B2000 '86 Breathing Issues / Power Loss

[B2000run]

I read similar to my issues from a post from 2006, titled “Instant Complete loss of power b2000 86”. My 1986 B2000 has a 6 month old rebuilt NIKKI carb on it (the carb runs great). The issue I am about to write about, was present before the rebuilt carb, and this situation is still present now…. Situation has nothing to do with the carb! About 4 months ago, the vehicle started to exhibit a “buzzzzing” on deceleration and also acceleration from about 2500 or more RPMS – it almost feels like there is some sort of back pressure?…. But I will address this symptom below. It seems it is not ‘breathing’ properly.

I brought it to a muffler shop last week, and the guy spent a lot of time test driving, and his hunch was the REED Valve in the air cleaner nozzle was bad. So then, I inspected this “reed valve in the air cleaner nozzle”, and it’s position doesn't change one bit (visually) when the vehicle is stone cold, or at operating temperature.. it is stuck at about a 60% angle (from horizontal). Further to note, I yanked the exhaust gas flex line from exhaust manifold shroud, to the air cleaner nozzle, (I did this years ago), so this air cleaner nozzle reed valve has served absolutely no purpose whatsoever, for “heating” air to the carb.

Have tried to read as much as possible (limited web info) on the quantity 3 EGR REED Valves that are positioned in the front of the air cleaner (connected to those metal tubes to the exhaust manifold). I really don’t understand how one is to “inspect” these reed valves to ensure they are working or not? I can tell you, that once I remove the air cleaner cover, this “buzzing” at RPM goes completely away, and the engine seems like it instantly picked up 20 horses under the hood.

I can pay a muffler shop $50 to 100 bucks to check the pre-cat (there are 3 cats, one at Rear, Mid and Pre-Cat at exhaust manifold). This would rule out the issue of back pressure from the CATs. Further, I have already proven that by removing the air cleaner the “buzzing” and the “lose of power” goes completely away. This tells me the REED Valves (front of air cleaner), or the reed valve in the air cleaner, or the CAT(s) are plugged.

Don’t really feel like throwing a ton of money at it, and would like to determine just what specific component is bad, and ONLY replace it!!!

TO SUMMARIZE: It is either: #1 CAT issue, (as the CAT(s) are 28 years old), #2) the 3 reed valves at EGR tubes that connect to the air cleaner housing, or #3) the reed valve in the air cleaner nozzle is bad.

I have now mentioned what I found to temporarily “fix it” (i.e. remove the air cleaner cover and it runs fantastic) but that is obviously just getting the engine more air, so I need to know How To Determine what component is screwed-up and just replace it?

Your input is greatly appreciated.

[B2000run]

An update:

It was the reed valves in air cleaner assembly. Quarantined that shitty EGR Reed Valve Assembly in air cleaner and the mileage, in this case, went from 19.75 to 23.5 MPG.

Also, for you B2000 /B2200 owners with the stock NIKKI carbs... if you start to notice vibration in the gas pedal, this is the result of improper vibration in the air cleaner (it will sound "tinny"), as the reed valves are faulty and the exhaust is vibrating against/within the reed valves. You will also notice a significant loss in mileage. It is most noticeable at > 2500RPM.

I'm not going into detail on what my fix was for the carb set-up, but I did retain the Nikki carb as it was recently rebuilt. There is a lot of whop-la (bragging) out there how "great" Weber carbs are, but my rebuilt stock carb gives 23.5 MPG in town, the auto choke works excellent and plenty of power for an old P.O.S. truck that most people would have retired 15 yrs ago.

Hope this helps someone else that is a cheap-ass like me, that refuses to retire their mid 80's B2000/B2200.

ISSUE Solved.

[Pootz22]

thanks for doing the update and congrats on finding your issue. I was the guy with the instant complete loss of power and I am a cheap guy like you. Having a pickup that has low cost (taxes/insurance) and provides benefits as a hauler is great.