New attempt: help regarding power loss

[Guest]

Hi everybody
i posted here before last year. Engine suddenly cuts out when driving still with choke. Started beautifully after the winter break but then engine stopped after having to go down hill. After that I can start the engine but feels like only 2 bhp. And I need the choke to get me up the hill again.

in the past I replaced carb diaphragms, rotor arm, fuel filter and pump. Cleaned the petrol tank.
i don't think it is ignition related as I can start the engine again. What's wrong?

[Guest]

Engine makes sort of spluttering noise and feels and sounds as driving on only half a cylinder bank when pressing the throttle fully down up the hill. It looks like there is a bit more of black soot coming from the exhaust. Might be related.

[grumpy2]

have you ever overhauls the carbs? possibly a sticking float needle. had similar symptoms years ago with SUs. Possible quick fix - tap the float chamber gently with a small hammer or screwdriver head.

read this

https://www.howacarworks.com/fuel-systems/how-to-overhaul-a-stromberg-carburettor

[022Dave]

I had a similar problem a few years ago; it turned out to be condensation inside the distributor cap.

Dave

[Guest]

Thanks Grumpy2
I haven't done anything to the carbs other than changing the diaphragms which was suggested last year but made no improvement also there were tiny holes.
But I had to replace the bottom O ring seal plug one 1 carb because it was leaking fuel. I did this in situ just prising the plug open with a screwdriver from outside and pushing a new plug in. Could I have damaged the float needle?

[Guest]

Thanks Dave
I had a look inside the distributor cap, all nice and dry.
However now I noticed that the HT leads on my Stag don't follow the connections illustrated in the rimmer book or bob postills head gasket replacement photos.
Is that odd?

[richardthestag]

Thanks Grumpy2
I haven't done anything to the carbs other than changing the diaphragms which was suggested last year but made no improvement also there were tiny holes.
But I had to replace the bottom O ring seal plug one 1 carb because it was leaking fuel. I did this in situ just prising the plug open with a screwdriver from outside and pushing a new plug in. Could I have damaged the float needle?

I dont think you will have damaged the float valve but you may have adjusted the float level or even punctured it. Flooding on carb will cause the issues from my experience.

when the carb floods if you remove the carb elbow to airfilter, you can see into the carb throat. lift the piston inside the carb and check that it goes up and down smoothly. that will also cause you issues. However if fuel is squirting out of the jet hole that the carb needle goes into then the carb is flooding.

do you have a fuel pressure regulator fitted? most newer fuel pumps kick out in excess of 5psi of fuel pressure. Strommies like 2.5psi or thereabouts otherwise the fuel pressure can overwhelm the delicate float needle.

however before going to a load of agro or checking carbs out ignition is easier and cheaper to fiddle with,

Still running points and condensor in the distributor? may well be a bad condensor is burning out the points

the ignition feed to your coil, is it via the Mk1 ballast resistor block or the mark 2 ballast resistor wire. Pink / White IIRC

I had issues with tha ballast resistor wire in my mk2 stag, diagnosed by running a wire from the battery +ive to the coil +ive when the issue occured. The problem was instantly fixed (you need to remove the wire from the battery and switch the ignition off to stop the engine)

fix will be a mk1 ballast resistor or a 12v coil with a new clean ignition controlled feed (from any white wire)

90% of fuelling related issues are ignition
90% off ignition related issues are fuelling

head for the cheap and easy fixes first

Carb float level is in the ROM, easy to do, just need float gaskets, steel ruler and a new o ring for the carb pedestal

[dasadrew]

Have you had a look at the spark plugs? You might be able to see if there are differences indicating single plugs, or a group of plugs which could narrow it down a bit.

Drew

[Guest]

Had a look at the plugs. 7 are a little bit black sutty, 1 is (no 2) light grey. Not surprisingly I believe as I can only manage short runs with choke so mixture is rich.

The fuel pump might be a bit powerful. But I installed it when the problems already occurred as I thought I had rust in the tank and hence pump when I found rust in the fuel filter and I guessed not enough fuel was coming through.

Must have a look at the float chamber. Ignition is electronic with luminition and a separate ballast resistor. I have a spare resistor. Maybe I should replace it?
Can I check on the coil?

[Guest]

if it's any help I may be able to take a look at it later this week.....(if you care to take a run down to the airport.......)

[Guest]

Ahmmmm Frankfurt international? I could take you up on that.

[Guest]

FRA of course, not that stupid little place in the middle of nowhere, well half way between Stromberg and Trier/Luxembourg
(=HAHN!)

Only Ryan could strong arm their way into such a bum airport as that!

[jbuckl]

90% of fuelling related issues are ignition
90% off ignition related issues are fuelling

Like that!

I dont think you will have damaged the float valve but you may have adjusted the float level or even punctured it. Flooding on carb will cause the issues from my experience.

when the carb floods if you remove the carb elbow to airfilter, you can see into the carb throat. lift the piston inside the carb and check that it goes up and down smoothly. that will also cause you issues. However if fuel is squirting out of the jet hole that the carb needle goes into then the carb is flooding.

do you have a fuel pressure regulator fitted? most newer fuel pumps kick out in excess of 5psi of fuel pressure. Strommies like 2.5psi or thereabouts otherwise the fuel pressure can overwhelm the delicate float needle.

however before going to a load of agro or checking carbs out ignition is easier and cheaper to fiddle with,

Still running points and condensor in the distributor? may well be a bad condensor is burning out the points

the ignition feed to your coil, is it via the Mk1 ballast resistor block or the mark 2 ballast resistor wire. Pink / White IIRC

I had issues with tha ballast resistor wire in my mk2 stag, diagnosed by running a wire from the battery +ive to the coil +ive when the issue occured. The problem was instantly fixed (you need to remove the wire from the battery and switch the ignition off to stop the engine)

fix will be a mk1 ballast resistor or a 12v coil with a new clean ignition controlled feed (from any white wire)

90% of fuelling related issues are ignition
90% off ignition related issues are fuelling

head for the cheap and easy fixes first

Carb float level is in the ROM, easy to do, just need float gaskets, steel ruler and a new o ring for the carb pedestal