240z misbehaviour diagnosis / suggestions

[Huw]

Well, after just dusting off the zed and taking him out a couple of times last week, he decided to complain about treatment today.  Breaking down on Lonsdale Street at 5PM was spiteful though and made me very unpopular.  Anyway, lost cylinders and power, sputtering and wallowing at 1-2k rev, wouldn't idle.  Tried to limp on until out of city but stopped and then wouldn't start again.

Once got home off truck have:

- cleaned plugs (rear SU carby choke 'sticks' and sometimes causes rear plugs to gum up - a rebuild is on the cards (or replacement with EFI).

- made sure I had fuel all the way through (I do)

- briefly checked that my 123 dizzy hadn't died - still connected and properly mapped).

Still doesn't want to fire.  Starter is strong and cranks but only weak attempts at firing after significant cranking.   Didn't take plugs out and check spark.

Ideas?    I have it either as ignition or carbys in my mind.

Was running (poorly) this morning.  Ran better on a brief run yesterday.

A bit time poor thus the request for ideas.   If not, he will be off to the doctor on Tuesday (need to get him on club plates anyway so...).  May get 6 new plugs just to eliminate gummed up plugs but that is a symptom and not a cause. 

Huw

 

 

[KatoKid]

Check spark first, your chasing too many things otherwise.

Im guessing its fuel related if its been sitting for a long time. Is it mechanical pump or electric? Is there an inline filter?

 

Edited October 15, 2022 by KatoKid

[Huw]

Thanks,  with a proper clean of all of the electrical bits and new plugs, fired up quickly tonight.

However, suddenly wants to idle at 2k with linkages all slack so something is still off.   Suspect will need to rebalance / adjust carby's but not set up for that where I currently am (all of the tools and space I need are up in the hills in the family shed, not at home).  

Now to wait for a morning/afternoon where I can skive off work and kid duty to figure out the balance and get it running nicely.   Carby's have needed a rebuild for a long time so may just bite the bullet to eliminate them.  Neighbours probably won't appreciate if I do it tonight once kids asleep :p  Once I get the idle down, it off to the shop for a proper tune and work through of the carbs.

[Edit: a 10 minute play today has revealed that at the very least the rear carby is contributing, the choke which previously got stuck and would 'snap back in' if you checked it now has significant play in it such it won't snap back and it is unlikely that the car would hold tune...going to have to take it off and have a proper look (or more likely, send it somewhere to rebuild them both)]

Huw 

Edited October 19, 2022 by Huw

[Huw]

Aside from ZTherapy (postage and US dollar scares me) - does anyone know of a good:

- source for kits for the Hitachi SU Carburettors in Australia?

- shop in Melbourne to send them off for refurbishment (on the basis that I probably won't have time to do them myself...)?

[gilltech]

I have seen them listed on eBay Australia occasionally. But during Covid in Jan 2021 and wanting to get projects progressed while I had some down time I just used a USA supplier via eBay, sounded like it was a Corvette parts supplier who had them in stock. Airmail posted really didn't cost that much.

Caution: Just be careful you get the right pair of kits! Ask me how I know... The '70 to '72 is one set, whereas the '73 is different (as in my case, which I eventually deduced after finding out that my carbs were incorrectly kitted with the front one running very very rich). On a '73 the front carb fuel intake valve is a different length/casting height to the one on the rear carb. A Nissan tweak for something to do with the tilt of the engine, apparently, from what I read online.

My 2c worth. Hope that helps some.

PS. Just checked my purchase history, Including postage ex USA they cost round about A$90 with the then exchange rate.

Edited October 21, 2022 by gilltech
Info added

[AndBir]

3 hours ago, Huw said:

Aside from ZTherapy (postage and US dollar scares me) - does anyone know of a good:

- source for kits for the Hitachi SU Carburettors in Australia?

- shop in Melbourne to send them off for refurbishment (on the basis that I probably won't have time to do them myself...)?

I purchased a kit from MLP Carburettors in Reservoir years ago (but then went with Webers) - they may also do refurbs, but I have no personal experience/recommendations.

Otherwise these guys may help : https://wilsoncarburettorservice.com.au/

Edited October 21, 2022 by AndBir