Need some expertise to bolster my newbie attempts. Have a rebuilt carb that will not start. Anything obvious I forgot to reconnect? Is there a clue in that both secondary barrels have around 1/2 inch of fuel sitting on top of the valves as shown in picture? (Forgive me if I am naming things wrong... newbie). Kind of at the end of my knowledge and diagnostic ability here.

Details details....
Car started and ran and could be driven before rebuild of carb, but would die if accelerator blipped. Diagnosed bad accelerator pump as no spritz at the main barrels when accelerator jabbed.
Rebuilt carb using Atkins rebuild kit. DID NOT replace the float needles and seats as read here keeping originals in place is recommended.
Rebuilt carb now back on car. First start attempt used two second spray of starter fluid down primary barrels and gave the accelerator two pumps before turning key. Engine tried to fire for about 2 seconds, then cranked over only on the starter motor after that. Tried three or four 10 second attempts but nothing but starter motor turning over engine with no sounds of hope eg trying to fire.
Assumed I'd flooded the engine. Pulled spark plugs and fuel pump fuse, cranked the engine for a couple of 15 second bursts. Big cloud of gas out the spark plug holes, I could see it from the driver's seat. Dried off the plugs (They have around 15 minutes of driving time on them) using compressed air and butane torch. Added three or four teaspoons of 2 stroke oil to lower two spark plug holes and turned over the engine three or four times using the main pulley bolt. Reinstalled spark plugs.
Tried to start car, again with starter fluid but this time did not pump accelerator before turning key. Cranks but no signs of wanting to start. Gave up after four 10 second attempts.

As the car sits right now, both float chambers show half full in their glass windows. Idle speed screw turned all the way in then backed out 4 turns. Idle mixture all the way in then backed out two turns. Primary barrels are empty, secondary barrels show around 1/2 inch of fuel on top of valve that if left alone drains away in around 20 minutes. Triangular recess between primary barrels half full of fuel that does not drain away.
Car is 1981 FB with a 12A engine. Everything is original to the car, nothing removed or adapted.

Thanks!

 

?????
1/2" of fuel sitting on top of the seconday butterfly? Maybe it's starter fluid. Didn't this motor start up and run after the rebuild? I say keep trying till it starts. Pump Pump Crank. Pump Pump Crank. Pump Pump Crank Crank VRoooooom!

 

Yes, 1/2 inch of fuel both secondary barrels sitting on top of butterfly, or building up below the butterfly and filling past the butterfly so top of fuel is above butterfly. Thought alike and wondered if starter fluid. Tested without starter fluid once the barrels had drained and dry and sure enough still have fluid filling barrels to above butterfly valve after a few seconds of cranking.

Did try cranking and cranking. But when I checked plugs lowers were wet so assumed I was flogging a dead horse. Plugs not dripping wet but I could see moisture and when I pressed the plug to my finger it left a wet print of the spark plug end.

I guess quick and simple question would be is it normal to see fuel in the secondaries above the butterfly after 10 seconds of cranking with no start?

 

There's nothing under the secondary butterfly except a long runner/tube into the engine, so it's not pooling up under the butterfly. I don't know why any fuel would be flowing to the secondaries below about 4000 rpm when they start to open.

Note- the secondary side is the larger barrels, on the passenger side of the engine. The primaries are on the driver's side and have the choke flap on top.

 

when you press the pedal, does anything squirt? did you double-check each gasket to make sure no channels are blocked off?

 

Oh man, that was a scary sight! Working on my own so was not watching what was happening in the carb real time as I pumped the gas pedal. But given your question I turned the key so fuel pump was running, jumped out to look in the carb.... and it’s a gosh darned jacuzzi in there!

Fuel is flowing at quite a clip starting in to the triangular recess to the driver side of the primary barrels. The fuel then overflows that recess, runs around the outside of the primary barrels, some pouring into the primary and the rest flooding around the circumference of the top of the carb until it pours in to the secondaries. I am working on a sloping driveway, which is why the fuel is flowing around the circumference rather than taking a straight line to the primaries.

Do another rebuild of the carb I assume?
- Did check that I chose the correct gaskets by matching them to the originals, since the kit did indeed include slightly different patterns. But will check again.
- Is the symptom I describe assignable to the float needles /seats not sealing? If so, maybe I should rebuild with the new needles and seats this time rather than using the old ones.
- The carb rebuild kit provided card style washer like gaskets rather than actual metal crush washers for the main jets, main jet access bolts and the hard fuel lines at the top of the card. Should I source actual metal crush washers?

Thanks again for pointing me in the right direction.

 

Def rebuild! For whatever reason, your floats are not pushing the needles in to stop the flow of gas.

