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Yesterday, I bought a 1986 F250 with a 300 inline 6-cylinder. When I started it up, after sitting for years, it misfired alot. The more I fucked with the ignition system, the worse it got until it would not fire anymore.

This morning, I replaced the following:
1) distributor cap
2) rotor button
3) plugs
4) wires
5) coil
6) stator
7) TFI module (hall effect device)

We set the timing to 10 degress advanced. It then ran, very rough, and fired on all cylinder. The bitch is that it misfires like mad and seems wayyyy rich on the fuel mixture.

I then pulled the top of the carb, cleaned it out checked the float level and the float valve. They seems to be correct. The accelerator pump works well.

At this point, I am stumped. She runs but sputters and misfires. The exhaust could burn your eyes out. (I smell like I have been on a snowmobile all day. :grinpimp: )

There is a needle valve attached to the actuator for the accelerator pump. It has an adjustment. What is this?

Also, is there a ignition control outside of what I have replaced that could be effecting this?

Help please! I have to drive this pig from GA to WI tomorrow... :eek:
 

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Man, your story is sounding like deja vu all over again...

I replaced the 240 I-6 in a 1970 F 100 with a newer 300 and had a lot of the same issues. I went around and around with the salvage yard - they saying I didn't know how to install the spark plug wires - me saying that the engine was screwed... Ultimately I discovered that the head was cracked and it never would run right - I ended up with 3 motors before I got one to run.

I would rebuild the carb - it is likely leaking into the manifold - check the torque on the manifold - make sure that the EGR isn't sticking (if it has one) - and make sure that you don't have the wires 180* off. (A Ford 6 will run that way - but poorly!) Also make sure that the exhaust isn't plugged (I know you said it was making smoke - but trucks that sit sometimes collect vermin in the exhaust pipe - I sure scared the family in my truck one time - I launched them over 50 yards when they finally came flying out!)
 

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Timing chain ?..you said after you advanced the timing, it then ran..........chain streached out ?......high milage ?
 

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you said it sat for years? did you get all the old gas out? bad gas will cause the problems you stated. if the gas smells like paint thiner or something other than fresh gas its bad.
 

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Discussion Starter #5 (Edited)
throttleboy said:
you said it sat for years? did you get all the old gas out? bad gas will cause the problems you stated. if the gas smells like paint thiner or something other than fresh gas its bad.
It was near empty. I put 16gals of fresh fuel in it.

I found the problem but not the fix. The main jet is dumping fuel into the barrel on idle. I pulled the card open again and replaced the float valve and the float based on the rebuild kit specs. It called for a .780" dry height. I also set the metering valve based on the kits procedure. I re-installed it and have the same problem... main jet fuel on idle.

What else can induce the fuel to the main jet on idle other than the float valve?

This thing is really starting to piss me off!
:mad3:
 

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The interior passages in the carb - idle circut, etc. - are likely plugged with varnish from the old gas. The cure is to soak the carb in carb cleaner, then insure that all the passages are clean. If the idle circut cannot flow correctly it will siphon fuel through the main circut.

Also, is there a free source of air into the engine - to provide venting for the PCV? It is possible that you are drawing too much vacuum and that is siphoning fuel out of the carb.

That is about the limit of my knowledge - anyone else out there have any ideas?
 

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Discussion Starter #8
glfredrick said:
The interior passages in the carb - idle circut, etc. - are likely plugged with varnish from the old gas. The cure is to soak the carb in carb cleaner, then insure that all the passages are clean. If the idle circut cannot flow correctly it will siphon fuel through the main circut.

Also, is there a free source of air into the engine - to provide venting for the PCV? It is possible that you are drawing too much vacuum and that is siphoning fuel out of the carb.

That is about the limit of my knowledge - anyone else out there have any ideas?
After 3 carb tear-downs, 20-sum beers and 2 cans of carb cleaner, I figured I would spare my liver. I ended up throwing a rebuilt on it. It took care of the flooding/richness problem. It sputtered and misifired though and was a total dog. I spent another 4 hours reinstalling parts I had changed out and diagnosing whether the ECM was screwing up.

I learned a couple of interesting was to diagnose the problem from a local tech. If you disconnect the SPOUT plug and have the same problem, it is not related to the ECM as that is it's only control on the ignition system. I also learned that you must place the coil of the timing gun as close to the spark plug end of the cable as possible. Otherwise, you may get too close to anothee cable and induce a false signal. I proved this one today
:flipoff2: !

Finally, keep your eyes open to the little things. After total frustration set in, I decided to check the plugs that I put in yesterday. It turns out that all of the flloding and carb cleaner fouled the 4th cylinder's plug. I cleaned it and she runs like a champ now. :zzz: It's time for bed now. Only 1,000+ mile to drive tomorrow.

I hope this is educational to learn from my mistakes. Otherwise, this post would be useless :flipoff2: :flipoff2: :flipoff2: :grinpimp:

Laters....
 

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Wow...

I'm glad you figured it out - and thanks for the further tune up tips.

I feel your pain - in the one I did it wasn't multiple carb rebuilds - it was multiple engine installs - It took 3 before I finally got an engine that worked from the junk yard (I never mentioned the first one that had the timing gear blwon al over the inside of the oil pan...).
 
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