# Truck won't start, sometimes!



## schreib (Apr 30, 2020)

Ford F250 Super Duty truck, 2003 and only 68K miles on it.
The other day I was at the home store and it would not start, battery and starter seemed great-- high starting revs and cranked well. The best it could do was try to start and take about two chugs and quit. Spent numerous times trying before calling a tow. Same thing happened to Repair shop and so they started out testing the fuel pump for flow pressure-- yep, had pressure but would not start. The next day when they planned search further it started right up?! Then, they tried it day after day for a week, multiple times a day and it refused to fail. So, the worst kind of problem-- intermittent failure. Can't diagnose because it is not IN failure mode. Good shop-- they charged me zero.

I have been using it for two weeks now and it just keeps running. Not a happy deal here driving a machine that decides on its own to operate. Can't feel secure taking it anywhere now. Previous owner had an odd thing happen to him-- what prompted him to sell it to the car dealer(Long story how I found this out!) He would be driving down the road and it would start running erratic. He and the dealer figured it was only firing on partial cylinders. They never were able to solve this-- over years!

I understand there is a "module" that handles all starting electrical and there is no starter "relay" as such.

*Any ideas for things that may be simple to just replace* so I can at least feel I have done SOMETHING to reduce the probability of failure??! This is nuts.


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## GrayHair (Apr 9, 2015)

No idea whether or not it's still there, but* if* it has a distributor, check the side for an "access door". You need a special tool to remove the door, but there is a module inside that can cause what you describe. Although I never heard of them going intermittent


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## Windows on Wash (Aug 30, 2011)

2003 will be DIS (Distributorless Ignition System). 

Check spark and coils. 

Crank position sensors can go bad on these as well.


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## schreib (Apr 30, 2020)

Windows on Wash said:


> 2003 will be DIS (Distributorless Ignition System).
> 
> Check spark and coils.
> 
> Crank position sensors can go bad on these as well.


Would the CPS have thrown a code if it was bad, or is that something you would know?
How about the coil (s). . . one on each cylinder or only one for the whole engine?


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## Nealtw (Jun 22, 2017)

Won't start sometimes, what do you have to do to get it started after it won't start?


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## SW Dweller (Jan 6, 2021)

Had the same thing happen to my F150. If the gas tank got below 1/4 full the fun began.
I finally noticed the relationship to empty tank and fuel pump. Ran it almost dry with 5 gallons in a can and dropped the tank. Replaced pump and filter, Never had another issue. Need a helper for speedy replacement. I did mine on the garage floor with jack stands.


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## iamrfixit (Jan 30, 2011)

Gas engine has a coil over each spark plug.

It can sometimes be the simplest thing! 

I worked on a friends 99 F250 with a 5.4 for months trying to narrow down a stalling problem. He had it towed numerous times, local used car dealer with a wrecker and repair shop usually towed him. Their shop installed a new fuel pump, then replaced that one about 4 days later after towing him in a second time. He didn't even make it home after the second pump install before it died again. Charged him over a thousand dollars for basically nothing! Warrantied the pump but charged labor twice for a faulty fuel pump diagnosis and they refused to make it right, or even help him out on the cost.

It would often die and then start right back up. Sometimes would have to be towed but by the time it got to wherever they took it, it would start back up. I changed the fuel pump relay after finding the fuel pump was not getting power. It ran for almost a month with no problem, but then died again. He called me repeatedly to pull it home or to my garage, I lost count of how many times. 

Finally one day we got it to my shop and it didn't start, so I began tracing. The fuel pump had no power, as I kept going down the line tracing each point I found that none of the ignition was getting power, not even the ECM. Was backtracking, checking a fuse in the under dash panel, going along and found a 30 amp fuse that had one side of it dead. Was going kinda quick and had to move back to the dead terminal to verify what I saw. Just as I touched the test point on the fuse again I heard something under the dash click and suddenly, everything had power. 

