I recently purchased a low mileage 1978 Ford F150 with the 400/c6 trans.
It started and ran fine for about three days. It started taking longer for it to start(crankin for two to five minutes). Once started it runs fine. Today it will not start at all. It will puff through the carb (soft backfire/flame). I did a spark check at the coil. The spark was orange and weak, the coil failed and ohms test on the primary windings. Replaced coil still wont start(bright blue spark.) I poured gas into the carb-no start. Based on ifo. from other posts on this sight, I went next to the ignition module. Took it to autozone it passed. Next I looked at the vaccum advance on the dist. If I apply vaccum to the hose the dist. does not move.I can move the advance plate with my hand, it moves freely. Next I pulled the plugs for a compression test. At this time I noticed the starter was cranking slowly. I checked battery voltage (12 volts) at cranking it drops to around (9 volts). I put the plugs back in it cranks at the same slow rpm. I will pull the starter this weekend. What next.????????

 

Might as well go ahead and have the battery tested. Could be as simple as your battery is getting old.

 

A fully charged battery should show 12.6 to 13 volts, usually anything under 12.4 is considered discharged and 12.0 and less is pretty much dead.

A good battery on a hot day will draw down to the 11's during crank.

Josh

 

old battery. chill, .....coulda been a chebby.

 

maybe check the voltage regulator?

i think my grandfather said he had a problem similar to this on a 77 merc with a 400. it wouldn't start until he let off the key, like it took just the right rythm to get it to start.

i swear he said it was the voltage regulator, coulda been the ignition module, but it seems like he had that checked out and it was fine and it was the last part he would have suspected to cause that problem. this was MANY years ago that he told me this, so i could have it wrong, but i swear he said it was the voltage regulator.

a bad voltage regulator would explain a bad battery also. I dunno, just something else to eliminate if nothing else.

 

Just how low exactly is the mileage on this 33 year old "lemon"?

 

The odometers of trucks of this vintage read to 99,999.9 .. then return to ZERO.

People look at the odometers, assume what is shown is correct, but are unaware, so they fail to add a 1, or a 2 or a?

And...do not believe a single word a seller claims. Private sellers can lie just as well as used/new car dealers, lawyers...and politicians.

The three step scenario of a failing DuraSpark ignition module:

1) Module overheats, engine dies. Module cools down, engine restarts almost at once.

2) Module overheats, engine dies. Module cools down, engine restarts in an hour...or so.

3) Sooner or later, usually sooner, the module overheats, BURNS OUT. Now the engine will not restart.

Since the module usually fails when it overheats, taking it to a parts store to be tested: It will usually test OK, unless the little charmer has burned out.

When replacing the module, use some spacers to move it further away from the fender apron. The more airflow around the little charmer, the better.

Inside the dizzy is the stator aka magnetic pickup coil. The symptoms can be the same as the ignition module.

Back then, these little charmers were such horrid terds, that Ford techs referred to DuraSpark as NeverSpark!

 

Either way the battery is toast and needs to be replaced.

Once the battery is replaced you can verify the output I the alternator/ regulator or just remove and take those in to be tested when the new battery is purchased.

If you have spark then there is no reason to replace the module or Stator unless the engine starts giving you fits after it has been running.

Josh

 

I wouldn't replace the battery just yet. If you've been cranking for a while with no start, you battery is eventually going to go dead since there is nothing to recharge it. My best guess is that you've got a flooding condition from the weak spark and pouring addition gas in the carb. I've seen spark plugs that would't fire after a bad flooding condition, even after they were pulled and cleaned.

 

Also, someone earlier posted about the voltage regulator causing a no start unless you let off the key, I am sure that what he meant was the starter solenoid, when cranking the engine the starter solenoid supplies 12 volts to the coil, when you let off the key the power is then coming from the key through a resistor to the coil providing 9.6 volts (or something like that). If you are seeing spark at the coil then this is not the problem but it is most likely what the earlier poster was talking about, I would charge your battery and have it tested, Autozone will do both for free if you dont have the means otherwise. Sounds to me like you are having a timing issue of sorts, may be the module, inductive pickup or (hopefully not) the timing chain. Sounds likely to me that the chain jumped a little previous and now more

 

that's another good check.

spin the motor over by hand to where your rotor points to the number 1 spark plug wire then see where your timing marks land at the crank. pretty easy to see if your chain has stretched or jumped a tooth that way.

as for my comment about the voltage regulator, i did mean voltage regulator. solonoid is a good check also, but while you are they pull everything out and get autozone to check em all.

im bettin on a bad ignition module or stretched timing chain. if it ran good for a while and slowly got worse, those are the two i'd be checking out.

 

The truck has 58,982 miles on the clock. I bought it from the one and only owner that I have known for ten years. The truck had been sitting for about 9 months. I knew going in I would have to do some work on the old girl. To eliminate the carb issuse, I pulled and rebuilt the carb. The float bowl was full of gunk, jets were plugged with stuff. I put it back on checked that it was not flooding out, still got spark, carb is not flooding and it will still not run. It puffs through the carb. I am putting a new battery in this weekend and I will check the timing chain .
Thank you everyone for the info.

 

I put in a new battery and the starter continued to turn slow. I pulled the starter and took it to the local autozone.... it failed all the test on their new fancy tester. Also I checked the timing chain to see if it had jumped, The timing marks and the rotor all lined up. I will buy a new starter and start form there.