1985 2.8 Carb Adjustments

[RonD]

Check the overflow vent, you WILL have gasoline in it if there is a problem, or unhook the hose and watch for gasoline when idling, COLD engine, lol, no reason to start a fire

No, no way to adjust float "wet" on this model carb

 

[ford4wd08]

I'm going to try and play with the choke a little more this weekend. It seems to be running a little rich tonight when I tried to start it in 40 degree rain.

I'm not sure I had the vacuum pull off set correctly until now. Just trial and error!

 

[RonD]

Carb tuning is by definition trial and error
Each carb/engine will be slightly different, and I am talking same models here
So you pick a starting point, mark it and then adjust up or down from there

Which is why I like EFI, spent my youth under hoods adjusting fuel and spark, except for few occasions I can't say I liked it all that much, lol.

 

[Uncle Gump]

I'm with you RonD... but if you would good at what you did... there was never a lack of work.

 

[ford4wd08]

I don't mind tinkering as long as I learn something.

It is definitely a test of patience, and it's not like I can find anyone around me I can talk to about it. Lol no one knows carbs! So I turn to the internet for help.

 

[ford4wd08]

So I did some more tinkering with it this weekend. I actually found it easier to mess with the fast idle adjustments while it was running.... seemed to work.

I was able to start it and leave it and let it run to get to operating temp. I didn't think the choke was opening fully, but I'm happy to report that after letting it get good and warm I pulled the air cleaner off to find what is seen in the picture.

I did discover I don't have two steps on my cam. Just one which is the V. But it seems to be idling well. And didn't die or smother out.

I'll just leave it be for now.

 

[ford4wd08]

It's like I take one step forward, then two steps back!

I went out to try and start it tonight after sitting all day, with lows near 30 degrees last night, the current temp is 43 degrees.

Press the accelerator once to close the choke and one more pump for good measure. Start cranking it, it will not start! Won't fire for crap. I'm assuming it is too rich. Let it sit for an hour and don't touch anything. Crank it and it fires off immediately, runs and stumbles for about 10 to 15 seconds then dies and I cannot get it to start again. I play with the accelerator some and it won't do it. Crank and crank and crank and it won't start.

How can it go from working one day to not at all the next?

Can you not get a flooded engine to start by cranking with the accelerator to the floor?

I'm not convinced I have the fast idle set correctly either.

@RonD and @Uncle Gump any advice?

I did remove the bowl vent and no gas came out during cranking.

 

[Uncle Gump]

Well it seems it didn't like the second squirt from the accelerator.

Lets make sure of something before we go any further.

Cold engine... one pump of the pedal. The choke plate should snap closed. And the fast idle speed screw should be lined up with the arrow like in your illustration. Once it starts... you would adjust the fast idle speed screw to achieve your fast idle speed.

Crank engine... as soon as the engine makes vacuum... the choke pull off should pull the choke plate open. The amount of pulling open action is adjustable. Your spec sheet should have a choke plate angle spec... maybe using a drill bit... maybe checked with an angle finder. Use a vacuum pump (without engine running) and pull vacuum on the pull off valve. If you can't measure it... I will say set it to 25 to 30 percent open from full closed. Sometimes there is a screw to do this... other times you bend the linkage to achieve desired opening.

It really sounds like it floods easily. When it started... run rough... then quit... sounds flooded again.

There is no clear flood made... lol. But holding accelerator to the floor should help to clear a flooded condition. Try opening the choke plate full open by hand and try to start it (I use to block it open with a screw driver). Just seems to me the pull off isn't opening the plate to allow it to run.

 

[RonD]

You can't light gasoline with a spark........................movie guys take liberties with that one

You can only light gasoline VAPOR with a spark
And you need 30% vapor in a cylinder to get it to fire

At 80deg you can smell gasoline, that's the vapor you are smelling
At 30deg................well hard to smell it, so very very little vapor

This is WHY we need to Choke a cold gasoline engine
The choke plate restricts the air flow but engine cranking still pulls in the same amount of "air", so with restricted air it sucks in MORE cold, low vapor, gasoline
The hope is by adding more COLD gasoline you will get at least 30% vapor level in the cylinders, and not WET foul the spark plugs, lol
Ether is a good Cold start fluid because it has a lower vapor point, so spark plug can ignite it at colder temps

The key is heating up the cold gasoline
What you can try, besides starting fluid, is to NOT set the choke right away
Crank the engine over a few times, compression = HEAT, so cranking heats up the cylinders and the spark plugs
Then press gas pedal down one time, setting choke
And then crank again to start, the warmer cylinder will vaporize/heat up the gasoline as it comes in

Also try a wider gap on your spark plugs, this was common thing to do in winter months, reset the choke and regap the spark plugs every winter and summer

Boy I love fuel injection, lol

 

[ford4wd08]

Well it seems it didn't like the second squirt from the accelerator.

Lets make sure of something before we go any further.

Cold engine... one pump of the pedal. The choke plate should snap closed. And the fast idle speed screw should be lined up with the arrow like in your illustration. Once it starts... you would adjust the fast idle speed screw to achieve your fast idle speed.

Crank engine... as soon as the engine makes vacuum... the choke pull off should pull the choke plate open. The amount of pulling open action is adjustable. Your spec sheet should have a choke plate angle spec... maybe using a drill bit... maybe checked with an angle finder. Use a vacuum pump (without engine running) and pull vacuum on the pull off valve. If you can't measure it... I will say set it to 25 to 30 percent open from full closed. Sometimes there is a screw to do this... other times you bend the linkage to achieve desired opening.

