HBF comes out of retirement

[HBF84]

Well, while awaiting the EGR valve, I thought maybe I could tackle the carburetor. Well, it came apart well enough and maybe the accelerator pump diaphragm was torn. The rubber was worn and there was a little crack in it. There were four rubber grommets on the link pump lifter that pretty much disintegrated. Having put it all back together, it seems that the throttle plate doesn't close in the throttle bore and the accelerator and idle setting screws are too far away to reach the idle cam. It seems like the throttle sensor assembly causes this because I need to open up the throttle plate to bolt the throttle sensor assembly in.

1) Is this normal? When I install the carburetor and electricity to the throttle sensor assembly, will it adjust the throttle plate and in turn the accelerator/idle setting screws?

2) I am not sure I did the metering rod adjustment correctly, and perhaps that is causing the throttle plate and accelerator/idle screws to be askew? Should I open it back up and try readjusting the metering rod? Videos online didn't help too much but now that I have re-read the literature on the YFA carb on this site, it makes a little bit more sense on how to do it.

And, when setting the electric choke, I stripped one of the machine screws (all three holes had screws as opposed to two having rivets.)

So, in general, I am happy I tried to rebuild the carb but I'm not sure I was successful... Just curious if I should slap it on and see if it works or redo a few items first. Thoughts?

Ok, so I finally drove Happy Blue Ford and when it warmed up, the engine was racing at a very high idle when my foot wasn’t on the accelerator. I wrote Mike’s Carburetors and they figured the very high idle was due to the electronic feedback gizmo keeping the throttle plate open. I just removed the electronic feedback gizmo linkage and then dialed up the fuel idle mixture and then curb idle speed. And then, the test ride went smoothly!

Ok, so any ideas if I should try to reset the metering rod with the electronic feedback gizmo already attached or just leave the EFG off?!? Have folks had this kinda trouble before?!?

[Gary Lewis]

Ok, so I finally drove Happy Blue Ford and when it warmed up, the engine was racing at a very high idle when my foot wasn’t on the accelerator. I wrote Mike’s Carburetors and they figured the very high idle was due to the electronic feedback gizmo keeping the throttle plate open. I just removed the electronic feedback gizmo linkage and then dialed up the fuel idle mixture and then curb idle speed. And then, the test ride went smoothly!

Ok, so any ideas if I should try to reset the metering rod with the electronic feedback gizmo already attached or just leave the EFG off?!? Have folks had this kinda trouble before?!?

I've not played with a feedback carb so I don't know how to answer your question. But I'd bet Bill has so I'll tag him.

However, we have the factory shop manual section on that carb at Documentation/Fuel & Air Systems/Carburetors, Chokes, & EFI/Motorcraft 2150 and then the Instructions tab. But I've scanned that and don't see anything that jumps out at me except for the discussion on Page 4 re Idle Systems where it says:

For feedback/altitude carburetors, metered air thru duty cycle solenoid/altitude compensator, enters the idle circuit at the junction of the booster support and the main body. This air initially starts from the auxiliary air intake on the air horn, metered through the duty cycle solenoid/altitude compensator valves as the case may be, tracked by horizontal and vertical channels in the main body and finally through a mating channel at the bottom of the booster support.

So the duty cycle solenoid can certainly add air and that would speed up the idle. However, I don't know what to do about that.

Bill?

[ArdWrknTrk]

I've not played with a feedback carb so I don't know how to answer your question. But I'd bet Bill has so I'll tag him.

However, we have the factory shop manual section on that carb at Documentation/Fuel & Air Systems/Carburetors, Chokes, & EFI/Motorcraft 2150 and then the Instructions tab. But I've scanned that and don't see anything that jumps out at me except for the discussion on Page 4 re Idle Systems where it says:

For feedback/altitude carburetors, metered air thru duty cycle solenoid/altitude compensator, enters the idle circuit at the junction of the booster support and the main body. This air initially starts from the auxiliary air intake on the air horn, metered through the duty cycle solenoid/altitude compensator valves as the case may be, tracked by horizontal and vertical channels in the main body and finally through a mating channel at the bottom of the booster support.

So the duty cycle solenoid can certainly add air and that would speed up the idle. However, I don't know what to do about that.

Bill?

The instructions tab just gives me a sad, dog eared page icon, Gary.

Are you hosting this at home?

I was under the impression that the feedback carburetors solenoid had a duty cycle and it operated somewhat analogous to PWM, but I'm no expert on EEC-IV.

I wonder if it is stuck or it's just getting bad/no signal?

[Gary Lewis]

The instructions tab just gives me a sad, dog eared page icon, Gary.

Are you hosting this at home?

I was under the impression that the feedback carburetors solenoid had a duty cycle and it operated somewhat analogous to PWM, but I'm no expert on EEC-IV.

I wonder if it is stuck or it's just getting bad/no signal?

Sorry Jim, but it is hosted on the cloud - my OneDrive. And it loads nicely on my iphone as I tried it while out with Steve bringing his '97 E-Series van home.

But I agree with you that the impression I had was that the feedback carbs had a solenoid that was pulsed to provide the tuning. But I don't know how it works really and was hoping Bill could tell us. But he just got another year older today so I'm guessing that he's celebrating.

[81-F150-Explorer]

The instructions tab just gives me a sad, dog eared page icon, Gary.

Are you hosting this at home?

I was under the impression that the feedback carburetors solenoid had a duty cycle and it operated somewhat analogous to PWM, but I'm no expert on EEC-IV.

I wonder if it is stuck or it's just getting bad/no signal?

Those feedback solenoids should have an audible ticking noise as they operate. If it is not ticking, then it has problems.

The O2 sensor is also crucial and can effect the system, add more air via the feedback solenoid if they are plugged or contaminated etc...

