very odd fuel cut out on Polini / 28mm oko

[cf_z]

So i've had this problem for ever now. On my elite build whenever i gun it hard and get moving after a certain amount of time (not long, barely long enough to get it up to 65 mph) it will totally bog down. It will also happen if i cruise for a little while, and maybe try to get going a little faster (give it a little more throttle), it will also bog down.

When this happens when im cruising, if i let off the throttle for a little bit it will come back to normal, but usually it will happen again rather fast unless i totally get off the throttle and let it decel or idle for about 15/20 seconds. then im good to go again till it happens all over. I am 99% sure it is running out of fuel. thats the only thing that makes sense. Runs out of fuel, get off the throttle, bowl fills up again and then im good to go untill it runs out again.

Heres the problem, i have no clue what it is! I figured it was the fuel filter just not being able to flow enough, but today i removed it and just ran a striaght fuel line from the petcock to the carb, and still the same thing.

Is there something i could have messed up on the carb? like i said its a 28mm OKO, the only thing i could think of is if the floats are miss adjusted. but i have no idea!
bad petcock?


let me know guys, im stumped.

[Kenny_McCormic]

Check float level like you said, could be the mid range out of tune.

[cf_z]

when i open it up, what do i need to check for to see if that is the case?



i dont wanna sound like a noob, but, i am so i have no other choice .

[Wheelman-111]

Greetings:

My Aero had identical symptoms. Except the 65 MPH part.

Turns out my vacuum line to the petcock wasn't quite airtight. It had enough vacuum to open fuel flow during normal operation, but the combination of lowered vacuum and increased fuel demand at WOT caused it to starve for fuel after 30-45 seconds.

If the filter's clean and your float's OK, check to see if that vacuum line is tight at both ends and perhaps if there's a little pinhole or a crack somewhere. Spooge in the float needle is another possibility. The fuel line itself could limit flow if it's kinked by installation of plastic.

BT reported no problems with a setup similar to yours, his advice got me to explorin'. PVC vac line's too stiff, wouldn't seal at the manifold nipple. The cure for mine was Genuine BMW German reinforced rubber vacuum line in ze correct size...
Achtung, Benzin: You vill flow copiously in zis direction --->

[Kenny_McCormic]

You need to find the float level specs to set float level.

[cf_z]

Greetings:

My Aero had identical symptoms. Except the 65 MPH part.

Turns out my vacuum line to the petcock wasn't quite airtight. It had enough vacuum to open fuel flow during normal operation, but the combination of lowered vacuum and increased fuel demand at WOT caused it to starve for fuel after 30-45 seconds.

that was a thought of mine also.

I dont know that my petcock is working right int he first place. When i removed the fuel line to take the filter out, it just spewed fuel out of it. It never shuts off.

i think i might just replace it with a shut off valve of some sort.

it makes me more mad every day.

[maddog]

the bladder in your fuel valve is shot, a petcock has an on/off lever.

[cf_z]

the bladder in your fuel valve is shot, a petcock has an on/off lever.

soooo, a new petcock is in order?

i might just do some custom shut off valve, i had so many AN fittings laying around from my cars fuel project its insane.