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Herald 1200 warm starting problems


Nick Bertram

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  • 2 months later...

Hi all,

I thought I would update you on the latest running issues.

Jumped in her for a long 2hr plus run the other weekend. Started finally after no spark again. Had to replace condenser again. 

Ran beautifully for 2hrs on the A40 - didn't miss a beat.

2 miles short of my destination on A43, loss of power then came back ok but a little further on loss of power again and this time terminal so coasted into a lay-by which was just there luckily. Checked for spark and plenty of that in all the right places. Fuel level good in tank. Drew/sucked fuel through from tank to inline filter (between pump and carb). Had a fag and burnt my mouth - no not really. Then checked primer lever on pump - not good! I had rebuilt the original pump a few years ago but it was not giving consistent pressure now. 

A long wait and journey back to London lock up on a low loader. 

New fuel pump bought and fitted. Still spark. So turned her over....... only to see petrol p*****g out the bottom spindle in the carb on to the manifold.

MMMmmmmm I thought. A bit like replacing your domestic boiler and your ageing victorian pipe junctions springing a leak with the extra pressure! 

Carb off and time for a clean up and rebuild. Duly completed - all jets removed/cleaned/clear, float not punctured, needle valve closing fine, accelerator pump diaphragm was replaced a few years ago and still good, spindles looked fine and closing ok.

Fitted carb back on this afternoon. Spark fine. Wouldn't start. Fuel in carb fine but guess what p*****g out the breather pipe and the throttle spindle all over the manifold.

What have I missed? Do I have to replace the throttle spindle? Do they wear? Is it better to just send the whole solex unit away to be rebuilt?

Many thanks in advance.

Nick   

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Start with fuel float not shutting off. Overfilling chamber  and  the spillage leaks out  the spindle 

as throttle is closed ,

You can get perculation where fuel syphons from the correction jets, but thats a long shot on an old carb

I suspect the float needle is not as good as you  think 

Pete

 

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Theres been a few complaints recently of replacement pumps giving too much pressure so overcoming the needle valve and flooding the float chamber. If the pump manufacturer has used a spring thats too powerful it will give a higher pressure and I believe the original Triumph spec was pretty low. Of course, as Pete says, it could be that the needle valve is past its best and I think thats the first port of call unless youve got a way to check the pump output pressure.....

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25 minutes ago, Pete Lewis said:

Start with fuel float not shutting off. Overfilling chamber  and  the spillage leaks out  the spindle 

as throttle is closed ,

You can get perculation where fuel syphons from the correction jets, but thats a long shot on an old carb

I suspect the float needle is not as good as you  think 

Pete

 

Hi Pete,

Thanks for that. I manually blow and check the float needle but I think I have a spare so will swap them out. I haven't changed the spacing either as I there is a washer in between the needle and the top body of the carb.

Will have a go at that and let you know.  

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23 minutes ago, johny said:

Theres been a few complaints recently of replacement pumps giving too much pressure so overcoming the needle valve and flooding the float chamber. If the pump manufacturer has used a spring thats too powerful it will give a higher pressure and I believe the original Triumph spec was pretty low. Of course, as Pete says, it could be that the needle valve is past its best and I think thats the first port of call unless youve got a way to check the pump output pressure.....

Hi Johny,

I haven't got a way of measuring no. 

N

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Much as Pete's diagnosis would have been spot on a few years back, with the number of reports we see of over-pressure on new fuel pumps I'd be very temtped to say that flooding a carb that didn't flood on the old pump is probably a pretty good indicative measurement in itself. See if you can get a second hand pump, or rebuld your old one. I have a pump off a 13/60 I could sell you for cost of postage - I know it works but it didn't pump enough for a 2L Vitesse, especially when it got hot.

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10 hours ago, NonMember said:

Much as Pete's diagnosis would have been spot on a few years back, with the number of reports we see of over-pressure on new fuel pumps I'd be very temtped to say that flooding a carb that didn't flood on the old pump is probably a pretty good indicative measurement in itself. See if you can get a second hand pump, or rebuld your old one. I have a pump off a 13/60 I could sell you for cost of postage - I know it works but it didn't pump enough for a 2L Vitesse, especially when it got hot.

Hi Rob,

Well to be honest I had seen a little seepage prior to the fuel pump going so I think I will start with the needle valve first. 

I rebuilt my old fuel pump a few years back with a reconditioning kit so I know the valves and diaphragm are good (checked again obviously). The springs and mechanism aren't broken. I am wondering if some crud has just stopped one of the valves working but it definitely was not delivering even pressure on manual pumping. Rather odd. 

Thanks for the offer. I may come back to you on that!

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  • 1 month later...

Ok, so this has now turned into full on starting problems. 

Rebuilt the carb. Still not starting and leaking fuel onto manifold.

Last piece of advice was to check the needle valve. Fitted a replacement.

New battery. Cranking and getting fuel to carb. Spark fine.

 Still not starting either with choke or without, with accelerator or without and leaking fuel as before. 

Fuel circulating around carb as I think it should.

Anyone know of a good mobile mechanic because this is driving me potty!!

 

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27 minutes ago, Nick Bertram said:

 

 Still not starting either with choke or without, with accelerator or without and leaking fuel as before. 

If it's leaking and not starting on choke or off then I'd guess it's still flooding and the choke is only making it worse. Is it still leaking from the same place as before?

Can you try a replacement carb as a tester?

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4 minutes ago, Colin Lindsay said:

If it's leaking and not starting on choke or off then I'd guess it's still flooding and the choke is only making it worse. Is it still leaking from the same place as before?

Can you try a replacement carb as a tester?

Hi Colin,

More if anything. Out through the bottom spindles and now out the manifold pipe. I don't have a spare carb. 

 

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Is it wet fuel out the spindles  , how long were you cranking before it leaked from the drain pipe?

It would seem its is over filling and has some needle problem or excessive pump pressure ?

Does the choke flap fully close when pulled out  and , open with a light finger touch when the choke is fully closed ???  

Do check the  firing order and that no1 is on its compression stroke and the rotor is pointing at no 1 lead on the dizzy cap 

Its easy for things to get muddled when chasing the  dream.

Youre a bit far off for a visit , Im a bit tight on freedom this month .. will have a think

Pete

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I ask about the choke flap as the flap has a automacity spring that with the choke shut it allows it to open on each piston induction stroke so when chanking the flap should chatter whith each stroke

If its solid then the manifold vacuum will suck excess fuel from the emulsion tubes and replicate flooding .

Pete

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