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whunter
Frequent User
Username: whunter

Post Number: 15
Registered: 10-2003
Posted on Monday, 10 November, 2003 - 13:25:   Edit PostDelete PostView Post/Check IP

Hello Everyone
1978 Silver Wraith II performance problem.
Massive sediment found in fuel tank, flushed fuel tank, replaced all three fuel filters, removed weakening valves (where stuck shut) cleaned replaced O rings, replaced spark plugs, distributor cap + rotor and original ignition coil wire.
Cold start is perfect, as it warms up it runs progressively worse.
Under light acceleration, it sounds like it is firing back through the carbs, heavy acceleration is no problem.
Looking for suggestions on how to proceed.
I suspect the carbs are gummed up and the O rings and diaphragms are bad, solution is to rebuild carbs.
I am looking at $300.00 USD for parts, is there an alternative through SU or other?
Am I blaming the carbs in error?
Also have a 1960 Bentley S2 just starting to act similar.
The carbs on both vehicles have not been serviced for three years or more and both sat idle for nearly two years.

whunter
RROC, Lake Michigan, Motor and Ohio region.
ASE Master Mechanic
asemastermechanic@juno.com
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David Gore
Moderator
Username: david_gore

Post Number: 137
Registered: 4-2003
Posted on Monday, 10 November, 2003 - 20:03:   Edit PostDelete PostView Post/Check IP

Bill,

Are you using fuel containing ethanol in your region?

If so, this could be part of your problem and I suggest you search this site using the key word "ethanol" for more information. Ethanol is notorious here for causing exactly the problems you describe with older cars especially those that have built up a protective "crud" layer in the fuel system over the years. One tank of fuel with ethanol will remove this crud and block up the system as well as affecting the rubber/polymer components.

Suggest a carburettor overhaul with a kit suitable for ethanol fuel blends will fix your problems - don't forget to eplace the SU fuel pump diaphragms while you are at it!
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whunter
Frequent User
Username: whunter

Post Number: 23
Registered: 10-2003
Posted on Thursday, 13 November, 2003 - 13:28:   Edit PostDelete PostView Post/Check IP

Thank you David
I see what you mean.
You are correct, many of our stations have ethanol in the fuel.
Now I will add the pump diaphram to repair.
whunter
RROC, Lake Michigan, Motor and Ohio region.
ASE Master Mechanic
Bloomfield Eurotech
45671 Woodward Avenue
Pontiac, MI 48341
Work Phone 248-334-6400 Fax 248-334-2363
asemastermechanic@juno.com
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Bob UK
Unregistered guest
Posted From: 172.186.40.203
Posted on Thursday, 20 November, 2003 - 05:23:   Edit PostDelete PostView Post/Check IP

Used brake fluid cleans varnish off of carb parts.

The best place for these parts is Burlen Services who own SU ---- Skinners Union.

They have a web site and will be more than happy to help you. Their replacement parts are ethanol compatible.

Fuel pipes as well

In the UK the petrol has small amounts of ethanol and we too sometimes get problems with older cars leaking fuel due to rubber bits going off. All replacement stuff is OK due to modern materials and we have an EEC directive about rubber and modern petrol

Well I say rubber and petrol but the modern stuff is not rubber and as for petrol it smells like dry cleaning fluid not au de la coulone 5 star.