Rough-Running 3000

[TAS525]

Problem seems to be solved after cleaning gunk off carb pistons and performing a drop test. Was careful to not switch the pistons between carbs as I learned that each carb is unique and most have its piston that was installed at the factory. As an experiment, I tried switching them and low and behold the the car suddenly ran great. Maybe a previous owner or shop person switched them. Anyway, so far so good. Thanks for all the help and info.

Great to know! That’s going to be my first point of inspection upon my return home! Happy motoring!
~ TAS

 

[Patrick67BJ8]

Problem seems to be solved after cleaning gunk off carb pistons and performing a drop test. Was careful to not switch the pistons between carbs as I learned that each carb is unique and most have its piston that was installed at the factory. As an experiment, I tried switching them and low and behold the the car suddenly ran great. Maybe a previous owner or shop person switched them. Anyway, so far so good. Thanks for all the help and info.

Have you checked at any time to see if your jets are centered?

 

[TAS525]

If I had a nickel for every minute I’ve wasted chasing the elusive “white rabbit,” I’d be a wealthy man indeed! Three + weeks now shot troubleshooting what could’ve been such a simple fix. At first I thought, like carguy, it must be a carb issue (what with modern ethanol tainted fuel and all the related problems).

After a thorough inspection and simple cleaning/tuning/balancing, however, this was ruled out. I even checked and adjusted the timing, which was found to be waaaay advanced.

With little to no backfiring, good slow idle and only missing at higher revs. (Around 2000 or so under load), I was convinced it must be fuel causing the issue and began replacing the old hoses and blowing out the lines where I could and installed a filter prior to the carburetors, which was long overdue.

Not sure where/when Dad purchased this fuel pump I added 4 years ago, but I had a rebuild kit sent to me and found that the only parts I could use were the sump gasket and main diaphragm! The inlet/outlet valves in this repro. are pressed in and not held with the retaining clip. Reassembled with what I had and it seemed to deliver good pressure.

Still, the car continued misfiring under load and gradually worsened to where it barely idled.

I moved on to replace the coil (Old Lucas still registered good resistance), spark plug wires and finally - FINALLY - the capacitor/condenser. EUREKA!!! This simple - $3.00 - part, which I actually replaced 2 years ago was the cause of all my problems!

Had I done better research, I would have found the excellent troubleshooting procedures for this very issue in the Ignition Chapter of my Haynes Manual (For whatever reason, the HM is typically the last place I look!). It describes an embarrassingly simple test for capacitor failure, so don’t make the same mistake I made. Save yourself hours/days/weeks and possibly hundreds of dollars if your engine begins suddenly misfiring.

According to other sources, there has been a rash of faulty condensers/capacitors lately. I ordered this one (Intermotor Brand) from Engel Imports here in Kalamazoo, MI.

That, my friends, is a lengthy way to let y’all know that my problem has been solved!

 

[Bob_Spidell]

I always figured--rationalized--that all the checking, cleaning, etc. of other things, though not the cause of the problem may have staved off the next.

 

[TAS525]

You hit the nail on the head there sir! That is the only way I can convince myself this is all worth the effort sometimes! Often, when Dad and I would find ourselves at a similar impasse in the garage, he would exclaim, with a grand gesture, “Just think Tommy, someday all of THIS will be yours!” It is strangely comforting to know the old man’s getting a chuckle of satisfaction out of my plight!

 

[John Turney]

I heard somewhere that 90% of carburetor problems are electrical. Congratulations on solving it.

 

[TAS525]

Love it! Definitely gonna file that away!

 

[vette]

What part of the electric carburetor is causing the troubles?

 

[kozelding]

Yeah, I've had the exact same experience.

Back when mechanical points were common on daily drivers, I never, ever remember having a condenser fail.

Now it's the first thing I replace whenever the Healey has the slightest hiccup.

 

[bob hughes]

Well done Carguyinaz, you can never tell what has been done by a PO with these old girls.

Tommy, sounds as if you are over fueling, check your needles, my old girl ran for years with no problems then all of a sudden things went pear shaped, spent a few pounds with my local guru and still it continued, we eventually diagnosed over fueling because the plugs were well sooted up, so I bought new needles, turns out that the original needles, correctly stamped, had been turned down and were much thinner than the new ones, once changed over the problem stopped. Still can't make out why it ran perfectly before though.