998 engine. Accelerates smoothly to 50/60 miles an hour and cruises there with no issues - as long as the road is flat. As soon as you hit a hill and place more load on the engine it starts to "misfire". I place it in inverted commas as I am not sure this is what it is doing - but that's how it feels. The following has been checked/adjusted/replaced - valve clearances, float, dashpot oil, points and condensor replaced with magnetronic, dizzy cap, rotor, spark plugs, carb mixture, timing (not sure if I got this right, hence previous post).

The problem occured before all these changes and persists. Someone has suggested that the petrol/gas tank may not be breathing adequately? Can anyone help?

Does it "misfire" if you try to accelerate quickly in top gear from (say) 60mph to 70 mph, on the flat?
I'm trying to ascertain if it's the load or the incline that's giving the problem.

Will test this weekend and let you know.

While your commenting on the test... does the misfire feel like the car has hit a wall and won't go faster? Does the car jerk forward and backward slightly when you reach the point of misfire?

Thanks for your comments to date. I did the test this weekend - accelerates fine on a flat road. Tried 40 to 70, 50 to 70, 60 to 70 - she was flawless. But climbs a hill...

I think the best description of the problem - is like some thing grabbing hold of the car from behind and pulling and letting go, pulling letting go... As soon as the hill in conquered it smooths out again.

Pulling and letting go and only under load is what I was looking for.

This may not be a misfire. Before you start replacing ignition parts look over the fuel system as it may be the beginnings of fuel starvation. Make sure the pickup screen in the tank is not covered in muck. Look for inline filters from the tank to the pump and from the pump to the carb(s). Replace any filters you find. Also check for debris in the bottom of the float bowl(s) and clean out the float valves to make sure their seats are clean.

I haven't seen a fuel pump fail to delivery the right amount of gas but I suppose it's possible. Do you have the mechanical pump, an electric SU, or an aftermarket electric (like a Facet pump)?

It is an electric fuel pump - not sure if it is SU or other. Is there an ideal/best make to install? It was my next set of check to go through the fuel system. Thanks for the tips on where to look and what to do!

I'd start by looking for the filters before thinking about a new pump. If there are plugged filters anywhere, a new pump won't fix a delivery problem.

The original SU is a great pump with an undeserved reputation. They are rebuildable using a manual and kits that can be ordered from the "usual sources". If you're not interested in the original pump, the common replacement is the metal, rectangular Facet pump in the low pressure range (up to about 3 PSI). These are available from most auto parts stores (sometimes sold under the Facet name, sometimes labeled Purolator). Depending on the source I've seen the price range from $25 to $50 for the Facet pump.

The link below is for a picture of my car's Facet pump. My pump has been repainted silver. Out of the box these pumps are yellow chromate colored.
http://home.mindspring.com/~dklawson/minipics/facet05.jpg

If it happens only going up hills, check the float positions. Not getting proper amount of fuel on grades, but is OK going level and down. Move the float slightly and retest until you are good to go all the time. May not take much. I'm going on the hill up only time! Assuming no less than a 1/4 tank of fuel.

I had a look under the car yesterday. It is a Facet pump - 4 psi. Looks and sounds ok and giving a good stream of fuel at the engine.
Will fiddle with the float on the weekend.

Any update for us?? How has it been running??

Errmm... The problem seems to have disappeared! About 2 weeks after posting this I took her for a drive again. Sailed up and down and along with not a hint of an issue!

This is not to say it won't come back so all suggestions are archived to follow if the problem "reappears".

Isn't that the way it goes?? Like a toothache to the dentist, ask about it and it disappears. Good to hear you are up and running!

I like a car that fixes itself. Those are keepers.

I had a Toyota that fixed itself. Then it had a relapse when I was going through a mountain pass in the middle of the night on snow covered two lane road without lights. Lost power, bucked and jerked, coughed and died as I slid sideways into a snow bank. The poor old girl had a fuel filter plugged full of rust and scale. Fortunately I happened to have a length of old fuel hose in the boot and bypassed the filter... no hose clamps... I had to wire the hose onto the metal fuel pipes.

My point is, be prepared for the problem to come back unless it was associated with something transient... like a bad tank of gas.

