Frustrating Crank/No Start situation on 2010 Mustang

[NotMyS197]

A buddy of mine is having an issue with his 2010 Mustang. One day, as he was backing out of his driveway, the car just stalled. He tried cranking and it just cranks with no start. He calls me up and I go verify that it has spark, but I don't hear the fuel pump priming. I check all fuses and relays related to the fuel pump and they all check out. I pull the fuel pump and test voltage at the connector to the fuel pump. I am getting 13ish volts to the fuel pump positive wire (yellow/white). I think "must be a fuel pump" and order/install a replacement. Even with the new no fuel pressure up to the engine, not even a peep from the pump. So, I double test the old and new pumps with direct power and they both spring to life. I then replace the FPDM, but once again, nothing. I try splicing into the (white/brown) fuel pump negative wire and jumping that to ground. The pump whirs to life and the car starts upon cranking.

SO, it seems the issue lies somewhere between the FPDM and the PCM. I am thinking maybe the fuel rail pressure sensor could be falsely reading too much fuel pressure, causing the PCM to not allow the pump to turn on? Does the FPDM break connection from the negative (white/brown) wire when it is told to turn off the pump? So far, we are $300 into this repair and getting pretty frustrated. Also, to splice into the wire, I had to remove a little bit of the shielding and unravel the wire one time around to get it spliced, am I good to solder/heatshrink this back and get the shielding as close as I can without causing issues with the PWM...? Thanks.

 

[07gts197]

Put a code reader on it and check the crank position sensor.


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[NotMyS197]

Put a code reader on it and check the crank position sensor.


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I should note that we already replaced the crank and camshaft position sensors. We also just replaced th fuel rail pressure sensor and still got nothing. We dont have access to a scanner.

 

[07gts197]

I should note that we already replaced the crank and camshaft position sensors. We also just replaced th fuel rail pressure sensor and still got nothing. We dont have access to a scanner.

Is the theft light flashing? Did it rain a lot before the issue?


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[NotMyS197]

Is the theft light flashing? Did it rain a lot before the issue?


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No, the theft light turns off a few seconds after putting the ignition in the run position. It was cold (around 35F), some water seems to have gotten in from the back window but I don’t see any exposed or damaged wires anywhere.

 

[Poonisher]

Could be water incursion into the smart junction box, or possibly fuel inertia switch by drivers kick panel.

 

[DieHarder]

It's a given this thread is a couple of years old however just dealt with a crank; no start condition. Car operated flawlessly up to this point. No indication of anything wrong; no codes.... In my case narrowed it down to the fuel circuit; switched a few things around; reset the inertia switch; tested a few fuses/relays; switched the diodes; checked the FPDM cabling/unit. Retested, everything working, probably something loose or inertia switch. Either way, back up and running now.

Actually found this YouTube vid of great assistance which helped explain the circuit front to back and the majority of the in-between things to check out & test. Showed me a couple of things I didn't know (not that that's hard mind you). Worth the time to review IMO.

 

[DieHarder]

So, the dreaded crank/no start returns; then vanishes again.

I have some puzzling symptoms.... intermittent crank/no start condition; the hardest kind of electrical issue to deal with. The car will turn over but not start. Fueling circuit; likely. But when it works obviously the symptoms aren't there. Difficult part is, it doesn't fail at home. Only while I'm on the road. Get her back home; mess with a few components or let her sit a few days and she starts right up, maddening.... Wish she'd just fail completely so I could find what's going on. Damn thing is vexing. Ideas anyone?

 

[GlassTop09]

So, the dreaded crank/no start returns; then vanishes again.

I have some puzzling symptoms.... intermittent crank/no start condition; the hardest kind of electrical issue to deal with. The car will turn over but not start. Fueling circuit; likely. But when it works obviously the symptoms aren't there. Difficult part is, it doesn't fail at home. Only while I'm on the road. Get her back home; mess with a few components or let her sit a few days and she starts right up, maddening.... Wish she'd just fail completely so I could find what's going on. Damn thing is vexing. Ideas anyone?