Pulled the fuse out and it looked fine, but one of the spades did feel a little loose, so I installed a new 30 amp fuse. The truck fired right up. Split the old fuse open with a chisel and the terminals came out in two pieces. This was a 30 amp fuse so it should have been pretty strong. I cracked a new fuse open and it stayed all one piece, didn't even break apart when i bent it. Knew right away that I'd finally found the problem. The fusible link inside the fuse had an invisible hairline crack right down the middle and had been making an intermittent connection. He's been driving it for about 5 years since that day and has never had another problem.

He paid to have it towed in probably 20 times, and I pulled him home with my truck at least that many. Don't know how much he spent taking it to the Ford dealer numerous times, plus the independent shop that charged him for two fuel pumps.


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## Old Thomas (Nov 28, 2019)

Check ground connections and all electrical connections. A bad connection or ground can cause intermittent problems.


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## Nealtw (Jun 22, 2017)

My son's wife had a pontiac with the same problems, the problem was in the ignition switch itself, there was a separate switch there just for the fuel when that got stuck the fuel pump would not run.
We first found it would run with out the weight of other keys hanging there, when that quit working we went on the hunt and found this switch stuck.
And that was after all the toe trucks and new ( this and thats) which some one guessed would fix it.


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## schreib (Apr 30, 2020)

Nealtw said:


> Won't start sometimes, what do you have to do to get it started after it won't start?


If it won't start I have no solution-- period. It sat at the repair shop for one day after they got it and would not start, then out of the blue, it just . . . STARTED. They were able to check fuel pressure and verify pump power and pressure but it kept on starting from then on. . . now, impossible to troubleshoot with it starting all the time. So, on pins and needles every time I drive it!


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## schreib (Apr 30, 2020)

SW Dweller said:


> Had the same thing happen to my F150. If the gas tank got below 1/4 full the fun began.
> I finally noticed the relationship to empty tank and fuel pump. Ran it almost dry with 5 gallons in a can and dropped the tank. Replaced pump and filter, Never had another issue. Need a helper for speedy replacement. I did mine on the garage floor with jack stands.


This sounds like a possibility since the tank was down to about 3/8 Full. But loses probability rating for me when you consider I put 4 more gallons in it and it still would not start, then, randomly started every time. To be fair I have not had the tank that low since. . . (in the note Below, _the 30 amp fuse sounds like a top contender!)_


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## schreib (Apr 30, 2020)

iamrfixit said:


> . . .* It can sometimes be the simplest thing!*. . . Pulled the fuse out and it looked fine, but one of the spades did feel a little loose, so I installed a new 30 amp fuse. The truck fired right up. Split the old fuse open with a chisel and the terminals came out in two pieces. This was a 30 amp fuse so it should have been pretty strong. I cracked a new fuse open and it stayed all one piece, didn't even break apart when i bent it. Knew right away that I'd finally found the problem. The fusible link inside the fuse had an invisible hairline crack right down the middle and had been making an intermittent connection. He's been driving it for about 5 years since that day and has never had another problem.


Wow, amazing. Great job trouble shooting. I will have to bring the truck in and have the shop check THIS out. Please, if you have any more specifics about the 30 amp fuse, location? fusible link or standard fuse? where located under dash? copy of elec. diagram?. . . any or all of this highly appreciated!
*thanks a lot*.


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## raylo32 (Nov 25, 2006)

The only time I ever ran into this was with my S10 pickup which, like yours, would randomly fail to start. Crank over fine, just no fire. I troubleshot all the usual spark and fuel stuff... long story short was that the fuel pressure was a little low while running but good enough at the very low end of the spec. But when I checked fuel pressure just on the battery (which was fine) the pressure was low out of the spec range which on that particular system = no start. A hot off the charger battery with max volts always started it. And out and about away from jump or charger if I kept cranking it it usually would eventually start... then the alternator's 14+ volts boosted FP enough to run fine. I scratched my head on this one for a long time but it was a weak fuel pump, IOW having seemingly good FP wasn't good enough. I wish it had outright failed. Not sure if that sort of thing can be an issue on your vehicle but something to consider and eliminate. Some are more sensitive to FP than others.