[81-F150-Explorer]

Sorry Jim, but it is hosted on the cloud - my OneDrive. And it loads nicely on my iphone as I tried it while out with Steve bringing his '97 E-Series van home.

But I agree with you that the impression I had was that the feedback carbs had a solenoid that was pulsed to provide the tuning. But I don't know how it works really and was hoping Bill could tell us. But he just got another year older today so I'm guessing that he's celebrating.

The Feedback solenoid is pulsed, and how fast the pulses regulates how "open" or "closed" the solenoid is.

They can stick open, closed or somewhere in-between when they fail as well.

[85lebaront2]

I've not played with a feedback carb so I don't know how to answer your question. But I'd bet Bill has so I'll tag him.

However, we have the factory shop manual section on that carb at Documentation/Fuel & Air Systems/Carburetors, Chokes, & EFI/Motorcraft 2150 and then the Instructions tab. But I've scanned that and don't see anything that jumps out at me except for the discussion on Page 4 re Idle Systems where it says:

For feedback/altitude carburetors, metered air thru duty cycle solenoid/altitude compensator, enters the idle circuit at the junction of the booster support and the main body. This air initially starts from the auxiliary air intake on the air horn, metered through the duty cycle solenoid/altitude compensator valves as the case may be, tracked by horizontal and vertical channels in the main body and finally through a mating channel at the bottom of the booster support.

So the duty cycle solenoid can certainly add air and that would speed up the idle. However, I don't know what to do about that.

Bill?

The only picture I could find quickly is a bottom view, but it does have the two control items on it along with the TPS (throttle position sensor).

I do not have the 1984 manuals, so had to use my 1986 one for a reference.

The two control items are ISC (idle speed controller) and the mixture solenoid. On the left side is the TPS.

The ISC is a servo motor and also contains a closed throttle switch. The switch tells the computer when the throttle is closed at which time the idle speed control is activated. This can be seen and heard, seen in the fact that the plunger will move in or out to reach the desired idle rpm, heard as a whirring noise from the motor and gears inside. The mixture control is a duty cycle solenoid and as has been mentioned, will make a ticking noise and if you put a finger on it you can feel the vibration.

The wiring diagrams for this system are on pages 56 and 57 of the 1986 EVTM.

I just went back and read your description of the carburetor internal condition. The pump diaphragm in these is a dual function part, the top side is the accelerator pump, bottom side is the power enrichment control for the metering rod. A hole in it and raw gas is being drawn into your intake manifold constantly.

One of the issues with this system, is the lack of a malfunction indicator light. The test connector can be used, but requires a proper scan tool, that parts stores do not have. Running pig rich may have loaded up your O2 sensor to where it isn't reading the mixture. This puts the sytsem into "limp" mode.

[81-F150-Explorer]

The only picture I could find quickly is a bottom view, but it does have the two control items on it along with the TPS (throttle position sensor).

I do not have the 1984 manuals, so had to use my 1986 one for a reference.

The two control items are ISC (idle speed controller) and the mixture solenoid. On the left side is the TPS.

The ISC is a servo motor and also contains a closed throttle switch. The switch tells the computer when the throttle is closed at which time the idle speed control is activated. This can be seen and heard, seen in the fact that the plunger will move in or out to reach the desired idle rpm, heard as a whirring noise from the motor and gears inside. The mixture control is a duty cycle solenoid and as has been mentioned, will make a ticking noise and if you put a finger on it you can feel the vibration.

The wiring diagrams for this system are on pages 56 and 57 of the 1986 EVTM.

I just went back and read your description of the carburetor internal condition. The pump diaphragm in these is a dual function part, the top side is the accelerator pump, bottom side is the power enrichment control for the metering rod. A hole in it and raw gas is being drawn into your intake manifold constantly.

One of the issues with this system, is the lack of a malfunction indicator light. The test connector can be used, but requires a proper scan tool, that parts stores do not have. Running pig rich may have loaded up your O2 sensor to where it isn't reading the mixture. This puts the sytsem into "limp" mode.

Mixture Solenoid = Feedback Solenoid.

.... Running pig rich may have loaded up your O2 sensor to where it isn't reading the mixture. This puts the system into "limp" mode.

Or worse, fool the system into thinking the truck is running lean, therefore pouring the fuel into it more. Or vise/versa think it's running rich leaning out the system too much.

Reading the codes would be helpful.

[HBF84]

Mixture Solenoid = Feedback Solenoid.

.... Running pig rich may have loaded up your O2 sensor to where it isn't reading the mixture. This puts the system into "limp" mode.

Or worse, fool the system into thinking the truck is running lean, therefore pouring the fuel into it more. Or vise/versa think it's running rich leaning out the system too much.

Reading the codes would be helpful.

Thank you!!!

Ok, so as I was rebuilding the carburetor and adjusting the metering rod, the TPS was not attached. The throttle plate closed nicely with the throttle barrel. When I went to attach the TPS, I could not attach it without making an 1/8th inch gap in the throttle plate and throttle body.

When I drove it, it ran at a high idle. I removed the TPS, and it’s running fine.

Should the TPS have been attached when I adjusted the metering rod?!?

[85lebaront2]

Thank you!!!

Ok, so as I was rebuilding the carburetor and adjusting the metering rod, the TPS was not attached. The throttle plate closed nicely with the throttle barrel. When I went to attach the TPS, I could not attach it without making an 1/8th inch gap in the throttle plate and throttle body.

When I drove it, it ran at a high idle. I removed the TPS, and it’s running fine.

Should the TPS have been attached when I adjusted the metering rod?!?

If the TPS is holding the throttle open, then something is wrong, TPS, the drive tang on the shaft for it, assembled wrong, or even bent.