# MGB quit. Bad gas? **URL:** \ **Category:** Factual Questions\ **Created:** [May 9, 2010, 4:26am UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786 "2010-05-09T04:26:17Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 10, 2010, 4:12pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/21 "2010-05-10T16:12:56Z")
> [@ducati](#): > > Cretin. [Moderator Note] **Ducati** , insults are not permitted in GQ. I’m making this a note rather than a warning on the chance this was tongue-in-cheek, but let’s not do this again. Colibri General Questions Moderator ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [May 10, 2010, 4:37pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/22 "2010-05-10T16:37:05Z")
**Colibri** : I’m sure it was tongue-in-cheek, and I took no offense. ---
**Author:** ![Saintly\_Loser](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saintly_loser/32/4045_2.png) [@Saintly\_Loser](https://boards.straightdope.com/u/Saintly_Loser)\ **Post date:** [May 10, 2010, 5:30pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/23 "2010-05-10T17:30:22Z")
> [@EvilTOJ](#): > > For the non-car people (like me) here’s an [MGB](http://en.wikipedia.org/wiki/File:MG_MkI_MGBs_%28Hudson%29.JPG). Purdy. I somehow imagine seeing you driving that wearing an ascot and smoking a pipe. What a beautiful car. My dream car is an MGA. I call it “the poor man’s XK120.” ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [May 10, 2010, 5:54pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/24 "2010-05-10T17:54:27Z")
> [@Saintly\_Loser](#): > > What a beautiful car. My dream car is an MGA. I call it “the poor man’s XK120.” [Here’s mine](http://s127.photobucket.com/albums/p143/1966_MGB/). ---
**Author:** ![ducati](https://avatars.discourse-cdn.com/v4/letter/d/cc9497/32.png) [@ducati](https://boards.straightdope.com/u/ducati)\ **Post date:** [May 10, 2010, 7:26pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/25 "2010-05-10T19:26:07Z")
Purely T-I-C! Mea Culpa. ---
**Author:** ![jasg](https://avatars.discourse-cdn.com/v4/letter/j/f0a364/32.png) [@jasg](https://boards.straightdope.com/u/jasg)\ **Post date:** [May 10, 2010, 8:19pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/26 "2010-05-10T20:19:03Z")
As a fellow MG(A) owner, you have my complete sympathy… ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [May 10, 2010, 9:09pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/27 "2010-05-10T21:09:50Z")
I ised to have a Honda CX500 motorcycle, and it would never (!!) start in the spring. Terrifying is trusting some moron to pull-start you on a motorbike when he doesn’t know when to stop… Lesson learned. Anyhoo, another major cause of spring stall is stuck carburetor float. This too is a side-effect of bad gas. The stuff turns to turpentine (not literally, but it sure smells that way). This makes the float in the carburetor stick in up position and no more gas goes into the bowl. After a tank or two of gas the carb is somewhat cleaner… Eventually I mentioned it to a mechanic acquaintance who told me what my problem was. A few light taps on the side of the carburetor with a hammer helped shake the float loose instead of an hour of engine cranking; as did turning off the gas and draining the carburetor bowls in the fall. Is that something you can do with an MGB? As others mentioned - empty tank over winter might accumulate water condensation; see if your fuel filter has beads of water in it. Keep the tank lid on tight if you leave the tank empty. Fortunately that treatment you mentioned should forestall tank rusting from water buildup, I hope? ---
**Author:** ![ivn1188](https://avatars.discourse-cdn.com/v4/letter/i/e480ec/32.png) [@ivn1188](https://boards.straightdope.com/u/ivn1188)\ **Post date:** [May 10, 2010, 9:14pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/28 "2010-05-10T21:14:08Z")
> [@Johnny\_L.A](#): > > Thanks, **Rick**. I’ll try the stuff. I’d hate to have to siphon out ten gallons of Premium it I don’t have to. Next year I’ll use the additive before I park it for the Winter. > > In case anyone is wondering, the fuel tank was thoroughly cleaned and then coated inside and out with some sort of fuel tank dope that will keep the tank ‘new’ for longer than I’ll ever last. Don’t run Premium. The compression on your MGB isn’t nearly high enough to benefit from it (it’s usually 9.6 to 9.8) – that little engine probably wouldn’t even knock on 70 octane fuel. You get the same detergents and such in regular fuel, by law. The only benefit to premium fuel is that it doesn’t knock as easily. Also, check your fuel filter from clogs or gummy residue, the crappy OEM ones suck almost as much as the electrical system. (Mine liked to kill starter motors until I put in some Japanese aftermarket job for half the price of a rebuilt one.) ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [May 10, 2010, 9:27pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/29 "2010-05-10T21:27:45Z")