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## iamrfixit (Jan 30, 2011)

schreib said:


> Wow, amazing. Great job trouble shooting. I will have to bring the truck in and have the shop check THIS out. Please, if you have any more specifics about the 30 amp fuse, location? fusible link or standard fuse? where located under dash? copy of elec. diagram?. . . any or all of this highly appreciated!
> *thanks a lot*.


Don't remember which one exactly, it was a green 30 amp fuse in the interior fuse panel right behind the lower dash cover. Was a main fuse that supplied power for the ECM and fuel pump relay.

When I've encountered strange, intermittent problems like this since then, the fuses are the first thing I take a hard look at. Cheap enough you can just change the important ones out. If the problem continues then you can still use the old fuses elsewhere. This wasn't the first time I've found a bad fuse that looked to be fine, but definitely the most frustrating. 

Get a good wiring diagram and establish some points that you can test. Carry a multi-meter so you can quickly check a few things if it fails to start. Nothing worse than a vehicle you can't trust. With all the electronics on modern vehicles its almost surprising they work as well as they do. Every year it seems they make the wires ever finer and move everything more toward computer network controls over conventional wiring. 

Troubleshooting a power door lock in the rear door of a 2017 pickup recently, just barely out of warranty. I swear the wire was only about 4-5 strands of a super fine wire. In the rear door pillar I found a connector and the factory terminal crimped on had all but cut the wires off with only the insulation was holding it together.


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## Windows on Wash (Aug 30, 2011)

CPS doesn't always throw a code.

Be sure to check the impact/inertial sensor as well.


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## schreib (Apr 30, 2020)

iamrfixit said:


> Don't remember which one exactly, it was a green 30 amp fuse in the interior fuse panel right behind the lower dash cover. Was a main fuse that supplied power for the ECM and fuel pump relay.


*Excellent, thanks*. I will check that out and carry a voltmeter along!


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## Windows on Wash (Aug 30, 2011)

Any updates? 

I am going with CPS or inertia switch.


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## schreib (Apr 30, 2020)

Kind of amazing here. Lots of replies and great ideas for top places to look:
CPS, main fuse, inertia switch. . . I posted the same text on Ford truck forum and got hardly anything.. . Maybe the DIY folks just "care" more . . .?!
thanks guys, when I find it I will let you know.


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## Brainbucket (Mar 30, 2015)

Question. Does it crank but no start or no crank. I need to know which way to go. That is 2 different avenues to diagnosis.


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## schreib (Apr 30, 2020)

Brainbucket said:


> Question. Does it crank but no start or no crank. I need to know which way to go. That is 2 different avenues to diagnosis.


Thanks for helping by the way!. . . cranks like a demon! Great battery and starting "system". It seems the highest probabilities are: partially tweaked fuse, CPS, Starter relay(soldered to main board), and inertia switch. Let's see where your diagnosis goes though, just the same. Unfortunately, I can offer no electrical testing results as of yet. Willing to test as you direct though! thanks again Brainbucket. . . 

in the meantime, it has been starting every time tried for the last 3 weeks!
Brian


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## Brainbucket (Mar 30, 2015)

It almost sound like a bad fuel pump or pump relay. Thing is when it doesn't start, you need to have a fuel pressure test gauge on it to see if you are getting fuel pressure and test for spark. Need to make sure you have voltage to pump when it's a no start. Pull a ignition coil and put a test light with a regular bulb and it hooked to ground and see if it has spark. Should be about an inch jump.


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## bob22 (May 28, 2008)

My Mopar car in the late 90's had a faulty engine computer that thought car was being stolen so it shut off the fuel injectors.
Sounded like it would start, putted a time or two, then just cranked.
Rebuilt computer and all was well again.


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## schreib (Apr 30, 2020)

Excellent guidance guys, thanks. Nothing about this sounds simple-- especially since the troubleshooting work can't start until it again, finally, refuses. . . !

My mechanic apparently felt this was fuel pump related too, 1st thing he tried, but then it started and all testing stopped.

thanks again for the pointers.


