Now that is interesting. That is why I love this site; you never know what you are going to learn next!

The Ford F-Series trucks went through quite a bit of changes from 1980 - 1986. Probably more so than any other generation. 1980 started out with a regular carburetor and Duraspark II ignition, then Ford got into electronic engine control in the form of Duraspark III and feedback carburetors and then EEC-IV, and finally ending with electronic fuel injection.

By the way, how many miles are on your truck, 81-F-150-Explorer? And doesn't your truck have the Duraspark II and electronic engine control with a feedback carburetor or something like that?

That's a good book to have, Galendor, especially that Ford manual. If you plan to keep your system, I would definitely get that book along with a code reader, because it is going to be difficult to find a mechanic to know what they are doing.

 

Ain't that the truth. My local Ford dealership has a full service department. I once called them to ask about getting a tune up. The head mechanic there told me to go elsewhere, saying "none of his mechanics would even know how to work on a truck that old". Not very impressive product support from Ford! So I've done it all myself and learned a lot in the process: new spark plugs and wires, coil, distributor cap, rotor, PCV, air and fuel filters, crankcase breather, new cooling hoses, O2 sensor, belts, thermostat, battery, brake fluid, all new oils including transmission and real differential, grease fittings, etc. Next I need a new exhaust because mine is a cheapy Midas and has a leak somewhere. My current exhaust appears to have 2 (!) inline catalytic converters and a metal air pipe leads from the first one up to the air pump. Then I want new front coil springs and new tires.

 

My truck has 600,000 aprox miles on it right now.

That's with 3 carb rebuild kits, and one feedback solenoid replacement in 30 years. All the sensors, solenoids have been replaced once in that time.

My truck has a MCU (Microcomputer control Unit) Duraspark-II system. It was the first diagnostic engine management systems. The MCU controls fuel mixture and ratios, the thermactor system, the evaporative emissions system with a canister purge solenoid, and timing with a spark retard EGR solenoid.

The MCU also uses various vacumm switches that sense, Wide open throttle, Closed throttle, cruise and engine temps.

 

This is quite normal on the early 80's vehices.

The first one is a secondary Catalytic converter, and the second one down stream is the primary one.

These two seperate converters on your truck are now sold as one universal unit in the aftermarket sector.

 

I think that takes the cake, 81-F-150-Explorer. 600,000 miles? Does ANYONE in ANY of the forums on this entire site have a vehicle that can beat that?

From your figures, that equals to about one rebuild kit every 200,000 miles, (do you have any tips to keeping your carburetor running that long?) and all the sensors have lasted on average of 300,000 miles, and all that over the course of 30 years of constant service and temperature changes! Is modern electronic fuel injection any more "reliable" than that?

My own truck had about 120K miles on it before it was hacked up (the previous owner hacked it up at that time when the carburetor just needed to be rebuilt).

scalladaballa's truck has 230k miles

Galendor's truck has 94K miles

and 81-F-150-Explorer has 600,000 miles on his truck!

And all of these vehicles are using the "unreliable" and "inferior" feedback carburetor system that even produced better fuel mileage than the early EFI systems. I realize that is only four examples, but that sample is from a small number of people on this site that is still using a feedback carbureted system. I think that rules out that the feedback carburetor probably didn't lose to electronic fuel injection because of reliability or efficiency issues.

 

Efficiency, adaptability, and complexity.

Despite the fact that many people whine about fuel injection systems being some form of sorcery, they're a lot easier to understand than carburetion, and a hell of a lot easier to tune. Yes, you have to buy special computer tools, but you can retune just about everything from the driver's seat.

 

600,000 miles!!! Wow. 81-F-150-Explorer, you should probably go out to the driveway, pop the hood, and let your carb know it is inferior. Apparently it never got the memo...

 

IMHO you're not tooting your own horn enough...

...you haven't' mentioned anywhere here your truck is a California native with California
emissions; THAT impresses me most!

Of course, I'm sure the Motorcraft Windshield Wiper Fluid helped there.

