Weber trouble...

I'm not sure as to what is going on... Today it snowed and I went to warm my truck up. As I started driving after a warmup, it idled at 500rpm. It took me a while to tune it just right to get it at about 8-900rpm, with the right mixture.

I'm wondering if the cold is going to affect how my weber runs, and whether or not the cold causes my accel cable to "freeze" up, or is it my return spring? I noticed this as I was blipping the throttle. It would stick...

So, when I had my truck tuned right to how I had it, it was puffing out black smoke. I started to mess with the mixture and I did'nt really get any response unless the screw was all the way in. I fear I may have also damaged the screw because the manual talks about it damaging something if you go too far? Well even then, I back it out all the way until it started actually dying. I turned it in and I'm about where I was before... I played with the idle screw also, and its where it was before.

I don't get whats going on? Howcome my truck runs bad on certain days and not others? I've turned the electric choke in clockwise 3-4 times, but I don't believe I made any difference?

Also, after messin' with it, I looked at my tach. It was where I wanted it to idle, and all the sudden it just starts to bogg down to 500rpm and then goes back to normal and then back down to 500 then back to normal. Normal is about 850rpm. I've noticed it has done it before, but not so dramatic. Before, it actually went up in idle a little...

One last thing, sometimes I'll turn off the truck and when it shuts down, the carb "back-fires". Whats that about?

Could anyone give me any insight?

Check ur timing.Should be 6 degrees BTDC.BJ

Wait a second, what is that going to change? I've had my truck on the rebuild for over 6 months and this was just now when it did it.

Well, interestingly enough, I actually found a vacuum hose that was not plugged from the intake manifold. I plugged it and re-tuned it. But I dunno if its going to make a diff...

But still, what is the timing going to affect with my problem?

U said that when u turn truck off it backfires thru carb.2 things cause backfire,timing off or mixture way too lean.U said truck puffs out black smoke which would indicate rich mixture so I assumed (may be wrong) that truck was off time.It can actually jump time by backfiring so I would check it just in case.Sorry if that 1st post didnt make any sense to u.BJ

vacuum leak, and looks like you already found it. The extra air creates a lean condition, and causes exactly what you were describing as symptoms.

I was going to suggest a vacuum leak at the carb base, seems like people either dont tighten them enough or tighten them too much and it creates a leak there after a few cycles of hot and cold. Real pain to find.

Glad you got it fixed.

When I get my oil change tomorrow at my school, I'll have them give a timing check...

I re-tuned my carb and it seems to be in that sweet spot. Although, when I recall, I think me and my brother set the timing on 0 BTDC.

Could that be the cause? But why would it backfire now when I have the new carb? I don't think its ever done it before.

Even now, sometimes it still idles low. But I think now, its because sometimes I don't give it enough time to warm up. Right?

...and thanks for all the help guys.

May be the vac line was the cause of your problem.Old Nikki carbs are notorious for running rich so new carb may be spot on but a little too lean for 0 degrees timing.Try 6 degrees BTDC first and if truck is a little rich bump it to 5 degrees,That is where mine is set with a Weber and it runs fine. BJ

Funny thing happened... This morning everything ran fine. Once I was like 6 blocks away from my school, it ran like crap! Died on my in an intersection! It was real foggy outside too. So I was thinking, what the hell? Not again! Sigh...

I got home and took a couple minutes and plugged ALL the vac lines with some screws. Lol, I have my emissions from my exhaust plugged with spark plugs, lol. I have'nt removed any emissions stuff yet because I'm betting I might fail with my carb and not stock OEM.

Anyways, I plugged the lines, and it ran like crap. I tuned it again and now its fine, hopefully! I noticed today too that I had gas leaking out the gaskets for the carb! Never happened until now... Weird! I dunno where I'm going to get gaskets to replace them now... I used silicone sealant to seal it, because I figure it would cause a vacuum leak.

But its runnin' fine for now. I could'nt get my timing checked out, but it does'nt backfire at all and runs like a purring kitten! So I wonder if its okay for my timing to stay the same still?

I hope my MPG improves because when I first put it in, my MPG was the same as before I had the carb; 12 mpg!