Ok. So spoke too soon However, there is an interesting development - I was driving at night and each time I experienced the drag/hesitation the headlights and dash lights became dim. When the hestation went away the headlights and dash lights became bright again. Interestingly too, the issue occurred constantly - not just uphill. I think it was just more noticeable previously under load - as you need all that the 998 can give you up hills at times

Checked a few elementary things when I got home - like fan/v-belt on the alternator (yes I have replaced the gennie with an alternator), checked and cleaned up the earth points. They all seemed nice and tight and cleaned.

Any other suggestions? Could it be a voltage regulator issue?

I would not expect it to be voltage regulator related... but it could be.

I suggest that you remove the belt and try spinning the alternator and the water pump by hand. You may find that one of the two has bearings that are beginning to fail.

Would the belt not slip if the bearings "stuck" and make that awful screeching noise of a slipping belt?

The belt may not necessarily squeak. I can't say with certainty that the belt would slip or even that the bearings are your problem. I'm only suggesting it as something to check.

Many years ago I owned a Honda Accord. It seemed to be having some pulsing when driven. I couldn't find the cause. While driving to my father-in-law's house the car practically did a nose stand while cruising at about 35 MPH. It was as if I'd punched the brake pedal and then suddenly released it. It did this three times in quick succession and then the car started moving again with pronounced bucking and surging. I limped the last mile to his house. When I checked under the hood I found the water pump had completely seized. When I fit the replacement water pump all surging and bucking was gone. Had it not been for the water pump bearings finally failing I wouldn't have thought to look at it. The car was otherwise running fine... no belt squeaks, no charging problems, and no overheating.

Thanks! Definitely worth an investigation. Will feedback after the weekend.

A friend of mine pointed out another thing to check. On most of the Lucas distributors there is an earth/ground wire INSIDE the distributor. This goes between the breaker plate and the dizzy housing. It's typically a cloth insulated piece of high-flex fine stranded wire.

If that wire is missing, the coil current has to pass through the bearing in the breaker plate. This can create intermittent problems. It may work for days without issue and suddenly the engine might start surging or may even stop. You can't just go by "oh it looks like it's there", you need to give it a gentle tug to make sure it isn't broken beneath the insulation.

sounds like you have a problem with some cable earthing out somewhere

Thanks for all the help everyone.
I tried all the advice here - took off the belt and checked the bearings on the alternator (only done about 2000 mi). No issue. Same with the waterpump - new from the rebuild, so also only about 2000 miles old. No issues.

Removed all earth points - cleaned and tightened up. Removed fuse box and cleaned and wire tightened. Battery terminals checked and tightened.

Recently replaced the points and condensor with a Lumenition electronic module. That all checked out ok.

Leads me to think I may have a sticky valve? Any thoughts on this angle?

Could it still be a fuel supply issue? The lights going dim could be a side effect of the rpm drop when the engine drags. Did you run through the filter, etc.?

Lumenition? Ok, I have one more long shot for you.

An acquaintance of mine on another board had problems with his ignition system after changing to Lumenition. As it turned out, he used the crimp terminals supplied with the Lumenition kit. Eventually he replaced the Lumenition terminals and all his ignition problems went away.

I know it's a long shot but it is an easy thing to try. Don't forget to try refitting the points and condenser again.

I still recckon it is more than likely a wiring problem only way it can affect both ignition and lighting at same time,either a main earth lead not earthing properly or a power lead earthing out with movement of the engine,thus pulling the headlights and panel lights down,as it has an alternator the engine revs should not affect the output from the alternator so doubt fuel problem.if this has only started since you changed to lumenition then it could be something to do with the lumenition going down to earth.

The problem was occuring before I changed to electronic ignition. So I do not think it is an issue with the ignition system. I have booked the car in with an auto electrician to check all the wiring et al for me. Will keep you posted.

OK, so it's not the Lumenition then.

As Mike said, this really does point more to some weak or damaged electrical connection since you reported on 5/8 that the headlights were also affected. Of course... it could also be something failing in the alternator.

