Morninglightmountain let me talk to you, i am just concerned because your problem has been going on for more than a year now, and it already garnered 4 pages of replies on this thread and STILL no fix(?), my honest guess is that your problem is more on electrical/timing/vacuum advance thingy/correct firing at high speed./ again, im going to quote a phrase from a very prominent figure in this forum, he once told me "Child,invest on a good set of Timing gun" i followed his advice and guess what, since then my mini ran so great. Although he never use a timing gun because he rans a 123 dizzy, i still follow his advice.

So what did you set it to ?

I've set the float. & i tried it adjusted to allow a higher fuel level.  no luck.  adjusted it back.

What have you set the float gap to ?

yes.  I've had the carb off a few times. checked double checked and have also replaced. 

Have you checked the internal filter in the carb yet ?

quick question.  
I've read on another forum a discussion from 2009 about possibly the ballast or resistance wire causing cruising speed misfire. 
My current set up at the coil is
red(from the pertronix dizzy) and a back wire to +.
blk(from dizzy) and an orange wire to -.  it looks red but it's orange(spliced the last 2 inches)
and there's a dangling orange wire not used tied up right next to the coil.

so 1 blk and 2 orange wires (factory?) run to the coil?

Anyone have any ideas about this?

I'll try to track down exactly where the 2 orange wires and the blk wire run to this weekend.


thanks!

Not just the plastic needles. I had two metal ones (not brass) that would expand with heat and bind on the barrel of the brass seat. In my case, it would stick open, resulting in overflow of the HIF fuel bowl. Excess fuel would flood and kill the engine - the overflow tube is higher than the top of the main jet. It was a long struggle with pumps, regulators etc, before I figured it out.

I was just at the Mini 57 in Tn and Mark Caldwells UK Moke was starving for fuel in the hills. He came to the conclusion that the needle and seat was sticking, replaced it and it ran fine. I had read somewhere that the plastic ones were maybe swelling with all this crap fuel we have and the cure was to lightly sand the sides of it to create more clearance, or of course they could be crappy parts but Mark restored his Moke 17 years ago and if his was replaced then maybe not the case. Worth a try and as your fuel filter is always full it may be the problem. I don't think the brass viton ones have this issue.

pulling the choke doesn't help.  but to be sure I'll try again. when I was trying that the choke cable wasn't put on correctly and it only engaged a little.
I believe I'll order a new coil.  if it doesn't work I'll have an extra coil.

Try to turn the engine on ,warm it up and rev in neutral up to 3k - 4k rpm and see if it will chug or hesitate without load. if you have the transparent glass filter(like mine/$9) rev and see if the glass filter is being filled up continuously,if it has empty space(air),then it's the pump...but i still won't discount the possibility that it's more on electrical/dizzy/ignition timing issue. This is when the 123 dizzy is of a big advantage, it has 16 advances, you can't go wrong. sparks at the right moment. sometime, someone told me to -"invest on a good quality timing gun"...i did and hmm it made sense, and made my life easy.

ps: omg , he keeps on ordering parts until he discovers the problem,    Uh, oh !! $$$$  ---see below! It's not bad tho

Following on what Ian said about the HS carbs, sometime it can be simple things.
I had an issue with a twin HS setup, chased everything, new pump etc.

It turned out to be the small neoprene O ring for the jet tube. I had carefully  checked multiple things many times, but the last time I  re-assembled, it got twisted. The car would idle fine, but would stutter at speed above a certain RPM.

Not much help because it is a different issue, but sometimes it is the simple things like the filter Alex mentions.
Terry

Before you spend any money on a new pump, refresh my memory.

When the car seems to be struggling, have you tried pulling the choke out a bit to see if it runs "better"?

I don't think you'll buy anything with a new pump... The old one seems to be doing all it should.  At 60 mph cruise you're only needing about 20hp (an 850 will do 72 mph with just over 30hp).... Say, maybe something less than 3 g/hr ???

One other thought..following on from Alex's comment re the small filter at the bottom of the jet.  I don't know if HIFs are like HSs in that the HS has a small O ring that seals the jet.  This is easilly displaced when the jet is installed and, if so, can partially block the flow of fuel into the carb.

The spring is part of the fuel metering system.  The correct Spring will ensure that the piston only reaches its full height at full revs and full load. (Ie max speed, foot to floor).  I don't know how you'd check this without a dyno ???

A bad coil will feel like a fuel issue in that, as the revs rise, the coil has less (insufficient ) time to charge properly ..and the mixture richens which makes the weak spark even less effective.

Cheers, Ian

My problem sure feels like a fuel delivery issue.  The only problem when it has happened I have cut the power to the car, puller over, and checked the clear fuel filter which is directly in front of the carb. it's always been full.
But at this point I'll drop another $60 on a new pump if you guys really think this might work.  

is the EMPI 41-2010-8 a good one? 2-4 psi  30gph

please advise.

Thanks!

also.  what about my dashpot spring?  I'm can't tell which one I have (no color). Could that cause the piston to be settling in the wrong place during cruising speeds? 

like I said, this problem happens every single time and you could set your watch to it. 

Years ago driving a 998 in Atlanta traffic I had a similar problem at higher speed (read that as 18 years ago, speeds around 80 - keeping up with rush hour traffic on I-285/I-75 - it was solved when I put in a facet fuel pump and a regulator.
  I used the Facet Red pump - it lasted 18 months and died. replaced it with another (same pump), that lasted around a year, completed to Facet - they sent a new pump - no charge.  When it died (they did acknowledge a bad batch of pumps at the time) I went to the square type as found at AutoZone etc. as referred to above and am still using it.  Only difference now is instead of an HS4 on a 998 I went to the HIF44 and 1380 and around 10 years ago a 1430 also with the HIF44.  My other Mini has the 1275S with the twin HS2's - no high speed problem with either of them.

On the other hand, if it did, by the time he was finished the motor would be supercharged, putting out hundreds of horsepower and would rev to over 10,000 RPM.

Naaah.. that will never work..  Without his computers he'll be useless… and you don't have the correct plug

Cheers, Ian

Malsal. I'll try rerouting the fuel line.
I don't think it's the electric dizzy because it was doing the exact same thing before with to points.

The formula 1 races are coming here to Austin in October.  My plan is to kidnap a top F1 mechanic and keep him in my dungeon until he solves me mini cooper 1275 misfire problem. 

Oh oo... Electronic dizzie ... IMHO you're now in no mans land...  I had an electronic ignition system (Piranha) once.  It lasted 20 years but when it went bad, the car stopped.  The problem then is that's there's really no way of testing what's wrong.  We just re-installed the points I took out when the Piranha was fitted..and it's been that way for about 10 years (one new set of points since).

I was going to suggest going to Pep Boys/Autozone/whatever and buying a generic coil (I think I paid something in excess of $5 for the last one I bought.).. However, I've no idea how this might suit the rest of your non standard ignition. A coil will not produce white smoke.... Or do anything that could cause same.

Don't worry about the tail pipe.  A blocked air filter can cause problems such as you describe but I do not believe the exhaust would be an issue.  

Cheers, Ian