17 replies to this topic

[unburntfuelinthemorning]

The best of faults; an intermittent one.

 

My engine has started cutting out with no particular pattern to when.  It seems to happen at cruise or light load.  I believe it is an ignition fault as there is no mis-firing or spluttering - it's as if the ignition switch has been turned off.  Sometimes if I dip the clutch I can bump start it before stopping - other times I have to pull over and it will then restart and run fine until it feels like doing it again.

 

It's been difficult to diagnose anything as I cannot reproduce the fault when stationary.  I suspected the supply to the coil - replaced the relevant crusty fuse box connections, ran a new wire from the fuse box to the coil - cleaned the coil connections.  Got a few hundred yards up the road and it happened again.  This time I had connected a bulb to the coil positive terminal and tied it to the dash so I could tell if there was power getting to the coil and there was so it doesn't seem to be the coil supply at fault. 

 

I presume it has to be coil/points/condenser related.  The dwell angle is correct.  The distributor/cap/rotor arm/HT leads/condenser are all quite new but the coil isn't.  Can a coil fault produce these symtoms?  Or a condenser fault?  Any other ideas?

 

[phillrulz]

I had the same. Stopped at traffic lights and she died. Pushed her round the corner and started checking for life. Had no spark. Push the fuse board around and managed to get a spark. Changed my fuse box and haven't had the issue since. 

[sledgehammer]

 If it is your problem -

 

most of the corrosion happens at the back of the fuse box

 

usually goes green on the rivets 

 

if it isn't a ballast coil , run a 12v feed to coil +ve (assuming -ve earth) see if it is better

 

if it is a ballest coil feed (pink / white wire) check the wire is ok , as prone to cracking

Edited by sledgehammer, 19 August 2018 - 02:55 PM.

[Spider]

It could be the Coil and also don't overlook the Ignition Switch as these can wear and give intermittent results.

[unburntfuelinthemorning]

Thanks for the replies.

 

I've tried a new condenser now but that hasn't helped.

 

I don't think it can be a problem with the supply to the coil as I have a bulb connected to the coil positive terminal and when the engine cuts out the bulb remains illuminated.

 

A new coil is next on the list to try I think. 

[unburntfuelinthemorning]

So got a new coil today from Minispares.  The old coil had a primary resistance of 2.2ohms so a bit out of spec.  New coil 3.3ohm - spot on.  New coil doesn't get as hot as the old one.  Seems I needed a new coil.  Result:  no change - still cutting out randomly.

 

I was sure it was ignition related but am starting to wonder if it is a fuelling problem as last time it cut out I floored it and got power back after a slight splutter.  Anyone else had a fuelling problem like that?

[Its a min]

I had something similar but not sure if it's the same problem.

 

Mine turned out to be the float assembly. Tiniest bit of grit got into he float chamber and wouldn't allow the float to stop the fuel. It decided to take up residence in the float needle valve. I only found out when she cut out and when trying to turn her over, noticed fuel spilling out under the car. Dismantled and cleaned the float chamber and a quick spray of compressed air through the float needle valve and good to go.

 

I hope your problem is as simple as mine was.

[unburntfuelinthemorning]

Thanks for that.  I'm sure it is something really simple but I'm ripping my hair out trying to find it! 

 

I removed the float chamber and jet to clean out the chamber as there was debris in the bottom which I thought could be getting stirred up before blocking the jet temporarily.  I cleaned it out thoroughly but still had the cutting out issue on the next drive.  I need to check whether the debris has reappeared or not and I will have a look at the needle valve seat then as well.  There doesn't appear to be any fuel overflowing though.

[gazza82]

Normally I go on these "rules":

 

Sudden stop - electrics

Stuttering stop - fuel

 

 

Might be worth changing the condenser .. but make sure it is a good one as some of the chinese ones are pants ..

[Retroman]

Sounds like you are having fun

 

I would think its electrics as its a dead cut out

 

Have you checked battery connections and engine earth ?

 

Broken wires and connectors not tight - fusebox / coil / dizzy ?

 

Sometimes the Lucar ends need a sqeeze

[unburntfuelinthemorning]

Normally I go on these "rules":

 

Sudden stop - electrics

Stuttering stop - fuel

 

 

Might be worth changing the condenser .. but make sure it is a good one as some of the chinese ones are pants ..

I agree; I thought it was electric but as I can't find a fault there I'm not ruling out anything.

 

I had a condenser which came with a replacement distributor from Minispares which is only a few months old but I have replaced it with the more expensive condenser that they sell which is supposed to be higher quality.  I presume both are working as the points are still in good condition.

[unburntfuelinthemorning]

Sounds like you are having fun

 

I would think its electrics as its a dead cut out

 

Have you checked battery connections and engine earth ?

 

Broken wires and connectors not tight - fusebox / coil / dizzy ?

 

Sometimes the Lucar ends need a sqeeze

Certainly is fun!  There's no high resistance anywhere there shouldn't be.  I replaced the engine earth lead as a precaution as it was quite frayed but it's made no difference.

 

I'm wondering if debris in the float chamber was getting stirred up, getting through to the jet/needle and blocking it causing an instant power cut (the problem seems to happen when the piston would be mostly closed i.e at light throttle or decelerating) and then clearing as the piston goes up (on restart).  I've cleaned the float chamber and then driven it but the cutting out is still happening so either that's not the problem or there's more debris coming through.  I'll have a look later.

[unburntfuelinthemorning]

Well there's not much debris in the float chamber now.  I decided to check the dashpot and noticed a tiny score which caught the piston ever so slightly when it's in the bottom position.  Gave it all a good clean which seemed to help and performed a drop test which was fine.  Went for a ten minute drive tonight and things seemed alright this time so who knows what's going on. 

[Its a min]

Well there's not much debris in the float chamber now.  I decided to check the dashpot and noticed a tiny score which caught the piston ever so slightly when it's in the bottom position.  Gave it all a good clean which seemed to help and performed a drop test which was fine.  Went for a ten minute drive tonight and things seemed alright this time so who knows what's going on. 

 

Fingers crossed for ya!

[unburntfuelinthemorning]

Well it's still been playing up but I was looking at the front of it today from a distance while it was idling when the engine cut out suddenly accompanied by a deposit of fuel on the floor as if it had just relieved itself.  So it seems the problem is sudden flooding which I couldn't see whilst driving.  I took the needle valve out again and retrieved a half inch long sliver of plastic or rubber from behind it, cleaned the float chamber again as there were some small deposits of something.  Put it back together and it ran for a minute then cut out again.  Dismantled it again but found nothing this time.

 

I reckon it's either tiny bits of debris randomly blocking the needle valve and/or it's the needle valve itself which is a Minispares CA90 type which I have found out from other threads is also know as a grose valve and sometimes also causes problems.  Time to get a new viton tipped valve and a fuel filter methinks.