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Miss fire and pop back through carbs.


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Im at my wits end with this now.

Ive renewed everything ignition wise.

mucked about with the advance and retard of the ignition.

all timing marks lined up

Given the carb a good going over for a laugh.

Head off valve seats fubar so got a decent unleaded head on now.

Still the same problem :(

pop pop pop no power

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Hi mate,

Have you got access to a Gunsons 'Colourtune' kit?

This sounds to me like a sympton of a weak mixture. Colourtune will allow you to see what colour you are burning at - mid blue = ideal, yellow = rich, pale blue/white = weak.

Works like the good old school bunson burners - if you follow.

Hope that helps,


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OK had another fiddle this morning

Compression test 10bar on all 4 cylinders

1 3 and 4 have lightly sooted the plugs (about right) 2 is white lean?

I filled the ports before i put the head on no leaks its a completely different head to the one i took off aswell.

Thinking about it the car did do this a few time before just for a moment when pulling away but then would sort its self out and be fine.

But now its just constantly broke.

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hi dont know if this may help but ive just spent last two weeks repairing my 1.8 ohc engine had similar problem was only running on 3 cylinders although cyl 4 had spark i removed and overhauled cylinder head after reffiting all parts was still the same had good compresion in desperation after much head scrating i changed the inlet manifold as a last attempt and all was perfect there was no visible defect with manifold but cured running problem the car has run lumpy since i purchased it but now runs a dream hope this helps somewhat faults are not always visually apprent good luck

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Or you may have a cracked cylinder head. If all else fails and you have to take the head off again. Get it crack tested before you put it back on.

This is the worst case though. I hope it turns out to be something more simple. like a worn camshaft, manifold gasket etc.

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hopefully by the weekend ill have all the parts i need to put injection on the beastie.

!st change it to electronic ignition rull out that side of life completely. Then injection and fingers crossed again

I used all new gaskets could be a carb to manifold gasket or a crack in the manifold will investigate further. Id like it to be running properly before i put injection on

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I would change to injection, but depending on what the problem is it might not go away.

If you need any advise on fitting the injection system drop me a pm.

If you are leaving the engine in make sure you cut your hole for the injection loom in the bulkhead before fitting the inlet & exhaust manifold.


The space makes life easier not only for cutting the hole but fitting the loom and getting the grommet in properly.

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  • 3 weeks later...

If the injection relay isn't working you wont get power to the pump. By pass the relay.

Off the top of my head I think the relay connections go something like this:

30 - permanent live, thick red cable.

87 - feed to fuel pump, thick white or blue

87b - feed to injectors, throttle switch etc, thick white or blue

15 - switch live from ignition switch for relay coil - thin black

1 - signal from ignition hall sensors, thin green

50 - switch live from ignition for relay and thermo time switch, cold start valve etc, thin red black

31 - earth for relay coil, thin brown.

Wire colours may vary on different cars .Also I might have the feeds the wrong way around. Some other manta nutter will probably correct me.

In an emergency or for testing purposes. If you suspect the relay then bridge terminals 30, 87 and 87b together. The pump should run (all the time!!!!) and you should have power to the injectors. The car should also start. You can drive like this but I wouldn't recommend it for too long.


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  • 1 year later...

Is that the same car? or a very similar looking car with the same fault?

Get the timing done first ;)

Yep agree totally. One thing to note with what you have done....do you know how much has been skimmed off the head and possibly block? If the head has been skimmed you can set the timing marks up perfectly BUT because the distance between the crank and cam has been reduced the cam timing will be out. The only way to sort this is with a vernier timing gear or mod a std one to re jig everything.



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This will be the classic worn camshaft problem. Misfire at idle but as you rev it it seems to clear? Seen it before aswell as all the head scratching and changing parts.

To check it, remove the rocker cover and coil lead (so it doesnt start), get a helper to crank the engine and watch the amount the lifters move out of the head. Usually Cyl 3 or 4 will have a lazy one or two moving about half or less than the others and only lets minimum air/fuel in.....

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