Nikki carb problem
 

Hi all
Car starts fine and idles ok. Problem comes in when driving and loud pedal is depressed at say 4000 rpm. Car doesn't die but splutters like petrol not coming thru. if i gradually depress loud pedal i can go all the way down to red line when buzzer kicks in no problem. as i say this only happens when i press pedal down quickly. Am i right in thinking i have a problem with my secondaries ?
If so, how do i start to fix this problem

thanks guys

it's possible your accelerator pump is shot.

Could also be that your secondary jets are clogged. Pushing partway down, you can still get enough fuel through for it to run right. But when you floor it, the fuel requirements are much higher, and the fuel may not be able to get through the jets to meet that need. I went through this issue myself a while back. Also, you might take a look at your fuel filter for the same reasons as listed above. Good luck.

if the jets are possibly clogged here's a way to fix it...

get an old shirt or something, take the filter assembly off the carb, rev the fucker up with your hand really high, i mean get the rpms up there (gradually as you may have to) then shove the shirt in the top of the carb but keep the rpms up as long as you can. once it gets close to dying down pull the shirt out.

mexico taught me this one and it works pretty well. do it a few times.

buuuut, you say that if you go slow... you can get the gas pedal to the floor. that doesn't sound like a jet problem.

do you have vaccum or mechanical secondaries? either way, when your standing over your carb and you give it gas watch to see if there is a nice stream of fuel shooting out.

more info and we'll go from there.

Hmm, when the car is just idling, what happens if you floor it quickly? Will the revs shoot up like normal? I'm trying to figure out if the issue is only present while driving, or if it does it at idle as well. If it revs right up while idling, but not while driving, then I will stand by the clogged jets theory because that is exactly how mine acted with clogged secondary jets.

good point, if it's not doing it at idle then pump should be fine. WOOOOT. easiest way would be to open up the carb and pull the jets out. but if you don't have a good top hat gasket to replace it with then you cant. they ALWAYS tear. and then you would be even worse off. try the trick i told you about to clear up the jets. after doing that if it still doesn't help then you gotta start looking for clogged e-tube or maybe even air bleed.

ok guys, this is whats happens

removed the air pan, started the car and idled.

stood over carb, looked in and revved her hard.
Revved fine. Although fuel only coming thru from primaries, no movement from secondaries at all. am i right in therefore thinking that secondaries come in while driving and effectively while engine is under load ?

took her for a run and problem persists. can rev all the way to red line if pedal is depressed slowly.....but depress pedal fast and then above 5000 she stutters like no fuel is getting thru. even at 6000 with the stuttering if you release the pedal slightly she will then rev smoothly

this is definitely a secondaries problem. how do i tell if the secondaries are vacuum or electrically or mechanically driven ? this is an 82 rex with 12a

Your secondaries are vacuum operated if they are stock. You won't be able to see them opening just by revving the engine. You might be able to move the linkage by hand and get them to open up so you can check for fuel flow, but my guess is that they're fine anyway. A carb rebuild kit will run you around 30 bucks.

I would take a look at fuel filter and fuel pump before getting into the carb.

Damn, I agree with CDRAD again. If not the pump/filter, it's gonna be the Accelerator pump.

yea, your carb is most likely fine. replace filter, and check the flow of your fuel pump. i remember the days of going thru stock fuel pumps like women.