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MGB MGB Stalling

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Stewart

Stewart

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My Dad has been kind and brave enough to take my 75 mgb out on the road to keep the fluids circulating while I'm away and has run into a problem. The car is running great but has been coughing while making 90 degree or so right hand turns. Yesterday it stalled and refused to restart. Over the phone I had him check the fuel pump and for spark and all seemed well but it would not start. At that point he called for a ride home and let it sit for a few hours at which point it started right up and ran great again. It sounds like its flooding for some reason but I'm not sure why it would. It's the stock zs carb. Any help would be appreciated.
 
My first thought is that the fuel shutoff valve may be faulty and is kicking in when it shouldn't. It's mounted on the firewall, next to the brake master cylinder, and stands upright, should be fairly easy to identify. It can be bypassed easily enough. That is my suggestion anyway, there will be more.
 
I will be very interested in any answer that describes the precise problem.

I had exactly the same symptoms. I finally solved it by totally rebuilding the carburator.
There was no doubt that it was flooding the engine. It was always on a sharp right turn from a start. You could make the same turn from a roll and "drive through" the stall(if there even was one).
Now that I think about it, this happened when the throttle was "wide open" accelerating from a stop. IOW when the throttle had JUST been depressed.
(By the Way, you could make all the left turns you wanted.)

If it were a downdraft style carb I would have said accelerator pump. So, perhaps the problem was somewhere in the accelerator circuit.

The major thing I found wrong, during the rebuild, was the float was a tad high (maybe 5-10 thousands) But of course, the Z-S got a thorough cleaning and all new "soft" parts.Somewhere in there I fixed the problem.

/ubbthreads/images/graemlins/driving.gif
Mike
 
[ QUOTE ]
Somewhere in there I fixed the problem. /ubbthreads/images/graemlins/driving.gif
Mike

[/ QUOTE ]

Ain't it the truth! This has happened to me so many times. It would make an interesting poll - to see how often just fooling around with something ends up fixing it, and you have no idea what you did to fix it!

Mickey
 
Most the time you don't know what you did to screw it up. Fix it, now that would be a miracle. /ubbthreads/images/graemlins/crazyeyes.gif
 
Well to update this thread My dad took it out again and it didn't stall on while making right hand turns instead it went 6 feet from the garage and died then wouldn't start. I'm leaning towards the auto choke gone mad theory and running the carb super rich. When I rebuilt and set the carb it was in the temp was in the low 100's and now its cooled off. Could the choke be thrown far enough off to flood the engine out? And if it was which way would I need to adjust the auto choke the lean out the choke?

At this point I'm about ready to give up on the ZS carb and do the hif-4 conversion now that I no longer have to pass smog.
 
[ QUOTE ]
At this point I'm about ready to give up on the ZS carb and do the hif-4 conversion now that I no longer have to pass smog.

[/ QUOTE ]

Stewart -

See the earlier threads about my "journey" into the mysteries of the HIF's. They're not immune to the gremlins that come with these wonderful cars. Point: even the best systems will sometimes throw you a curve, and you can't take anything for granted (like I did /ubbthreads/images/graemlins/blush.gif).

Mickey
 
i had the same problem with my 76, i looked at the ignition, which was the dreaded omni, replaced it with an ignitor and never had a problem since.
 
Well to finally update this post I finally got back home for tgivings and pulled the B out. Started right up quit about 10 minutes later and wouldn't start up again. Let it sit for a while and started fixing a few other small items and checked the autochoke and reset it. Sputtered a bit but no luck. Was finally able to borrow a car and pick up some tools as all of mine are back in ND along with 4 new tires and a set of new plugs. Plugs were fouled out and with a quick swap she started right up and ran pretty good.

For the first time in 7 years I took her for a good drive. Drove for about 20 minutes around town and had a blast. Perfect afternoon in socal and back in a convertible with the top down you just cant beat it. Mixture is still off a bit but I will hopefully have that dialled in tomorrow. I forgot how much of a blast these are to drive
 
Your thread has been interesting. I would bet that you have a flooding problem of some sort with the ZS. The auto-start choke is not a good piece of work. The water heater and gasoline combination is very problematic. The rest of the ZS is a fine carb but a single unit definitely does not permit you to take advantage of the MGB potential. I use twin SUs on mine with an appreciable advantage over the single unit. If you keep the ZS, the best improvement you could give it is to install a manual choke kit available from Moss or most sosurces of MGB parts. With the positive control of a manual choke, problems such as flooding or running too rich will be minimized. Hope this helps.
 
Yeah the choke was giving me grief for most of t-givings week and was causing the stalling. The new plugs helped quite a bit and the car wouldn't stall but starting when warm became a royal pita.

After an afternoon of messing with the choke and actually getting it to work properly followed by a full tune she's running stronger than I can remember. I've put about 250 miles on her and its running better and better.

I have thought about switching to the manual choke for the zs carb but I just can't justify the money for the conversion kit for something I would like to remove in the near future. The hif would be my first choice right now as it would be a quick swap. I have been seeing the dual carbs and manifold on eBay relatively cheap and it is tempting to go that way. My worry about going that way is will they fit with the 75 brake reservoir being where it is.
 
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