My 69 F250 with 360 V8 and C6 had been running real well and just the other day it started running rough at stop signs and stoplights. I could kick the shifter into N and feather the gas pedal and it would smooth out. It has gotten worse, to the point it won't stay running. Starts, runs smooth for a few minutes in Drive or Park then stutters like its loosing fire and dies...vacuum gauge in the cab surges up and down when it stutters.
I checked fuel delivery...pump has good flow, I see two strong squirts down in the carb when I work the throttle. I also have spark at the plugs, points, coil wire. This morning I went through all the ignition tests in my Clymers manual for breaker point ignition. It passes all the ignition tests but I don't have the wire and other resources to do the ignition switch test and resistor wire test.
What bothers me in all this is I have white/yellow spark instead of a nice blue spark...I work on old magneto style outboards, so I always look for a fat, blue ignition spark.
I can have the coil tested at the parts store, but how can I test the ignition switch and resistor wire?
I've run the tank down close to E...it's at 1/8th of a tank, but haven't run it down far enough to pull crap into the fuel line...so I doubt the carb is at fault.
Need to get this resolved cause I have to have wheels to look for work.
In the past 3 months I have replaced points/condensor/dist. cap/cleaned plugs/and new plug wires. It was running like a top before this.
Any ideas?

 

Bogging down, hesitating, stumbling from a dead stop or when accelerating at speed: Defective accelerator pump diaphram and check valve. Both come in carb kit or available individually.

Carb kit same: 1962/74 all FoMoCo vehicles with Auto-Lite/Motorcraft 2100 series carb: D4AZ-9A586-A (Motorcraft CT-499D).

Corrogated paper cartridge fuel filter (C4AZ-9365-B) inside metal cannister that threads on/off fuel pump. Some peeps are unaware, so it hasn't been changed Nixon was prez.

COLF 12250-A .. Resistor Wire-Ignition Coil (Motorcraft DY-37) / 61.49" long / 1.30-1.40 ohms resistance / Color coded Pink / #20 gauge wire.

LA LA Land geezer, now dead as Julius Caesar, once worked for Floyd Clymer, specialized in repairing magneto's found on old old rolling piles of misery. No one knew his real name, everyone called him "Magneto."

Clymer was a car dealer before he was a teenager. His dealership in Berthoud CO sold makes of cars most peeps in today's world have never heard of.

 

Thanks Bill. Yeah, I can do the carb kit...accel. pump, etc. but don't understand the check valve reference...you mean power valve? I'll dig into the carb if necessary, and I'll check the fuel pump filter, too. I'm leaning more towards a bad ignition switch...it looks stock and very old/dirty behind the dash...or a short in the resistor wire (probably also stock). I may replace both first if I can't find out a simple way to test both.
Also plan to clean and re-attach the ground connections. Front ground by the battery looks good, but the right, rear ground cable from manifold to firewall looks ancient...I can see bare wire through breaks in the insulation.
Interesting reference about Magneto and Clymer...ironic, too, since my 69 came from the Front Range before I got it...Andersens Ford Inc. according to the big step bumper. Maybe Clymer sold Studies, Hudsons, DeSotos and Packards?
How do you install a new resistor wire...one end to the coil, I know, but do you splice the other end into the back of the ignition switch?
For some reason it bothers me that the spark is yellow/orange instead of blue.

 

Time to reset the idle air mixture screws. Might be something stuck in the orifice? Enough to lean it out at idle causing stalling.

I would think that if the spark was to blame, it would be down on power also.

 

Behind the accelerator pump diaphram is the check valve (C4AZ-9576-A / Motorcraft CM-825). It has a tiny tit on it that fits into the carb.

Installing the little charmer into the tiny carb hole can be a challenge, cuz the tit is notorious for snapping off!

I forget what cars Clymer (1895-1970) sold, he opened the dealership when he was TEN! Dudsons (1909), DeSouses (1929) were introduced much later.

Stupidbaker was the distributor for crappy EMF's (Everett-Metzger-Flanders) better known as: Every Mechanical Fault, Every Morning Fixum, Every Mechanics Friend thru 1913 or so.

Packard intro'd in 1899, but Clymer never sold them. I have all the original factory literature that lists every dealer from 1903 thru 1956, so I know this.
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Edit: Since you have a 1969. be aware that:

1968/69 F100/750's, 1970 F100/750's (before serial number G90,001), 1969/70 Econolines and 1968/69 FoMoCo Passenger Cars came with an ignition switch (C8AZ-11572-A) that shorted out...

And caught FIRE! / Engine running or not, made no difference.

1971: FoMoCo came out with a replacement ignition switch that included a plug with pigtailed wires. The plug is used with this switch, the wires were spliced into the dash harness.

There were no recalls back then, it was up to the dealers to notify their customers when things like this occurred. Some did, some did not.

If your switch doesn't have spliced wires, it's the original POS!

D1AZ-11572-C (replaced POS C8AZ-11572-A) .. Ignition Switch ~ Includes plug w/pigtailed wires (Motorcraft SW-1054) / Available from Ford.