> [@md2000](#): > > I ised to have a Honda CX500 motorcycle Me too. 😃 > [@ivn1188](#): > > Don’t run Premium. The compression on your MGB isn’t nearly high enough to benefit from it (it’s usually 9.6 to 9.8) – that little engine probably wouldn’t even knock on 70 octane fuel. I have empirical evidence to the contrary. My first '66 MGB and this one will knock if driven aggressively, up hills, and on hot days using regular gas. Hot days are not too much of a problem up here, but in stop-and-go traffic the cooling system isn’t adequate. (I don’t want to retrofit an electric fan.) Based on my experience with this car and my previous '66, regular isn’t enough. Here where it’s cooler, I could probably use mid-grade. But if I drive it to Seattle, I want the premium in case I get stuck in traffic. The engine really doesn’t like to be hot. (And yes, the cooling system is running to spec.) ---
**Author:** ![needscoffee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/needscoffee/32/1076_2.png) [@needscoffee](https://boards.straightdope.com/u/needscoffee)\ **Post date:** [May 11, 2010, 1:15am UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/30 "2010-05-11T01:15:04Z")
My husband suggests you check under the distributor cap to see if you got moisture in it, perhaps when washing the car. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [May 11, 2010, 2:13am UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/31 "2010-05-11T02:13:14Z")
Ha! That was the first thing I did when it quit! 😛 Dry as a bone. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 11, 2010, 3:18am UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/32 "2010-05-11T03:18:39Z")
> [@Ionizer](#): > > Careful doing it. I _know_ some electric fuel-pumps will be ruined if/when they are run without fuel (ie fuel acts as a ‘coolant’ for pump). I have no idea if this particular car would be affected, or length of time it takes for pump to be ruined. Just wanting to alert as to the possibility, not the probability, of such happening in this case. Seems just as easy to pop hose off and let gravity do the work to remove that possible risk - ymmv No worries with the type of fuel pump he has on his MGB > [@Johnny\_L.A](#): > > I doubt it’s the fuel pump. Like everything else, it’s new. BBBBBBBBBBBBBBBBBBBBBBBBWWWWWWWWWWWWWWWAAAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHH! ::: wipes tears from eyes::: BBBBBBBBBBBBBBBBBBBBBBBBWWWWWWWWWWWWWWWAAAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHH! ::: Wipes away more tears and tries to catch his breath::: OK, I’m better now. You don’t have much experience with SU fuel pumps I see. To quote a great book on British car repair “The SU fuel pump has caused British car owners more problems than all of the local police departments across the world put together.” However your symptoms don’t match those of a bad fuel pump, or I would have mentioned that. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 11, 2010, 3:35am UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/33 "2010-05-11T03:35:40Z")
> [@MC\_E](#): > > To be fair, the odds of an MGB breaking down approach 100%, so it’s really just: What are the odds of having a British car mechanic as a neighbor. > > 😃 > [@Hi\_Medlo](#): > > My experience with an MG Midget and a Triumph Spitfire indicate that a British car mechanic as a neighbor should be standard equipment. : ) How do you think I became the mechanic that I am today? I owned British sports cars.😃 ---
