rotarymike83

I rebuilt my Nikki on Sunday and I'm having major problems. It idles great and has plenty of power but when accelerating hard or driving over 45 mph it falls on its face and wants the stall. The more gas I give it the worse it gets and the car slows down. Then if I pull over and let it idle for 30 seconds its has some power again and does the same thing again. Its acting like its fuel supply can't keep up with the demand. I changed the fuel filter and no difference. I am guessing the floats need to be adjusted because they are below the halfway point. But I never adjusted them when I replaced the needle and seat.

The original problem was the accelerator pump was bad and was leaking externally. It never had a fuel starvation problem over 3k rpms.

Any suggestions?

Kentetsu

Did you remove and clean the fuel jets located in the bottom of the float bowls? If so, are you certain that you put them back in the correct locations (two different sizes)?

How low is the fuel level in the float bowls? If low, was it that way before you rebuilt the carb? If they are low now, and weren't before, then I would look at the installation of the floats to make sure that they were installed correctly. Adjusting them would be a last resort because it can be very difficult to get them right, and they don't usually require adjustment unless the carb was dropped or something.

Do some reading on the carb over at www.sterlingmetalworks.com Lots of info, troubleshooting, and advice to be found there.

Good luck!






.

flight_of_pain

Check the screens under the fuel inlet banjo bolts on top of the carb, at least 1 out of 4 Nikkis that i work on they are clogged.

rotarymike83

The screens did not look good so I left them out. I figured the fuel filter would take care of things. Also the jets are in the right place. After rebuild I put the carb on and it had power but I realized I didnt hook up the accelerator pump linkage. So I removed the carb and connected it and had the carb upside down when I did it. Maybe one of the floats shifted. But I noticed the front and back float is filled a little less then a quarter of the way up.

rxtasy3

iTrader: (2)

sounds kinda like the fuel level in the bowls is too low and ur running it out of gas.

Kentetsu

Try banging on the top of the carb. New float needles tend to stick after a rebuild.

flight_of_pain

A plastic screwdriver handle works wonders here. Is there any chance you bent the tabs on the floats at any time?

rotarymike83

I don't think I bent the float tangs. I was pretty carefull about that. Its looking like the float height and drop are wrong on both of them. But how can they both be low. It makes me think it could be a fuel delivery problem before the carb or where it enters the carb. The two screens that were under the banjo bolts were in bad shape so I removed them. I don't see how that could create this problem. But like I said its weird that both floats are low. I also changed the fuel filter and that made no difference.

Oneiros

sounds like your fuel pump cant keep up with the carby's fuel demands. a slightly low float level won't cause you to run out of power like that. and a disconnected AP wont do that either, as it only operates under light throttle.

rotarymike83

I just replace the Carb with a Sterling Nikki and put on a second inline clear fuel filter by the carb. I figured out the fuel pump is going bad. I wanted a better carb anyway What is the best fuel pump to put on without needing a regulator? Thanks!

rxtasy3

iTrader: (2)

i think that sterling will work fine on the stock pump. anything else will have more pressure and u'll need a regulator.

Sterling

The modded Sterling Nikki should have a 7 lb pump with a 1-4 psi regulator and a good gage.

85TIIDEVIL

iTrader: (2)

Hey STERLING... Is this one of your 8 other customers that leaves you tooo busy to remeber what you did to my carb..???

rotarymike83

Here is an update. I put in a new delphi fuel pump in this weekend. It does fill up both bowls but it will start for a few minutes when cold and then dies as if It runs out of gas (pulled plugs and verified). I then can get it started for a second or two by pumping the gas 3 or 4 times. I know it is not ignition because 1 it fires when you pump the pedal and 2 I put a timing light on the leading and trailing wires for the front and back rotor assembly and get a nice consistant pulse. This is doing the exact same thing my last carb did that I just rebuilt. I did notice one thing and I think this is the problem. When I put on the base gasket under the carb a few of the holes got plugged by Shellac that I used on the gasket. I was trying to make a better seal and got careless. I am hoping this is it and I'm going to make a gasket and put it back on next weekend. Before I started all this it did run with a smooth idle and no puff of smoke at startup. Reason I rebuilt my original Nikki is because the accelerator pump was non functional and leaking externally and base gasket was leaking too.