MSRP: $66.40 // FTE sponsor tousleyfordparts.com price: $40.17 / Tousley Ford = White Bear Lake MN

If you buy this switch, have the partsguy VERIFY that the plug is in the box. Otherwise, the switch will be a useless as teats on a mule.

 

Now that you mention the rubber tit, I know what you are talking about. Looks like I replace the ignition switch first after check the wires behind the switch for splicing. Will have coil tested...replace if necessary...and get a carb kit and maybe a resistor wire, too, if the local parts store has one.
When I moved the truck around the driveway last night to accomodate the daughter's garage sale, it started and ran rough and would hold its own idle at 1800 rpm without the choke on or my foot on the pedal...making the carb a more likely suspect I guess.
Thanks for the info...very much appreciated.
My granddad wrenched in the trenches for Uncle Sam as a doughboy in WWI. He walked out of the mechanic's pits when he started seeing V8's overhead...way out in Calyfornia and New Mexico. Herman Humphrey McA was a real card.

 

I'd first check for a vacuum leak with some quick start spray any line that pulls a vacuum. Even any tranny line ,power brake booster & line. If carb has a good pump shot the little red/pink acc-pump check valve is ok. If it was bad you would have a weak to little pump shot in the carb. To install the little check-valve first lube it before pulling in into place wd-40 works for me. To by pass your whole ignition system to test color of spark just hot wire it. Hot wire from Battery+ to + side of coil to make test. Also check voltage at resistor wire coil end most run around 8-9-+ volts.. Also If was ever changed to the later 70 's type with the choke pull down vacuum diaphragm on the top of the carb. If these start to leak the choke will hang closed plus suck vacuum making it stall and rough running. this has 3 screws in it. The upper arm hooks to choke butterfly.. orich

 

Thanks Orich. I'll try the ignition bypass on Monday...next day I can get back to the truck. Will also have the coil tested and put in a new ignition switch. If no go after that...I'm into the carb. Anyone know if the filter element and metal filter cannister for the old-style fuel pumps are still available at parts stores...or do you have to buy the Carter pump with no filter?

 

My truck had the round contacts which had been replaced b4 I got it. after many yrs of trying to figure out why it was so hard starting if it didn't start with in the first crank of the key like it should. I needed to replace the old ign key & cylinder and ended up getting the whole switch with a pigtail.Reason was after looking at the back of the old pigtail plug it was cooked from over heating. So put in new switch that had the round contact pins and about a haft of turn of the motor it started.
I'm thinking wow all that time I had the slow starting issues were now gone.
So I'm thinking hell this crap is going to happen again one day so, I now changed to a new switch that has the flat blade tabs. Theirs no way this switch we ever do what the other one did that had the round contact did. So if your switch has the round pins I'd say change it to the flat spade tab type for longer reliability. You may also have some bad spark plug wires that can only be checked with an ohm meter you could have a weak condenser. Coil mostly get weak when they get hot, but not always..buut still sounds like a vacuum leak..orich

 

US Army staff cars during WWI were Cadillac's. Cadillac intro'd the first V8 (L-head) in 1915, beating Cole to the market by a month. Cadillac also intro'd the first OHV V8 in 1949, beating Olds to the market by a month.

 

Yeah. I have a full list to do tomorrow. Vac lines, fresh gas, fuel filters, ignition bypass, coil test, and ignition switch...then a carb cleaning/rebuild. Enough to keep me free of the devil's workshop.

 

Does it happen more often or get worse when the truck is warmed up or hot? If so, try replacing the coil. A coil going bad will act just like fuel starvation, and will be worse when the engine is warm.

 

Update on the stalling mystery. This morning I reconfirmed fuel to carb, so I put 5 gallons of high test gas and a can of sea foam in the tank, pulled the carb and did the rebuild kit. Then I put the carb back on and it fired right up and ran good for about 10 minutes...then sputter, sputter, die.
So, I pulled the coil wire off the dist. cap and checked for spark...none at all. Next I checked for fire to the coil via the resistor wire...had about 8 volts there on the voltmeter so I figured the coil is at fault.
Had the old coil tested at Autozone and resistance was too high, so I bought a new coil and put it on. Now I have intermittent spark from the coil. Back to the parts store for an ignition switch, got that installed and still have intermittent spark from the coil. Found out at Autozone that they can't get the resistor wire anymore so I guess I'm hosed unless Advance Auto or O'Reilly's carries it.
Tomorrow I check the ground connections again and check the timing...can't imagine it has jumped time cause it fired right up right after the carb rebuild and ran sweet, but I'm running out of ideas here.
Any input is appreciated.

 

check you wire to coil for cracks could be grounding . buy some of the split flex tube and cover the wire across manifold .

 

Buy BWD Ignition Coil Resistor RU13 at Advance Auto Parts_____

I think napa carries them also, you could always use a resistor block.

I had trouble with the wire that goes from the coil to the dist. was old and cracked, grounding out. Black wire.

http://shop.advanceautoparts.com/web...RPTUNEAMS_____