lwilson7

1972 240Z: recently professionlly rebuilt hitachi su carbs. fuel lines flushed x2. fuel tank replaced and flushed. now still cuts out at >2500 rpm--will even die, if pressed. where to look for solution? catalytic convertor? have'nt checked float levels due to inacessibility. ideas?
I have a very good method for flushing fuel lines, if you get in touch, I'll outline.
Larry W:

NismoPick

Sync the carbs... check the choke, spark plugs, wires, cap, rotor, coil, etc. If you just installed the carbs, they need to be tuned / sync'd. And welcome to ZDriver!

lwilson7

Thanks for the reply. I've checked all but the distributor and tuning the carbs. I may be getting in over my head! Larry W

NismoPick

You can get a carb sync for a good price. MSA sells two. Pretty simple... you adjust each carb to the same flow.

http://www.thezstore.com/page/TZS/PROD/TE/60-9965 ($30)


or

http://www.thezstore.com/page/TZS/PROD/TE/60-9976 ($40)

lwilson7

Thanks--again. I'll get one and let you know how it goes. Larry W
I'm coming to realize that many outo repair shops don't know much about this.https://www.zdriver.com/forums/images/smilies/086.gif

lwilson7

More help, please...have got rid of the Bosch Platinum spark plugs (trying them seemed like a good idea at the time!) and replaced them w/ NPK(?)'s
and that made a world of difference. Synch'ed the carbs--adjusted the mixture as well as I know how (so far), but it still gets 10-11mpg--no apparent leaks. Ideas, anyone? LW

ps: after driving, w/ the enging off there is a faint hiss for a few minutes (from under the hood) that seems to be coming from the front left quadrant of the compartment---we can't see anything amiss, nor locate it. Anything in that area prone to such a noise? Sound like a case for The Car Guys--doesn't it? Thanks

snwbrderphat540

10 mpg? that like...... a little low, i wouldnt think a carb'ed L could reach that low MPG and still run. lol. you sure about that MPG rating?

lwilson7

Yeah, pretty sure; I measured it not too long ago--and today I drove 20 mi and it was evitent (about 25%) on the fuel guage. I'll calculate in a couple of days when I fill up again. I sure hope you're right and the #'s are wrong---my BW (beautiful wife) says we can't use it as a 2nd car, if I can't make it do better than that! Thanks for you're help==any ideas about the 'hisss'? LW

snwbrderphat540

no. hahaha. just start her up and look for the hiss. and the guage isnt accurate, no fuel guages are very accurate. full and empty is teh only thing you can trust on a guage. fill her up. drive about 50 miles. fill her up again and then do the math. our tanks arent that big. post up here how much you put in the second time and what the mileage on the tripometer were er at least the total miles you went from fill up to fill up. 10 is rediculous and doesnt even seem plausible, at least not for a burn rate. maybe if it was leakin out some where.

lwilson7

/Users/bonniewilson/Desktop/desktopstuff/240z images/DSCN1530.JPG

snwbrderphat540

uhhh yeah.... that doesnt exactly work ^^^^

lwilson7

Guess what!! Found A leak---accidentally. After filling the tank and calculating a very dissappointing 7.5 mpg, I inspected again--for the 400th time--nothing. About 30 min. later, I looked one more time. Nothing under the hood and not much underneath except a 6" dark spot on the asphalt that was rapidly shrinking in the Texas heat--but not wet. Looked directly above and soggy area around a splice in the fuel line just about 8" from the tank--this placed during it's last shop visit. Had it back to them at least twice specifically to try to find the to source of the low mpg! "Doh--can't find nothin'." I'd have taken it back to them, but if anyone's going to to do shoddy work, I want it to be me--at least I'll know how it was done and where to look! This is my old friend that I drove home new from the Datsun Dealer.--Enough of this rant---!! This repair of one leak may not fix the whole problem==I'll keep posting. LW

midgez

I am finding that I need to learn how to work on my own car! Not many mechanics out there that know the old Z's. If you find one, hang on to them. I finally found someone to work on my carbs until I learn more. I had lots of fuel leaks for about a year. Are your fuel lines old? Mine were and it seemed like one would split, fix it, another split, etc. I finally think I found them all. Also, check your fuel pump. It leaks when it goes bad. Good luck.

NismoPick

Make sure you you proper fuel line. Vacuum hose will crack after a short time of being exposed to fuel.

lwilson7

Evidently, I haven't found one yet. These guys sent it back to me w/ the carbs totally unbalanced, the fuel mix 'way off, a fuel leak in the rear where they had spliced the line and lots of particulate rust and dried fuel in the lines---and charged lots of money----and remain denying and defensive. Sorry about the rant! https://www.zdriver.com/forums/image...es/disgust.gif

The fuel lines aft of the engine compartment are mostly original, if there's still a leak it's really occult. No leak under the hood. Thanks for the fuel line advice.
Good luck w/ yours--and keep posting. This forum is a great find.
Larry W
ps: Have you figured out how to post inages, yet?

lwilson7

Thanks for the advice, NismoPick-----LW

Cronicus

ive got a problem to
im getting about 12-15 mpg at best AT BEST
in my 78 280.
ive ran butloads of injector cleaner plugs are great, ngk's
wires cap and rotor exclent, threw in an excelll coil.
in my opionion its got a lil bit o blow by more than expected for its age, changed out the pcv and just the faintest traces of white smoke out the tail pipe, dosent apear to be burning water or oil though.
btw a few friends of mine told me im shooting out flames sence i removed the cat, and muffler, went to 2.25-2.5 pipes to the back if that has anything to do with it.?????
unburnt fuel????
its defintly not leaking fuel and i replaced the fuel filter.
honestly the way i am i love throwing parts at a car for no apperant reason just to hope it will get faster and smoother maybe more mpg's to.
so if a list of additional parts can be generated by whomever on the next parts i might wnana try it would be so greatfully apericated.
-dave