 

Crimeny, a 1/2" of fuel on the butterflies? I think that's a new record .

Jokes aside, I was first going to say stuck floats, but if I read correctly the sight glasses show fuel only halfway up? Do they show only halfway up even when the fuel pump is running? Because if that's the case we have an interesting situation that I've not seen before.

I'm going to guess that the sight glasses are not actually halfway up with the pump running, in which case you have a stuck float or gunk in the needle/seat. First thing to check is turn on the fuel pump (key in run position for 82 and older) and go look down the carb. Is there fuel dripping from the boosters (the smaller venturis in the middle of the barrels)? If so, that points to a stuck float. Sometime this can be fixed on a fresh rebuild by lightly tapping on the carb with a small hammer, but usually it means pulling off the air horn (the top third of the carb).

I have a funny little ritual whenever I put a new carb on where I turn on the fuel pump the first time and then shake the car while staring at the sight glasses. 7 times out of 10 the float bowls over fill but they don't actually get stuck and drip out the boosters. Shaking the car is similar to tapping the carb - it helps the floats and needles seat the first time since they've just been hanging dry and loose. I probably look nuts doing it, but it's never let me down.


Anywho. That was all to say check if fuel is dripping from the boosters when the fuel pump is on. If so, lightly tap the carb with a small hammer (or even a screw driver handle) while the pump is on and see if the dripping slows and eventually stops. If it does, neato. If not, you need to pull the air horn off.

Edit: I forgot to add that the baseline mixture setting should be 3-4 full turns out. Factory baseline is 3.5 - only 2 turns out might make things a little more troublesome for you.

 

I would bet you are correct. I only checked the levels in the windows with the pump off. Was a huge amount of fuel, secondary barells filled to the top when pump was on, then drained over a few seconds to 1/2 inch over the butterfly.

Pretty sure though that the fuel was was coming from the triangular recess circled in red in this pic. That even possible and if so still a float /needle / seat problem to go after?

 

If fuel was coming out that triangle area it means it's backing up high enough to get into the vent system (that triangle is the fuel bowl vent). I've seen fuel in there before as well, but usually only after the boosters are dripping quite profusely.

I've honestly never seen the barrels fill up all the way to the top. Perhaps if you hadn't noticed it for a while and it was dripping for a long time, but otherwise that's pretty uncommon. If it filled up to that level quickly then I'd be suspicious of some pretty wonky needle and seat stuff going on inside. The most a stuck float usually produces is a consistent drip - if it's a steady stream I'd be concerned.

Does the car still have the factory or an equivalent replacement fuel pump? Just want to check before we go chasing float issues.

 

Just trying to shotgun ideas here, could this be caused by fuel/return hoses being installed backwards? Or would that cause not enough fuel to get into the bowls?

 

Really appreciate the excellent help here. In answer to your questions original fuel pump, and fuel lines are the original with different diameters so don’t think they can be accidentally swapped? Fuel immediately pours from that triangular vent by the primaries. Trying to think of a comparison to describe the rate of leak.... it’s pretty high. Actually scary! Ever had one of those fake Japanese waterfall bonsai battery operated plant pots? That kind of flow rate. I am going to take apart the carb today and see if I see anything obvious.

 

The hoses look to be the same diameter (at least on my car which is still all stock), the return hose has what looks like a check valve in it.

 

The fuel hoses are different sizes (5/16" feed and 1/4" return) so they shouldn't be able to be accidently swapped around. Even if they were, there is a restrictor on the carburetor for the fuel return, so you'd likely see less fuel flow if they were backwards, not more. The check valve could be backwards though, so perhaps check that. It's pretty tough to blow through even on a good day, so don't just chuck it if it seems restrictive (not much fuel flows through it anyway). The check valve is located in the middle of the fuel return hose.

If it's leaking out the vent (triangle section) then it should be leaking from the boosters as well since the vent is above them - also if the barrels filled up that would imply the boosters are dripping.

I'd test the check valve first since it's the easiest. Generally speaking they don't get flipped around since most people just remove the fuel line from the carb, but if you pulled everything off then it's possible. If it checks out then you'll want to pull off the air horn - a leak that bad is going to be more than a hammer tap fix. Take a photo of the floats when the air horn is sitting upside so we can see what height they are at.

 

Checked and fuel lines are different diameters and were not taken apart or removed from fire wall so don’t think the problem is there.

One more clue. Am testing the hammer tap idea. Put carb in a bucket as don’t want any more fuel in the engine. However fuel now pours only from the opening circled in red. Looking at photos I took before car removal this outlet appears to run under the rats nest and end up at the center iron below the oil fill cap. Surely sending gas there cannot be correct? What is the circled outlet and where should it connect.

will be removing the top portion of the carb today. Will let you know what I find.

