weber carb conversion and backfiring?

[bravekozak]

zoe is correct about the radio suppression connector lead. No effect.
That is just so you won't hear any static on your radio.

Again, is the backfire in your intake system or exhaust?

[hugginsvilleH&A]

ok this damn weber has pissed me off more than my exwifes, no kidding, i went BACK thru everything again, the disty looked good ,the vacuum advance was working properly, good vacuum with the gauge, i truelly beleive the problem lies within the weber itself, it is still stumbling/backfiring out of idle, WTH? what pisses me off is i got 300 bucks in this setup and its damn useless at this time, you should be able to bolt on and tweak a little and be good to go, you would think! i should not have to tear down a brand new out of the box carb to get it to work , maybe?
i feel like festy alluded to that its something with the accelerator pump lagging coming off idle and maybe leaning out momentarily ? IDK , i need to figure out if there is a check for this. This is the only thing i can think would possibly cause my problem.

the vacuum numbers i watched today, they were idle-19.5, revving it would drop off, during the transitions it would peak around 23-24... i also tweaked the mixture and speed settings in every damn imaginable position to no avail

bk i am damn close to pulling the trigger on the carb you mentioned due to this BS, question what kind of adapter did you use, will rocket mans weber adapter work, or would i have to start all over again from the manifold up = more $$$.....

BK the backfire is totally in the INTAKE everytime, the thing stumbled/backfired at some points till it almost felt like it was trying to run backwards, till i steady pumped the gas pedal to bring it out of the stumble then it idle pretty as you please and again once cleared of the stumble it rev to the moon and sounded sweet, i just dont get it???

arrgggg man this is total BS, sorry for the rant but i am pissed about spending good money on some high dollar product that does not deliver,,,,


ps. i do wish this weber would prove me wrong but so far it has been nothing but royal PITA and not worth the money in anyway!

oh yeah do you fella's have anymore suggestions i would like to hear them and try them ,, maybe all the way up to loading this weber up into a clay pigeon thrower and letting it fly and blast that SOB with my 12 gauge Benelli

[bravekozak]

Mikuni diagnosis.

Is your choke fully open when warm?

[hugginsvilleH&A]

could it maybe be a sticking valve??? but would that not be a constant thing? like i said when revved on up it really sounds nice like it want's to take off to the races, i am just trying to think of every angle.

[hugginsvilleH&A]

yep it takes a couple minutes and the choke opens up pretty as please, perfect everytime

[drddan]

12 gauge Benelli

Nice shotgun! :mrgreen:

I've been reading this thread for a day or 2 now, and you shouldnt be having such a hard time with a Weber...really....
So I have a couple Q's for ya!

Have you been inside the Weber? I mean not just the jets, I mean took it all apart to see if the needle valves are seating, all springs in place, you know its all as its supposed to be inside? And have you checked the float level?
Improperly adjusted choke?
I did see that you had the choke wire, hooked to the Festy alternator. The alternator only supplies 7 volts!!! The weber choke needs 12volts!
Hook the choke to a 12 volt "key on" source(you have several available from all the sensors you removed)

Here is a complete rundown checklist for tuning a weber and will answer ALL the Q's you have asked above...and a few you prolly havent thought of yet! lol

http://www.racetep.com/webjettune.html

Follow the instructions from step one, to the end. Do not skip steps unless instructed to!
Hope you find the cause, and when you do' i'll bet you'll smack yourself in the forehead and say "....WOW! Finally! .... and it was right there in front of me!"

P.S.
What is your secondary main jet?
You should have a slightly SMALLER secondary than the primary. I see you have .100 in primary?
I would have at least a .115 primary and .100 secondary, maybe even .125 primary and .115 secondary.
I run .140 and above with my B6

[hugginsvilleH&A]

very interesting, this sounds like my problem

http://community.ratsun.net/topic/2125-weber-carb-hesitation/

but again a brand new out of the box carb should not have to have this

[FestYboy]

Festy when i run the throttle up by hand it would go up to in the mid/upper 20's i beleive, it seemed to not backfire when i did it by hand and slow rolled into it, but from the drivers seat and pedal it backfired everytime, i am using the bracket they sent with the carb, all rigged up to hold the factory cable (this is temporary till i make/buy another one bracket) Could that possibly bind up or something? it all looks to be functioning fine tho.

festy how do you check the accel pump jet function?

there should be a small protrusion into the primary barrel (typicaly brass). hold open the choke plate and look down the barrel (engine NOT running). hit the throttle hard, if everything is good, you should see a hard stream of fuel squirt into the barrel. if you don't see fuel, check your linkage to make sure the accel pump diaphram is being actuated. if all looks good on the outside but still no fuel, you need to open the carb up and clear the debris.

