I suppose the battery and points go to earth on the engine anyway on the traditional system. Just never needed to consider it since college over 50 years ago.
Technical What's the likely cause of this fuelling (?) problem
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Technical What's the likely cause of this fuelling (?) problem
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Arrgh what a frustrating problem. It's infuriating that such a simple engine can create such a difficult to trace down problem.
Clutching at straws for ideas, have you got a good earth between engine and chassis? A dodgy engine ground can cause spark issues.
Bit of a random suggestion, but its a simple & free test... As it seems it's going really rich, have you tested with the air filter disconnected (just open top of carb)? If somethings blocked it up drastically that might cause your issue with only running at idle. A friend of mine once had an issue where his Mr2 turbo wouldn't run above idle after he'd had it apart, he'd left a big wedge of blue roll in the intercooler pipework and it was only letting just enough air through to idle.
Is it still only fouling one plug and I assume it is petrol not oil on it?
smart51
Established member
Let's play take your pick.
This evening, I took my crimping tool to the car and put a spade connector on the new ballast resistor so it could connect to the new coil. I removed the new spark plugs to inspect them (slightly grey, with a tiny bit of fouling on No1 cylinder. I removed the lid of the carb in situ to check that the main jet hadn't come loose. It hadn't but there was some reddish brown granular residue in the freshly cleaned float bowl. I cleaned all that out and did a test run with the intake silencer thing removed. It runs. Not perfectly, but it runs at all revs and at all throttle openings. I did a short test run with all kinds of wide open and part open throttle. There were couple of coughs at maybe 4500 RPM, and a small lack of smoothness but it runs. I don't know what changed it, but it changed. It runs with the filter back in place too, so it wasn't an air restriction.
The car still vibrates madly at middling revs, but the engine now runs which is progress.
This evening, I took my crimping tool to the car and put a spade connector on the new ballast resistor so it could connect to the new coil. I removed the new spark plugs to inspect them (slightly grey, with a tiny bit of fouling on No1 cylinder. I removed the lid of the carb in situ to check that the main jet hadn't come loose. It hadn't but there was some reddish brown granular residue in the freshly cleaned float bowl. I cleaned all that out and did a test run with the intake silencer thing removed. It runs. Not perfectly, but it runs at all revs and at all throttle openings. I did a short test run with all kinds of wide open and part open throttle. There were couple of coughs at maybe 4500 RPM, and a small lack of smoothness but it runs. I don't know what changed it, but it changed. It runs with the filter back in place too, so it wasn't an air restriction.
The car still vibrates madly at middling revs, but the engine now runs which is progress.
It is annoying not to be able to put your finger on "the smoking gun" of a cause.
What do you think the reddish brown deposit in the float bowl is, it must be fine if you have a good paper filter in the system.
Just a thought , the deposit isn't magnetic as in fine rust dust particles, could that get on the porcelain insulator as a deposit near the electrodes of the spark plugs causing a misfire. Though didn't one plug run cleaner than the other?
Does it run better after just fitting the new plugs?
Sorry it's all clutching at straws.
What do you think the reddish brown deposit in the float bowl is, it must be fine if you have a good paper filter in the system.
Just a thought , the deposit isn't magnetic as in fine rust dust particles, could that get on the porcelain insulator as a deposit near the electrodes of the spark plugs causing a misfire. Though didn't one plug run cleaner than the other?
Does it run better after just fitting the new plugs?
Sorry it's all clutching at straws.
smart51
Established member
Is it ferrous (ie will a magnet pick it up)?
smart51
Established member
I cleaned it all out the other day and didn't test it. I just discovered the photo so I thought I'd post it.
If it's from the tank it will return.
I forget, did you have a paper element fuel filter?
I forget, did you have a paper element fuel filter?
smart51
Established member
I had one briefly but was advised to remove it. I might refit it up at the front.
I would guess it’s likely from the tank. Might as well pull it and just use electrolysis to clean it out. A day or so of that will get it nice and new looking on the inside.
