Hi
I am trying to help my father with an issue he is having with his 55 F100 239 V8 (100% original). Truck ran perfect but needed the idle increased a bit and the oil changed. Picked it up from mechanic and it ran perfect all the way home but noticed the temp and gas guage are not working. Then while backing it into the garage the engine just stopped. No coughing or sputtering, it was like someone killed the ignition but the battery and oil lights remain on.

Engine turns over strong but would not start, then out of the blue it just started.

Could these two things be related? Trying to feel for loose wires I did stick my hand behind the dash and I could feel the ignition was not real tight in the dash. Maybe I screwed up the ignition and the guages is another problem????

Can anyone help??

Thanks,
Deb

 

Welcome to FTE!, You will find the answer to your question here.. it may take some time, and you will learn some stuff along the way..but lot's of good info.

1st a few questions, you already stated the vehicle is original,..Great!, as this eliminates all the modified and "other-than-stock" possibilities..though there may very well be modifications to "the stock" system..most folk's here can refer to the known stock electrical diagram and follow along. Do you have a repair manual for it? The repair manual will have a wiring diagram for you to follow.If not This would be a good 1st step, Dad may have one already.
Do you have any experience with electrical circuits-either a/c or d/c?
How comfortable are you with a VOM (volt.ohm meter)..tracking down electrical problems becomes much easier with an understanding of the VOM operation.
Intermitant electrical problem are both the most exasperating.. and rewarding when the problem is finally found. A vehicle that intermitantly stalls-out/quits is neither fun to drive or safe in certain situations..
Loose connections from a recent repair are the 1st places I would look,..around the igniton coil/distributor, around the lite swx ( the lite swx is a major power distribution point on the stock vehicle)...
The time spent with Dad tracking down this problem will be enjoyable to both of you..don't rush thru it..take some time and "talk" to each other, make/steer and keep it fun..that's what this hobby is about, it does't matter if you fix the danged 'old truck or not.. the time spent together will pay off in spades later..

 

Hi
Thanks for the reply. We do have the manual which is very detailed and helpful. It appears that the owner before us in an effort to protect the wiring wrapped it all in black electrical tape so it is very hard to see the colors of the wires.

I am going to go out right now and look for the things you pointed out. The mechanic did do a carb adjustment so there is a possibility something go touched.

This has been a great hobby. My father is 73 and has always wanted a classic truck. I only wish we did it sooner but we will have plenty of good times. Of course, my mother is a bit nervous where the engine simply cut out while driving it.

Is it possible a piece of crap in the fuel tank could have briefly clogged the carb. It started up right away and ran perfectly today but the guages still don't work.

We are not real familiar with electrical systems but we have a friend who is so we will give him a call. I may just get myself one of those voltmeters so we can learn some new stuff. I would be very satisfied to find this issue.

Thanks,
Deb

 

General rule of thumb :
If it spits, sputters and dies, fuel problem
If it just up and dies, electrical.

If all your gauges and lights work, it could be the back of the ignition switch. I'd suspect something under the hood tho, around the distributor or coil as the "shop" was mucking about under the hood with the carb. Look for loose or broken wires between the firewall and coil/distributor. It could be nothing more than the ground wire from the coil or points being loose/broken/bad.

Oh, an additional thought. If all the electrical dies, look around the voltage regulator at it's battery terminal. They might have done some damage leaning over the fender disturbing the connections there.

Good luck

 

Yep!, You bring up a couple of very good points..every engine has to have the basics, those are Spark, Fuel, Air and compression...because your problem is "intermitant"..I'm willing to bet the farm that lack of air is not the problem...lack of air would most likely be the result of a major mechanical engine issue..again, because it runs fine ..then stalls,..compression sounds like it's ok too!..That really only leaves 2 choices..Fuel and spark. Start zeroing in on these two..

Does the fuel tank have gas in it and is it good, recently purchased High grade stuff?
Gas get's old and looses volatility after awhile,has the fuel tank been flushed or cleaned sometime in the recent past to eliminate the possibility of crud/rust flowing downstream and into the carburator?..remove the top of the airfilter, and with the ignition"off" and the trans in neutral..with a flashlite, peer down into the carb while at the same time rotating the throttle lever..you should see a steady stream of fuel down inside the carb.If you do, then there is fuel to the carb. Does the carb have a 'sight-glass' on it showing the carb fuel level? Is it full? At "idle" you should see some also..be careful about sticking your face over the carb at any time "running or not", a backfire/missfire will blow flame up and into your face! Normally the carb will make a slight 'gurgling' sound as the air and fuel mix and move down thru the carb. A see-thru inline fuel filter is a handy modification..with one placed "after" the fuel pump you will be able to tell at a glance if- 1) you have fuel..(is it full?) 2) your fuel pump is working..hopefully more folk will chime in about placement in your 'stock' confiquration..

