Engine " stuttering " during WOT

[RocFreya]

84' SJ410 -- Canadian made. The Aisin 80010 carb is one w/ extra electric peripherals to help monitor air flow. Currently has extra sensors disconnected because they are themselves broken. Cannot find new ones. Hoping to replace carb. soon with an easy swap, BUT she ran fine for the first few months & never gave me this type of trouble until now.

Engine stutters HARD at WOT - once engine warms. Thats when it happens most. Sometimes it doesn't take WOT or high speeds. When I shut her down, she wont cut off smoothly but instead hesitate for a moment then stall out. Sometimes after longer drives she'll continue to run for a up to a minute even after ignition key has been turned off until finally she hesitates enough to stall out.

Doesn't always happen, but when it does, the stuttering just gets progressively worst until engine wont do anything else but bog down completely & die when throttle is engaged. If I keep the ignition engaged through stuttering, sometimes she'll back fire.

Shut her down & let her cool off & she wont do it again until engine warms.

Idles fine, but if accelerator is depressed too quickly, immediately bogs down & stalls. - This has always been the case since I first got her in time & running.


- Will Samurai carbs fit the sj410?

[courior]

Sounds like the Choke is stuck on. So when its warmed up it floods the motor.

[Rhinoman]

I'd start by replacing the fuel filter if it hasn't been done recently.

[RocFreya]

Gota new f10a carb. in the mail.

The bottom "fuel- looking" inlet is for a breather hose / filter right?

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[Tramp]

I've no idea what bit does what, but aren't new parts great? I love it when they come in boxes and they are clean and new and shiny. Then you fit them, everything in the bay is dirty but your new part stands out! In the uk I think you can swap the standard 410 carb for an SU although in not sure what size? Apparently the side draft aisin carb isn't a bad carb unlike the samurai's down draft who's choke is known to fail,

[RocFreya]

Fuels spitting out the bottom too, cant figure what goes what, return line? Who knows?


Put the old one back on cause atleast she runs. When i turn off ignition, it STAYS RUNNING.

Major issue. I'm thinking its the root problem..

Maybe fuel shutoff solenoid is failing? or Slow jet is failing? I know the needles all need replaced. Total rebuild is prob. necessary.

[twiss]

The fuel pump has a return on it, so the carb probably will not.
It possible that the fuel shut off solenoid isn't working, but at the same time, turning off the key should also stop the ignition coil.
Possible that its running much too lean and the hot pistons are continuing to ignite the fuel?

[ScottieJ]

that doesn't look like an sj f10a carb to me

it's far too over complicated, the standard carb doesn't have a fuel return.

[RocFreya]

Well, yup the new "410A carb" I got didn't fit, got the stock one on still.

Decided to pull the CAT - didn't make a difference. At least I know it's not that.

Gotta be something with the carb.

I got the idle down real smooth, but the high speed jet always seems to not affect the carb while im tuning it.

Also, if the tamper screw covering ( located above the smaller brass high speed adjustment screw ) is not fully in place, engine will not run. Don't know if that's normal, but it makes adjusting the high speed more difficult because it has to be adjusted, then tamper screw replaced.

Would an engine bog at WOT after warmed up from too lean or rich of a mixture?

I have a inline fuel filter right before the carb to monitor whats going on. As soon as the engine sits off, I can visually see fuel flowing back towards the tank. If she sits for a day, I have to turn the engine over for 30 secs or so intermittently & pump the accelerator in order to get gas back into her & started. Is that normal? Shouldn't there be a fuel canister or some sort of pressure regulation going on to prevent that back flow of fuel?

Appreciate ya'll alot.