Thread: Pre-ignition and it's solutions

Does it have a fuel cut-off solenoid on the carby and is it working?

P.S. I assume you have checked the timing.

Run a tank of Premium through it - fuel conditioner - injector cleaner. ( A clean out of the petrol tank wouldn't go astray either - probably a fair bit of gunk floating around inside....). Check to see if the carby is clean and secure too - it all helps.

depending on how carboned up it is.....

warm it up, pull the air cleaner off, rev it up to about "its about to explode" RPMS let the butter fly snap closed and at the same time use a hair spray bottle to spray some water into the carby while its over running.

you can do the same thing with the subaru internal engine spray stuff.

run a tank of avgas through it.

lean the mix out a bit take it out and give it the italian tune treatment

but ultimately the best solution is to pull the head, clean it up properly and reassemble.

check the spark plugs as well they could have carbon built up on the ends.

Originally Posted by discomuzz

Does it have a fuel cut-off solenoid on the carby and is it working?

P.S. I assume you have checked the timing.

I doubt it has a fuel cut off in the carby. As for the timing, I haven't checked it yet. I have been told to have a look at it. However, can you explain to me how timing has an effect on pre-ignition? I have heard it can be the cause, just don't quite understand how.

Originally Posted by langy

Run a tank of Premium through it - fuel conditioner - injector cleaner. ( A clean out of the petrol tank wouldn't go astray either - probably a fair bit of gunk floating around inside....). Check to see if the carby is clean and secure too - it all helps.

Yeah my Dad suggestion running some premium through it also. As for the fuel tank, I inspected it when I bought it a few weeks ago and it was pretty clean. As for the carby, it definetely needs a rebuild/replace.

Originally Posted by lambrover

check the spark plugs as well they could have carbon built up on the ends.

That was the first thing I thought, but I've put new ones in only a couple days ago and it still diesels on. Seams to run smoother though with new leads and plugs

Thanks for the advice so far guys. I'll give it all a go and if there is no improvement I'll look at pulling the head off and giving it a clean.

Originally Posted by subasurf

..... and if there is no improvement I'll .....

Stick injector cleaner in a full tank of Premium fuel and go take a drive to Corrigin and back again

Mike

Originally Posted by subasurf

I doubt it has a fuel cut off in the carby. As for the timing, I haven't checked it yet. I have been told to have a look at it. However, can you explain to me how timing has an effect on pre-ignition? I have heard it can be the cause, just don't quite understand how.

1. I'd be surprised if hasn't got one. Must be original. Just check for a single wire running to the idle jet area.

2. If the timing is out, the spark has been and gone (or yet to arrive) by the time the piston and fuel meet at the top of the stroke. It then uses compression and whatever heat is in the cylinder to ignite the fuel (like a diesel engine, hence 'dieseling'). Not a healthy situation. This is why they put fuel cut-off solenoid's on them.

I have seen a petrol motor running with no distributor cap on just by squirting degreaser down the carby.

Do the timing and check the dwell angle on the points before stripping it down. Surely a quicker option.

P.S. Incorrect timing is a more likely explanation for your carbon build-up than the type of fuel previously used.