This makes no sense to me. When the truck decides not to start, the Check Engine light stays on while cranking. If it decides to start, the light goes off during crank. Various thing have fixed the problem, but not allway. When this first happened, I checked the plugs, they were dry. Ah, a fuel problem, I thought. When the tow truck arrived, the driver checked for a spark, NO Spark!. evidentely, if one doesn't work, the computer prevents the other from working. Anyway. The ECM was changed, and all was fine. a week later the check engine light came on. The system was analized and found that the wrong ECM was installed. The original one was put back and the truck ran ok. 2 weeks later, it won't start. Another tow truck driver say's that he knows Fords, and presses the schrader valve on the fuel line. Truck starts on teh first attempt. This happens again, so I tried the schrader valve. Doesn't work this time. Called a Tow truck. We pushed the truck out of the garage. Just before towing, I tried the engine again. It started with the first attempt. left it at the Ford Dealer for 2 days. They tried starting it many times. It started on every attempt. Next time it happend arrange for the Ford dealer to make a house call. While it was cranking they checked fuel pressure, it was normal. They check for a spark, there was no spark, they installed a known good coil, still no spark. They left to get some other equipment. While they were gone, i managed to get it started by fiddling with the Overdrive control in the engine compartment. It would fire one time then stop. I repeated this operation several times until the engine continued to run. But when I closed the hood, the engine quit. I opened the hood and started the engine again. When I closed the hood again, it stopped. next time, it kept running. Last week, when it wouldn't start, I tried the schrader valve again. Engine started with the next crank. Following day, at lunch time, it wouldn't start. 2 hours later it started at the first attempt. I hadn't even touched anything. At 5pm, it wouldn't start. a minute later, after leeving the ignition switch turned ON for a few seconds, it started right up. The following morning, same problem, this time nothing fixed it. So, this morning, I decided to do a bit by bit close inspection of every component. First, I tried startin it. It didn't start. I opened the hood, but before touching anything, I gave it one more attempt. IT STARTED WITH THE FIRST CRANK!. There is nothing being touched by teh hood hinges. The only common denominator in all of this is the ignition switch. It is used every time. So, I will buy a replacment and hope that works. Anyway, to my question. Does anyone know if there is a seperate circuit in the ignition switch dedicated to the ECM? If all this doesn't work, does anyone know if priests will exorcize demons from an F150???

 

That is a very strange set of problems and fixes on that truck. At first with the no start condition I figured well this guy just needs a new TFI module ( thick film module or in other words ignition module). Then as I read on I noticed that different thigns would temporaly fix the problem. It really does sound like some sort of electrical problem, like something grounding out or lossing power.

I know some Fords in the past have had a problem with worn keylock cylinders. Might try that first and make sure all start and ignition wires are in good shape and not touching anything. It's widley known that the wires cinnected to the starter like to corrode and cause problems. Also, if it has the fender mounted starter solenoid check the ignition wire (small wire) to it. The next time it will not start pull a plug wire, stick a spare spark plug in it and ground it out. If there's no spark on them then it's either module, coil, ECM, or distributer pick-up gone bad. Better yet buy a spark tester and do it safely. Also, hold the foor open each time you go to start and listen to make sure the fuel pump starts (you'll hear a whine).

This is my best guess's without having the truck in front of me.

 

Does the fuel and EEC relay click when you turn the ignition? I would assume so if you have fuel pressure.

If you are not getting spark, its possible a wire is damaged or shorting. First test your coil wire for spark, which bypasses the rotor, cap and other wires. On wire that goes into the coil is the ignition wire and should have 12 volts with the key on. The other runs to the TFI module. This is what excites the coil causing it to send a "spark." I am not sure how to test if this is getting the proper signal, but you can test for continuity in this wire between the TFI and coil. Also, the TFI can be tested, but in my experience they just up and quit working all together. Besides, if its intermitent, testing it might be inconclusive. T

There is also a small plug (gray on mine) in a wire off of the distributor. It simply connects the TFI module to the computer, and the plug completes the circuit. It is used to time the engine and unplugging it removes the timing signal from the computer, and lets the distributor determine the spark. You might try unplugging it to make sure there is not a short in that wire, or that the computer is not causing you problems. It will run without this plug in it and you should get spark if all else is well.

Also, there is a "pick up" assembly in the distributor. Its simply a magnetic type pick up that originates the spark. It can be replaced but you have to pull the distributor and dissaseble it. I bought a reman distributor for mine for $80 and the pickup was $30.

I had to rotate the distributor to get the TFI module off (7/32" and a tight fit I believe). If you rotate or pull the distributor, make sure to put match marks on it and the block. Remeber or mark the placement of the rotor in comparison to the engine if you pull it.

Intermittent problems are a B.... You cant hardly diagnose them. Good luck.

