MGB: Falls flat on its face...

So I've surfed this forum for a little while, and I have to say that there is some really knowledgable and talented people here. I've tried to search, but couldn't find an answer to my problem. I'm assuming it's probably common or easy thing that I am missing. I've inherited my sisters abonded 71 MGB. I've got the little guy running and it will idle all day. Not long ago I rebuilt the brakes and finally got to take it for a test drive. Man it is fun to scoot around in it, but after driving for around ten miles or five to ten minutes the car falls flat on its face and doesn't want to run. If i let it sit a couple minutes and cool it will run, or I can keep it in gear and limp it home. The fuel pump was replaced before the vehicle was driven, and I've cleaned and checked many wire and ground connections. Unfortunately I am slightly unfamiliar with points and condensor style ignitions, so I'm assuming the problem may be there. I was really hoping that maybe someone here may be familiar with an issue like this and have some insite to what may be holding me back from enjoying this awesome little car.

:S

Thanks

samiam

That sounds like fuel starvation. If you have a fuel filter try fitting a new one.

Wiz is right. It could be astressed and overheating fuel pump. It could also be a failing ignition coil, rotor, or condenser. I'd look at the pump first. Make sure the electrical connections are extremely clean and tight.

In addition to checking the coil and condenser, check for a clogged fuel filter. If there is debris in it, even if it isn't clogged, then you may have a clogged pick-up strainer in the fuel tank. In that case the tank should be removed and boiled out.

Wow, thank you for the quick repsonse. I had replaced the fuel pump and filter, because the car didn't start when I got it due to a bad pump. But I've been reading about the tank vent. Is the vent servicable at all?

**edit: I have a new coil, condensor, and points coming for it.
And did you say boil the tank? I'm not sure what that is. Is it close to the price of the new tank?

Last gas tank I had cleaned was $40. Radiator shops usually do it. I also had a car that had the same symptoms. It was a bad coil. Good luck, I have a couple of 71 roadsters. Just plain fun!
Bruce

The strainer is soldered (or brazed?) onto the pickup tube inside the tank. It is not easily removed. Boiling the tank is done at most radiator shops for far less than a new tank. I had one done a couple years ago for about $25. If the tank is full of rust scale then it's probably worth simply replacing since that scale had to come from somewhere, and there are probably pin holes throughout the top. You can peek inside the tank by removing the filler neck (on top) and/or the sender unit (on right side).

I see what our talking about. I guess the boiling is similar to the "boil out" stuff I used to use in fast food fryers when cleaning them. I guess I'll drain the tank and inspect. Also had a someone tell me the coil may be bad if it gets hot when my condition occurs, so I'll check that first. Thank you all for great and quick input.

samiam

Welcome to the forum, what part of Tennessee are you located?

[quote=samiam]
Also had a someone tell me the coil may be bad if it gets hot when my condition occurs, so I'll check that first. Thank you all for great and quick input.

samiam[/quote]

coils always get hot, real hot, and work just fine. So that's a red herring.

also, ignition parts are usually available locally. Don't waste your money mail-ordering them. NAPA stores carry a well-made brand, "Blue Streak".

Coils always get hot when you use them, so don't let the temperature trick you. They ALL get hot with use.
When coils suffer heat related failures, they almost always fail 100% dead, until they cool again. The rotor and condenser are more likely candidates than the coil.

Don't listen to that old man Mac.The girls tell me that he can fool most of THEM but this car stuff is man stuff! ROTFL :-)

The cleanest and quickest "test" is to substitute a known good internally resisted coil. Not draining, or crawling under the car.

Plug in the substitute coil, you don't even have to bolt it down, and go for a drive. It usually takes about five or ten miles to get the primary windings inside to open or short so your symptom could easily be that. If the sub coil eliminates the symptom you are done.

The other things dealing with the fuel systm "could" certainly be your problem, but the "coil check" is the first thing that I would try. BTW: There is no "test" that I know of to check the coil in situ when it is cold or even "warmed up". A scope might show a weakness but it wouldn't show a failure as the engine wouldn't be running..You have to sub the unit and carry your cell phone.

