9 replies to this topic

[Retro_10s]

Hey guys..

Right,... basically, I can't get my 1984 998 auto to fire. I've definatley got spark, and I've definatley got Fuel (have checked.) All it wants to do is backfire through the carb!!

Now... I've done the old, 'whip spark plug one out and make sure the piston is the top when the points are open' and that was fine,.. I've adjusted the points to the correct gap, I've put a brand new starter on.

Back firing through the carb is caused by incorrect timing,.. correct?... so it's firing at the wrong time,.. when the inlet valves are open right?

I can make it backfire more,... or less,.. depending on which way I turn the dizzy however no where will start!

The coil wiring had been messed with by the looks of things in an attempt to run a 12V coil, as I understand it.. a 1984 mini should have a Ballast resist Coil running off a 4 terminal solenoid. All seems fine, and the spark is healthy (though it is an orange... condensor breakdown?..) Ballast wiring afaik is,... A yellow/white wire, and a pink wire on the + side of the coil, and two black/white wires on the - side, all seems fine,.. is there meant to be a wire coming from the dizzy to the coil?... there seems to be one present but it's not wired directly to the coil.. it disappears into the loom.

Iv'e ordered a Mutimeter so I can find out what coil i'm definatley meant to have and so i can trace electrical problems easier but for the time being I'm a Bit stuck, could anyone clear any of this info/thee symptoms up for me?....

Edited by Retro_10s, 17 August 2007 - 06:30 PM.

[GraemeC]

Certainly sounds like a timing issue! Have you done the old 'whip spark plug one out and make sure the piston is the top' of the compression stroke 'when the points are open' ??

You'll need to take the rocker cover off and check the rockers on no1 are rocking (loose).

Alternatively line up the marks on the bottom pulley and timing case cover or if you have the inspection hole on the clutch cover look in there until the marks on the flywehhl match up with the little pointer in the hole.

[Retro_10s]

Have you done the old 'whip spark plug one out and make sure the piston is the top' of the compression stroke 'when the points are open' ??

yep..,..

Now... I've done the old, 'whip spark plug one out and make sure the piston is the top when the points are open' and that was fine,.. I've adjusted the points to the correct

You'll need to take the rocker cover off and check the rockers on no1 are rocking (loose

blast, forgot to check that...

It definatley makes me think it's got to be timing related as otherwise it wouldn't spark at the wrong time... But with the coil as it is...hmmm could be elctrical fault too.

Outta interest... converting ballast to 12V... how? (yeah i know it's technically not as good as ballast.) just interested

Edited by Retro_10s, 17 August 2007 - 06:54 PM.

[Retro_10s]

dk... i see you reading this thread, c'mon man... share the knoweledge

[dklawson]

No, backfiring out the carb is not typical of timing issues, it's typical of fuel starvation.

You said you've got fuel. Where did you check this? If you disconnected a hose to see if the fuel was reaching the carbs, that's only part of the situation. Did you open the float bowls to make sure fuel was in them? Has the car been sitting for a long time... long enough for gum and varnish to build up on the needle and jet tube? Is there a lot of sediment in the float bowl? Go through the fuel system carefully and make sure fuel is in the float bowl and that there's nothing preventing it from passing through the jet tube.

You've now obviously made electrical adjustments. Start at square one and reset everything electrical before moving on to the fuel system. Set your STATIC ignition timing. Make sure your points are clean and gapped correctly. Fit a new condenser if in doubt. Confirm that the spark is strong and blue at the plugs. Once you know you've got a strong spark at the right time, return your attention to the fuel system.

EDIT: by the way, that orange spark may indeed be a failed or failing condenser. Replace it as part of going through the electrical checks then check the condition of your spark. Likewise, if you've got a 12V coil (3 ohms primary winding resistance) and you're powering with the pink wire from the ignition switch, it's not getting enough voltage and will produce a week spark.

Edited by dklawson, 17 August 2007 - 07:54 PM.