Question DieHarder, how hot is it getting where you are now? Next time (if you keep a scan tool in your ride) the car shuts down on you & you get a crank\no start situation, hook the scan tool up & check the car's FRP........you might be experiencing fuel vapor locking (bubbles forming in fuel line\rails causing momentary loss of fuel to injectors until the system cools down\sits long enough for the bubbles to disperse allowing fuel to return to the injectors then car starts up as normal). I know this may sound odd but even fuel injection systems, especially returnless systems, can vapor lock (why check the FRP for abnormally high press.......symptom of PCM trying to arrest vapor locking by raising the FRP above the desired operating 39-40 psi to raise the fuel's temp flash point to stop the bubbles from forming).

Your comment "only while I'm on the road" is saying to me the intermittent crank\no start issue may be heat-related & the engine fuel rails come to my mind, especially if you have any coil covers installed (I have these installed on my car & I'm already seeing FRP's at idle after a run up as high as 46-48 psi.... it's only May & AAT's are in the high 80's at the moment in the US 4 Corners area) then slowly come back down to normal as the under hood temps drop so something else to consider.......if you haven't already.

Hope this helps.

 

[DieHarder]

Around 70's - 80's right now. No coil covers installed. I've got a DOB on it with mods to the FPDM and a Walbro 405 fuel pump. Everything was very reliable up to a couple of weeks ago. Never had a problem in the past no matter how hot environmentals were. Other symptoms I experienced when it acted up the second time was the engine would try to start and then act like it was starving for fuel. Towed it home. The next day started right up. Drove it to the airport and back; no problem. Then the very next day it wouldn't start. Left it in front of the house for three days. This afternoon she started right up.

Thinking I'm going to trace electrical for the fueling circuits; ensure everything working as it should and maybe pull the pump if there's not a good way to ensure it's actually coming on. Have an SCT x4 and the car is wired for tuning (by Lito). Can I check FRP w/an x4? Or, would running a file possibly reveal what's going on? No codes and no faults that I can find.

 

[DieHarder]

If I'm experiencing what you're describing as heat related fuel vapor locking. How can that be dealt with? Can't have the car stranding me just because it gets hot.

 

[GlassTop09]

Around 70's - 80's right now. No coil covers installed. I've got a DOB on it with mods to the FPDM and a Walbro 405 fuel pump. Everything was very reliable up to a couple of weeks ago. Never had a problem in the past no matter how hot environmentals were. Other symptoms I experienced when it acted up the second time was the engine would try to start and then act like it was starving for fuel. Towed it home. The next day it started right up. Drove it to the airport and back; no problem. Then the very next day it wouldn't start. Left it in front of the house for three days. This afternoon she started right up.

Thinking I'm going to trace electrical for the fueling circuits; ensure everything working as it should and maybe pull the pump if there's not a good way to ensure it's actually coming on. Have an SCT x4 and the car is wired for tuning (by Lito). Can I check FRP w/an x4? Or, would running a file possibly reveal what's going on? No codes and no faults that I can find.

If any of the gauge file PIDs are set in file to allow the X4 to access PCM's FRP PID then yes it should be able to display it.
Always in a situation like yours, running a datalog while driving the car when it acts up will be valuable info to assist w\ diagnosis. It's what I would do before doing anything else as at this time I think you've already touched on the most common causes but keep coming up short.

A PITA I know, but sometimes getting\having the running data can expose the intermittent issue when it occurs.

 

[Midlife Crises]

Fuel pressure and temperature are available in your SCT datalog along with the fuel pump performance.

 

[GlassTop09]

If I'm experiencing what you're describing as heat related fuel vapor locking. How can that be dealt with? Can't have the car stranding me just because it gets hot.

2 things can cause vapor lock.......unstable fuel (meaning the fuel's temp flash point has changed or is off.....lower than it's tested rating should be.....unleaded fuel's temp flash point is usually around 73*F, will have to look this up for ethanol) or high heat hotspot(s) somewhere in the fuel line to engine (usually w\ LTH's installed where they come into close proximity to the fuel line headed into engine fuel rails or the fuel rails themselves from trapped heat causing the fuel temp to rise above this flash point causing the fuel to start vaporizing--bubbling--in the system causing the fuel flow to slow & become very erratic.....enough to starve the injectors of fuel thus engine dies). The PCM can detect this happening thru the FRP sensor & tries to stop it by increasing the fuel system's pressure to stop the fuel from vaporizing.......this is why I made suggestion to check the FRP for abnormally high pressures under a low load\no load scenario.......a telltale of this occurring. When it's a fuel pump\wiring issue the FRP will usually immediately drop rapidly (or spike high & stay high) but never spike up high before the drop happens.......This particular symptom usually will be associated w\ your right foot....or a malfunctioning FPDM.

