Stall then failed hot start

[DeanG]

This should be an easy diagnosis for those of you with experience with the old stuff. I have a BMC-A with stock ignition and dual SU 1 1/4 carburetors fed by an electric fuel pump. Today was the second (and 3rd time) that it stalled at a stop and the car wouldn't restart.

 

* had drive a few miles & temperature on was 180 F

* There is fuel in the carburetors

* The fuel pump ticks over

* A hit of starter fluid on each air filter wouldn't make it kick

* After waiting a bit with the bonnet off it seems to want to fire although it seems that it wants to fire when I turn the key from start to run.

* Once restarted it seems like a cylinder or two are not contributing. After a just a bit of elevate rpm running it smooths out.

 

Once home I let it sit for a while and it starts right up and runs fine.

 

I will be replacing the fuel filter (it is due) points & condenser.

[jlumba81]

Might be ignition coil getting too warm. There's a few guys who had similar experiences. Hopefully they'll see this soon.

 

This thread might help.

Edited July 21, 2013 by jlumba81
Added link

[JimmyHilton]

Check the carbon contact in the cap, and the condition of the rotor to cap spark jump.

[DeanG]

Thanks. I won't be doing much checking for a bit. Pushing the car to the side of the road did my back in.

[rx7locost]

Could be many things coil, rotor, condensor. I have had them all with BMC B series engines. They all had somewhat similar symptoms. Somehow you are getting too much fuel. this is shown by your starting fluid not doing anything and the fact you have to run for a bit to run on all four.

 

However there is one other alternative to check into. Unlike he old leaded gas, today's E10 fuels will actually boil in the fuel bowls when no air is flowing thru the engine compartment to cool them. This is exasperated on the BMC engines where the exhaust mainfold is below the SU carbs. On the MGA, this usually causes a lean condition and can be verified by pulling out the choke a bit when it starts stumbling. Some have cured this with adding a bilge pump to blow outside air onto the fuel bowls at stop lights and slow traffic.

[cs3tcr]

I would put my money on the condensor. When they start to break down, they work fine when they are cold to warm, but once they're hot they stop working. When i was still in the british car trade (almost three years ago now), we had a hard time finding a good supplier of condensors for the 23D/25D Lucas distributors (or should i say inexpensive good condensors). Failing that, try swapping out the rotor, these too give headaches when they crack.

 

I had a very similar problem with my Eleven rep (uses a 23D distributor on a Climax FW), started up fine, drove fine for about 4 miles, then started to crap out, and finally wouldnt run at all. Had it towed home, let it cool down, and it started right up. Decided to change the condensor and havent had a problem since (about a year and a half now).

[MHKflyer52]

Try replacing the rotor as they are known to cause some of the issues you have described because they tend to develops very small crack under the contact on the top which tends to open up with use and as long as high rpm is being maintained such as normal engine running above 1000 rpm will still work but once below that say 850 rpm will die such as at a stop sign and will not start until it cools down enough to close back up. You wounded how I know this I have a BMC 1800 in my car and have had similar issues in the past. Hope this helps.

PS: Check the coil wire to the cap for any sign of it having been bent and causing an internal crack if it has a carbon core.

[DeanG]

Thanks. If my back holds up I will be replacing all the ignition except the cap & wires this weekend.

[Kitcat]

My X-Flow wld respond to a similar hot start problem (not the stall part, tho) if I unscrewed the gas cap, let it breath a few seconds, screwed it back in.