 

The fitting circled in red is the second float bowl vent. When the vent solenoid has power (the single wire connector by the fuel lines) that fitting should be blocked off and the vent is routed through the triangle section in the carb. When unpowered (aka the car is off) the solenoid allows air and fuel vapor to flow from the fuel bowls into the evap system.

Since the vent is on the table, might as well also check the vent solenoid. Pretty darn simple to do, just turn the key on and listen to the vent solenoid. It should make an audible click. It's generally loud enough to just barely hear from the drivers seat.


Edit: I might be wrong about that red circled fitting actually becoming fully blocked when the solenoid is powered, I haven't actually tested that. There's a decent chance it still flows some air even when the solenoid is powered. Seeing that fuel pours from the triangular vent that also implies that the solenoid is working, but it still doesn't hurt to check. I can say that the car will not run properly if the vent solenoid is not working, but it shouldn't affect the fuel overflow issue.

 

Now have the carb apart. Can totally see that if the float chamber filled to the top fuel would overflow to behind the solenoid then exit through the triangular vent or the fitting I circled.

photos of floats attached. I did not adjust or reset them giving warnings here not to mess with float levels.

- Do I have the spring and needle rigged to the float correctly?

- Should I replace just needles, or the needles and seats? I hear getting the seats out can be a bugger.

really appreciate the help through this.

 

Your float heights are way too low. Check the fsm for the specs, but if I recall correctly the "upside down" setting as seen in your photos is 16mm from the gasket to the end of the float. The droop spec is 50something mm (not as critical). Again, check the fsm to be sure, but that's definitely a big part of your problem.


Edit:
Link to the carb manual here (link from Foxed.ca): Nikki Carburetor Manual
Pages 88-89 (in the pdf) show the float specs and where to measure them from.

 

Excellent info. Manual I have says 16mm +-0.5mm. My calipers say 11mm on one and 12mm on the other. Will reset to 16, then reassemble with new needles and springs and see what happens. May also bench test it before putting it back on car. Am I wieird to find to find this kinda fun? Beats crawling under the car to remove the transmission!

 

Reset float heights, installed new needles and carb is back together. Tested by connecting fuel lines and turning key so fuel pump running. No gushing gas! Nothing from the vents or dribbling in the barrels so looks like float valves are working. Should have carb fully installed by end of day and will let you know how it goes. Really appreciate the help. Would never have looked at float heights as car was running well at its existing float heights before I tackled carb rebuild to fix accelerator pump.

 

End of day. Tries to start but no go. Letting it dry out for 24 hrs before trying again. Let me know if any wrong assumptions in what I tried listed here:

Carb reinstalled.
Deflooded by cranking starter with fuel pump fuse and spark plugs out.
Couple of tablespoons of 2 stroke in each lower spark plug hole. Hand cranked by pulley 1/2 dozen revolutions to spread it around.
Burned off plugs with butane torch and reinstalled.
Two second squirt of starting fluid in top of carb.
Cranked without pumping accelerator, engine fired and ran for three or four seconds then died. Fair amount of white smoke and a trail of something wet out of the tail pipe on the ground which evaporated in 10 mins. (Gas?).
Hit the carb again with the starter fluid and cranked again with same result... runs for three or four seconds then dies.
Pulled plugs, wet, so working theory is engine is still flooded. Given the pretty massive amount of fuel I saw flowing out of the vent and down the barrels the carb issue must have put at least a pint of raw gas into the engine yesterday.

Leaving plugs out for 24 hrs, hopefully that will help dry out the gas inside the engine, then will try another deflood / spark plug clean / start attempt tomorrow. Will let you know how it goes.

 

Do the deflood procedure and hit the plugs with brake cleaner and a wire brush. Should help with the flooded engine.

 

Are the float valves the only gate between the fuel line and the float bowls? Eg if I can hear the fuel
pump running and know by testing that fuel is making it as far as the end of the rubber fuel line where it attaches to the metal fitting on top of the carb.... is the only possible reason there is no fuel on the float needle valves stuck in the closed position?

Yesterday I had gas overfilling the bowls and exiting through the vent right next to the primary barrel. So adjusted the floats to 16mm / 51mm as recommended in manual and installed new needles using a very light oil and keeping original seats. Now I have opposite problem as no fuel in the bowls.

 

"No fuel in the bowls" ??? No fuel or just won't start?

 

No fuel in bowls would tell me floats are stuck shut. Try lightly tapping on the carb with the pump running to see if they shake loose