Possible Electrical problem - car refuses to rev & accele..

[Mini_Lund]

Hi all, just a quickie!

I have had a tempremental problem with my mini which I suspect to be electrical. I have replaced the wire from the loom to the live on the coil, fitted a new coil, new set of points, but not condenser. Champion HT performance leads, and champion spark plugs.

However, sometimes wen I put my foot on the accelerator to pull away the car coughs splutters and wont rev, jst a 'murrmur noise'.

I've been trying to get to the bottom of this problem for some time now on my own accord, but so far, have been unsuccessfull! So guys what could it be?

I'm going to try a working set of plugs tomorrow to see if its any different.

The timing has been set with a timing strobe light and is spot on.

What is the job of the condenser. What are the symptoms of a failing condenser?

Anybody else has this kind of problem?

Thanks in advance, help me out!

Tom

Edited by Mini_Lund on Sunday 23 November 21:52

[Plank]

Dry dash pot? Timing chain jumped? Dizzy cap? Condensor? Plug leads? Damp? Fuel pump? Little wire in the distributor? just a few of the many faults that have made the planks mini's cease to proceed. Good Luck.

[odyssey2200]

split diaphram in the SU?
air leak into the manifold?

[Mini_Lund]

Plank said:

Dry dash pot? Timing chain jumped? Dizzy cap? Condensor? Plug leads? Damp? Fuel pump? Little wire in the distributor? just a few of the many faults that have made the planks mini's cease to proceed. Good Luck.

Dash Pot is full with dashpot oil. No nasties frm the timing chain as far as im concerned. Dizzy cap is old and quite worn inside - possible factor. The earth wire in the dizzy is abit shabby, but would that really make a difference?

odyssey2200 said:

split diaphram in the SU?
air leak into the manifold?

Where's the diaphram in the SU? I havent come across one. Could possibly be an air leak, but I sprayed around the areas with WD when engine running, no bubbles or note in engine change, even on the butterfly spindle.

.

Thing is its temprement, after setting the timing with a strobe, it ran amazing for about 5 minutes, then all downhill again from there. theres definately somehting wrong and almost a year down the line, still no luck.

Put foot down on accelerator doing 30, she almost slows down rather than picking up speed.

[odyssey2200]

Just realised I have mixed my carbs up


But

on the top of the carb is a black screw cap

take it out and there is a piston on the end, which should sit in some oil which acts as a damper.
Make sure there is oil in there or the piston will move up too fast and the engine will die.

[Mini_Lund]

odyssey2200 said:

Just realised I have mixed my carbs up


But

on the top of the carb is a black screw cap

take it out and there is a piston on the end, which should sit in some oil which acts as a damper.
Make sure there is oil in there or the piston will move up too fast and the engine will die.

Theres plenty of oil in the dashpot, its even genuine dashpot oil.

[odyssey2200]

Mini_Lund said:

odyssey2200 said:

Just realised I have mixed my carbs up


But

on the top of the carb is a black screw cap

take it out and there is a piston on the end, which should sit in some oil which acts as a damper.
Make sure there is oil in there or the piston will move up too fast and the engine will die.

Theres plenty of oil in the dashpot, its even genuine dashpot oil.

If you put your finger in the carb, can you lift the piston freely and it drop back down smoothly?

[Mini_Lund]

odyssey2200 said:

Mini_Lund said:

odyssey2200 said:

Just realised I have mixed my carbs up


But

on the top of the carb is a black screw cap

take it out and there is a piston on the end, which should sit in some oil which acts as a damper.
Make sure there is oil in there or the piston will move up too fast and the engine will die.

Theres plenty of oil in the dashpot, its even genuine dashpot oil.

If you put your finger in the carb, can you lift the piston freely and it drop back down smoothly?

Theres quite abit of pressure against me when lifting the piston with my finger, it falls back down slowly but surely, if i push it too far up it will stay at the top for a while..

[Snake the Sniper]

It should slide up and down quite quickly. Sounds like it's sticking somewhere. This could either be the needle trapping against the jet, or the piston body rubbing against the carb body. Has the carb been rebuilt recently?

PS I was once told the 90% of electrical problems are down to fuelling. This has been fairly true for me thus far.

Edited by Snake the Sniper on Sunday 23 November 22:28

[Mini_Lund]

Snake the Sniper said:

It should slide up and down quite quickly. Sounds like it's sticking somewhere. This could either be the needle trapping against the jet, or the piston body rubbing against the carb body. Has the carb been rebuilt recently?

PS I was once told the 90% of electrical problems are down to fuelling. This has been fairly true for me thus far.

Edited by Snake the Sniper on Sunday 23 November 22:28

I cleaned the carb recently yes. The needle is an AAE needle as the mini's stage 1. Old needle was ADH (was also bent!)

What can I do about freeing up the slide motion?

[odyssey2200]

does the vacuum advance in the dizzy work smoothly?
BTW if your condensor was shot your points would be burnt and melted.

