This is going to be a long one. But I want your problem to be fixed. Read up. .....
That is an AWESOME post! I have read many threads, articles, the 2100 2V Carb section of the shop manual (guessing, pdf), my Hayes book and the rebuild kit instructions. None of those sources are as clear and easy to follow as what you just took the time to explain. That post should be put in the "How To" section. Excellent.
I'm printing those instructions and will follow them to the letter this evening. Sounds like the most difficult part will be readjusting the float to the exact factory setting. I'm a little concerned about that part because you mention that it should be done once the engine is at operating temp and while running. That isn't possible. It will never stay running long enough to reach operating temp and it certainly won't idle long enough for me to perform some other task. All I know to do there is to adjust it close enough to the factory settings (very tiny adjustment anyway) that I can perform the rest of your instructions and then go back and make any fine final adjustments once it can idle on its own. The rebuild kit did not give a factory (wet) adjustment setting. It said refer to shop manual. I don't have one nor have a seen a suggested setting.
It's nice to know that there is hope in sight. I really didn't want to drop $400 on a new carb. By the way, how important is the throttle solenoid? You haven't mentioned it in any of your posts that I remember.
Glad to hear that info will be helpful to you. As for the wet-check, if you cannot run the engine long enough to get this to work, I would recommend removing and draining the carb, and setting it using the dry procedure. Both methods equate to the same regulated fuel level in the bowl. It the motor is giving you so many problems that you can't run it long enough to check it wet, then check it dry. It will be much easier that way.
The throttle solenoid, also referred to as an "idle-stop" solenoid or "anti-dieseling"solenoid, was introduced because engines in the smog era required a higher idle to run smoothly. However, this increased curb idle combined with hotter-than-usual combustion chamber temperatures would cause dieseling (run-on) when the motor was shut off. The purpose of the solenoid is to allow the idle to be high while the motor is running, but at the same time, allow the throttle plates to be (near) completely shut when the motor is off.
When the ignition is on, the solenoid is energized and the plunger on the end is what actually holds the throttle back to set the idle. A long hex screw moves the throttle solenoid mounting bracket back and forth to set the idle. When you shut the motor off, you are also cutting power to the solenoid. The solenoid retracts and lets the throttle plates shut, to cut off air intake into the engine. As a side note, the throttle plates don't completely shut - instead, they are intended to still rest slightly on the curb idle screw to keep the plates from bottoming out in the throttle bores.
You have basically two options. You can retain the throttle solenoid to go with the factory setup. Or, you can remove it and use the curb idle screw on the carburetor (the large one on the drivers side of the carb) to set the idle. Either one works serves the same purpose. However, if you remove the throttle solenoid, your throttle plates will be at the same position when the motor is idling, and when it is shut off. There's nothing wrong with that, unless you have problems with dieseling. If you remove the solenoid and your engine starts dieseling when you try to shut it off, you'll need to reinstall the solenoid.
i have run on problems with my truck now. i just rev it up, then kill the motor. always works for me.
1974 Ford F-100, Straight 6, 3 speed on the Tree, 2wd. mostly stock....for now!
(10/6) NEwS flaSh: new clutch, new gear oil in the tranny.
thoughts on fixing daily drivers: work now, sleep later
Ok, it's been another evening of toiling with the carb from hell. Since I couldn't properly perform the wet check, I did as suggested and pulled the carb and adjusted the float using the dry method. I took my time, read the directions several times (gas fumes) and adjusted it spot on. Then reinstalled the carb and moved on to the choke adjustments. I followed everything to the letter and it made perfect sense as I went. At this point everything is properly adjusted. While the carb was on the bench I removed, cleaned and readjusted the idle mixture needles. 2.5 turns each. At this point I am supremely confident that the carb and choke have been calibrated within tolerable limits for a smooth idle.
No such luck. The truck acts exactly the same as before. So that should narrow it down somewhat.
One interesting thing to note. I did make the mistake of adjusting the fast idle screw only to realize that it affected the fast idle index adjustment I had previously made. So I performed the procedure again. During the process I flooded the engine (from opening the throttle over and over). When the truck finally cranked, it idled for about 20 seconds but died an ever slowing death as it consumed the extra fuel. As the rpms fell, the idle became more and more erratic. It was even missing and heaving as took its last breath. Clues to the problem?