Any help is appreciated.

rxtasy3

iTrader: (2)

no need to use anything to seal gaskets in the carb, or the carb to intake.

rotarymike83

I agree that we should not need to use a gasket but it was leaking at the base before I removed the carb so I had to use something to seal it. I am going to make an exact cork gasket and put it on this weekend. This should fill in any abnormalities of the base and carb.

The question I have is if a few of the ports were blocked on the very bottom of the carb. Would it make it starve for fuel and die? On a regular carb you have ported vacuum and venturi vacuum with manifold vacuum underneath the carb. If any were blocked the engine would still run... So I don't know if having those ports accidentally sealed would make it act the way it is. Only Sterling would know that. These Nikki carbs are a far cry from the carbs I used to rebuild when I was a boat mechanic.

rotarymike83

What I thought was the problem is still not the problem.... I have attached a video to this so any help would be appreciated. I know I must be missing something I just don't know what.

http://s92.photobucket.com/albums/l2...t=MVI_1319.mp4

Thank you for your help.

Oneiros

i would be compression testing it, since you've already changed carbs and tested ignition...

rotarymike83

I thought of that too... But then I took my gas can and dumped gas down the carb. It ran for about 15 seconds and then died (much longer then before). If compression was bad it wouldn't run. I'm thinking a huge vacuum leak somewhere. My next step is to removed the butterfly on the shutter valve and then remove the spacer. Then with a gasket I made connect the carb directly to the intake. No advance of course but it would remove that spacer from the equation.

Sterling

No, it's one of three ongoing discussions I'm currently having for sales I didn't make.
I don't remember what I gave you on your "rebuild" simply because I couldn't remember if I rewired your crappy cob-jobbed secondaries or not, and if I did, did I then also install an accelerator modification for you because I felt badly for having taken so long (?).

I can either help you, or you can continue to act like an impatient kid that needs spoon-feeding because he's too lazy to read my rather extensive website. Simply email me -without an attitude, and I'll be glad to help.
Take it or leave it, your choice.

Sterling

This is a problem.

Fire85GSLSE

iTrader: (29)

mike,
I was running a stock fuel pump for a while, then upgraded to a mr. gasket ($50). They have two, one for imports 2-4psi and one for American cars 4-8psi. I had the carb on my car when the mr gasket one was on their but soon found out my motor had something going on so I had to pull it.
I also was using a holly FPR with a respeed fuel gauge on it.

That set up seems to do good on a stock 12a (w/180K miles) now and a Dellorto 48 sidedraft that is in the car.

I did add one mr gasket import fuel pump to my Rx2 and it seems to be a little bit more than the stock FP so I added a regulator to it.

Hope that helps.

eViLjAy

If the carb is half full this is not a lack of fuel issue. I can let my carb fill up and keep the pump off and it will run for a solid 3 minutes or better before it is empty. Those bowls simply do not go dry in a matter of seconds as seen in your vid. You mentioned having vacuum holes on the bottom of the carb plugged. I would start by fixing that issue...

Fire85GSLSE

iTrader: (29)

coul dit be that your running off the accel pump only? If you can pump and its ok but not pulling fuel down thru once the motor is running it does sound like the intake has something blocked not allowing the fuel circuits to work?
Do I need to send you a intake manifold or have you pulled that one and cleaned the crap out of it?

If I remember correctly some sterlings carbs had a base gasket that sealed everything off. Kentetsu, do you remember this? If so then maybe mike needs to get one or make one?

Let me know mike as Im sure I have another intake sitting around.

Chad

eViLjAy

also did you remove the plastic spacer under the carb when you did the rebuild/replace? Possible the spacer is upside down?