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MG MGB Technical - 1979 MGB won't start

I have a 1979 MGB with a Weber 32/36 DGV carburator and the standard 4 cylinder engine. The engine will crank, but won't turn over. It was running fine about 5 weeks ago, but after a recent fill-up, the car started, and ran for about 15 minutes. I shut the engine down for a few minutes, then started it again, where it started and immediately stalled out. I could not get the engine to start again. I have completely disassembled, cleaned and reinstalled the carburator, replaced the fuel filter, and appear to be getting a charge on the spark plugs. Does anyone have any suggestions as to what could be keeping it from running?

Thanks,
David
David Palmer

Is your fuelpump ticking?
Cheers
erik

fuel pump is working fine. Learned this the hard way because I forgot to reconnect the fuel lines after I dismantled and reassembled the carburator.
David Palmer

David. I am somewhat unsure of what you are saying. "The engine will crank, but not turn over". This indicates that the starter is spinning, but the engine is not being turned by the starter. Is this correct? If so, look to a starter or ring gear problem. If the problem is the engine is turning over, but will not fire, charge up the battery and run a compression check. You should have at least 100 psi on all cylinders. Then, remove the air cleaner and manually pump the throttle on the carb while looking in the primary venturi or barrel. You should see a stream of gas shooting into the barrel from the accelerator pump. If not, you still have a carb problem. Remove the fuel line from the carb end and stick it into a small jar or bottle. Have an assistant turn the ignition switch to run and see if the fuel pump is delivering fuel. If these look good, hook a timing light to the number one spark plug and have an assistant crank over the engine. Check the timing to see it is about 10 degrees BTDC while cranking. Your car should start at this setting. If you have good timing, good compression and are getting fuel, you can only have two other problems. First, choke is not working. It always takes a little choke to get my cars started when using the Weber DGV carbs. Second would be the fuel you got. Bad fuel will not burn properly. As a test, pour a little fuel into the open throat of the carb and try to start the car. Always nice to have a friend with a fire extinguisher around when you do this. But, smothering a carb fire, that is not leaking gas, with a rag makes for easier clean up. Let us know what you find. Les
Les Bengtson

Les,

I guess my novice abilities as a mechanic are showing. You are correct in that the engine is turning over, but will not fire. The battery has a full charge, unfortunately I am not sure how to run a compression check. As for gas getting to the carborator, that is not a problem. I get the stream of gas into the accelerator pump that you described. As for a timing light, is this something I can pick up at a local auto parts store, or something I would need to order special?

Thanks for the assistance.
David
David Palmer

David. You can pick up a compression tester and a timing light at any good auto parts store or at places like Wal-Mart. They are basic tools which you will need to keep the car running properly, so spending the money now is a good idea. Run a compression check and post the numbers and we will have a better idea of what is happening. Les
Les Bengtson

David,

How about trying some starting fluid (spray)? If it doesn't fire at all, then you should probably concentrate on timing/ignition. If it fires, then the carb is likely the point of failure.

Good luck,
DGV
Dan Vukmanich

One other reason could be you filled her up with diesel instead of gas.
It's just a thought but it does happen.
Carl

I assume that you've checked the fuel system for leaks? It's also worth checking that you haven't created a vacuum in the petrol tank ie the vent hole in the filler cap isn't blocked (although I think that this is unlikely as the car would run for a short period and then stall).

If the car worked ok up to you filling it up, I won't claim any stars for suggesting that this is the root of the problem. If the tank was unusually empty its possible that you've flushed dirt into the system (and carbs). Was the old filter dirty (dirt could have got round or through the filter?

Bob
Bob Everick

Dear David,
Everyone else has commented about fuelling faults and I have to admit I dont know much about Weber carbs. However, I too have a 1979 car, which I have had for just over 2 years. I have a continuing problem with the Low Tension lead from the coil to the distibutor. It seems that due to vibration the lead breaks up and I seem to have to re-joint it every 1000 miles or so, which is a nuisance, but at least when the motor cuts out suddenly I now know what the cause is. Sometimes I get a warning series of hiccups for a few miles before it packs up and other times I dont - it just stops , or, wont start at all. This can be very annoying when you are in the queue from the paddock to the start line for a hillclimb. I have replaced the LT lead at least once a year, but the same fault still recurrs. However, the fracture is not always in the same place -usually somewhere in the middle of the lead, but at least once it has failed at the connection with the points connector. Hope this helps you get going!! Philip.
Philip Methuen

This thread was discussed between 06/05/2002 and 12/05/2002

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