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MG MGA - Stopped and won't go

About 3 months ago I acquired a 1600 A. All was fine until a couple of weeks ago when driving along it started to miss and then stopped about 1 km further along, luckily close to home! Had used about a 1/3 of new tank of fuel without any problem up till then.
Checked fuel supply from pump into a bucket-okay. Checked float bowl inlet strainers - okay. Checked float bowl level- okay. Decided to heed the BGs advice - 90% of all carburettor problems are electrical. Checked points gap - okay. Check LV side okay. Disconnected and shorted HT lead from coil to engine block-okay. Back to fuel side - lifted carby pistons and let fall back -okay. Tried to start again, no go!
What do you recommend as the next step?
Mike Ellsmore

Was the spark at the HT lead big enough ? A misfire is often the onset of the condenser(capacitor)in the distributor about to fail - worth replacing this anyway - good luck with the fault finding. Cheers Cam
C Cunningham

My vote is for the condensor every time
dominic clancy

How about a cracked/earthing rotor arm? I have had this TWICE!

Andy
Andy Dear

Mike, you should also check for spark at the plug end of each high-tension lead to make sure that there is spark there. In addition to all the other suggestions look for a cracked distributor cap. Let us know how you are doing with it.
Good luck/ gil
gil

Hi Mike. Engines need 3 things to run. Spark, fuel, and compression. Try dumping a thimble full of gas down each carburettor and try starting. If engine starts,runs and then quits, then you likely have a fuel problem. If the engine does not run, then check for spark at all 4 spark plugs. If you get no spark, or very weak spart at the 4 plugs, then there is likely a problem with the ignition system. If you have good spark, then you need to test engine compression. It is very rare that a previously well running engine would lose all or most of it's compression, but it is possible, if the timing chain broke, or there was some other catastropic failure. I would almost bet money that your no start problem is igition or electrical in nature. In addition to things forum members have suggested checking, I will add this: Inside the distributor, there is a very fine wire, which is insulated. It runs from the external electrical terminal on the distributor, to the breaker plate. This fine wire flexes each time the distributor automatic advance moves the breaker plate, and it moves frequently. This fine wire eventually fatigues, and breaks. When it breaks, it stops the ignition system dead in it's tracks, and the car wont start or run. This fine wire usually breaks inside the insulation, so the break cannot be readily seen. If you can find no other reason for an ignition malfunction, then check this fine wire. Cheers! GLenn
Glenn

I'll bet you'll find the problem's in the distributor somewhere, probably one of the parts under $10.00. Gil's right: Just shorting the coil to the block only tells you that the coil's working. If you have spark from the coil HT lead but not at the plugs it's in the dizzy somewhere, rotor, condenser, cap, as previously mentioned. I had a rotor that failed with no visible cracks or carbon trails, but it failed nonetheless. Puzzled the hell out of me. Good luck.
Mark

Thanks guys. Australia Day long weekend coming up, I will try your suggestions and get back to you. Feel sorry for you guys on the top of the world - it has been 35-40 C here the last week, great for the top down (that's if I can get it to go again)
Mike Ellsmore

Mike

It's also great with the top down up here on top of the world - It's a warm +1.5c today. Beats a cup of coffee or an apple for waking you up!

Do you by any chance know a mate of mine in the Melbourne area - Barry Gannon? He owns and rebuilds MGAs privately as a hobby. A rebuild of his (red 1600) won the concours prize at a 2004/5 event in the Melbourne area.

Steve
Steve Gyles

Agreed that cap, rotor and leads can only be checked by substitution but the condenser can be checked by shorting the main lead from the coil to the head. Yellow feeble spark and the condenser is US, fat healthy blue spark and it is OK.
Iain MacKintosh

I had a similar problem a couple of years ago. The problem turned out to be a worn rotor arm. There were nice fat sparks at the plug with the rotor arm held in place on the distributor cap, but none with the cap and rotor in place on the distributor.
Dan Smithers

Guys, an update on my progress. Installed a new capacitor - no joy. Checked again, spark from coil - it was fine, drew up to 1/2". No spark at the plugs. Checked distributor cap and leads for resistance as per Barney's specs (IG-106) One plug lead and the coil lead were well out of spec. Centre graphite pin to screw resistance was also very high (had to put a new battery in my multimeter to get it to zero on x100 scale when leads crossed - I reckon it's 15 years since I replaced that battery so I got my money's worth). Installed a new cap and leads - still no spark at plug end (frustrating). Inspected rotor - looked fine, measured resistance from contact plate on the top to the retaining spring plate in the recess that holds it snug on the dizzy shaft - 40,000 ohms! That looks like my problem - another trip to the parts shop!

Steve, I don't know Barry Gannon as yet but have seen his name on the local MG club website. I am only getting back in to sports cars after a 30 year lay off (kids grown up, etc). Will introduce myself when I join the club.

Glen, I checked the continuity between the moving plate and dizzy body and it was okay - wire does look flimsy as you say, the insulation moves freely on the wire - can you just replace this wire or is it easier to buy a new moving contact breaker plate - it looks like it will be the next to go.
Mike Ellsmore

Hi Mike. Yes it is possible to just replace the fine wire. If you replace it, be sure that you use identical wire to what is there. The fine wire is specially made, to permit constant bending withoutout premature failure. If you replace the fine wire with regular wire, it WILL fail prematurely, likely leaving you stranded. This fine wire, complete with external distributor terminal attached, is available from Victoria British, and likely other Brit car suppliers. Cheers! Glenn
Glenn

Problem solved - new rotor $A6.50. Engine started first pull on the starter button. Take a bow you guys who picked a faulty rotor! It's worth having a spare for a long trip - it was frustrating what happened to me - going a long fine, then a miss, then 1 kilometre further along the road engine completely dead - no other warning.
Mike Ellsmore

Mike- Glad that you got it fixed-- thanks for letting us know what you found, and have fun....
/ gil
gil

Hi Mike. I agree that a part failure can be very annoying. I carry a small but useful inventory of spare parts and tools with me at all times. Some of the parts include points, plugs, condenser, thin braided primary distributor wire and terminal, distributor cap, rotor, fuel pump, rad hoses, heater hose, throttle cable, throttle springs, duct tape, and baling wire. These are components that can fail and leave one stranded. Duct tape and baling wire are for quick n dirty patch jobs. These items take up little trunk space, and it's comforting to know that I can handle most any non catastrophic break down with confidence. The small tool kit I also carry, enables me to install any of the above listed parts without having to borrow or buy any other tools. Many of the parts and tools I carry are used, but "known to be good" This saves on expensive new parts, while providing peace of mind. cheers! Glenn
Glenn

By recent experience, I'd add a spare belt, even a temporary one. Or even a pair of pantyhose might have saved me!
Tom

Hi Tom. I knew I left something off my list, and yes, I carry a spare fanbelt also. Thanks for the reminder. Pantyhose actually does work reasonably well, if a real fanbelt is not available. Cheers! GLenn
Glenn

Sorry guys, but I can't seem to shake the mental image of some MGA owner flagging down cars and asking the ladies if they'd be willing to donate their pantyhose for an emergency repair. Fade to a black eye and a husband pummeling the guy...:)

GTF
G T Foster

Mike, don't worry about the insulation falling off the ground wire on the contact plate. Give the wire a good tug! If it comes loose, solder in a replacement.
Jeff Schlemmer

This thread was discussed between 23/01/2006 and 03/02/2006

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