When it does stall, and you have determined that the carb has fuel..the next thing would be to check for spark.. the quickest way is to carry an old spare sparkplug around with you..then..,when the engine stalls,coast to a safe spot, pop the hood and remove any sparkplug wire "at the sparkplug"..place your spare into the sparkplug wire boot, and lay the combo someplace where the sparkplug metal housing is sure to touch a good chassis ground (but not near any raw fuel), then have someone turn the ignition /starter on-try to start the vehicle...if it does not start.., look at the spare sparkplug and look for a bright Blue spark across the electrode. Lack of spark means you can now swx your diag from fuel problem to electrical problem..or conversely..if you have a good spark...maybe you will need to look closer at the fuel supply..

Determining if your engine problem is fuel or spark related is a "major" step in the troubleshooting process...the two more often than not,resemble each other in "symptom", and must be positively seperated and confirmed..Good Luck going Forward!

 

DumbLuck raises raises a couple of good points,

"Always suspect the last repair- or anything related to it"..your mechanic may be the best mechanic in the world..BUT they "may" have unknowingly touched,bumped,moved something not touched in a long time..These old wiring systems, while pretty simple, are old.., They are susceptable to connection signal loss..grounds, power supply,crimped conectors,corrosion,dirt and the like..

Care should be taken when inspecting all wiring so that no additional problems are 'created'..and it is very easy to do.
I would be inclined to start with the instrument panel problem..was it the gauges not working ? ..or was it the instrument panel lites? either way, as simple as the stock electrical system may be, it still uses what would be termed today,50 yrs later, 'antiquated' principles and methods and technologies.
It would not be surpriseing at all to learn that the problem with the gauges/panel lites, is the same one causing the stalling.. have Dad sit in the seat and watch the gauges/panel-lites while you gently poke,tug, and move wires and harness under the dash..a loose connection at the ignition swx could cause both..a common denominator so to speak...or do the opposite, start the truck, then gently start poking,tugging,moving the electrical harness..under the dash and under the hood..if you get a stall,start looking closer..a movement that gets an engine stall AND a gauge panel reaction at the same time, would be a home-run!

 

Thanks for the help. I really think there must be a loose wire somewhere. The stalling problem has only happened once since the guages went out so it may just be a coincidence that it occurred on the same day.

I suppose at some point it would be worth re-wiring the truck. We would like to keep it stock so we will most likely stick with the 6V system but some of these 55 year old wires are really brittle and should be replaced.

Has anyone done a full stock re-wiring job on a truck like this? I will most likely pay someone who is more familiar with this stuff but just trying to figure out how big of a job it is.

Thanks again for the replys. This is a great forum full of good info.

 

If you can solder, you can make your own wiring harness. I just replaced mine wire by wire after pulling the whole mess in one piece. It looked way worse than it was.

 

Welcome.

With the help of a friend, we re-wired my whole truck with a home made harness. It's a much more intimidating task than it is difficult...and the hardest part is starting. I am no wiring genious...just know enough to get in trouble.

 

I am going to bring a volt meter home from work to see if I can find the dead wire.

Where is the best place to attach the clip on the ground end. Someone here said the frame of the truck can be used for the ground clip but I want to be sure so I don't mess things up more.

Thanks

 

My first guess would be the ignition switch, this would be the first place I would test for continuity. It seems likely since the problem you mentioned involved the dash instruments and also the motor quitting intermitantly.

Pardon my manners, welcome to the site and good luck with finding the problem. Like said above, you came to the right place for help. There is definitly good advice from the members.

 

Ditto on that. I had the same issue on my 59 Chevy once...

 

most any good clean piece of metal or bolt head in the cab should work for the ground clip. It just can't be insulated by paint or rust. If you set the meter to ohms and touch both ends to metal and see the meter go to zero or close to it you're in business. If the truck is positive ground, the red wire clips to the cab somewhere, and you poke around with the black lead. Negative ground the black wire gets clipped to the cab, and ya poke around with the red lead. Look at the battery terminal connections. If the cable on the + terminal goes to the frame, it's positive ground. If the - terminal cable goes to the frame it's negative ground. One other tip. count the filler caps on the battery. 3 caps, generally 6 volts. 6 caps, 12 volt. Have fun.

 

Thanks everyone. I just orderd a new ingition switch. I didn't think about that before because the battery and oil light still work so I guess I thought it would be all or nothing. These parts are easy enough to get so it's worth it just to replace the whole thing and eliminate one possible culpret.

I am still going to get a volt meter and test the wires as well. I haven't been brave enough to order new wiring harnesses and tackle replacing any wires yet.

 

Well I just installed the new ignition switch which was pretty easy. The gas guage now wiggles a little when I turn the key on but still does not go to full as it should. Before it didn't even move so there is some improvement but not fixed.

Where should I look next?

Shame on me but I did learn today that this truck was converted to 12V but the previous owner chose to keep the push button start. I assumed it was still a 6V system.

I did see one loose wire near the fuel guage. It is red/blue and has a large connector on the end. I'm not sure if it is a wire that was no longer needed with the 12V system or if it got disconnected somewhere.