Nikki Rebuilt: Odd issue
 

So I rebuilt my Nikki in anticipation of dropping in a rebuilt 12a. I had this issue before I rebuilt it too, but it's gotten more complicated.

Before pulling the motor that spun a bearing (it was a bad year for Jim and 12a's...) I noticed that my secondary barrels were filling with gas when I was cranking the motor. I found this very odd, and so I decided to rebuild the carb to see if there was something sticking.

It took me about 2 months to rebuild the carb, as I could only put 30 or so minutes a week (at most) toward work on my 7 (graduate school, girlfriend, and work makes personal time non-existent...). I have the motor in the car, carb on the manifold and everything is plumbed.

I check fuel levels in the sight glasses, and I have fuel in the rear sight glass. None in the front sight glass.

Tap front bowl with a dead-blow hammer to see if I have a stuck needle. Nothing.

I pull the top of the carb off, and notice that there is fuel up to the bottom of the sight glass, but it's funny colored (kind of a green color...)

Replace the top of the carb, turn the key, and I have a slight fuel leak. Fix that, and take a look at my sight glasses. No dice, or so it seems...

There is a bubble at the TOP of the front sight glass. Both fuel bowls are completely filled. WTF.

No fuel is traveling to the accelerator pump. No fuel is going into the primary barrels when I actuate them manually at the carb.

I crank the motor over with the key to see if the secondary barrel issue is still there, and it is. They fill with fuel almost immediately.


I think it started after I unhooked the wiring harness that connects to the passenger side of the carb. What does that plug actuate? Could that be causing this issue?

I dug out that wiring harness and re-connected it, but now I need a new battery, so any more testing will have to wait until I start my new job next week (back working as a Research Intern...DGRR2012 here I come...).


Just to re-iterate: There is fuel going into my secondary barrels when the BUTTERFLIES ARE CLOSED. No air is traveling through the venturies to pull air into the barrels. This was happening pre-rebuild too.

that is weird it almost sounds like a check valve gone bad. Are you on mechanical secondaries or vaccum?? Also does the car start and just fill the barrels or does it not start?? Also what year is ur car as the nikki did have minute changes over the years.

Motor doesn't start. No fuel is coming out of the accelerator pump nozzle. I haven't pulled the AP to figure out whether it's getting any fuel.

Vacuum secondaries. No air is going throug the secondaries when it's cranking.

Fuel pressure overwhelming the needles? Needles not seating? Needle seat seals left out when installing?

Hmm...I didn't dip the top of the carb in ChemDip. I'm not sure what you're referring to the Needle Seat Seals.

If the problem was going on before and after the rebuild, that would indicate something amiss, yes?

I forget what it is but something needs to have 12v power connected on the nikki or the secondary bowls fill with fuel.

Maybe someone can speak to what exactly that is.

Vent solenoid.

Hmm...I'll do some research into that...

search for the fuel bowl vent solenoid, if this isn't hooked up you will get flooding after the engine is turned off and left for a while. the problem then crops up on start up, the next day or whenever it happens to be.

The vent solenoid really only causes a problem after the car has been running. Drive the car, shut it off and it will drip constantly. It needs to be open. Many people cap it after removing emissions, bad idea.

The needle seat seals are the aluminum washer-shaped seals that go between the needle seats and the bowl cover. Without them, fuel pump pressure forces fuel past the threads and into the bowls.

pictures? i'll search tonight when work isn't censoring the images.

According to this post:


and this post:


I didn't remove those parts. Never pulled them, so I shouldn't need to replace them.

So I was thinking about another thing:
when I went to put the top of the carb back on, i saw that there were two pointed cylinders that were hanging from the top of the carb. What are they? I'll snap some pictures of them and put them up tomorrow when I have internet access again. Two of them came with my rebuild kit...

And what would be causing the AP nozzles to not squirt fuel? I soaked the nozzle in ChemDip to clean it...

mine does the same thing sort of.. it was dripping steadily when idling... buddy told me it was a vacuum leak, turns out it was and the accelerator pump was leaking, resealed it and the block off plate gasket for the air pump and it stopped..

as far as the bowls go i have no clue.... i have a terrible habit of breaking little connectors on the ends of things, nothing is plugged into my carb.. dont know if its right or not but it runs...

figured out one of my issues:

didn't put the needles in the correct place (not installed...) feel like a schmuck...

Yes, they do work better when they are actually in the carb. And in the seats, instead of hanging down.

Grats; at least it's not a fatal error.

Also make sure you dont cap of the fuel vent hole itself if you removed emissions. It will floord you car horribly after driving and turning off. it would produce the same issue if the vent solenoid is not connected. Also when you rebuild a carb you take of every jet and you clean and dip all the components in cleaner and blow compressed air through it to make sure that nothing is clogged. good luck

Ya got lucky. Mine was flooding and leaking onto my thermal reactor, thus my title under my name...

Picture of the vent hole?

Love the name. Hilarious.

In my experience fixing non functioning AP's on carbs people have rebuilt, the most common is not putting the check ball and weight back in correctly.

Isaac

[QUOTE=OneRotor;10929794]Picture of the vent hole?

I will take a pic when i get a chance, but its located to the left of the banjo bolts were the fuel inlet goes in. ill take a pic when i get a chance if i can find a spare carb i have since i converted to efi.

I placed the check ball in followed by the weight. did I do that incorrectly?

You did it correctly :nod:

this may be worth a read:

http://sterlingmetalworks.com/the_nikki_carburetor.htm

Alright, so I had my FB running again this weekend. It was warming up at ~4k rpm with the choke open. I was monitoring block temp with a Thermal IR gun ($50 at your local Ace hardware), and it only got up to ~175f.

I noticed that I was getting massive amounts of fuel in my secondary barrels (to the point where they filled completely with fuel and drowned my motor out). I pulled the electromagnetic solenoid on the passenger side of the carb, and it didn't actuate when I was turning the key from "off" to "on". What is this solenoid used for?

I'm kind of at a loss. Getting frustrated. I had read somewhere about using some QuickSteel and a penny to block off where that solenoid goes in. Is this something that is done often? What benefit would it give me?

I may have some time Friday night to work on her again. Any suggestions?

Thanks

-Jim

Also: I am not getting any fuel to my AP. I pulled everything apart and I have no blockages between my rear bowl and my AP. I have the proper weights and check balls in (in the proper order) and still nothing.