[drddan]

also, a tiny pinhole in the accelerator pump diaphram can cause it to fall on its face.

Hugginsville, I hope you saw the link in post #36 above.....

[hugginsvilleH&A]

Drd all i did was change the main jets, i did not go thru the rest of the carb, i didnt think about doing that to a new carb, it was purchase from weberarbsdirect.com,, it looks like i will be going thru it if i want it to work, the choke worked great but i will find a 12 volt source and give it a try, also will give that link and setup list a try , as many times as i have been thru the setup procedures so far i should be a pro by the time i get this figured out!

i did my jets after reading what some have done on here, that are more or less in the same part of the country( elevation wise) as me.. and settled on .100 main and .115 secondary(i think) due to the fact i am trying to keep it as economical on gas as possible , my commute to work is a 110 miles round trip

i will check the accelerator pump according to the link i posted above, and start from ground zero and go thru the whole darn thing, if it was not an internet purchase i would return it for sure

[hugginsvilleH&A]

festy thats what i needed to hear, will give that a try, bet i will be going thru the carb for sure, thanks guys , Rick

[95Compact]

Rick, if you still have the original .140 jets, put those in and try it again wiht no other changes.

Also, I don't know if you need the Holley fuel pressure regulator that you mentioned earlier;

I don't have one on mine, it's just fuel line - mechanical pump - filter - carb.

[bravekozak]

my commute to work is a 110 miles round trip

I'd move.

[drddan]

Drd all i did was change the main jets, i did not go thru the rest of the carb, i didnt think about doing that to a new carb, it was purchase from weberarbsdirect.com,, it looks like i will be going thru it if i want it to work, the choke worked great but i will find a 12 volt source and give it a try, also will give that link and setup list a try , as many times as i have been thru the setup procedures so far i should be a pro by the time i get this figured out!

i did my jets after reading what some have done on here, that are more or less in the same part of the country( elevation wise) as me.. and settled on .100 main and .115 secondary(i think) due to the fact i am trying to keep it as economical on gas as possible , my commute to work is a 110 miles round trip

i will check the accelerator pump according to the link i posted above, and start from ground zero and go thru the whole darn thing, if it was not an internet purchase i would return it for sure

Well, just had a member contact me a few weeks back, he was having similar issues as you. He had .100 pri and .115 sec
I suggested switching them to .115 pri and .100 sec and and his issues went away.
Thanked me greatly, and said it now accelerates smoothly from 0-80 mph!
Yes do read the tuning aid, if ANYTHING mentioned in the aid is not right or skipped you may continue to have problems.

I agree with you, as, you shouldnt have to go through what you are going through with a new carb, but... it does happen occasionally.
I do however have thoughts about vacuum leaks, timing issues, and the accel pump diaphram, with what you have described.
Good luck! I do hope you find the issue quickly!

If it comes to this, here is a cheap rebuild kit, comes with the pump diaphram. Believe it or not, the whole kit is cheaper than buying just the diaphram!

http://www.ebay.com/itm/REBUILD-KIT-...r#ht_550wt_879

[hugginsvilleH&A]

Drd i will be removing the carb and switch the mains around look at the accelerator pump parts and see what i get ,


BK - no way , i have worked in a big city for 20+yrs you can have it, my job offered a position in a coastal town( Savannah ) so we got us some land out in the BFE and set up a small farm complete with chickens, goats , and just got us 2 calves to be raised for milking next year,

funny thing here is it takes me about 55-60 minutes to travel the 55 miles ( absolutely NO traffic) into and home from work, when i lived in Atlanta i lived 16 miles from work and most days it would take me about 45 minutes on a good day travel that and on a bad day it would push 1.5-2 hrs to travel 16 miles, nope not for me and dont get me started on having to deal with the people there and the crime, tho my HVAC business was better in Atlanta, it was just a side job and not the main bread winner, everything is a trade off, less money but better quality of life where we are and our kids dig being in the country with the critters , 4 wheelers, and now they are working on me to put up more fencing and get some horses, will probably get THEM a horse , I ONLY do IRON horses tho, wish i still had mine but had to sell it for the move down here... Oh yeah did i mention its on the coast, man i love the "low country" down here, close to SC coast, Ga and FLA atlantic side,, yeah buddy they can have Atlanta, hope i never have to return there!

its my weekend now so hopefully i will have time to tear into the stiva this afternoon, but i got to go move a chicken pen now for the wife / kids (no kidding)