Spark but no start

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Squidviciousnorth
Newbie
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Joined: Fri Feb 03, 2017 9:39 am
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Spark but no start

Post by Squidviciousnorth »

Hi. New member and problem with series 3 Oxford . It has new coil and points. Seems to have good spark, but it only fires when I pour a little fuel into intake. Thought it must be carb problem so cleaned that but still no joy. Installed another carb but still only fires when I bypass carb with fuel. Am I barking up the wrong tree assuming it is fuel problem ? Could it be ignition timing problem ? Any advice would be appreciated.
firehor5e
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Re: Spark but no start

Post by firehor5e »

check the fuel pump is delivering fuel!
1968 2 door 1275
mogbob
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Re: Spark but no start

Post by mogbob »

You've landed on the wrong forum as this one concentrates on Morris Minors. If you search on the Internet for "Morris Oxford owners club " you will find a more "model specific " Morris Club.
Firehor5e has identified you problem in 7 words. It's a fuel delivery problem.

An SU pump was standard and most probably the electric points have worn out / got stuck and need either cleaning or more likely
replacing. Ideally , with an assistant , listen by the pump body when the ignition is switched on for a few seconds. Can you hear a ticking sound as the pump tries to fill the carb float bowl ? Sometimes a quick jolt / light tap with a rubber hammer kicks it into life , if you're lucky. But order a replacement set of points now !

If it ticks , switch off immediately, disconnect the rubber hose to carb and put it in glass jam jar and ask your assistant to switch the ignition on ( don't try to start it ). In this state , pump ticking , does it deliver any fuel into the glass jar ? If it doesn't then the diaphragm in the pump is damaged / split. Replace the diaphragm (can be bought separately ) as part of an overhaul kit , as this would signify that the pump is overdue an overhaul.
Usual safety precautions , out in the open air ,not on a hot engine , rags to catch drips, fire extinguisher , no naked flames or other sources of ignition.
http://www.sucarb.co.uk for your parts requirements ( satisfied customer , no other connection ..there are other suppliers )
Bob
Squidviciousnorth
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Re: Spark but no start

Post by Squidviciousnorth »

Yes. The pump works, but I have had it disconnected and have been filling the float chamber with fuel thinking that this should be enough to get it to run. Does it need the pressure from pump in order to make it run ?
firehor5e
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Re: Spark but no start

Post by firehor5e »

If the float chamber is full the engine should PULL fuel into its cylinders.When was this car last used/run? It could be any number of causes,stale fuel, low compression(do a compression test)if the compression is low,check the valve clearances and repeat test.Inlet manifold/carb gaskets failed/incorrectly fitted.siezed choke/incorrectly adjusted carb,incorect firing order/timing,plug gaps/type......the list is endless!First try starting with your hand over the carb air intake(air filter removed)this should clear any blockage in the carb.
1968 2 door 1275
Squidviciousnorth
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Re: Spark but no start

Post by Squidviciousnorth »

Thanks for your replys. This car was running fine. I had replaced points & coil and swapped faulty S U pump for a modern pump, and it used to start no problem. One day it just died. I found a lot of sediment and junk in bottom of float chamber even though I had in-line filters. I thought this had got into carb and that fuel was not getting through so all my efforts have been carb related. I am no mechanic but if it fires when I bypass the carb does that not mean the carb has to be the problem ? Can something break in the distributor to effect the ignition timing yet still give you a good spark ?
MarkyB
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Re: Spark but no start

Post by MarkyB »

Did you blow through the pipe to the jet when you cleaned the silt out?
Enough can accumulate there to block delivery to the engine.

"Once you break something you will see how it was put together"
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