Take-7

no seriously that's what's going on... i rebuilt my junkyard nikki. and now BOTH float bowls fill up and leak profusely. in fact, i can literally watch the fuel run out of the nozzle on the two small venturis rear and front (those are primaries right?) the one on the front pours a ton out, the small venturi on the rear dumps a small dribble. i have read up on sterling's site about this and he said three things:

1) stuck needles after rebuild- i addressed that by "burnishing" the needles (i just rubbed them down with a little oil to prevent sticking) when i turned the car over the rear bowl filled halfway, the front bowl runneth over. i cranked it anyways, it started,ran choppy, then i shut her down. checked the carb, MASSIVE amounts of fuel dumping from front and rear(small venturis only).

2) sterling said it could be an aftermarket fuel pump delivering too much PSI- so i bought a adjustable FPR and set it to 2PSI, cranked, nothing, checked bowls, no fuel at all, empty. then i turned it up to 2.5PSI, oh how my bowls runneth over! again with the dumping...

3) sterling mentioned the possibilty of a FBVS failure- i checked and confirmed 12VDC at the FBVS connector and ground. unconfirmable was the operation of the solenoid itself, so i just now today ripped the guts out, high temp liquid gasket'd a little penny in the hole and put the remainder of the FBVS back on, screwed it down.

i have yet to confirm if this has done anything as i have ran out of time today, but would like to get the consensus of the nikki-holics if this is pretty much everything i can do, or if there is more to checked. i don't know if the fuel pump is aftermarket, i looked under the car, but it doesn't say anywhere on it if it is. looks stock...
also, a little background history, this is a different carb from the factory one i had on the car, the previous niiki caught fire to... yep, you guessed it, overflooding. i didn't catch it in time and was soooo excited about having it run that i neglected to check that. then my wife came and told me the car was on fire, and the fire dept came and ruined my day.... now here we are 3 months later, rebuilt carb (same year) and we are back at square one. the FPR is a "Mr. Gasket" adjustable, so it only has a dial that can be turned in "1/2 PSI" increments. sterling says stock nikkis need 2-2.5 psi. true?

arghx

iTrader: (3)

I saw the thread title and seriously thought it was about bowels for a second

mazdaverx713b

iTrader: (91)

if you checked out the needlees and seats, check the floats for proper adjustment and ensure they are not sticking up. floats that are stuck will cause an overflow of gas form the carb.

CobraStngSVT

I'm 99% sure it's stuck needle valves.

83Limited

As the others have said, sounds like stuck needles and seats or your float level is way off....one more thing you can check is that you have the restrictor in place in the fuel line and that the bypass (return) line back to the fuel tank is clear....and for kicks and grins, you might try tapping the carb bowls with a rubber mallet to see if you can get the needles to unstick.

Take-7

oh i've tapped. ive tapped, whacked,slammed, and even threw in a haymaker for the heck of it. i still want to go back to needle seats too. someone on here mentioned instead of "burnishing" they used a razor knife and "scraped" the needles down to get it smoother... this sounds dodgy. but i'll try anything. how can i tell if the floats are binding? they freely move up and down, they are set to FSM specs for drop and opposite. this is getting old and i'm ready to throw down some cash on a weber.

Take-7

that's gonna happen soon if this thing don't get fixed...

Twilightoptics

iTrader: (1)

I built my carb some 3 years ago and never had a problem until a few months ago.

When I first put the carb on, it took some tapping to get the needles to get in there right and seal.


Recently. Short drive. Came out, went to start it, and it fired up and washed itself out. Popped the hood, and sure enough flowing over. I tapped and couldn't get it to mellow out. Left it at my shop for a few days. Then went to start it and move it to get it to a better place to pull the carb, and it's been fine since.

I think a little piece of something stuck the needle open, and when it sat, it moved out of the way.

clykins

iTrader: (1)

Maybe a problem with the return line? I would lean towards the stuck needle, but I'd check the return line and the return line check valve too personally.

