MGB & GT Forum

I listed this problem before but even after several repairs it still is present.

Problem.......we get the car running right then set it in the garage for a couple weeks and after that when you are running down the road it just quits.

Here is the information.

1--I have owned the car for about 3 years or more.
2--When I first got it the carb would leak gas out when stopped after running it for a while so we rebuilt the carb last June.
3--That's when this started. I took it back to the mechanic and they fixed it 2 or 3 times each time it worked fine but when I would let it set in my garage for a couple weeks the problem would return. (stopping after a mile or two)
4--I put this problem out on the forum and someone told me it may be the fuel line.
5--and I noticed one time this year the pump did not work as it should. (small number of clicks when ig is turned on)
6--so we put a new fuel pump on and all the "rubber" pieces of the fuel line was replaced. Also the fuel filter replaced and the metal line was blown out but nothing was in it.
7--when the new pump and lines were put on the shop drove it a lot and said it ran fine also I took it for a drive and it was fine.
8--then I put it in my garage for 2-3 weeks and today I drove it for lunch (about a mile) it ran fine. After lunch it stopped in the street after about a 1/2 block. It then restarted with the starter. I thought maybe just a fluke so I drove the rest of the way home. Then went to the bank (again about a mile) and it quit on the way there but I was able to down shift and get it running again. After coming out of the bank I went about a block and it quit again. Got it restarted with the starter and drove back to my garage.

Some things to consider.
-- The garage that worked on my MG works on older cars all the time and is very good.
-- when the car stops the tack goes gradually down to 0. (coasting down the road) It does not drop like the electricity is shut off.
-- I believe the carb kit came from Moss and the mechanic rebuilds carbs all the time. We were talking and don't think there was a new float in the kit but do think there was a new needle and seat.
-- of course it no longer leaks gas.

this has been going on for a year.......frustration is not a good word for me.

Thanks for any and all help.......dave......I'd sell it but I don't want to give anyone this problem.

Are you sure the fuel tank is properly vented?

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"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

"Who do you think you are? I am."...Pete Weber

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...

x2 on the tank vent issue. Does the coil get hot? The fact that it restarts takes some stuff out like timing, etc. Right recap if you would the setup. Year, engine, carb setup etc.

I believe the tank vents through the carbon canister. These can get blocked. Disconnect the tank vent tube from the carbon canister and see if that helps.

andy

There is a small orifice pipe connector in fuel vent line near rear axle that often plugs up.

Make sure you can blow through the above disconnected tank vent tube (back through the Vapor Separator) into the Fuel Tank

I will try this one.....thanks........dave

I am going to try to track down the tank venting.

Here is info you requested.

1980 MGB
I think stock 4 cyl but have been told the exhaust manifold is off another year. So don't really know what's been done to engine.
Air pump/polution stuff has been removed.....not by me.
Weber carb.
I believe a new gas tank by prev owner. Car sat in barn several years according to him then he bought it put on new gas tank and new interior. Many other new parts also but I don't know what.

Hope this helps.......dave

You can also remove or loosen the gas cap and go for a drive as well. If it cures the problem you can then look to see where the problem is. If it still dies, it's not a venting issue.

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"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

"Who do you think you are? I am."...Pete Weber

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...

I suspect you have debris or old gas in the fuel tank and once awhile it clogged the fuel pickup.
If I was you I will flush the gas and inspect if the "vented" line is not clogged and the interior of the tank you could do that by looking directly into the tank via the fuel assembly.

I will do the same with for the fuel line between the fuel pump to the fuel filter is not clogged.

Something else to double check the filter inside the weber you might not know but the carb has a filter/screen at the gas entry it might be clogged; it is in plastic. http://www.webercarbsdirect.com/product_p/37022.010.htm

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1977 MGB Red 'Victoria' and 2018 Jaguar XE 'Meghan'
All Classics:
Married, 2 children, MG MGB May to December, Jaguar the rest of the year.

I can have the filter inside the weber checked but I suspect that was cleaned when the carb was cleaned.

Also in order to make sure the fuel line was not the problem all flexible line was replaced with new filter also then metal line was blown out and mechanic and I agreed that if anything came out of metal line we would replace it but he said when they blew out steel line nothing came out but air.

Thanks.......................dave



Edited 1 time(s). Last edit at 2015-10-06 10:09 PM by ripperfarms.

Hi Dave,

I feel that you are somewhat reluctant to try the simple thing of removing the gas tank cap and driving with the tank open to air. This will easily, and cheaply, tell you if you have a tank vent issue. If the problem doesn't raise it's ugly head, with the cap off, then there is a venting issue. If the problem persists then there is something else amiss.

Herb

None of that says to me tank venting !

The fact that the tach dies slowly means that at least the points side of the ignition is still working and the fact that it will restart fairly promptly and drive normally again also effectively rules out the coil, the cap, or the leads.

That leaves you with a fuel problem and the fact that the problem only started after it was rebuilt should be a clue so my advice is to strip it and recheck for muck and particularly the correct a correct float level.

BTW a small number of clicks does not mean that there is something wrong with the pump, on the contrary, fewer strokes means that it's putting out a good flow and pressure and filling the carb quickly !

I had an MG Metro that would loose power then not start, but would start after about 30 seconds. It had all of the symptoms of fuel however I was advised by an engine designer to check the compression. Turned out to be a blown head gasket that lifted when the engine was hot then sealing when it had cooled a bit.

Interesting concept although I don't think 30 seconds really qualifies as 'cooled for a bit' !

As I said I will try the tank cap venting fix first. I also remember that this was mentioned last year when I started to experience this problem. But at that time I think I only "loosened" the cap and drove it around with the same problem happening.

So today I took off the cap and put a piece of duct tape on the hole leaving a gap so air could get in. Then I drove the car.

I started the car with 1/2 choke. I drove it about 1/4 mile and turned on a country road and down the road about half a block it started to die but this time I pumped the accelerator a couple of times and it started running again. After it began running again I remembered I had the choke at 1/2 so I shut the choke off. I continued on about a 6 mile drive which the car drove fine. It had never went that far without dieing. I stopped at the mechanics and he said one drive does not totally prove the problem. So later that afternoon I took the car to the bank (about one mile) then out on the same 6 mile drive and going through several stop lights and turns. The car ran fine "until"......I was pulling into my driveway, which it was Idling fine then pulled into the garage. As soon as the car got into the garage the tack went to 0 as it died. So I restarted it. On the first try it fired but the tach went to 0 again. I tried to start it a 3rd time and this time it went back to idle and ran fine.

Thanks for any more help........ sorry this is such a pain.

I am wondering if I am dealing with two problems.............don't know............dave