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Kentish

Original Poster:

14,717 posts

117 months

[news] 
Tuesday 14th April 2009 quote quote all
It has an electric pump and that appears to be working as it runs fine after starting but it is difficult to start regardless of whether hot or cold.

I can't really hear the fuel pump running on start up but it will eventually fire and then die, after a few goes and sometimes with your foot on the floor it will eventually run.

It has points and condensor, all not too old. Plugs and leads look in good condition too but these would probably not manifest in the issues experienced.

I'm thinking that perhaps the fuel pump is weak and not pulling fuel from the tank (which is quite new) as quickly as it should be.

I think I may unhook the fuel supply at the twin SU carbs and use a bottle full of petrol elevated above them to see whether it fires up straight away.

Any other ideas?

Kentish

Original Poster:

14,717 posts

117 months

[news] 
Tuesday 14th April 2009 quote quote all
Anyone able to offer any thoughts?

Mr Will

12,532 posts

89 months

[news] 
Tuesday 14th April 2009 quote quote all
You don't have waxstats do you? and the choke mechanism is working correctly?

The simplest test would be to take the fuel line off the carb and put it in a jam jar. Turn the ignition on and see how much fuel the pump is pumping, you shouldn't need much on a carb engine so it will be obvious if there is a problem.

Kentish

Original Poster:

14,717 posts

117 months

[news] 
Tuesday 14th April 2009 quote quote all
Mr Will said:
You don't have waxstats do you? and the choke mechanism is working correctly?

The simplest test would be to take the fuel line off the carb and put it in a jam jar. Turn the ignition on and see how much fuel the pump is pumping, you shouldn't need much on a carb engine so it will be obvious if there is a problem.
Not sure about waxstats, will need to check.

The choke is manual and appears to all work as expected. Not needed for long just to start.

The reluctance to start is exactly the same whether cold or hot which makes me think it's a general issue rather than a choke issue.

I'll try the fuel line check to see how much is pumped up there.

Thanks for your help smile

Mr Will

12,532 posts

89 months

[news] 
Tuesday 14th April 2009 quote quote all
Kentish said:
Mr Will said:
You don't have waxstats do you? and the choke mechanism is working correctly?

The simplest test would be to take the fuel line off the carb and put it in a jam jar. Turn the ignition on and see how much fuel the pump is pumping, you shouldn't need much on a carb engine so it will be obvious if there is a problem.
Not sure about waxstats, will need to check.

The choke is manual and appears to all work as expected. Not needed for long just to start.

The reluctance to start is exactly the same whether cold or hot which makes me think it's a general issue rather than a choke issue.

I'll try the fuel line check to see how much is pumped up there.

Thanks for your help smile
If you do have waxstats then google "2p waxstat fix", sorts an awful lot of starting problems the Spitfires suffer from at least.
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aka_kerrly

7,089 posts

93 months

[news] 
Tuesday 14th April 2009 quote quote all
so the difficulty is in starting but once the engine is running it behaves fine- correct?

I realise you are refering to a carb equipped car but i had very similar problems with hot an cold starting which was due to leaky injectors that were flooding the engine each time it was switched off, it would then be a nightmare to restart but once started ran fine.

It would be worth taking the plugs out after trying to start the car and checking if they are oily/wet /stink of petrol as this may give you a clue.

Also, it all good checking the volume of fuel but it might be the pressure (lack of) that is the issue, if your car has a pressurised system that has a accumilator in it then when the accumilator fails the fuel pump has to work harder to build up pressure before actually being able to supply a decent amount of fuel.

once you know you have a decent spark and a decent supply of fuel then you can start digging deeper an deciding if you need new parts.


Kentish

Original Poster:

14,717 posts

117 months

[news] 
Tuesday 14th April 2009 quote quote all
Thanks for that, I did google and found this http://www.theminiforum.co.uk/forums/lofiversion/i...

I'm not sure this is my problem though but well worth checking into in case mine does ever have hot running issues.

I also wondered about plug temperatures but is that only an issue on hot starting or cold starting too; I've only recently bought my MGB GT so I'll go through and check all the correct parts are fitted (plugs, cap, rotor, points, condensor, coil etc).

I do have a twin K&N on there and I did notice that some owners have running issues with them, can't think why on an older car with no MAF but I'll certainly look into it if the parts I mention are all OK.

