OK! That's something to add to the "I'd never think to check THAT!" list.  Maybe we all missed venting because most Minis don't have the vent drip line down over the flywheel housing. Mine had one but it wasn't connected to anything and I assumed it was a left-over from a P.O.'s quick Metro lump transplant. When I much later had a carb overflow issue, I figured out what the long-removed tube was for.

Well......found the problem....Step one, don't let the customer get involved until the car is fixed. Step two, when checking lines for being clogged...don't over look the short rubber hose that connects the two metal lines. The small bit of rubber hose that comes off the float bowl (overflow vent) that attaches to the metal line that runs along the side of the transmission that piece of two inch long hose was plugged up with trash. Blew it out an it runs great. I kept over looking this as I was a little pissed off at the customer after he stated that he didn't feel he should pay me for working on it if I didn't fix it.

Just want to say thanks for all the input from everyone that wrote in on this.

I'm back to the coil. If you swapped it with yours, try a third one.

It does have a tach. Does not jump around. Going to check fuel pressure her in a while. Servicing my other Mini right now getting it ready for a road trip next weekend.

Do you have a tachometer in the car? If you do when it stumbles does the tach jump around erratically ?
Trying to narrow it down to fuel or electrical.

Stock mechanical fuel pump on it.

Electric or mechanical fuel pump? Aftermarket or stock? If it is aftermarket, perhaps the pressure is too high and overwhelming the needle valve in the float chamber and flooding the engine.

Pop the dashpot off and remove the piston assembly, turn the key to run, without starting the engine, observe the jet inside the carb and see if fuel is pouring into the carb.

Fuel line connected correctly? I have seen where the fuel line is connected to the carb overflow, which causes troubles/

something else to mention, car fires up right away. Idles great for about 3 or so minutes then starts slowing down an kind of starts loping/sputtering and dies. if you give it fuel it just gets worse. If you force it through this its fine till it starts doing it all over. But if you let it die then its hard to start, like its flooded.

MiniMike... just did not get a chance to check the valves, will do that tomorrow.

not sure what size needle is in the carb but will look tomorrow. did replace the whole carb with a working one that came off of my daily driven mini and it didn't change a thing.

Again I just want to say thanks in advance for all advice. I hope I don't come off rude or sound bad in any reply to anyone if I say I have done that or checked that. I'm just at a loss right now with this car as I have gone over most of the basic things I could think of on it with no improvements.

Here is what I have checked, adjusted, changed as of tonight:

Been back and forth with the timing

have had two different carbs on it

have checked for vacuum leaks

checked float, needle and seat, replaced float in one carb as it was cracked.

have gone lean to rich back and forth with the fuel mixture.

cleaned the contacts inside the distributor cap and rotor.

new spark plugs.

disconnected the break booster and plugged off the line.

no leaks between the carb an manifold.

running it this whole time with no air filter as well just incase its the crappy foam filter they have on it.

where is the jet in the carb?  Level with the inner ring ?

did you move the carb needle in or out?

What needle is in the carb?


Why not check the valves?

Minimike I have checked that as well an its all good.

check the needle in the top of the float bowl for grit.  (remove the lid, remove the float by sliding the pivot pin sideways,  needle will now be free to fall out of the lid)  

Also when driving it around, when you take a turn around a corner it tries to die like its running out of fuel. No in line fuel filter, and the fuel in the bowl is clean as can be.

Single HS4. Just swapped out carbs to eliminate problems. No change between carbs. Have not checked the valve clearance yet. This car was advertised as running great. Talked to the guy that sold it an he said it ran fine.

You said 1 1/2" SU on your first thread then both carbs. Are you running twin carbs or just alternating between two carbs ? Are they HS carbs or HIF carbs. Have you checked the valve clearances, if so what are they set at ?

Both carbs are complete and working, springs were inside. even changed springs between the two.

Did you check that the spring is present in the dash pot?

Ok guys, have one that is driving me nuts. Its a 1991 rover mini with a 998, 1 1/2 SU, header, electronic ignition. Car is not mine, working on it for a friend. Car is stumbling at low RPMs. I have chased all possible vacuum leaks, fuel leaks, adjusted timing changed carbs, plugs, undid the brake booster, ran without air filter, played with fuel mixture, different weight oils in the carb.

This car runs great in 3rd and 4th gear, bucks like a mule in 1st and falls on its face in 2nd. now if I hold the piston down with my hand in the carb it revs great, but if I just rev it like normal it stumbles till the RPMs get fast enough.

What am I missing? Going out now to do a compression test. Only thing I have not change out is the distributor.