View Full Version : light hesitation

01-28-2007, 01:42 PM
ok heres the deal...87 sammy,stock, 36K
getting ready for the yearly emissions\safety inspection.
Changed plugs,oil,air filter,set timing, gas additive
Idles like a dream, runs well......like a samurai
TEST #1----2-speed idle test- this is what i blew
HC---high speed -4094!!!, (std 220) low speed-706(std 220) FAILED!!!
co ----hs-.48 (std 1.20) LS-.21 (std1.20) pass
Smelt a little rich on the exhaust....
Went home, rechecked the timing,cleaned EGR,Checked hoses for vacumm leaks-made adjustments,Added tank of Shell Premium -and a bottle of Rubbing Alcohol.
Test2---2-speed idle again
HC- high speed Now -2969 (dropped it 1125) Ls 333 (dropped it 373) FAILED!!
CO- hs 1.07 (went up .51) Ls .16 (lowered .05) passed.
I've even checked the valve lash, reset valves.Theres is a slight hesitation when you Ease up the throttle( not a sputter or a hick up) . COuld this be a Carb problem??too rich or a Lean Misfire...i know where the adjustment is but i haven't touch it yet. The carb is a rebuid from Bap-Geon-and did fine last 2 inspections right on the numbers.
I only drive it appox 2k a year.....
any help would be great..

01-28-2007, 02:44 PM
I have to deal with emissions also I an also did the rubbing alcohol trick. THe problem is the rubbing alcohol gumms up all sorts of crap. Something to do with the alcohol mixing with gas and air in the carb causus it to gum up badly. I rebuilt mine for emissions failed, tuned up, failed and then ran 2 gallons with a bottle of rubbing alcohol and passed. On the way home my carb stalled like you describe and I pulled the carb apart just to rebuild it again. Drain the tank mostly and alcohol it up and pass. Then rebuild.

01-28-2007, 02:49 PM
Do you have the carb vent tube installed? If you dont know what this is, it is a aftermarket mod that is installed in the carb, I dont know if it will help your emmision numbers, but it is designed to stop the hesitation. (not really an aftermarket mod but after manufactor design change)

Here is a write up on the mod.

How is your cat converter? Does your engine run hot? Have you checked for any vacuum leaks? Run some Sea Foam through your tank and then change your fuel filter after it is all gone.

Welcome to the site!!

01-28-2007, 02:55 PM
You can get the vent tube from http://www.petroworks.com/ Click the link and go to the engine section.

01-28-2007, 08:07 PM
good advice guys,sorry to take so long ot respond,,,, my fuel pump on my Zr2 s-10 died and had to change it out---3 bills later...Ouch
yA KNOW back to the carb..... i'm not for sure wheter has a vent tube in it or not....Hummmm got to check..but would that cause the CO2 on the emission to take a DUMP,rather a Spike like that, i mean since last year i've driven her,appox 2k and last years emissions it hit the numbers right on the nose and i didn't even jack with the alcohol...
It doesn't run hot, the plugs were pristine when i changed them out and i had the cat checked last year it wasn't bad...would a bad cat make the CO2 spike ??
I've rebuilt holleydouble pumper and rochester quadra jet carbs before-how hard is the sammy carb?

01-28-2007, 08:56 PM
Sammy carbs are easy. I learned to rebuild on them. Just make sure you know exactly how the springs on the side go. Pull your o2 sensor and clean it with a dry rag. This will get the surface crap off and might unlodge the other crap in it. Never hurts to pull and clean.

01-29-2007, 08:49 AM
thanks,i;ll give it a shot!