classic car forum header
Classic cars forum & vehicle restoration.
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
How To Register     Posting Photographs     Privacy Policy     F/book facebook.com/oldclassiccar

Is it fuel vapourisation?
Post new topic   Reply to topic    Classic cars forum & vehicle restoration. Forum Index -> Mechanical Restoration
Author Message
trampintransit



Joined: 09 Aug 2010
Posts: 166
Location: Edinburgh

PostPosted: Mon Apr 23, 2018 5:02 pm    Post subject: Is it fuel vapourisation? Reply with quote

Took the Armstrong Siddeley Star sapphire into town the other day. First time it's been doing town driving on a hot ( well hot for Edinburgh) day. I spant an hour driving about waiting for the inevitable stutter from fuel vapourisation. ...but she ran like a dream till I stopped . Then she wouldn't restart and the clear filter in the engine bay was empty .....Classic fuel evaporation symptoms. Wouldn't start till the bonnet had been left open for ten minutes ..then she ran ...but here's the weird bit . My previous experience of vapourisation issues are that one the car is one the move with a fair bit of throttle the flow of fresh cool petrol eliminates the problem, but it didn't. Being an auto with a very low speed change up ( the kick down function is variable on a star but doesn't work on mine and as a result she changes up pretty early) it's difficult to get revs on, but dropping it to 'L' does push the revs up obviously and the engine runs ok as I scream along at 15mph. ...as soon as I let it change up it starts missing and spluttering again. ... Wosre as soon as it faces a proper load, ie; a hill it gets worse.
I wonder if I'm barking up the wrong tree a nd it's really a weak spark under load due to a hot coil?
Ignition is on the advanced side by the way.
The carbs are Zenith W1A......the FEELING is the same as if it's flooding rather than starving of fuel...I'm thinking of disabling the accelerator pump and seeing what happens?
Any thought anyone?
_________________
'60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!!
Back to top
View user's profile Send private message
peter scott



Joined: 18 Dec 2007
Posts: 6206
Location: Edinburgh

PostPosted: Mon Apr 23, 2018 10:54 pm    Post subject: Reply with quote

It could be vapourisation but another very common heat problem is cheap copies of rotor arms where the black (supposed) insulator becomes conductive.
Hence the popularity of red rotor arms (no carbon in the mix) when modern replacements are required.
http://www.oldclassiccar.co.uk/forum/phpbb/phpBB2/viewtopic.php?t=20261

Peter
_________________
http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 litre saloon
Back to top
View user's profile Send private message Visit poster's website
trampintransit



Joined: 09 Aug 2010
Posts: 166
Location: Edinburgh

PostPosted: Wed Apr 25, 2018 9:38 am    Post subject: Reply with quote

Good point ...a call to Distributor doctor methinks
_________________
'60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!!
Back to top
View user's profile Send private message
Clactonguy



Joined: 20 Mar 2018
Posts: 65
Location: clacton on sea

PostPosted: Wed May 23, 2018 9:55 pm    Post subject: poro running Reply with quote

sound slike a fuel. issue rather than. ignition. today fuel has. ethanol in it and we have to use additives to enhance it. in hot situations it can get worse.
noticeably so after a shut down for a while and heat ask affects fuel by forming gas bubbles!
often get. such issues in my rover p6. now added the 'metal' tablets you. drop in tank to upgrade fuel .notice difference on starting ,,much easier . though still having running issues in hot weather or after a long stop.
looking to fit electric fuel pump hopefully over come any inline issues but expect may have to add some sort of fuel carbon canister as they did on later '80s to many cars to absorb gas bubbles.
hope you find a way to overcome issue on your car.
Back to top
View user's profile Send private message
trampintransit



Joined: 09 Aug 2010
Posts: 166
Location: Edinburgh

PostPosted: Fri May 25, 2018 1:06 pm    Post subject: Reply with quote

New rotor arm from Distributor doctor....cannot replicate fault at all..even on a day hotter than before.


Every day's a school day.

I was suspicious of the fuel idea since it didn't clear up as fuel flow increaded which has always been the case with previous vapourisation cases for me.
_________________
'60 Armstrong Siddeley Star Sapphire
'80 Reliant Scimitar
'47 Jaguar MKIV --- in bits!!!!
Back to top
View user's profile Send private message
alanb



Joined: 10 Sep 2012
Posts: 433
Location: Berkshire.

PostPosted: Sat May 26, 2018 11:06 am    Post subject: Reply with quote

If there is no fuel in the carburettor bowl then the problem is with fuel delivery not vaporisation. Fuel vaporisation happens when the fine fuel mist from the carburettor vaporises before reaching the combustion chamber causing poor running or not starting.
_________________
old tourer


Morris 8 two seater
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Classic cars forum & vehicle restoration. Forum Index -> Mechanical Restoration All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
Forum T&C


php BB powered © php BB Grp.