With an intermittent problem, bench testing the alternator may not reveal any problems. However, it sure sounds like it would be a good idea to check the wires to and from the alternator and be sure to check the battery cable where it exits the channel under the car (near the exhaust pipe). I know several people who's car died because this cable came out of the channel and shorted to the pipes.

Perhaps the uphill missing/surging you've got is the alternator kicking in/out as a connection is made or broken... particularly if its a short of the main battery cable.

She was dead this morning. Just plain refused to start! Motor turned, by not even a hint of life. May be easier to trace the fault now... Will keep you posted

DOH!!!

Do let us know what you find.

Had a quick look when I got home. Tried to start her and she fired up! However, there was a loud clicking noise (best I can describe it) from the distributor. So turned off and popped the disi cap off. I seem to have a lot of up and down movement of the shaft - more than I think there should be. I would guess about 3 to 4 mm (0.11 to 0.16 in).

Am I correct? Is this too much movement? Should there be any? It is a Lucas 25D.

Up and down movement? That seems a bit odd. The drive dog has shim washers to minimize the up/down freeplay of the shaft relative to the housing.

The 4-lobe cam is a separate part held onto the main dizzy spindle by a phillips head screw. Remove the rotor and you may or may not find a felt pad in the center of the 4-lobe cam. If you see the felt, pull it out and you should see the center screw. Tighten that screw and see if you still have motion up and down. You really shouldn't have much motion when that screw is tight.

If after tightening the screw you still have axial play in the dizzy I'd pull it out and go completely through it to see where it's coming from. I'm not sure how it would be related to your surging problem and it really should have no bearing on the headlights getting brighter or dimmer, but it's certainly something I would look at.

Thanks Doug!
Your advice has been really helpful!
Will keep you posted.

That screw could not be tightened anymore. So distributor was pulled and sent for repair. Will let you know when it is back - what the synopsis was.

Distributor was repaired. They also bench tested it for me and found that the spark was not strong enough. Distributor was converted to electronic ignition about 4 months ago. Everything is working - the issue seems to be the ballast that Lumenition say must be in place. Without the ballast - spark is good. With ballast spark is poor.

Question: Can I run a Lumenition Magnetronic system without the ballast? Or with this damage the module?

Distributor was repaired. They also bench tested it for me and found that the spark was not strong enough. Distributor was converted to electronic ignition about 4 months ago. Everything is working - the issue seems to be the ballast that Lumenition say must be in place. Without the ballast - spark is good. With ballast spark is poor.

Question: Can I run a Lumenition Magnetronic system without the ballast? Or will this damage the module?

Lumenition is stuff I have not worked on. You may want to put posts about this in the Spridget and MG forums. The Mini, the Spridgets, and the MGB all use the same series of Lucas distributors so you're likely to find someone who can answer this there. Meanwhile, I'll post your question on a U.K. board I frequent since Lumenition is more common over there.

Can you type a bit of the Lumenition instructions that discuss the ballast? Typically the ignition system is expecting a total series resistance of some value. If you're using a low-resistance coil a ballast resistor is often added to bring the total resistance back in line.

Interim Post:

Humor me by telling me some more about your car without my having to re-read the previous three pages of posts. What year is your Mini? What ignition is on the car (Lumenition Optronic with the optical chopper, or Magnetronic with the Hall Effect sensor)? What wires are on each coil terminal?

Please review the following.
(Optronic Lumenition)
http://www.lowflying.dk/images/PMA50ins.pdf
SUITABLE FOR coils or coil/ballast combinations of not less than 3 ohms.
NOT SUITABLE FOR use with low resistance (i.e. less than 1ohm) electronic ignition coils

(Magnetronic Lumenition)
http://www.lumenition.com/new/support/magign/mtk003_instructions_v1-3.pdf
No mention of ballast requirement

Some Minis in the early 1970s did have a ballast ignition system. Typically these had a pink/white resistor wire from the ignition switch to coil (+). They also had a yellow/white wire between the starter solenoid and coil (+). Does any of this sound like your car?

The notes on the Optronic kit are really important to interpret correctly. Note that they say your TOTAL series resistance (ballast + coil) should be 3 Ohms. This does not mean you necessarily have to run a ballast.