 

Despite the fact that many people whine about carburetors being some form of archaic form of sorcery, they're a lot easier to understand than fuel injection systems because they have a lot less parts, they are simpler and cheaper, and a hell of a lot easier to tune because all you need are basic hand tools.

Did you not learn anything in this thread? The feedback carburetor system has an engine computer and uses the same computer tools as electronic fuel injection systems!

 

I think the point made was that you can tune the EFI within the drivers seat with a computer tuner (reprogrammer) to change spray length, timing curves, etc.

To my knowledge this can not be done on the feedback carb. To change mixture...this is done by screws. There is no tuning of the timing curve because there are no tools able to do it. There are a few for the Mustang EEC-IV systems...but can't be used...at least for me in my setup.

LARIAT 85, you do bring up a good point that Feedback carbs have greater reliability than traditional...and at the time of EFI introduction still got better mpg's...

Feedback carbs are reliable and long lasting...I love mine...I know that.

But EFI is a better air/fuel mixture device. Carbs just do not compete in this arena. Even with the feedback solenoid. For the feedback carbs still rely on the venturi assembly to atomize...EFI relies on high pressure and nozzles to atomize the mixture.

IMHO, of course.

 

Like EFI, the feedback carburetor system uses engine information sensors to supply data to an engine computer to manipulate the air/fuel mixture close to the stoichiometric ratio of 14.7:1.

The heart of the feedback carburetor systems was the EEC-IV engine management computer, the same engine computer that was later used for electronic fuel injection. If both systems were controlled by the same computer to produce the same air/fuel mixture ratio from reading the same O2 sensor, wouldn't both fuel delivery methods produce the same results?

The only thing left to answer is this:
Did EFI had produce less emissions than feedback carburetors in 1985?

If so, I will go along with the fact that EFI is a better air/fuel mixture device from an emissions point of view.

 

Let's see...

EFI has:
O2 sensor
4-8 fuel injectors
throttle body
MAF or MAP sensor (or both)
IAT sensor
TPS sensor
IAC motor
Fuel pressure regulator

Carb has:
Choke
Throttle body
air horn
primary jets
secondary jets
float
accelerator pump
vacuum advance
advance weights and springs
Fast idle cam
A/C idle solenoid
(and can have: secondary throttle linkage, vacuum diaphragm for secondaries)

To tune EFI, you need:
Cable adapter,
laptop computer
possibly chips depending on the ECM.

To tune a carb, you need:
Screw driver
mixture screw driver
Jets
power pistons
vacuum pump/gauge
distributor machine
advance weights
advance springs

The feedback carb is actually the WORST of the two as far as maintenance is concerned, because you need to go at it with basic hand tools AND a voltmeter. None of the "simplicity" of a carburetor, and none of the simplicity of a fuel injection system.

 

They have may used the same base computer...but both systems were, in fact, two different systems. They may share some of the same connectors and some sensors...but that's pretty much it.

There are more sensors on an EFI setup. More sensors, more measuring devices...more measuring devices.

To answer the logical answer to the results of both fuel delivery methods are not going to be the same. If one system uses a fuel spray nozzle and one relies on venturi vacuum, they will NOT produce the same results. They are, in fact, two different systems with TWO different results. Going back to the fact that MPG's were lower in the 1985 EFI versions.

To measure the emissions as a basis for better/worse air/fuel mixture is not an accurate measuring tool. We can get better performance by not having emissions equipment, but that wouldn't be very green...oh darn.

 

According to the EPA website, fuel economy and emissions were BOTH worse for 1985 302s with carb vs EFI. However, it doesn't tell me which carburetor that was.

Which engines had an EFI and feed back carb variant?

 

Although both computers are EEC-IV, you are correct on the engine computers being different because of the extra sensors on the EFI version, scalladaballa.

OK, I can go along with the fact that they will not produce *exactly* the same results. That is evident with the fact that feedback carburetors got better fuel mileage, and I am assuming that EFI got better emissions? Can anyone verify this?

Does that also mean that, by design, WITHOUT AN ENGINE COMPUTER IN THE MIX, a mechanical fuel injection system would be a more accurate device for metering air and fuel than a mechanical carbureted system?