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Poor Running - Is It Coil/ht Leads?


Guest Ian Marr

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Guest Ian Marr

Cheers Paul. Took the plugs out and cleaned them. They are okay.

 

I asked Webcon about fuel pressure and got the detail below ... Thought it worth sharing.

 

Dear Sir

All Weber carburettors require the same pressure of 2.5-3.0 psi

With best regards

Allan Smith

Technical Sales

Webcon UK Ltd

Unit A1, Dolphin Road, Sunbury, Middlesex. TW16 7HE. UK

Tel: +44 (0) 1932 787100 Fax: +44 (0) 1932 782725

Email: sales@webcon.co.uk Web: www.we

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Guest Ian Marr

Just done the leads and plugs. Not much better, running a little better on tickover, but under load it took some revs to get it past the 'dead spot'. Cleared a bit like it has before, but the underlying power dip is still there and highly likely to return. I ran it to the fuel station about 500 yards down the road and back ... Made it, but felt like a fingers crossed moment. Have not wound back the regulator, but as it is reading 0.4 bar, which is about 6 psi. No idea what high pressure does to a carb, but if the gauge is right it is excessive.

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Guest Ian Marr

My gut reaction was fuel Lee, and swaying back that way. I was going to replace the mechanical pump like for like as it is probably as old as th engine and stood for a while (haha) during build, but ended up getting a Facet electric pump. Not fitted yet, but might try a rough fit before work tomorrow.

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Guest lotusPaul

There is a fine mesh filter in the carb.I'd strip carb and clean out all the components and rebuild. There is also a fine mesh filter in the pump too. Can you strip and clean the pump?? Do you have any other possibly blocked filters in the fuel system?

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Guest Ian Marr

Don't think the pump is stripable. Only other filter is in the regulator and I bypassed that with no change. Not tried to strip and clean a carb before.

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Guest mcramsay

It sounds like you have a fuel flow restriction, disconnect the fuel inlet to the carb and run it into a clear bottle and run the car on the starter and see if you are pulling fuel from the tank

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Guest lotusPaul

You say you can replace pump with another..I'd try that but before connecting blow line back through into tank.

 

I'm not too convinced on blockage as it would deteriorate over time and not suddenly. But I'm aware it happens.

 

As for carb please post exact model and serial numbers if posdible

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Guest Ian Marr

Carb is a Weber 2V 30/34 DFTH, not sure of the serial number but will look and report back.

 

It is the one driven by the ESC11 and has a motorised stepper choke valve. Donor car being a 1987 Sierra Sapphire 2.0 GL, original reg E27 UWE

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Guest lotusPaul

Thanks Ian I'll look into it, I have a few suggestions for you to try tho. Firstly how old is the fuel? If its old try fresh fuel.

I'll look into your set up and see if we can get you up and running

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Too much pressure to a carb will probably show up as a leak from somewhere. My twin 45s are restricted by the regulator to about 3psi and that stopped the leak problem. They need flow not pressure. Lots of it judging by the way they drink fuel.

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Guest lotusPaul

I agree on a low fuel pressure.of top of my head lotus Excels had a pressure of 2.7psi from an SU electrical pump feeding twin Delortos. If you suspect high fuel pressure perhaps that SU pump is a good swap? Not sure on cost but sounds an option

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