Rotor_Venom08

iTrader: (3)

1st off THROW THAT MR GASKET POS AWAY!

for one its not accurate its 1 psi low. set it to 1-1.5 for the right amount of psi for a stock nikki, 2.5 is actually 3.5 and its to much.

then if its still happening check for vacuum leaks., if not take the carb back apart and try again

btw i am currently running one in my car and i HATE IT, only because my holley low psi reg died two days after the warrnety expired, and yes you read correctly. TWO DAYS!!

i hope any of this was helpfull.. lol

oh yeah unhook an incoming gas line and measure how much comes out in a bottle per second or so, it should barley flow

t_g_farrell

iTrader: (1)

+1 and its worse than that. I had one on my Dell setup and it affected the overall
flow as well at top end. Its a restrictor as well as a regulator. Even the cheapie
Holley reg is better IMHO.

mazdaverx713b

iTrader: (91)

hey man, i think i have a new set of needles and seats. if you want them, pay shipping and i'll mail them to you.

Rotor_Venom08

iTrader: (3)

yes, thats definitely step one, to be honest i think it costs just about the same at the low psi holley. its about 23-26 bucks on summit racing. return it asap and get your money back or keep it as an emergency back up like i did.

and you need to figure out what pump you have. and how much flow its outputting, this " i looked and cant tell" isnt good enough, if its to much you can kill the regulator and youll go threw them like candy so, test it and find out. although it does sound carb related. id start back and work your way forward. (hats what she said)

btw what did your gastank look like after 25 years of sitting? any rust? you clean it out? check the strainer? blow out the lines? even change the filter? some more background info on the event leading to this would be helpful. i mean hell the last time this happened you burned the car down.

Adonis Blue

iTrader: (1)

I'll just share an experience I had.

Rebuilt my carb and after reinstalling it I had the same problem, figured float was wrong or needle sticking. Took it apart again checked everything readjust float a bit and still same problem.. In short I took that thing off and apart more times than I care to remember. Went out and bought a FPR and set it about 3psi, but I also installed an in cab pressure gauge. And so what was happening then was my fuel starting spiking up and down and I ended up driving it like this for a couple weeks after deciding to take a step away from my frustration of figuring out my problem.

Anyways after talking to some hot rod builder friends of mine they gave me a used fuel pump to try. Thinking that, somehow this was my problem even in lou of having the FPR. Which should of been able to maintain a constant pressure (at least that my understanding of its purpose)

After changing the pump problem was solved! (even thou my pump seemed to be fine prior to the carb rebuild) also the pump they gave me was the exact same carter pump I had been running all along! I even removed the FPR and had no problems thereafter.


Now of course I cant say I think this is your problem but its something that worked for me after many many days/nights of frustration.



Also maybe worth noting if the shipping is not to much and it turns out your carb is faulty or something.. I have a rebuilt nikki sitting here that's in perfect working order.

PercentSevenC

Not to mention they're a fire hazard.

DivinDriver

iTrader: (15)

Look ye here:

https://www.rx7club.com/build-threads-293/project-resurrection-running-log-770184/page4/

Scroll down to post #69 ("Days 155 & 156") to see what I ended up having to do testing-wise, to try to get my freshly-rebuilt carb to stop flooding, back around 4 years ago.

Short version was, initial brand-new needle-seat combinations weren't sealing reliably; swapping needles into opposite seats solved it.

Oneiros

Try scraping the needles with a razor knife rather than rubbing them like Sterling suggests, it works for me every time. It requires a careful eye though, to remove the top layer of finish and keeping an even result across the whole needle.

Take-7

I assume I need to scrape the shaft if the needles, not the pointy cone part

DivinDriver

iTrader: (15)

Yes, only the outermost corners of the needle shafts... idea here is to make the needles slide more easily in the bores.

You need a very light touch; you're out to smooth the finish, not remove material.

crazycarl

iTrader: (1)

My nikki got rebuilt and now I'm having the same problem! Do'h. So far tapping method hasn't paid off

mazdaverx713b

iTrader: (91)

make any progress on the carb?

Kentetsu

Might be of some use: http://www.nellump.net/peri/epi/firs...odedCarbs.html



.

crazycarl

iTrader: (1)

Awesome. Thanks for that!

Twilightoptics

iTrader: (1)

"Leaking fuel tank: The fuel tank must be air-tight ("pull a vacuum") in order to suck excess fuel back into the tank. When opening the fuel filler cap after running the engine for some time, a hissing sound should be heard. If not, this may well be what caused the carbs to flood."

Um what?

crazycarl

iTrader: (1)

Is that hissing sound not normal? I got excited when I read that because mine has the hiss, especially on an empty-ish tank..