 

Thanks, KY and Spaceman.
Both Fuel pumps work. I can here them power-up when the ignition is turned on. Besides, fuel pressure was checked when the no-start condition occured. Both pumps put out approx 40lbs. The manager and service tech/mechanic from the local Ford dealership made a house call, free of charge (Great people. I'm going to write a letter of gratitude). They checked for a spark from the coil, but there was none, although there was low voltage to the coil input. To verify if the coil was the culprit, they installed a known good coil, but the same problem existed. The module within the distributer has been replaced.
One would think that if it is a intermittent connection that can be made or broken just by opening the hood or wiggling some wires, then the engine would cut-out when the vehicle is being driven, particulary on a bumpy road.
I have to assume that teh problem is in a "start only" circuit, that once the engine is running, the circuit, or lack of, has no affect.
This condition makes no sense to me. There is no logical path for me to follow. Sometimes the symptoms seem electricl based, sometimes fuel. For example, one time when it started, after a no start condition, the engine would not keep running initially, when it did, it sputtered and progressively ran smoother. That too me indicated fuel. Problem is, the computer controls everything, so it could still have been electrical.
Oh for the good old days, when all I needed to check was fuel from the power jet or a spark at the plugs. And then only a couple of wires from the engine. Back then, it was worth carrying a tool kit in the trunk along with a spare coil and set of points. With all this technology, do engines really run that much better??? Enough to justify the complexity?
As I said before, the only thing common to everything is the ignition switch, and it is not used when the engine is running, which would explain why the engine, once started, continues to run. I proposed this to the Ford service tech. yesterday, but they said that there is no auxilliary contact within the switch dedicated only to enabling the module to allow the engine to start. But, the switch costs only approx. $20, so I'll replace it anyway.
My only other option is to leave the truck with the dealership until the problem occurrs again. then they can attach the analyzer and hopefully find the cause.
Thanks again for all your suggestions.

 

OK Let me throw in an educated dumbass thought.

I seem to remember an issue of a shorting problem at the ECU connector. I think it was a moisture encroachment problem but I don't remember what the source of the water was. I want to say the A/C lines condensing and dripping off onto it. Anyhow. You display symptoms of an ECU problem. Particularly the Check engine light symptoms and the fact that an ECU was already pointed to. The fiddling with things, hood up, hood down, etc. would be just enough movement to disturb a short enough to open it up again. I'm suggesting that you have a bordeline short at the ECU harness. Try disconnecting and removing the battery, removing the ECU connector, inspecting that for signs of corrosion or moisture. If it has signs of either, spray a good cleaner in it and try that. Then make sure its securely re-attached. I would also check the ground connect to the firewall for the same type thing. That can drive the system absolutely nuts if that connection is iffy. That is right next to your main junction box on the firewall. It will be a little green colored bolt with an exposed cable attached to it running back to the engine.

All of the fiddling things are probably unrelated, just enough disturbance to the harness to move it ever so slightly and bring about just enough change to get you going again.

Good luck hope this nails it for you.

Toughie to figure out by looking at a screen like this.

 

I thought of something else.

If all that fails. Hook-up an OBD-II interface to it and crank the engine while monitoring the outputs. You will probably be turning that starter for a good 90 seconds so realize that you should do this as fast as possible to avoid a new starter.

Anyway. Monitor the sensor readings. I bet that it will say RPM=0. Even though the engine isn't running, the sensors put out when the engine has voltage and rotation. If the RPM says 0 then you have pointed to a faulty sensor there. With a 0 RPM the ECU will never attempt to start the engine at all. No RPM signal, means no fire. It was to protect the ignition system from trying to fire on an engine that had a key on but not running condition. It should read something like 20 or so (RPMs) if the ignition is in the start mode and the engine is rotating.

 

Thats definantly not in the manual.

A starter is only designed to turn for 15-20 seconds before it gets too hot. Plan on a new starter and a lot of wear on your battery.

 

No its not in the manual. Neither is A/C lines shorting out the ECU in the manual either.

No it won't burn out your starter or your battery.

But I wouldn't make a steady diet of it.

I have used this technique more than once on more than one vehicle. Never burned up a starter yet.

But yes I agree it isn't the best on your starter.

Of course neither is trying to start a non-cranking engine over and over.

Hey sometimes you need to get a little drastic.

Besdies $300 worth of troubleshooting everything else ain't as bad as MAYBE a bad starter for what $125 (don't know never had to buy one...:-O) to be able to fix it.

 

Thanks to everyone for the suggestions.

This morning, it started on the first attempt. 2 hours later, it wouldn't fire. Still won't.

I have checked all connections for moisture and also all ground connections. I also forced the engine control relay closed, which had the desired affect of turning the "check engine" light off, but the engine start was not enabled. I don't have any way of doing a system check and will rely on the Ford service tech.

I hope it continues to no-start long enough for the Ford Tech to connect an analyzer. But based on past history, it will start up before that.

Below is a link to some photo's. Spaceman has very good taste on Rims. I bought the rims just after they were introduced. I would have like to used the 10" Rims but didn't want to raise the front end. The driver's side tire does scuff the inside of the wheel well if I hit a sudden bump, but it's a minor thing.