Write back and tell me a bit more about your car, its coil wiring, the coil you've fitted, and whether or not you've got a multimeter. If not... it's time to buy one.

Hi Doug

You are quire right! I checked the insructions at home and when I did the install I misinterpreted the diagram to "have to include" the ballast. It is not necessary - unless it was previously ballasted. It is the magnetronic system.

The coil fitted is the Lumenition specced ans supplied coil. Coil was tested and is still strong.

It is a 1000cc Mini station wagon - 1968. There is no ballast wire. I do have a multimeter.

Hope I have answered all your questions. Its now time to get the distributor back in the car and back to the original problem - the reason for this lengthy thread!

I'm not familiar with Lumenition's coils. However, with NO wires connected to it, use your multimeter to measure across its low tension terminals. If you find close to 3 Ohms... you're golden and don't need the ballast.

This may be why the car refused to start last week. If you have a 3 Ohm coil and you added a ballast resistor in series with it, the amount of current flowing through the coil will be significantly reduced. This would be true at highway speeds also. Even though you say the misfire happened with points... test drive the car for a while without the ballast resistor and see if it's better.

Hi Doug

I got 2.85ohms on measure. So hooked everything up - with new ignition leads - and with the first turn of the key she fired up - having stood for a week!

I will let you know if the original problem is still there - but for now she is running sweetly.

Thanks for all your help.

2.85 Ohms is basically a standard coil. You'll have a much hotter spark now without that additional ballast resistor.

After you've driven the car for a few days be sure and post back and let us know how it's running.

I have driven the car now for 5 days or so and the original problem has not recurred! Yahoo!! However, I have noticed that the difference between the brightness of the headlights at idle and above 1000 rpm is substantially different. Last night I drove through a rain shower - I had the headlights on and the wipers going. The wipers were quick while running and slow while idling - again a substantial difference.

I have had the car at an auto sparky twice. He is adamant that the alternator is not overcharging - said I would now if it was as the battery would start to give of a sulphorous smell.

This normal? Any advice? You think I am just being paranoid?

Well, you say it's running better and that is the good news.

I have a couple of suggestions for you that will be interesting little side projects.

First, either buy a new volt gauge or look for a nice used one on eBay. Look for VDO if you can find it (not Smiths). The VDO gauge will respond quickly to changes in voltage while the Smiths has VERY slow response. Once that's wired in, glance at it periodically while you're driving... particularly when you notice the headlights dimming. It might just be a minor fluctuation in the car's operating voltage that is the issue. However, you'd really like to see the car's charging system operating at 1V to 1.5V over what the battery shows with the engine off. You do not want to see alternator output higher than about 14.5V

The other project that may help with the headlights (possible... but harder on the wipers) will be to make and install a headlight relay panel. There are kits out there for this but you can easily make your own using Bosch/ISO relays. These relays are regularly available at auto parts stores and online from surplus companies like bgmicro.com. The advantage of adding the relay panels is that the supply to the lamps is more direct through low resistance contacts. Most people report consistently brighter headlights with relays installed. The relays also take the load off your dash wiring and standard headlight switch. This extends the life of those parts.

Thanks Doug.

I have already put my headlights onto relays. So the switch activates the relay and pulls the juice directly off the battery as opposed to through the switch. I have also upgraded my headlights to take a modern H4 fitting and I am running 60/55 xenon globes. The lights on my Mini are excellent - I would venture to say as good as my late model BMW.

I will take your advice and put in a volt gauge. Will get back to you and let you know.

Something weird happened.
I posted a comment, came back an hour later and its gone??

Anyway here it is again.

I have ordered the VDO Voltmeter. In the meantime I borrowed a temporary setup from the auto electrician - I think I am driving him mad!

Before starting the meter measures 12.2V. On starting (before revving) the needle flicks to about 12.8V after about 2 seconds. Revving the engine and the needle jumps to about 14.4V. And sits there more or less consistently even with headlights and wipers on. So it seems I was being over cautious - but better safe than sorry

I will still install the voltmeter - so I can always be sure.

Everything sounds OK to me.

I had a similar posting problem about a month ago. Very frustrating indeed.