74 f600 won’t start

[bigred1951]

My 74 ford f600 dump truck is getting bitter in its old age. It's always run great and never failed to start until the other day. I drove it an hour away to my in laws house. I stopped about 10 miles before I got there and got something to drink. Come back out it started fine then went on to their house and parked it. A couple hours later I went to move it and it wouldn't start just kept cranking. I thought might have been fuel pump went out so poured a little gas down the carb and still wouldn't hit. Well a couple days later went back and it fired right up like nothing happened. Then today I drove it around 30 miles round trip to the dump and back. Started fine this morning no problem. It sit for a few hours when I went to get in to bring it home again it just cranked and cranked and wouldn't hit. I'm betting tomorrow I can go and it'll fire up first crank. I looked for a icm or brainbox we call it because I've heard they are bad for going out but didn't see one. It's a 330 v8. Any ideas what's causing this.

[WV Sawmiller]

   No mechanic but could a needle valve or something be sticking in the carb? Might tap it with a wrench or something the next time it happens. If it is a good cleaning might fix the problem. Good luck.

[mike_belben]

Put a timing light on it.. Ill bet theres no spark during the no start period, and that its that little finned aluminum ignition box thingy on those old fords.  Had a bronco that did this often.

[bigred1951]

The little aluminum looking finned thingy what I was referring to when I said the icm which is ignition control module. Or as a I've always heard it called the brainbox. I looked for one on it but couldn't find it no where.

[caveman]

I think '74 was a few years before Ford started using electronic ignition on their trucks.  You probably have points and a condenser in the distributor.  If you are getting no spark when it will not start, that may be a good place to start looking for the source of your problem.  Another possible culprit may be the ignition coil.

Don't overlook the simple stuff.  It is a good idea to ensure all of your grounds are good - does not cost anything to check/clean them.  Good luck with it.

[jcbrotz]

Remove the coil and turn it upside down and back if you feel liquid move in it its bad. Unless its been retrofitted it would not have electronic ignition.

[LAZERDAN]

Yep,,,,,,,,,,, check the coil wire also                                                    Lazerdan

[PineNut]

I had a similar problem on an old GM school bus. While going down the road, it would decide to quit. I finally tracked it down to a small crack in the rotor in the distributor. I could not see the crack but it must have been there. Whenever it got warm, it would change enough to ground out the spark. Replacing the rotor fixed the problem.

[scsmith42]

I would check the resistor and coil first.  What you describe is a classic case of either one going bad.

To check the resistor, first locate it and then keep a small jumper wire with you.  The next time that the truck won't start simply bypass the resistor with the jumper wire.  If it starts, you've found your problem.  Don't leave the resistor bypassed long term or your points will burn up.

[mike_belben]

Check the distributor rotor for slop in the bushings.  Once the shaft starts drifting around in there you cant maintain breaker gap and they get arced up and eaten away quick.  Id pull your condensor and just go match up another theyre only a few bucks and not easy to test. The coil can be tested with a meter pretty easy just google it. Replace breaker plate and reset gap if youve never done it. 

 And if youre gonna keep that old girl, buying a few spare parts is a good idea, its going extinct. The 4cyl ford in my bobcat has an obsolete distributor.  I finally had to buy an entire pertronix setup @ $300 ish to have spark.  

[woodmaker]

I don't know about the larger fords in 1974,but my dad had an f 100 that had something called t.f.i. for an ignition ( thin film or thick film,I don't remember,and my books aren't here).What i remember is you had to change both components if one failed; we didn't,and it failed again in a very short time.

[bigred1951]

I'm gonna go later today to see if it'll start again and bring it home. I'm sure it'll fire right up. My father in law seems to think that it's vapor locking. You shut it off it starts right back. If it sits for a couple hours it won't.

[dgdrls]

you get that ford home yet?

D

[jwilly3879]

It was an intermittent ignition switch on my old Ford, it would engage the starter but not put any juice to the coil (sometimes.) I found this by putting a jumper from the battery to the coil and it would fire right up.

[Weekend_Sawyer]

On points ignition a failing condenser will heat up and quit.
I would start by doing a basic tune up, plugs, wires, points and condenser and distributor cap.

[bigred1951]

Yea it's Home. Like I thought it started right up and drove the 50 miles home just fine. When I got home and shut it off it fired right back up. I didn't go try it after it set for a couple hours though.