Cutting out at 1800 RPM

[TBO CRUISER]

So I have been slowly replacing parts on the emissions and fuel delivery side in the hopes of getting my 2F to run better (smoother acceleration and deceleration). I had the motor rebuilt approximately 15k ago. Recently I replaced the original carb with a rebuilt unit from cruiserparts.net as well as the vacuum switch that operated the FCS and I replaced the EGR modulator. The truck still stumbles when accelerating through 1600-1800 rpm under acceleration and as many others have experienced not with regularity sometimes its bad sometimes non existant. The plugs/wires/cap are fresh and the timing is set to 7 degrees.

Something else I have discovered when just sitting in neutral and slowly rev the motor through 1600-1800 rpm the motor cuts out and falls back to 1000-1200 rpm before catching itself and climbing back to 1800 rpm. With the choke in the morning I can reproduce this same scenario. The rpm's build to 1800, fall back to 1200 or so and then start climbing again.

Any help on this matter is greatly appreciated.

Sorry for the long post.

[NocalFJ60]

Unhook the power to the VSV for the EGR valve so it can't open the EGR valve. Drive around like that and see if the problem goes away. Also if you have the smog FSM go through the test for the EGR system. Double check the hoses on the side of the carb by the valve cover all go to the right places.

[TBO CRUISER]

Thanks, I will give that a shot.

[hank14]

I would second Kevin's suggestion- EGR valve issues- could be the emisisons "computer", VSVs, EGR modulator, or EGR valve itself. I removed and cleaned my EGR valve and my 60 has been running much better since then.

Good luck.

[TyWebb]

I experienced what sounds like the exact same problem, it turned out to be a bad emissions computer. Have you tried bypassing the fuel cut solenoid? This was a temporary fix for me until I bought a new computer, which are cheap and might be worth a shot at replacing (it's located behind the drivers side kick panel). My exact problem occurred under light acceleration through that rpm band.

Hope this helps.

[Kavik]

Originally Posted by TyWebb

I experienced what sounds like the exact same problem, it turned out to be a bad emissions computer. Have you tried bypassing the fuel cut solenoid? This was a temporary fix for me until I bought a new computer, which are cheap and might be worth a shot at replacing (it's located behind the drivers side kick panel). My exact problem occurred under light acceleration through that rpm band.

Hope this helps.

x2

Fuel Cut solenoid, vacuum switch circuit, emissions computer

Search for "green wire mod"

[TBO CRUISER]

Thanks everyone. I will try both the emissions computer/ FCS fixes and then the EGR.

I always appreciate the help I get/find on this site.