**Author:** ![ivn1188](https://avatars.discourse-cdn.com/v4/letter/i/e480ec/32.png) [@ivn1188](https://boards.straightdope.com/u/ivn1188)\ **Post date:** [May 11, 2010, 3:39am UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/34 "2010-05-11T03:39:45Z")
> [@Johnny\_L.A](#): > > (And yes, the cooling system is running to spec.) By which you mean it fails miserably, right? An aftermarket radiator is a great upgrade, unless you’re into trying to keep everything stock/NOS. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [May 11, 2010, 3:41am UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/35 "2010-05-11T03:41:45Z")
This is my fourth MGB. I’ve had a ‘doughnut gasket’ crack on the exhaust header, causing the car to stall when it was stopped (engine bay filled with exhaust); on a '77 there was a fault that would cause the electric fan to turn on for no apparent reason and run down the battery in the middle of the night; I’ve had a generator go bad; I’ve had a winking headlight. Once on my first '66 the right-front axle snapped. Never had any problems with a fuel pump. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [May 11, 2010, 3:48am UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/36 "2010-05-11T03:48:14Z")
> [@ivn1188](#): > > By which you mean it fails miserably, right? An aftermarket radiator is a great upgrade, unless you’re into trying to keep everything stock/NOS. It works OK except in heavy traffic. It really needs the airflow. I think the radiator is new, and is a higher-efficiency one than the original; but it looks like an original. (It’s possible it’s original and has been overhauled, but ISTR buying a new one.) I am trying to keep it as ‘original’ as possible. I did have it converted to negative-earth, and I have a Pertronix ignition that looks original. The wiring harness is new, but it’s a copy of the Lucas one and the guy who put it together even put a Lucas sticker on it. (You can see it [here](http://i127.photobucket.com/albums/p143/1966_MGB/DSCN0138.jpg) on the harness near the voltage regulator.) ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [June 5, 2010, 11:44pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/37 "2010-06-05T23:44:09Z")
Could be worse. Could be raining. I put the Sta-Bil in a few weeks ago, and ran the car for about 15 minutes. Then I took it for a spin, braking and steering back and forth to try to mix it. A week later I started it up and it ran fine for 15 minutes before I shut it down. Today I made it about seven miles before it stalled. I let it sit about ten minutes and it started. I made it another mile. I let it sit for 20 minutes, and it started but was backfiring. I knew it wouldn’t make it the 2/3 mile home. So I came home. I’ll drive back and see if I can get it started, and see if it will make it up the little hill. Looks like I’m going to have to drain the tank. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [June 6, 2010, 12:11am UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/38 "2010-06-06T00:11:04Z")
Went down to where I parked it, and it ran like it was supposed to. I wonder why it starts again after resting? Water going to the sump? It likes the lower temperature? ---
**Author:** ![smithsb](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/smithsb/32/12107_2.png) [@smithsb](https://boards.straightdope.com/u/smithsb)\ **Post date:** [June 6, 2010, 6:03pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/39 "2010-06-06T18:03:33Z")
> [@Johnny\_L.A](#): > > This is my fourth MGB. … Never had any problems with a fuel pump. Do not, under any circumstances, utter those words again. You’re doomed I tell ya, dooooommmed:D:D:D Can fuel pumps read your mind? ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [June 6, 2010, 6:26pm UTC](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786/40 "2010-06-06T18:26:37Z")
> [@Johnny\_L.A](#): > > I doubt it’s the fuel pump. Like everything else, it’s new. > > What is the mechanism that causes a car to quit with ‘bad gas’. Is it that the engine gets a slug of water? As a pilot you should know about water in a fuel tank. Planes accumulate more water from condensation (than cars) because they sit for longer periods of time. I’ve fueled my lawn mower and other power tools from gas that sat for years (in a sealed container). The gas has certainly gone “sour” but it still burns. [Previous page](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786.md?page=1) [Next page](https://boards.straightdope.com/t/mgb-quit-bad-gas/538786.md?page=3)