. If so how did you make sure that every thing was lined up 'timing wise')

Did the cap go back on nicely

These are good reliable engines, that do need to be set up correctly

An example video:

http://www.youtube.com/watch?v=4qayyc9Z4E0" onclick="window.open(this.href);return false;

Work safely, one bit at a time....

Its a VW thing..

Cordialement,

[Choppski]

Hello again. Fuel filters, were checked and the pump (electric) appears to be working fine.
I have standard solex carbs (34 pict 3's i think) running a electronic ignition (std VW) with two lines of vaccum running off the dizzy.

i did check the HT leads went on the right way, then checked again. i made sure it lined up by checking that the No1 lead was in line with the notch on the dizzy at about 4 o clock - which is where it was when i pulled it off. BTW i did not alter or move the dizzy for timing advance/ retard.

12V is getting to the coil when the ignition is switched on.

The coil was a new Bosch black one from JK. It replaced an old German Bosch coil.

Well after a lot of head scratching, amazingly the engine started the next morning. Then wouldn't, then would.....very strange. A friend came over to help me problem solve and the best we could come up with is a loose wire connecting to the coil. so changed to a new connector (it was wobbly and fairly furred up). then the engine fired up a few times.....then died again. I tired a continuity test and few wires to the coil and the electronic booster and all seem fine. Thought i's try it again and the engine fired up no problems. Since then i've done several short trips and no issues.

What the heck was wrong - no idea- but she is running!

My fried suggested it could be a loose ignition barrel connections, but i waggled it a few times when the engine was running and no issues- kept going.

I'm not complaining, but any other things to check? sorry for the essay, but it helps with more info i find. Nice link Saran1955!

[ajsimmo]

I got my wife to turn over the engine while i disconnected the coil plug to the dizzy and held it close to the engine - blue spark - but only one? Not the rapid fire Haynes suggested i'd see.

Well after a lot of head scratching, amazingly the engine started the next morning. Then wouldn't, then would.....very strange.

My fried suggested it could be a loose ignition barrel connections, but i waggled it a few times when the engine was running and no issues- kept going.

I think your friend may have been right here. I had a van in that did the same thing, and had no spark when turning over until you let the key return from cranking to "ignition on" position, then it sparked once causing the engine to fire on one cylinder. Gave the impression it was just about to fire up if you tried again, but of course it didn't - just did the same thing again.
Problem was in the ignition barrel so that when you turned the key to crank the engine you lost the ignition feed to the coil. Pressed the plug tighter onto the back of the barrel and van started up fine. I could then start it or recreate the fault at will. The wear was inside the barrel switch (loose/worn connections) and once the plug was cable tied on tight to the back of the barrel the problem was eliminated.

[Choppski]

funny thing is it has been starting and purring like a kitten.....i'll have to have a look after the camping this weekend. Will keep you posted.

thanks for the replies so far guys.

[Choppski]

Well the update is - she is still running and starting sweet. bloody weird. but at least she is working ok. fingers crossed.

[morzov]

This might be complete rubbish but i had a similar problem. Then last week whilst doing some work in the battery compartments I put the much newer leisure battery under the driver's seat and the van has fired up first time every time since.

[Choppski]

This might be complete rubbish but i had a similar problem. Then last week whilst doing some work in the battery compartments I put the much newer leisure battery under the driver's seat and the van has fired up first time every time since.

Thanks - but i think i forgot to mention i had put a brand new battery in 2 weeks ago (used several times with no issues). i too thought it could be a battery issue but checking the voltage at the starter battery showed 14.2V, so it looks to be charging ok. I did go a check fan belt tension as well though, just to be safe.