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## HotRodx10 (Aug 24, 2017)

bob22 said:


> My Mopar car in the late 90's had a faulty engine computer that thought car was being stolen so it shut off the fuel injectors.


That just jogged my memory. My cars with chipped keys will crank but not start if it doesn't read a valid code from the key. If it does it again, look at the security light on the dash to be sure it went out, indicating that the computer is reading the chip in the key.

Additional info:

Found this on Justanswer -

Q:
I have a 2003 Ford F-150 and the anti-theft system isn't recognizing my keys and it sometimes will not start. Does the dealership have to fix this ? When I turn the key initially,
the theft light on the dash flashes quickly and the odometer has dashes across it.

A: Usually this isn't the theft system at all. The dashes in the odometer are the clue. In 03 models when this happens it is usually caused by a bad pcm relay in the underhood fuse box. Replace the relay and this should solve your problem. We see this all the time!

This was for the F-150, but it might be the same on yours:


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## wrangler (Oct 9, 2008)

Agree with possible ground/short issue. Had a silverado that had intermittent starting (all lights would come on but no crank) or start right up. Starter seemed fine so decided to replace ignition switch. Nope. Decided to replace starter to eliminate that as a possibility and while undoing the terminals noticed some plaque/corrosion on them. Cleaned them up and never had another issue. Another truck with intermittent issues had a bad motor ground issue. Father-in-law's truck issue was an intermittent short in one of the wires running to the fuel pump. 
I feel for you because intermittent issues are the hardest to track down, much like the hairline crack in the fuse mentioned earlier.

Good luck and let us know if you resolve it!


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## schreib (Apr 30, 2020)

thanks again guys. This F250 has standard, non-chipped key; the remote and auto-locks were stripped out a couple of years ago by a tech who claimed that was the source of it not starting. ironic, huh?! I don't go there any more. 

I wish I could say I have actually done something in the way of solving this. Hopefully I won't wait until I am stranded again. Don't think it is a main ground since it cranks like a banshee, but the intermittent break in the wire to the pump itself sounds probable. I will add that to the list: no order of priority. . .

-- wire break to pump, 
-- fuse bad, 
-- bad fuel pump relay soldered to PCM board, 
-- inertia switch, 
-- CPS, 
-- no spark from coils
-- lower probability is low fuel pump pressure from battery alone.


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## schreib (Apr 30, 2020)

wrangler said:


> Agree with possible ground/short issue. . . . intermittent issues are the hardest to track down, much like the hairline crack in the fuse mentioned earlier.
> 
> Good luck and let us know if you resolve it!


Well folks, unfortunately I did not solve this by sleuthing expertly using all the great input here. I waited until I was stranded again. Returned to the same shop who tested the fuel pump and last November they pressure tested again and installed a new one right before I had to drive 150 miles to a doctor. I filled the tank after the new fuel pump install and it never fully hit *F *mark. After driving about 30 miles to the doc it was down to nearly 3/4 Full. I was really having the YIPS! Well, long story short I arrived with about 3/8 tank and came all the way home before refilling when on "*E*", and it was *not* necessary. Still, about 5 or 10 gallons in tank! I ran it all winter and two weeks ago had the mechanic look at it and he replaced the pump with yet ANOTHER one for free. I figured he could just reset the zero or calibrate it to read the level correctly! Nope, no adjustability for that. I am still on the 1st tank after the 2nd install. We will see how close to zero it "goes"! I will update. . .


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## HotRodx10 (Aug 24, 2017)

schreib said:


> ...the mechanic look at it and he replaced the pump with yet ANOTHER one for free. I figured he could just reset the zero or calibrate it to read the level correctly! Nope, no adjustability for that.


My guess: He just didn't want to admit that he bent the float arm when he installed it.


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## schreib (Apr 30, 2020)

HotRodx10 said:


> My guess: He just didn't want to admit that he bent the float arm when he installed it.





HotRodx10 said:


> My guess: He just didn't want to admit that he bent the float arm when he installed it.


yep, likely did NOT install a new one, just bent it back in place!


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