Computer controlled carb.

[SFord]

I bought this quadrajet off of ebay(Computer Controled Rochester Quadrajet M4ME 4 BRL. # 17085210 / 1895 / HKP ).Is there any way I can use this on a 1984 k 20 non computer engine?

[frogman68]

Not sure but from the numbers it came from a 85 Chevy with a automatic

[JJSZABO]

Does it look like this?



If so, the carb is a dual capacity pump.  The electronic connection is for the pump solenoid.  This is a NON-COMPUTER controlled carburetor.  When the engine is cold, more fuel is needed for transition from idle to part throttle.  When engine warms up. less fuel is required.  Dual capacity pump solenoid is activated by collant temperature sensor.  At 170 F pump solenoid energizes dual capacity pump valve opens and pump capacity reduces by about half.

See:


It will work, but I do not know how to wire it in.

[SFord]

Yes sir thats the one. Would be nice to know how to wire it so it would work. Anybody got any ideas? Truck is a 1984 k 20 4x4 350/400.

[VileZambonie]

The M4M series (M4MC, M4ME, M4MED and M4MEF) Quadrajet carburetor, Figs. 2 through 5, is a four barrel, two stage unit consisting of three major assemblies: The air horn, float bowl and throttle body.
A single float chamber supplies the fuel to the four carburetor bores. A float, float needle and float seat are used to control the fuel level within the float chamber. A vacuum operated power piston and metering rods control the air/fuel metering in the primary throttle bores. The tapered metering rods are attached to the power valve piston assembly, moving in fixed metering jets to provide the various fuel flow requirements of the engine. A factory adjusted part throttle screw is used on all models to properly position the metering rods in the metering jets. The M4MEF model, in addition to the part throttle screw mentioned previously, also contains a rich stop adjusting bushing to position the enrichment portion of the metering rods in the jets. This bushing enables an adjustable wide open throttle mixture control capability. During wide open throttle operation, the air/fuel mixture in the secondary bores is controlled by air valves and tapered metering rods operating in fixed jets. On M4MEF models, the factory adjusted secondary well air bleed adjusting screw provides additional control of the air/fuel mixture during wide open throttle modes.
The accelerator pump system on all models uses a conventional throttle actuated pump plunger operating in a pump well, to provide additional fuel as needed. In addition, M4MED models are equipped with float bowl mounted dual capacity pump valve and solenoid assemblies. These assemblies provide a smoother transition from idle to part throttle operation during cold engine driving modes.
All carburetors use either electrically or hot air heated choke coils. The heated coils provide choke valve closing force for cold starts, as well as correct opening timing during warm-up. Vacuum break assemblies control initial choke valve opening during starting and warm-up periods.
Curb idle speeds are controlled, depending on engine and application, by either an idle speed adjusting screw or an idle speed solenoid. On vehicles without air conditioning, the idle speed solenoid provides desired idle speed, while preventing dieseling when the ignition switch is turned off. On vehicles with air conditioning, the solenoid maintains smooth idle during compressor clutch engagement. Vehicles without an idle speed solenoid are equipped with a throttle kicker assembly. The vacuum operated throttle kicker holds the throttle open during deceleration, thereby reducing exhaust emissions. On some engines, it is also used to increase idle speed depending on accessory load.


On E4MED models, a dual capacity pump valve and combined mixture control/dual capacity pump solenoid assembly is used. These assemblies provide a smoother transition from idle to part throttle operation during cold engine operation.
An idle speed solenoid or a throttle kicker assembly, depending on engine and application, is used to control curb idle speed. The throttle kicker is vacuum operated and controlled by the electronic control module. It maintains primary throttle position during deceleration, above a specified RPM. The idle speed solenoid, used primarily on air conditioned vehicles, maintains correct curb idle speed whenever the compressor clutch is engaged.
All carburetors use electrically heated choke coils. The heated coils provide choke valve closing force for cold starts, as well as correct opening timing during warm-up. Vacuum break assemblies control initial choke valve opening during starting and warm-up periods.

[SFord]

So does that mean im screwed ? I preciate what you wrote vile,but I still confused.

[JJSZABO]

If you use that carburetor, you need to wire in the pump solenoid.  If not then too much fuel is dumped into the carburetor causing a rich condition and wasting fuel.  Ask me how I know?   It will run that way but use way too much fuel.

I couldn't figure out how to wire mine sooo.... I just scrapped it for an earlier 4 bbl Q-jet M4ME model that does not use a dual capacity pump.  I bought it from National Carburetor (http://www.nationalcarburetors.com/).  It came with a lifetime warrenty and the price was reasonable 230.00 dollars.

Works for me.

I know someone on here should be able to tell/show/explain how you can wire it in.  Good luck.

[VileZambonie]

It's not worth it in my opnion. Just get a different carb

[SFord]

Thanks for the input Jeff.Probrobly gonna get an older model q jet ,unless someone knows how to wire in that pump solenoid. Anyone Know

[VileZambonie]

What is the carburetor originally off of?

[SFord]

   This carburetor came off a 1985 Chevy / Gmc  P/U  V8 5.0L & 5.7L auto. trans. I thought it would work since the desription said non comp. controlled,but I didnt know about the pump solenoid that requires a plug(electrical) to work.

[SFord]

I have just found out that the pump solenoid on this carb is mainly used on blazers or 4x4 trucks that see wheeling action, such as going up inclines and such. The incline will cause the pump solenoid to open and allow one percent more fuel into the carb so it wont stall. It wont have any effect on my truck,except that when im on an incline it wont give me the extra one percent. But now I know that thats not my problem anyway. So I can keep the carb.

[VileZambonie]

Click here

[JJSZABO]

But where does #39 PNK/BLK goto on the engine harness?

I hate reading wiring diagrams

Looks like it goes to the ENG CHK LP 

This is why I installed a new rebuilt one that uses no electronic controls except the electric choke.

Thanks Vile, I couldn't get my electrical diagram to come up and be ledgible.

[VileZambonie]

I have the entire schematic for you. What is your email address and I'll send it to you in a .pdf