Silly A15 carb issue

[Datsun fan]

Ok here we go

The engine is totally stock A15 except for Mitsubishi electronic dizzy

and 70 amp Mitsubishi alternator, the carb is stock Hitachi coolant type

that has run awesome for 3 years "An advantage for Ratsun members"

Last week a problem appeared that I start the engine, tap the gas pedal

several times in order to stabilize the engine all OK, once the rpm reaches

3200+ the engine boosts the hell to 4900 rpm and keeps it up, to get rid

of it I've to either shut it off then start normally or ignition off for

a second or so then ignition on and it get back to normal smooth idle,

Again if reached 3200+ rpm the shit will happen even if in gear and high

speed it run crazy lol .Except of that it runs perfect

 

the fuel pump is stock .

It's not the pedal cable, no carb flooding and fuel level is correct ,

no black or white smoke ,no signs of worn outer linkages or so.....

I just dont want to tear it down if I don't have to

 

Anybody has a clue

[Jseoung]

Well, if you need any replacement part i have an a15 engine that i am pulling out that i can part out.

[ggzilla]

Sounds like a nice engine, i love teh A15 it is a superb engine.

 

 

once the rpm reaches 3200+ the engine boosts the hell to 4900 rpm and keeps it up

Doesn't sound silly to me, sounds disturbing. Sounds like the secondary is opening to soon, or maybe it is sticking. With engine off, does the throttle open smoothly and fully and snap back when you let go? Open it fully, then manually rotate the secondary open. Does it snap back?

[ggzilla]

Is this the kind you have?

[Datsun fan]

Thnx man for the fast reply I really appreciate that .

Sure the kind in the picture is the one I've . The one I've is coolant type, is the one in picture coolant type also?

My guts tell me it is the secondary that sticking , anyway I'll check what you asked and get the answers .

[Datsun fan]

ggzilla.........

I checked the carb rear :primary it's good and snapping back good, But the secondary isn't because of gunk/crap sticking the secondary and preventing it from snap back in addition to loose nut. Cleaned and tightened and now the problem is gone .

Thank you ggzilla for the hint

[ggzilla]

Another Datsun saved!

[Datsun fan]

By the way, Do you know a trick to disable the auto choke cos it's annoying that if I turn ign off for 5 mins then start the choke the stupid sequence is restarted again although its the summer now.

I'm looking for easy/temporarily/cheap trick, Blocking some choke mechanism maybe???

[ggzilla]

Yes, use a paper clip or other wire, and tie it in the open position.

[Datsun fan]

Thanks again.