My vacuum routing looks nothing like the diagram I have for my truck. However, I am missing a couple of pieces (air cleaner snorkel, temp actuated vacuum gadget). What's left is very simple and seems like it should work, after all it was working. The EGR valve is connected directly to the EGR port on the front of the carb. The vacuum advance is connected directly to spark input on the passenger side port on the carb. The PCV is run inside the oil refill cap and to the large port on the back of the carb (the other side pulls clean air from the air cleaner housing). There is a multi-port on the intake beneath the EGR. One line runs to the trans. There is no return line from the trans. I checked it and the other port on the trans is open. Nothing on it, not even capped off. The other two lines on the multi-port are looped together (capped off). I haven't been able to detect any vacuum leaks using the "spray in a suspected area" method. The hoses seem to be in decent shape and not cracked or leaking.
So, very long story short. I'm back to square one and stumped.
The first thing that comes to mind is your idle circuit is plugged in the carb. But after reading some of the posts i would check your timing and your timing chain for being out a tooth. Just a thought.
That was going to be one of my next tasks. Along with checking the gap on the points. I think it would be odd for it to be off, but who knows. I ran it for 30 minutes after it sat for nearly 2 years. It's just mad I guess. I replaced the wires, cap, rotor, plugs and points soon after I got the truck that fall. I drove it a few hundred miles and took it apart in the spring. So those parts shouldn't be worn, but they may have fallen out of proper adjustment. I was going to check the point gap the other night but I couldn't find the proper gap setting. Anyone know? Also, I think the timing should be 6 degrees btdc but i'm not sure.
The EGR valve is connected directly to the EGR port on the front of the carb.
Big no-no. The EGR valve must go through a ported vacuum switch to prevent the EGR valve from operating below operating temp. A ported vacuum switch threads into a water jacket, usually near the thermostat. It simply lets vacuum pass past a certain temperature, and shuts it off below that temperature. You need to fix this. As for your trans, what do you mean by "other port?" There should be one line running from direct manifold vacuum down to the vacuum modulator, but but that's it as far as vacuum to the trans is concerned. There were some older systems that had two lines running to the trans, but there was still only one port on the trans itself. These old setups ran manifold vacuum to one line, and actually ran ported vacuum to the second line and they then teed together near the bottom. Ford did this because it was initially thought manifold vacuum would drop when the EGR valve opened, so the second line was added to maintain vacuum for the trans. This is not actually the case and this setup did not last long. Lastly, did you set the timing after you reset the points? Here is a vacuum diagram I made a while back. Consult as needed. The only thing I have left off is the hot-air intake system on the air cleaner, which will source off of manifold vacuum.
FMC just hit on something that is really worth checking into.
EGR, if the valve is on--either via a mistake in vacuum routing--OR if a chunk of carbon is blocking the internal port open?
That will have a horrible effect on engine idle. That valve is only meant to be open after the temp ported vacuum switch is 'on'. And it's only meant to be open using ported vacuum. It dumps a metered amount of exhaust back into the intake in order to reduce emissions. However it is only meant to do this when the engine is well 'off idle'. (going down the road @ a good throttle opening)
This should be easy to sort out, if that's the main issue. Just remove and cap the vacuum line going to the EGR valve. If the truck all the sudden starts to idle right? There ya go! If not? Pick up an EGR gasket from the local yoyo's at the parts houses. Remove the valve and inspect it. You'll see two openings. One is exhaust "in", and the other is exhaust "out" to the intake manifold. Use some compressed air and see if the valve is in fact--closed without any vacuum applied. (put the compressed air into the "intake" side of the valve, and see if you feel/hear air rushing out the other port)
The gasket runs a few bucks (do not attempt to make one out of gasket 'do it yourself' stuff, the gasket is made to handle the heat from the exhaust flow) If the valve is in fact, stuck open? You might be able to hose the passageway out using carb cleaner to dislodge any carbon deposits blocking it open.
I should have thought of this much sooner, as it's one of the basic items that can tank out the air/fuel mixture at idle.
The old girl is as follows:
1975 Ford F250 Camper Special
Rear Wheel Drive.
Last of the vin: W69956
fmc400, no I didn't reset the timing after replacing the points. However the truck ran better than ever. I wasn't aware that a timing adjustment was in order. I suppose I'll need to pull the EGR spacer and valve and examine those closely this evening. Will it run/idle if I bolt the carb directly to the intake? Not for a long term solution but I'm just curious. If the EGR is the issue, if I remove it completely the problem should clear up, no? I would have no intention of running the truck that way permanently if it did work but that may help diagnose the problem.
Also, my vacuum system is (supposed to be) totally different than the diagram you posted. My truck was never equipped with some of those items in your drawing. Mil1ion sent me the correct diagram for my truck a couple years ago. I have a very good version on my computer but I'll link the not-so-good version from my gallery. It does show 2 lines on the modulator on the trans. Hopefully it is clear enough you can see at least what it should look like in general.
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