The truck has 65,000 miles. It has a stock 5.0 engine with the standard 3 speed w/od auto tranny. If I do anything with the drive train, it would be to change the tranny. I don't like the way this one shifts on kickdown or on hard accelaration.

The photo's were taken a couple of years ago when it had BFG 285/70-15 T/A radials. They weren't suitable for the vehicle and I had to run the pressures at ~15PSi so they would wear flat. They felt like balloons. I have since changed to the BFG Sport Truck T/A's in the same size. Much better. I have aslo added Stainless Steel bed rails. Oh yeh, also added dual exhaust with 3.5" dia tail pipes.

Next year, it's going into storage. 10 - 15 years from now, it should draw some attention.

Thanks again to everyone for all the help. I have no objection to running the starter motor for an extended time, but I think this now needs expert analysis. hopefully the readout will give a specific reason for the failure.

If the problem still can't be found, I'm bringing in a Priest. If that doesn't work, then I'll try a Rabii.



https://www.f150online.com/galleries....cfm?gnum=1862

 

Rugby,

Nice truck. Now lets get the darn thing started.

By the way I'm across from you in Melbourne, Fla.

Almost neighbors

 

Very, very nice truck you have there, and yeah I do like those style of wheels. My friend that I bought mine from put them on. The only thing I dont like about them is that you cannot put wieghts on the outside to balance them. My truck has 220k on it and I drive it 20k a year, and will It was basically mine and my buddies first nice truck, so it too will be around for ever. Im planning a ground up resto in about 5-10 years. Ill probably have over 300k on it before I resto it. I dont know if anybody else takes me seriously or not but barring any idiot from smashing the thing to smitherines, Im like you, it will be sitting in my garage all nice and pretty again in a few years. Its more than a truck to me. 'Nuff about that.

Does your truck seem to do it when it is hot but after it cools down its fine? I had that problem. It seemed intermitent and very similar symptoms as yours. I never really noticed that it was after it was hot, and there was one morning that it wouldnt start. Mine would start after about 2 hours of cooling down. a couple times I wasnt getting fire and I'm not so sure that I didnt have 2 problems going on. I replaced the TFI module and coil, but I still had problems getting it started. Frustrated the bejeebeze out of me. It ended up being the TPS sensor was putting out 3 volts, where as its supposed to only put out one volt at idle. It was putting out like it was at hwy speeds and flooding too much fuel in (although I never smelled it). The mechanic told me that he got it to start by pushing the accelerator all the way down so that the air intake met the fuel demand. Anyhow, the TPS was the culprit.

BTW, you can buy a code reader from the local parts store for about $25-$30, if your computer is not OBD II. I am told you can read the codes using a paper clip, but sounds a little kinky... I mean complicated to me. The reader comes with a book and list of codes, and is simple to use. Your truck should store codes from past running times (like the past 40 or something?) so you might be able to pull the code and find out. I bought one since I had problems.

Let us know what you find out.... Im interested.

 

Thanks Guy's

I'll let you know the cause, if and when I found out. By the way. The no start condition happens when it has been sitting for a while. But not all the time. Somtimes it "decides" to start.

And they say there's no such thing as artificial intelligence. BS!

 

Hello All,

Lot of good guesses but you answered the question with your first statement. What's Wrong? the crank sensor.
On a Ford, while cranking, if the check engine light does not go out, there is no signal from the crankshaft, there fore the computer will never fire anything. If the light goes out, then the crank signal is present, and there are other problems.
I'm a tech and that's what they said in Ford School 101. Has worked for me a couple of times in the past. Ask your Ford mechanic about it. The "check engine" light is the clue.

 

See randymechanic agrees. The crank sensor will give the RPM signal for the ECU to detect. I didn't call it the crank sensor sense I didn't know if that is what they called it on the 95s. I thought it could have been a Cam Position Sensor I have a 97 so I didn't want to assume the set-up was the same. But this is the same discussion. You can't really verify it though unless you can watch the output, short of changing it out as a hopeful fix.

 

Here's an update.
First, I installed a new ignition switch. It only cost $19. so I figured it was worth a try. The truck started on the first attempt. Ran great all day. The following morning, it didn't start. I wiggled the harness to the switch, then it started. Well, at least the exercize proved that my logic, about the switch being the common denominator, was incorrect.
The engine quit again while I was driving to work. Nothing I did would get the engine started, So i had it towed back to the Ford dealer where it started on the first attempt. It has not failed since.
The technician at Freedom Ford, in Oldsmar. feels that it is the crank position sensor. I can't say enough good things about the guys at Freedom Ford. Dennis, the technician and Craig, the manager, have spent a lot of time already without charging a dime. The truck is presently inhabiting one of their bays with the break-out box attached. Now we are just waiting for it to no-start.
If the truck does not fail to start within the next 2 days though, I will take Dennis' advise and have the Distributor and sensor changed.
Thanks Randy and TallTom for echoing Dennis' idea. I feel more confident now about the fix.