Carbs problems

[sutantonio]

Hi!

I'm from Spain, fj1200 club. I'm restoring a 1988 FJ1200 3CV. My problems are the carbs and microexplosions from the admision to the Air filter. I tested valves, are well, I changed all o'rings of the carbs an I installed a complet jet kit, except the needles and diaphragms (are well). The sparks are news. The Air filter is the orinal and the exhausts are Busso. When I start the fj on cool, It starts very well, whith starter pulsed, good sound and rpms stable,
When the fj takes temperature and I give gas to 3000 rpms, begin the microexplosions from de admision to the Air filter and leaks fuel from the rubber tubes. The explosions leak fuel pressure from the admision, I can see the fuel psssshhh (carbs number 1 & 4). The floats are to 22,5 mm, I dont know what's happen, I'll change the needles, today the fj use the olds. Thanks.

[FJ_Hooligan]

Spitting back out of the carb intake is typically an indication of a lean condition.

What groove are the needles on?  If you can, drop the clip a groove or 2 to raise the needle position.

Have you adjusted the idle mixture screws?

If fuel is leaking from the overflow/vent hoses, the fuel level in the float bowl is too high.  Adjust your float of make sure there is no debris lodged in the needle seat.

[sutantonio]

Thanks, I'll put standard settings, I think the needle is in 3rd position. The floats are in standard settings. My FJ's friend Alf, is helping me....I'm waiting for a Carbtune, then change the needles and standard settings, mixscrew and see what's happen. I have a vídeo..

https://youtu.be/e7B13ip1ECQ

[Pat Conlon]

Before you focus on a suspected carb issue, Rule out ignition.

1) Remove your air box.

2) Listen closely to identify which cylinder is making the noise.

3) Switch plug leads. If the noise is coming from #2 carb, switch #2 plug lead with #3 (and vice-versa). If the noise is coming from #1 cylinder, switch plug lead with #4 (and vice-versa)

4) If the hiccup moves to a different cylinder, then your problem is spark, probably a bad plug or a bad resistor plug cap. The oem FJ silicone insulated/stainless steel core plug wires are very durable and damn near indestructible, so I would be surprised if that was the problem.
It has been common for a bad resistor plug cap to mis fire at idle only to wake up and let the spark through at higher rpms.

5) If after switching plug wires, if the hiccup remains on that specific cylinder, then investigate carb issues.

Hope this helps.

Pat

[racerrad8]

After watching the video a couple of times, I'm going with lean fuel mixture. Plugged pilot jets and/or passages.

If you are referring to fuel coming out of the fittings on the sides of the carbs, that is going to be caused by the pressure from the popping on the carbs/intake runner.

If you pull the choke cable when it is popping like that, does it stop?

What jetting did you install from the jet kit?
Idle mixture screw setting?
Have you done any kind of sync yet to ensure they are all working equally?

Randy - RPM

[sutantonio]

Hi!

Thanks for all, the mixture screws are standard settings, 2 turns. When I push the choke, the fjs go very well, good sound. I used a keyster kit to repair the carbs but I used old needles, but I dont remember the position. Today I've received the carbtune to Sync the carbs. I Will Sync first, then adjust mix screw with the tutorial (500 rpms and half turn). I'll post in a few days.

[Motofun]

Just my 2 cents...The "choke" is really an enrichener.  It effectively doubles up the capacity of the idle jets.  If pulling the enrichener makes it run smooth, I would suspect the idle jets as being FUBAR.  The idle jets are the smallest jets and usually the first to foul.

[sutantonio]

What's this? I've cleaned this hole some times with a wire.

[FJ_Hooligan]

That's the Main Air Bleed.  It provides a passage for bleed air that gets mixed with fuel in the needle jet, or emulsion tube.  

If it gets clogged, the mixture drawn into the carb throat will be overly rich.

It's a fixed orafice that performs essentially the same function as the removeable Air Pilot (Idle) Jet on the opposite side of the intake.  The Air Pilot Jet controls the amount of bleed air that gets mixed with fuel from the Idle Jet.  The resulting mixture then travels to the Idle Mixture ports.

If you've installed an aftermarket jet kit but are still using the stock needles, that might be a problem.  Most aftermarket jet kits have needles that are different diameter and taper than the stock needles.

[sutantonio]

Thanks, I'll install the aftermarket needles  and Sync with my new carbtune jijijijiji.

[Sparky84]

What's this? I've cleaned this hole some times with a wire.

Mine gets filled with fuel when sitting and I can suck fuel out with a syringe.
Is that how it should be?

[wainot-Phil]

Hi!

Thanks for all, the mixture screws are standard settings, 2 turns. When I push the choke, the fjs go very well, good sound. I used a keyster kit to repair the carbs but I used old needles, but I dont remember the position. Today I've received the carbtune to Sync the carbs. I Will Sync first, then adjust mix screw with the tutorial (500 rpms and half turn). I'll post in a few days.

You say that you have your Mixture Screws set at  2 Turns out ,,  This setting  is way to Lean ,,  Try Setting  all your Mixture Screws   at  4 Turns out and see if that fixers the problem,,, Or even 4 1/2 turns out ,, Just my 2 cents worth

[oldktmdude]

Hi!

Thanks for all, the mixture screws are standard settings, 2 turns. When I push the choke, the fjs go very well, good sound. I used a keyster kit to repair the carbs but I used old needles, but I dont remember the position. Today I've received the carbtune to Sync the carbs. I Will Sync first, then adjust mix screw with the tutorial (500 rpms and half turn). I'll post in a few days.

You say that you have your Mixture Screws set at  2 Turns out ,,  This setting  is way to Lean ,,  Try Setting  all your Mixture Screws   at  4 Turns out and see if that fixers the problem,,, Or even 4 1/2 turns out ,, Just my 2 cents worth

   I agree with Phil, 2 turns out  is not enough.
   Regards, Pete.

[sutantonio]

Hi!!

After Christmas, I've installed th new needles (kit) and I put the mix screws over 4-3 1/2 turns. Now I've the same problem, leaks fuel from 1-2 carbs evacuator tube. I'll check these floats parts. 

[sutantonio]

Hi!!

Well, after tests and more tests, tested with honda coils and tested the coil resistence, I' ve talked with Alf, and we've discarded carb problems. I've disassembled the camshafts and I've discovered that the timing is wrong  the marks arent in timing. I mounted they wrong, because in the manual I cant see the pictures well  . When I assemble well, I'll write the test.