Air/fuel solenoid........?

[JDPascal]

87 B2200 manual transmission.

At about 15 mph in 1st gear 25 mph in 2nd gear, 40 mph in third and 55-65 mph in 4th and 5th gears produces a surging or bucking sensation when holding a constant speed.

Cant attribute this to bd cause the clutch isn't being used.

I am looking for ideas as to the cause. Plugs, wires, cap and rotor have all been replaced. Timing is set correctly.

My reading on the subject has shown that there is a air/fuel solenoid somewhere but all the diagrams that I've found do not identify it.

Could some one identify it on the picture below for me. I've lettered some of the possibilities but it might be something else.

Thanks




JD

[90944S2]

A = Coasting enricher solenoid valve
B = Bowl vent solenoid valve
C = Idle shutoff solenoid valve

Mixture solenoid is inside the carb beside C that you can see the wire coming out on top.

[JDPascal]

Thanks 90944S2. Just got back from a camping trip late last nite

I take it that you have to remove the capb top to get at it.

Is there any common failure with this part that would contribute to the surging/bucking that we are experiencing.

The solinoid appears good electrically 33ohms and 3.2 amp draw so it would be a control problem or a mechanical problem with sealing/metering of fuel???

Any help here would be appreciated.

thanks guys

JD

[Foodgod1]

Good Lord, I've seen this posted about 6 times on this site and I have yet to see an adequate answer for the problem. I have seen "surging/hesitation", "bucking and surging", etc. I even posted one myself because my 88 B2200 does the same thing. You'll pardon my frustration, but the so called experts have yet to help. Lets see, I've changed the O2 sensor, MAP, Tune up, fuel filter, EGR, the carb was replaced 40,000 miles ago, yet it still bucks on acceleration at the same point in each gear. You can hold the pedal at almost the same spot each time and it will do it. you can punch through it by giving it more gas. All the bucking has now worn out the rear U joint which can't be replaced so now I have to get a half shaft at the salvage yard. Man talk about frustrating. If you find the answer, PLEASE LET THE REST OF KNOW

[scooter493950]

Originally Posted by JDPascal

87 B2200 manual transmission.

At about 15 mph in 1st gear 25 mph in 2nd gear, 40 mph in third and 55-65 mph in 4th and 5th gears produces a surging or bucking sensation when holding a constant speed.

Cant attribute this to bd cause the clutch isn't being used.

I am looking for ideas as to the cause. Plugs, wires, cap and rotor have all been replaced. Timing is set correctly.

My reading on the subject has shown that there is a air/fuel solenoid somewhere but all the diagrams that I've found do not identify it.

Could some one identify it on the picture below for me. I've lettered some of the possibilities but it might be something else.

Thanks




JD

Jd i have an 87 b2200 doing the same, does yours kinda bog out like its not getting fuel. i changed the pressure switch on the fender,and the 02 sensor,and it help some.I think i am going to build the carb just to see if the accel. pump or bore may be bad.

[Foodgod1]

The a/f solenoid is built into the carb. The is a pin that can be knocked out on the passanger side that gives access to 2 adjustment screws is what I am hearing. It shows it in the hanynes manual. Having said that. You'll also have to check voltage at the O2 rec for proper voltage to make sure the carb is adjusting right for that too. I am going on my 2nd carb for my b2200. This one only has 40000 miles on it. The A/F solenoind is bad and I don't think there is a way to fix them. Aftermarket carb is 300 bucks. Getting kinda tired of this.......

Rick