Mr Will

12,532 posts

89 months

[news] 
Tuesday 14th April 2009 quote quote all
aka_kerrly said:
so the difficulty is in starting but once the engine is running it behaves fine- correct?

I realise you are refering to a carb equipped car but i had very similar problems with hot an cold starting which was due to leaky injectors that were flooding the engine each time it was switched off, it would then be a nightmare to restart but once started ran fine.

It would be worth taking the plugs out after trying to start the car and checking if they are oily/wet /stink of petrol as this may give you a clue.

Also, it all good checking the volume of fuel but it might be the pressure (lack of) that is the issue, if your car has a pressurised system that has a accumilator in it then when the accumilator fails the fuel pump has to work harder to build up pressure before actually being able to supply a decent amount of fuel.

once you know you have a decent spark and a decent supply of fuel then you can start digging deeper an deciding if you need new parts.
Good call on the flooding, I hadn't thought of that and it's definitely one worth checking.

Kentish

Original Poster:

14,717 posts

117 months

[news] 
Tuesday 14th April 2009 quote quote all
Good points too aka_kerrly, different situation being on carbs with no pressurised fuel rail but what you said has made me think about other possible causes and one could be a porous float in the float chamber causing over fuelling.

The car does blow out partially burnt fuel at start up when it's cold which could be down to excees choke but I'll check to see whether it does it when it's hot.

If it does then a porous float or an incorrect float chamber level could be the cause but even then, I'm wondering whether that would be an issue on cold starts as the car needs more fuel.
Perhaps that and the choke combined are too much. It doesn't need much chocke to start it which could be an indication of this fault but even with little or no choke the car won't start until after several goes.

Putting your foot to the floor also helps but i don't like starting any car at full throttle when cold!

I'm still getting used to its little traits so will take it for a spin tonight and get it nice and hot then see whether it is reluctant to start if I leave the throttle alone and also check the fuel delivery before i go out.

Dogwatch

3,797 posts

105 months

[news] 
Tuesday 14th April 2009 quote quote all
Something in the distributor? I know you have new points and capacitor but capacitors can be 'duff' from outset. Is the Advance mechanism moving freely?

odyssey2200

18,650 posts

92 months

[news] 
Tuesday 14th April 2009 quote quote all
does your modle have a ballast resister on the coil?

Kentish

Original Poster:

14,717 posts

117 months

[news] 
Tuesday 14th April 2009 quote quote all
So, I took a look at the B tonight and the choke is all working fine and I set the carbs fast idle correctly to around 850 rpm, it was set too high at 1200 rpm but once set correctly I noticed the car is hunting indicating a rich mixture. I need to check the workshop manual for the correct idle setting as 850 was a guess. I wound it up slightly to just under 1000 rpm and the idle is a lot smoother with no hunting.

The K&N twin air filters look quite dirty so I'm going to replace those.

The carbs appear to be in quite good condition with no play in the linkages to speak of and I gave them a thin coating with lithium grease followed by a liberal coating of silicone spray to get everything nice and smooth and free and it all seems OK.

I'm not going to mess with the carbs too much now the idle speed is OK.

I'll first go through making sure the correct distrubutor cap, rotor arm, points, condensor, plugs, coil and ballast & leads are fitted.
I'm also going to check all chassis earths and also the live connections between battery and starter etc - just to make sure.

I took the broken bakelite steering wheel off too and replaced it with a new Mountney leather wheel and new boss. The only trouble was the horn button and connections were completely different between each wheel so I had to fabricate a new push system and connector to fit into the new horn push with an adjuster stud screwed into the push and then adjust that until the push made contact with the stud (used a continuity tester on a mutimeter to check this), once in place the stud would make contact with the sprung connector coming up through the column which appeared to have a circlip missing so I made a new retainer from a fibre washer which worked well. I cleaned the paint off the inside of the boss where the horn push side contact is located and bent the side contact out slightly to obtain a tighter fit. Popped the horn push into place and connected the horn up, pressed the new horn push and perfect, I have a working horn again!

One job down smile

Then I noticed a leaking rear wheel cylinder frown

It's only to be expected on a 40 year old car that's maybe done 3k miles in the past 6 years. And I'm having fun, I got a real buzz out of making the connector up for the horn and it all working perfectly - only a small thing I know but really satisfying when you make up your own parts smile



Edited by Kentish on Tuesday 14th April 22:21

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