My V8S will not start - HELP Please

[morph2006]

I was driving down the A1(M0 just after midnight when the car just cut out and would not re start, electrics worked and fuel in the tank but no spark on lead from coil to dizzy.

I've replaced the coil and the lead to the dizzy also checked the resistor attached to coil which seems ok, fusses, battery ok but still will not start.

The car will turn over but does not start up, I can hear the fuel pump start and as it just cut I think it is more likley electrics.

Help any one please

Thanks

[GreenV8S]

It does sound like an ignition fault, which is good news, because the ignition circuit is quite simple. Since you know there is no spark on the coil HT you have already eliminated the dizzy cap, rotor arm etc as the cause so it leaves us with a duff coil, amplifier, pickup or wiring fault.

The standard coil is unballasted so the resister you mentioned is a bit of a worry, but since it was working OK prior to the problem I'll assume it is a component failure and not just the wrong parts fitted. Can you confirm nothing else has been changed recently?

As the first sanity check do you have 12v on the positive side of the coil?

If so, do you also have 12v on the negative side of the coil with the ignition on & engine stopped?

If so, do you get a spark at the coil HT terminal when you momentarily short the coil -ve to earth?

[burblev8]

I got some really good knowledge of the electrics and particularly ign/fuel system recently when I had a similar cut out. As GreenV8S says check liveliness of the coil first and trace back from there. Try a search on ignition failure etc. on this forum for a full list of likely suspects.

The good news is that in the tracing process you are bound to find several other problems waiting to happen that could have caught you out in the future. Good luck and let us know what you find just for the record.

[morph2006]

On the positive side of the coil there is no voltage until I turn on the igition and then I get 11.75v on both the positve and negative sides of the coil.

I have changed the coil and the HT lead from the coil to the Dizzy, everything else is as it was when working, tried the same test with the resistor disconnected but got the same result.

Cannot get a spark from the coil HT lead when I turn over the engineand and hold the HT lead against the engine block.

Thank you for the help, I was wondering about checking the relays ???

Andrew

[GreenV8S]

morph2006 said:

On the positive side of the coil there is no voltage until I turn on the igition and then I get 11.75v on both the positve and negative sides of the coil.

The coil primary winding is OK then. Did you try shorting the coil -ve* to earth briefly with the ignition on? If the coil is OK this will produce a spark at the HT terminal.

If no spark then the coil is duff.

If you do get a spark, suspicion moves to the ignition module on the side of the distributor. It isn't easy to test this, the best you can really do is crank the engine over and test whether the -ve terminal on the module cycles between 0v and 12v. If it does, you may have an LT wiring fault between the coil and the distributor. If it doesn't, you probably have a duff ignition module.

If the ignition module seems to be at fault and the replacement also doesn't seem to work, you can do a similar test on the electronic pickup inside the distributor. It's unlikely you'll need to do this though, my guess is the fault will turn out to be a duff ignition module.

Edited to add:

 • make sure it is the -ve one; if you earth the +ve you will blow the ignition fuse.

>> Edited by GreenV8S on Sunday 15th January 13:56

[morph2006]

Ok, sorted the v- of the coil and got a spark on the HT lead with the ignition on.

Got a bit tricky after this as I'm on my own today but finally got multi meter leads attached to ve- of aplifier mod. and an earth. When I turned over the engine voltage did not change so I'm now off to see if the local Halfords has one. If not I will get one on Monday from Rimmer Bros as they are just the other side of town from me. Lucky me!

Thank you for your help

[morph2006]

Just rang Halfords they have the dizzy but not the amp mod. so that's it until Rimmer Bros. open on Monday.

[GreenV8S]

morph2006 said:

Just rang Halfords they have the dizzy

Impressive, out of curiosity what price were they asking?

[morph2006]

Sorry did not ask price, but will no doubt be in there soon so will find out and post.

[morph2006]

Still not running, but getting to know how my car works !!!

Now have the following new parts on the car ...

Amp Mod.
Coil
Coil to Dizzy HT lead

And at last a spark on the HT lead from the coil, however only when the Dizzy Cap is removed. Which I guess means it's the Dizzy.

Have checked the resistance accross the connectors on the Dizzy to the Amp Mod. and got 3.5k ohms so it is ok.
New coil and Amp Mod also check out ok.

There is some dampness in the Dizzy Cap and on the pastic cover inside the Dizzy so left it to dry out, but will be going to get a new cap, rotor and leads in the morning as now I have gone to the trouble of removing all the leads to the spark plugs ( had to to get look inside cap ) I'm not going to the trouble of re-fitting without putting new leads on.

[GreenV8S]

morph2006 said:

And at last a spark on the HT lead from the coil, however only when the Dizzy Cap is removed. Which I guess means it's the Dizzy.

That sounds a little strange, can you clarify?

Do you get a spark at the coil HT terminal when you momentarily short the coil -ve to earth with the ignition on?

Do you get a similar spark when you crank the engine over?

I'd expect you to test for the spark by shorting the coil HT terminal to earth with a small air gap, for example connecting an HT lead, putting a spark plug in the end and resting the spark plug on top of the plenum. For this test the coil HT would not be connected to the dizzy and I wouldn't expect it to make any difference whether the dizzy cap was fitted or not.

[morph2006]

She runs ...

Changed the Dizzy Cap and rotor arm and she fired 1st time.

YES.

Thank you

[morph2006]

Details

I did get a spark when shorted to earth but never got any spark until I removed the Dizzy Cap. Inside the Dizzy was damp and when compared to new cap the old carbon rod in the centre of the cap was very worn down plus the rotor arm was also a little warn and marked.

There was also marks and build up of some white stuff on the contacts inside the dizzy cap leading to the ht leads.

[GreenV8S]

morph2006 said:

She runs ... Changed the Dizzy Cap and rotor arm and she fired 1st time. YES.

WooHoo! Well done!

[morph2006]

Thank you for your help.

One last detail ... just been looking at the old Amp Mod. and its got a hugh crack running accross the front face right through the case, so was worth changing.

[morph2006]

An update ...

You can get the Dizzy cap on 180' out, this is not stated in any of my manuals and I did it! The car will start all be it very rough, there is a small notch inside the cap which need to line up.

[greenv8s]

If you fitted the cap the wrong way round you're lucky that the rotor arm didn't smack into the cap.