[Retro_10s]

Doug, i appreciate the time you take writing out replies mate,.. greatly greatly appreciated.

You said you've got fuel. Where did you check this

plugs are definately wet

Is Difference in spark colour signs of condensor failiure?.... It's running on spitfire plugs (these are what were in there) i think i'll change them to NGK, but the splitfire ones wouldn't stop it starting surely?...

Has the car been sitting for a long time

I believe approx 2 years.... (have changed petrol because of this.)

About the condensor... is it something a knackered condensor could do... to change the colour fo the spark?.... is it a sign the condensor's knackered anyway regardless of the other probs?

[Retro_10s]

hmmm, ok... I just went outside and looked at my dizzy... Was the condesnsor ever fitted outside of the dizzy itself or always on the inside?

There is a cylindrical object strapped to the dizzy next to the vaccum advance unit.. I assumed this was a suppressor,... but after having opened my dizzy to find no condensor i'm not so sure,...

[Retro_10s]

Noooo, i know why it has no condensor inside.........

It's a ducellier.

Edited by Retro_10s, 17 August 2007 - 09:03 PM.

[dklawson]

Electronic ignitions don't use condensers. I don't know anything at all about the Ducellier distributor. In answer to your question, yes, a failing condenser can make a weak yellow/orange spark.

When was the last time the car ran? Was it prior to the 2 years you say the car was sitting? If so, don't assume wet plugs mean things are correct with the carb(s). Were I in your position, I'd start by finding out if the Ducellier has a condenser and replace it. Make sure all the other ignition settings are correct. Invest in those new NGK plugs and if the spark plugs, cap, rotor, or wires look the least bit bad, replace them. Get all the ignition issues put aside as possible causes, then move onto the fuel.

Which carb(s) is this? Are you running a single carb or duals? Regardless, I'd paint mark the vacuum chamber to carb body position, then carefully remove the vacuum chamber with the piston and needle. CAREFULLY clean the needle with carb cleaner to remove any gum and varnish. If you have spray carb cleaner, insert the spray tube down the carb's jet tube and spray it full of carb cleaner. Work that plastic spray tube up and down in the jet tube to work loose any deposits. If you have compressed air available, blow through from the float bowl into and out of the jet tube. You want any deposits out of there. Continue your cleaning by taking the float valve apart and flushing out its seat. Then check and set the float level. Don't forget to refill the dashpots with oil.

Just because the plugs are wet doesn't necessarily mean the carb(s) is/are in good order. As I mentioned, reset all the ignition settings then turn your attention to the carb(s).

Edited by dklawson, 18 August 2007 - 12:31 AM.

[Retro_10s]

cheers doug, I realised as soon as I opened up dizzy and compared it to a haynes that it matched a ducellier dizzy.

I don't know anything at all about the Ducellier distributor

Unfortunatley it's Got a reputation for being totally totally useless, points need adjusting every 2-3 weeks in most cases, condensors seem to fail very quick on them too,.. generally regarded as a big pile of rubbish.

Most people seem to get round the problem by Getting a Lucas carb built for the same engine and then it's in the rough area it needs to be... hmmm. this engine is not going to be in for long but i'd like to get it running at least.

don't assume wet plugs mean things are correct with the carb(s). Were I in your position, I'd start by finding out if the Ducellier has a condenser and replace it. Make sure all the other ignition settings are correct. Invest in those new NGK plugs and if the spark plugs, cap, rotor, or wires look the least bit bad, replace them. Get all the ignition issues put aside as possible causes, then move onto the fuel.

Single carb, Hs4.... it's very dirty but seems to be working ok... On tuesday I shall take it off... take it apart, clean it up and see what i've got underneath all the gunk. Then I'm going to buy a condensor for the dizzy, get some new plugs and pop some new points on it... also going test i'm getting the right juice to the coil etc when my mutlimeter arrives... After checking a part code on the Coil... it seems I have a standard 12V,.. but it's meant to be a ballast type, so that's something else to change.

Again, thanks for your invaluable words Doug.