This is where a running datalog of the FRP operation can shed some light on this intermittent issue to determine if the fuel system (or something else) is actually the cause of this or not & if it is, what part to focus on based on the captured data results.

 

[redfirepearlgt]

I had a similar thing happen on my 99 F150. Turned out to be the fuel pump was bad. The FP relay was energizing and providing voltage through to the FPDM and voltage was getting to the fuel pump but I never heard the pump energize at KOEO. Then suddenly I did hear the pump cycle on with another attempt after putting everything back together the truck started. Drove it around the block, parked back home, shut off, and then would not restart again with same symptom. Don't assume you are out of the woods here unless you actually verified that the inertia switch you 'reset' was truly tripped and you saw zero volts coming off pin 1 of C282 (white wire) with a voltmeter when you went to KOEO. Inertia switches don't just up and trip out unless a door or trunk is slammed extremely hard. Learned not to do that on my 1984 Escort GT when I was mad about something once. Car would not start and had to be towed. The service guy showed me this thing called an inertia switch, reset it and away I went after paying the bill. Lesson learned. Best of luck.

 

[Juice]

I am struggling with the vapor lock theory. Fuel is under much higher pressure in the supply line in EFI cars vs carb'd.
So, Im going to assume return style fuel system, aka, "fuel warmer". I know this first hand w/my fox. However, it never vapor locked even with fuel boiling in the tank.
I suspect the heat issue is with the electrical modifications to the fuel system. That would be my best guess. So, next time it wont start, remove gascap and see if there is any pressure buildup in the fuel tank to support or rule out vapor lock.

 

[DieHarder]

I do have a datalog setup; Livelink (used to tune the car) so I'll check to see what PID's are in it; run a datafile and post. Before that however I'm going to go thru the fueling circuit and recheck everything. BTW, I have a 2006; not 2010 but same basic engine layout sans a few differences. If I find anything wonky I'll post for the group to chew on.

 

[DieHarder]

I am struggling with the vapor lock theory. Fuel is under much higher pressure in the supply line in EFI cars vs carb'd.
So, Im going to assume return style fuel system, aka, "fuel warmer". I know this first hand w/my fox. However, it never vapor locked even with fuel boiling in the tank.
I suspect the heat issue is with the electrical modifications to the fuel system. That would be my best guess. So, next time it wont start, remove gascap and see if there is any pressure buildup in the fuel tank to support or rule out vapor lock.

Not a return style system; stock setup save the upgraded pump.

 

[DieHarder]

I had a similar thing happen on my 99 F150. Turned out to be the fuel pump was bad. The FP relay was energizing and providing voltage through to the FPDM and voltage was getting to the fuel pump but I never heard the pump energize at KOEO. Then suddenly I did hear the pump cycle on with another attempt after putting everything back together the truck started. Drove it around the block, parked back home, shut off, and then would not restart again with same symptom. Don't assume you are out of the woods here unless you actually verified that the inertia switch you 'reset' was truly tripped and you saw zero volts coming off pin 1 of C282 (white wire) with a voltmeter when you went to KOEO. Inertia switches don't just up and trip out unless a door or trunk is slammed extremely hard. Learned not to do that on my 1984 Escort GT when I was mad about something once. Car would not start and had to be towed. The service guy showed me this thing called an inertia switch, reset it and away I went after paying the bill. Lesson learned. Best of luck.

Already knew about the Inertia switch. No change. Was thinking of bypassing it for testing; just to rule it out. If bypassing it increases reliability I'll look at getting a new one. Will do some testing and let you know what I find out.

 

[DieHarder]

I am struggling with the vapor lock theory. Fuel is under much higher pressure in the supply line in EFI cars vs carb'd.
So, Im going to assume return style fuel system, aka, "fuel warmer". I know this first hand w/my fox. However, it never vapor locked even with fuel boiling in the tank.
I suspect the heat issue is with the electrical modifications to the fuel system. That would be my best guess. So, next time it wont start, remove gascap and see if there is any pressure buildup in the fuel tank to support or rule out vapor lock.

Hadn't thought about the gas cap. Will try that next time it won't start. Only electrical mods were adding larger gauge power wire to the FPDM and a higher capacity fuel pump. Otherwise stock.