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240z won’t start pls help
- Thread starter inz4in
- Start date
I'm sure some more experienced people will chip in but if it was all working fine before you changed the airbox out then I'd suspect you've knocked the adjustment on the bottom of the carbs out.
I recently knocked mine out and it took forever to get them balanced up again (the measuring thing only really works if the carbs have been unlinked and if the engine is up to temperature). At one point I had a similar issue and it turned out I'd made it way, way too rich.
I recently knocked mine out and it took forever to get them balanced up again (the measuring thing only really works if the carbs have been unlinked and if the engine is up to temperature). At one point I had a similar issue and it turned out I'd made it way, way too rich.
stuart barrie
Club Member
Fuel filter top left of screen looks rather dark is there rust in it. From tank.
Farmer42
Club Member
First of all, don't try starting it with the choke. You don't need it in this weather. Secondly, if you are smelling fuel, your carbs are flooding. That could either be choke or your float valves are stuck.The way to check overfuelling is to whip out a couple of spark plugs one from either end and if they are black you are running way too rich. You will need to clean or renew them (NGK BPR6ES - 1mm gap).
To check float valves, Carefully take off the tops of the float chambers and see how much fuel if any is in there. If its empty it's stuck closed but my guess is that they could be stuck open and not cutting fuel at the right time. It only takes a little bit of crud to stop them working properly. Move the float up and down whilst blowing through the inlet pipe to listen for air flow & stop.
Lastly, you need to check the float height. Turn the float lid upside down and measure the gap between the float and the lid. I think it's around 4mm but you need to check. A drill bit is a good measuring tool.
If all is well with all that, the next area is the dizzy. If you are using a mechanical points dizzy, you will need to check the gap. Also check for pitting on the contacts.
To check float valves, Carefully take off the tops of the float chambers and see how much fuel if any is in there. If its empty it's stuck closed but my guess is that they could be stuck open and not cutting fuel at the right time. It only takes a little bit of crud to stop them working properly. Move the float up and down whilst blowing through the inlet pipe to listen for air flow & stop.
Lastly, you need to check the float height. Turn the float lid upside down and measure the gap between the float and the lid. I think it's around 4mm but you need to check. A drill bit is a good measuring tool.
If all is well with all that, the next area is the dizzy. If you are using a mechanical points dizzy, you will need to check the gap. Also check for pitting on the contacts.
Huw
Club Member
Not an expert with carbs, but just a question for my edification. The radiator overflow and what appears to be tubes from the carb float chambers are feeding into the same blue bottle/tank like thing. I’ve not seen anything like that before, whats the purpose of that? I can’t see that being very beneficial to the operation of the carbs, are you sure that’s not the cause for your problems?
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Farmer42
Club Member
Good spot! Looks like some sort of pressurised bottle. Surely can't be nitrous could it? If it is pressurised, then it is pressurising the float chamber. those are supposed to be overflow pipes that should have attached to the back of the original airbox. A pressurised float chamber will either cut the fuel or as I am probably thinking, it will force it into the intake and stop the float from working as it should thus flooding the carb. Float levels are really important on SU carbs. I would disconnect those to start with.
I've said this so many times - make sure your fuel filter isn't blocked. That's where I'd start, it's a common problem with these cars.
SacCyclone
Club Member
With both chokes OFF, push up on the main jets of each SU to make sure your mains have not stuck in the rich position.
stuart barrie
Club Member
We still don't know if there is to much or not enough fuel. Plugs will give us a clue.
I had a similar problem a few years back. Blowing compressed air through the fuel rail solved it. First rod it with electric cable as far as it will go (ie before the bend). Then blow compressed air from the top return rail first (the top rail has the small restrictor hole). Also get a small syringe and suck any crap from the bottom of the fuel bowls. May or may not be your problem