It really sounds like it floods easily. When it started... run rough... then quit... sounds flooded again.

There is no clear flood made... lol. But holding accelerator to the floor should help to clear a flooded condition. Try opening the choke plate full open by hand and try to start it (I use to block it open with a screw driver). Just seems to me the pull off isn't opening the plate to allow it to run.

You can't light gasoline with a spark........................movie guys take liberties with that one

You can only light gasoline VAPOR with a spark
And you need 30% vapor in a cylinder to get it to fire

At 80deg you can smell gasoline, that's the vapor you are smelling
At 30deg................well hard to smell it, so very very little vapor

This is WHY we need to Choke a cold gasoline engine
The choke plate restricts the air flow but engine cranking still pulls in the same amount of "air", so with restricted air it sucks in MORE cold, low vapor, gasoline
The hope is by adding more COLD gasoline you will get at least 30% vapor level in the cylinders, and not WET foul the spark plugs, lol
Ether is a good Cold start fluid because it has a lower vapor point, so spark plug can ignite it at colder temps

The key is heating up the cold gasoline
What you can try, besides starting fluid, is to NOT set the choke right away
Crank the engine over a few times, compression = HEAT, so cranking heats up the cylinders and the spark plugs
Then press gas pedal down one time, setting choke
And then crank again to start, the warmer cylinder will vaporize/heat up the gasoline as it comes in

Also try a wider gap on your spark plugs, this was common thing to do in winter months, reset the choke and regap the spark plugs every winter and summer

Boy I love fuel injection, lol

Thank you both for the help! I understand the basics of the choke and what it does, I am just trying to figure out a couple of things.

First, this might be a starting procedure error or operator error lol -- next time I try to start it, tonight after work (wife doesn't understand why I have to go out to the driveway after dark when it is cold, best time to play with a choke!) I am going to crank it prior to touching the accelerator. I believe the choke will still be close because it hasn't ran since the last time I reset it. Well will see where that gets me.

As to the vacuum pull off, it has a screw to adjust, I used my own "vacuum" to pull on it and adjusted it to the what the specs and manual posted in the tech section said -- 1/8" inch. I used a drill bit to set this. I might go a little larger than this to see if it helps.

What I am really having trouble with is the fast idle adjustment. It doesn't make sense in my mind for some reason. @Uncle Gump when you say that fast idle speed screw should be lined up when the choke is closed mine isn't. In my mind I picture it as when the engine is cold, when the accelerator is press, the choke goes to fully closed. As it warms up it the choke thermostat moves the cam and the fast idle screw drops at the mark so won't go all the way back until the thermostat is cold again and the accelerator is pressed. I only have one step on my cam. Is that right? If the screw is supposed to be at the mark when the choke is closed, I don't have it set right.

Also, in my mind the only time to choke should be ever fully closed is while it is cold and during the first cranking, as soon as it begins to run, the manifold vacuum kicks in and open it via the pull off correct?

I also don't understand what the "dechoke" setting is in the table or the "choke cap setting" that says "3NR" for the 1985 model year. Since this was the last year for the feedback carb, I think they made some silly changes.

I also attached a picture of when I first got the BII home. I took a picture of the carb before I took it off for a rebuild. This is in June of 2019, so fairly warm outside. Just as a reference.

 

[ford4wd08]

Thinking and typing at the same time, is the V or mark where the fast idle is supposed to be as soon as the vacuum pull off hits when the engine is running? Instead of the thermostat gradually taking it there as it opens, it is supposed to be there as soon as the engine starts?

 

[Uncle Gump]

First of all... don't even worry about the choke cap setting. Turn the choke until it snaps closed cold with a push of the pedal. Set it to just close... no extra tension holding it closed.

Fast idle cam... item 4. It should have steps... as pictured above... speed screw aligns with the V. This should happen when the choke closes. No key on... no crank... no vacuum. It should be there with a push of the pedal. If not... adjust screw 5 to get it there.

So using your personal vacuum pump... pull the pull off open. Double check it's with in specs (drill bit) and adjust as necessary. No key on... no crank.

Start the engine... with engine vacuum supply connected. Engine fires... pull off opens the choke plate to spec... adjust fast idle speed screw (4) to desired fast idle speed... 1300 to 1500 rpm's.

 

[Uncle Gump]

Thinking and typing at the same time, is the V or mark where the fast idle is supposed to be as soon as the vacuum pull off hits when the engine is running? Instead of the thermostat gradually taking it there as it opens, it is supposed to be there as soon as the engine starts?

See the above... the V and screw should align when the choke snaps closed. The pull off shouldn't change this.

 

[Uncle Gump]

I also don't understand what the "dechoke" setting is in the table or the "choke cap setting" that says "3NR" for the 1985 model year.

I forgot to address this part....

Dechoke setting. I believe this is an adjustment so that you have an "unflood" option with an automatic choke. This should "open" the choke plate by holding the pedal wide open. So when pedal is wide open... cold engine... the choke plate should open to a spec listed in your instructions and adjusting it as specified.

 

[ford4wd08]

Thanks for the step by step @Uncle Gump I'll try to play with it more tonight.

I understand more of what you are saying now. It should never be positioned farther than the mark on the cam. That could be a lot of my issues.....

I believe I only have one step on the cam for the linkage. I'll try and take a picture tonight.

The tech library also states "V-notch" in 1984 and "Hi-cam" for 1985 -- what is the difference?