Jack

If you replaced the points and condenser then make sure you properly gapped them. I had a VERY similar problem with my car and all it required was a proper gap. If you don't know what you're doing it'll take a few tries to get it just right.

Can you describe the limping home.

Is it missing?

Or just gutless?

Is the lack of power even, or fluctuating?

What about the heater valve leaking water onto the distributor?

How about the gas cap may not be venting?

I'm with Dwight. This sounds like a fuel starvation problem. Take that gas cap off and drive it around. If the problem doesn't recur, your tank isn't properly vented. Try the simple and inexpensive stuff first :-)

Fuel filter is the easiest item to check,remove it and try blowing through it in the direction of flow.It should be fairly easy to blow through it once the fuel is dispeled from it.

The rusty bits in my tank clogged up the coarse screen on the intake side of my fuel pump. The result was very like what you describe. It would run for a few minutes then starve and die. A few minutes of the fuel pump running would refill the float bowls and I would be off again for a few minutes. Limped home a bit at a time.

I will agree that coils get hot and still function fine. However, the coil I mentioned never got hot to the touch. The car would start normally, run for a few miles, start to stutter and stop. Classic fuel starvation symptoms. Let the car sit for 10 minutes and it would start all over again. First order of business was to replace the fuel filter, Quick, easy and cheap. Then check the fuel pump, all was OK. After checking everything we could think of (this was an auto mechanics class many years ago), we put the car on the scope. Coil would flatline when run for a few minutes. No red herring there. A coil is easy to switch, as is a condenser.
Bruce

Check the points and condenser first, I think it's the condenser. How close are you to Memphis? I live about 40 minutes north of the city.

Samiam - For tips on troubleshooting a fuel related problem, see the article, Fuel Delivery Troubleshooting Guide in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/
Cheers,

Do the easiest and cheapest things first....

When it falls flat, it just wants to cut out. If I keep it in gear (I use second cause I'm only in my neighborhood) I can keep it going. It runs like a dog though like it’s lost its desire to live, no performance after that. Starvation sound very plausible. The points look new, so I'm gonna check the gap. I've heard of the heater valve being an issue (even looked on YouTube on how to adjust, University Motors was a very giving shop to make all those videos.) I have the new coil and condenser, so I will be installing that (wasn't sure about the coil getting hot thing, I've never touched one I wasn't working on.) Then after a good test drive I'll see if condition happens again, if so I'll pull the gas cap and see if she does alright. If it still feels ill, I’m gonna hit up Dave's fuel system trouble shooting guide, and inspect the tank. Ya'll are on the same page as me, start with the easy and inexpensive first.

Got a check list for today, I'll be back tonight to let ya'll know the out come.

For my Tennessee friends, I'm an hour north of Nashville maybe a spring mid-south cruise would be fun?

Thanks for all the help,
samiam
:)

Alright, checked the points gap and found the points and condensor have already been replaced. I found out from my sister that my two uncles replaced them. I trust those two with any thing I have. Checked the heater valve and found the cable to it isn't attached because it's snapped off, and the valve itself is siezed in the high position. After all that, it's not leaking onto the dizzy. I installed the new coil, found an added wire going to the positive side terminal. I left it off and attempted to start the car. Car starts, it even idles better (used to have to keep the choke around 1800rpm to keep running when cold.) I watched the RPM and oil guage start working intermittently. Reconnected the add on wire and still the same. While starting the car at one point my father said there was sparks arcing from the air cleaner to the brake lines near the master cylinder. Crap. Couldn't test drive the car cause local PD was all over my neighborhood all day and car isn't registered. So I'm gonna test drive tomorrow.

samiam

Almost forgot, removed the fuel line after the fuel filter and powered the vehicle, it flowed fine through the filter. And thanks for the info Mac, I wish I had known NAPA had a good brand for a coil. I had already ordered one from Moss.