Performed TSB to relocate fuse 27, but truck still wont start

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Rmz450rider70

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Back story: I have a 2013 Screw with 70,000 miles. Around 60,000 miles I had my first occurrence of "crank but no start", but after the first failed attempt to start the truck all I did was turn the ignition all the way off and try it a second time, it fired right up.

Two months ago (approx 1500 miles) I had my second occurrence of "crank but wont start." Coincidentally it happened right after having fat fingers and hitting the remote start button one too many times to where it did half a crank and stopped. I was walking up to the truck when this happened so instead of trying remote start again I just got in and turned the ignition. I tried it twice and it just cranked but wouldn't start. First, I checked my tuner for any logged codes, then I pulled out my phone and began to search good ol' google. Unfortunately before I could find the numerous threads about the infamous fuse 27 I tried starting the truck again and it fired right up. At that point I assumed that when I mashed the remote start button 3 times instead of 2 that I had triggered some sort of fail safe and I just had to let it "time out", thus why it fired right up for me about 5 minutes later.

Current situation:This is my third occurrence of "crank but wont start". It didnt take long to figure out that Fuse 27 was blown due to the black $h** stain on top of the fuse. I replaced the fuse and the truck still wouldn't start. I started researching and that's when I found all the forums about fuse 27, so I ordered the relocation kit. I crossed my fingers that the reason simply replacing fuse didn't temporarily fix the issue as it has for every other person in every forum I read so far was because by the time my fuse 27 finally completely let go it took the fuse terminals to the grave with it. I installed relocation kit with out any issue, but the truck still wouldn't start.

So I started trying to troubleshoot further:
-I switched relays 6 and 8 and nothing changed.
-I have removed and visually inspected every fuse in the engine compartment fuse block.
-I have tried using both keys.
-I had my girlfriend turn the ignition on and off and I DONT hear the fuel pump priming.
-I also listened and placed my finger on the relay as the ignition was being cycled and I CAN'T feel the relay click on when the ignition is cycled on, but I can FEEL it click as the ignition is cycled off...
-I have confirmed no less than 9 times that I cut and soldered into the correct wire while installing the kit
-I checked for voltage at the fuse terminal, then plugged the fuse in and checked voltage at the relay, all voltages are the same.
-Here is where I'm getting stumped, I switched the DVOM to resistance, and with the positive lead going into the fuse block disconnected, and Fuse 70 and Relay 8 removed, I and placed one lead of the multi-meter on the new blade connector I installed during the fuse relocation kit (power coming out of the fuse) and the other lead on the connector for power coming into the relay and I got a reading of 1.4ohms. I know there shouldn't be that much resistance in a wire that short. Also, I am very confident in my ability to simply solder 2 wires together, but I have seen crazier things happen.
(Note: When installing the fuse relocation kit I cut the blue w/ red stripe wire about 1" below when it came out of fuse 27, so most of that wire is still in the system)

Time for y'alls feedback: Do I have an issues somewhere in the rest of that blue/red wire between fuse 27 and relay 8, or am I getting a faulty reading out of my multi-meter. If the wire is fried, OR if I'm getting a faulty reading out of my meter then why do I get the same voltage reading at the fuse as I do on the other side of the wire at the relay (disclaimer: I haven't checked amperage). The only reason I haven't just gone ahead and replaced this wire entirely in order to eliminate it from the equation is because I don't know where I can get a new terminal connector for the relay side of the wire. Should I continue to focus my attention around the fuse block? Or should I go ahead and just throw a FPDM and/or a fuel pump at (I hate throwing parts at stuff) it since I don't have schematics to continue troubleshooting the rest of the wiring?

Any and all help/suggestions is much appreciated!

Fuse 27.jpg
 

BenBB

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Not an expert or electrical engineer but...could the range on the DVOM maybe set to like milliohms or whatever? Thorough diagnostics BTW. Symptoms sound to me to point to fuel pump OR burnt wiring between that relay and the pump itself. So were it me I'd double check that resistance, try a jumper wire there first, pull the pump and attempt a bench test (which would likely result in some sort of redneck flame thrower), and if that checks out trace the entire length of the wiring harness (I've seen a few threads about that particular harness running along the LH frame rail getting pinched or pulled and there's a great how-to on here somewhere about relocating it, worth doing IMO). That fuse being THAT burnt may well point to melted wire somewhere. Good luck!
 

The Car Stereo Company

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check voltage instead of resistance. start with one end of the meter at the bcm and the other end at the relay. work your way back from there to find where (and if) the broken connection is.
 
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Rmz450rider70

Rmz450rider70

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Update: I really appreciate the couple suggestions I've received so far. The time I've had available to work on the truck has been limited and spotty. I'm very grateful that I have a second car, however, this has made me realize that my car needs some TLC too since I always choose to drive my truck over it. Yesterday I rebuilt the wire going from the fuse to the relay, and the small gauge wire connected to the relay side that jumps over to the pull up side of the relay. That way I could be confident my problem wasn't there, and then move on to troubleshooting the wiring harness from there back. I tried to start her up after replacing that wire and she still wouldn't start.. I dropped the spare tire in order to access the plug for the Fuel Pump Driver Module. I visually inspected the wires at the plug and wiggled them to see if anything felt off. When I unplugged the connector for the FPDM a decent amount of sand came out of the connection. I blew both sides of the connection out with compressed air, plugged it back in, and went to go try to start her up. I turned the key and immediately heard the fuel pump. Vola! she fired right up!! I started the truck 3 times with no problem and then had to drop everything because I had somewhere to be and was already running late.

Now then.. what was the problem? What came first the chicken or the egg? Was the sand in connection the reason it wouldn't start, and in addition to that the poor connection it caused was also a factor in fuse burning up? -Or- Did the fuse blowing out cause problems downstream in the wiring harness and me wiggling the wires around allowed said problem to make enough of a connection to allow the truck to start now?

Once I get home in about an hour I'm going to:
1. Try to start it again without touching anything.
2. If it still starts then I'm going to wiggle the wires some more, disconnect and reconnect the FPDM connector, attempt to start the truck, then repeat the process at least a half dozen times in order to see if the problem resurfaces.
3. If I still can't get it to "crank but wont start" then I will just leave the spare off and drive it around for a few days, then recheck.

I will update this thread when I figure out more information.
 

BenBB

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Awesome, I was thinking about this thread and hoped you'd post an update. The more I thought about it, the less probable the pump itself seemed (sure it COULD have failed exactly when fuse 27 finally gave up, but more likely not), and even a burnt wire in the harness would likely result in unrelated symptoms (if the wire got hot enough to melt it could cause short circuits in, say, taillight wires or whatever else is in that harness). I had to google FPDM and found this thread in another forum:
https://www.f150forum.com/f4/fuel-pump-driver-module-check-yours-152908/
Looks like a common, or at least potential, failure point. Considering that, I would guess that in your case the sand in the connector contributed to the fuse 27 failure, as it wasn't making a good connection and drew too many amps...just a wild-ass guess though. Anyway good info and here's hoping you solved the problem and you don't wind up unraveling a wire harness looking for a burnt wire or dropping the fuel tank for a new pump.
 
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