Edited by odyssey2200 on Sunday 23 November 22:35

[Mini_Lund]

odyssey2200 said:

does the vacuum advance in the dizzy work smoothly?

Yes I recently bought a genuine new unit, the advance is working correctly, seemed nice when looking at it with the strobe.



You need to feel it on the accelerator really, she just wont accelerate, almost a continuous misfire, as if some component is restricted! If i pump the throttle a few times and build up the revs that way, she managed to rev, then i pull away dodgily! Makes me look like a complete idiot >.<

Edited by Mini_Lund on Sunday 23 November 22:45

[Snake the Sniper]

Mini_Lund said:

Snake the Sniper said:

It should slide up and down quite quickly. Sounds like it's sticking somewhere. This could either be the needle trapping against the jet, or the piston body rubbing against the carb body. Has the carb been rebuilt recently?

PS I was once told the 90% of electrical problems are down to fuelling. This has been fairly true for me thus far.

Edited by Snake the Sniper on Sunday 23 November 22:28

I cleaned the carb recently yes. The needle is an AAE needle as the mini's stage 1. Old needle was ADH (was also bent!)

What can I do about freeing up the slide motion?

Has the engine been playing up since around the time of either cleaning the carb or fitting the new(er) needle? Do you have a H or HS series SU? The HS is self centering, but the earlier H is not. Either way, pull the piston out and remove the needle. Then see how freely it slides up and down. That will tell you which bit is rubbing. If it's the needle, then just refit it and adjust to suit. If it's the body jamming, then a quick clean around the bottom edge of the piston with the wet and dry should sort it out. If that doesn't do it, the easiest bet is probably a new carb from a scrappy. Although I doubt it'll get that far.

[odyssey2200]

silly question but does the car have a fuel filter on it?
Is the fank vent OK?

[Mini_Lund]

Snake the Sniper said:

Mini_Lund said:

Snake the Sniper said:

It should slide up and down quite quickly. Sounds like it's sticking somewhere. This could either be the needle trapping against the jet, or the piston body rubbing against the carb body. Has the carb been rebuilt recently?

PS I was once told the 90% of electrical problems are down to fuelling. This has been fairly true for me thus far.

Edited by Snake the Sniper on Sunday 23 November 22:28

I cleaned the carb recently yes. The needle is an AAE needle as the mini's stage 1. Old needle was ADH (was also bent!)

What can I do about freeing up the slide motion?

Has the engine been playing up since around the time of either cleaning the carb or fitting the new(er) needle? Do you have a H or HS series SU? The HS is self centering, but the earlier H is not. Either way, pull the piston out and remove the needle. Then see how freely it slides up and down. That will tell you which bit is rubbing. If it's the needle, then just refit it and adjust to suit. If it's the body jamming, then a quick clean around the bottom edge of the piston with the wet and dry should sort it out. If that doesn't do it, the easiest bet is probably a new carb from a scrappy. Although I doubt it'll get that far.

Hold on, does the screw in the side of the piston (to fix the needle in place), adjust the centre of the needle in the jet?? If so, that will need adjusting.

Its always played up >.< old needle was bent, this needle is straight but unsure if its jetting right, getting emissions set up saturday.

SU HS4.

I'll test how freeley it slides up and down tommorrow... no doubt it will be pi**ing it down!

[Mini_Lund]

odyssey2200 said:

silly question but does the car have a fuel filter on it?
Is the fank vent OK?

No fuel filter. Just mechanical pump and fuel lines!

[Snake the Sniper]

In the HS4, the screw in the bottom of the piston should hold the needle into a spring mounted holder thingy so the needle can wobble about a bit from side to side. I can't remember quite what shape/size it is though, and since it's raining, I'm not going out to the garage to check!

[Mini_Lund]

Snake the Sniper said:

In the HS4, the screw in the bottom of the piston should hold the needle into a spring mounted holder thingy so the needle can wobble about a bit from side to side. I can't remember quite what shape/size it is though, and since it's raining, I'm not going out to the garage to check!

Yes your right, the needle does wobble, think its called a 'floating needle'. All seems well that side of things.. will definately check the piston for a smoth glide!

[GTRMikie]

You appear to have replaced everything in the ignition system apart from the condenser. This is the part most likely to fail. It is the first thing I replace whenever I have a misfiring problem, and it usually does the trick.

[Snake the Sniper]

Mini_Lund said:

Snake the Sniper said:

In the HS4, the screw in the bottom of the piston should hold the needle into a spring mounted holder thingy so the needle can wobble about a bit from side to side. I can't remember quite what shape/size it is though, and since it's raining, I'm not going out to the garage to check!

Yes your right, the needle does wobble, think its called a 'floating needle'. All seems well that side of things.. will definately check the piston for a smoth glide!

It sounds like the piston may be jamming up then. I've had it once before and it was sticking due to a build up of tar/glaze type stuff that petrol leaves behind. A quick clean and it worked fine. Make sure you're not overly aggressive with the cleaning though, as the sliding fit of the piston is quite important! Just back to clean metal is fine.