Crank but No Start - Low Fuel Pressure

[Yoyofatboy]

Hello all!

Been running through getting my pre-owned 2018 FiST back up to speed. Just this week got a P1450 code for the purge valve so I ordered the fuel feed line assembly that includes the valve (D2BZ-9C047-E).

Today after driving for groceries it stumbled and sputtered for a second when pulling up to my driveway. Now I'm getting a crank no-start condition and its throwing P0087 & P00C6 as well as the old P1450.

Fuel pressure from the sensor is showing around 10psi, and I believe the sensor is working as intended as when i unplug it, no reading is given. I removed the rear seat and cleaned up the pump top to prep for replacement, and I can clearly hear the pump prime in acc mode and send during cranking. The pump has clearly been replaced before as noted by the mangled metal hole.

I ordered a new Low Pressure Fuel Pump, but it wont come in until Friday. Any tips or suggestions on where to check and test while I wait?

Thanks in advance!

 

[XR650R]

That's a tough one. I'll just bump it and hope someone else has something useful to add.

 

[TyphoonFiST]

Which fuel sensor? The low pressure sensor on the fuel line near the firewall or the High pressure sensor on the fuel rail?

 

[Yoyofatboy]

Which fuel sensor? The low pressure sensor on the fuel line near the firewall or the High pressure sensor on the fuel rail?

I unplugged the one on the fuel rail to test, but I can try the one on the firewall if you think that would yield a different result or provide further insight. The readout was just an overall “Fuel pressure at rail” reading from my basic scanner

 

[ShakenCoffee]

This person on Reddit had the P006C code you have, and replacing the low pressure sensor seemed to fix it for him: https://www.reddit.com/r/FiestaST/comments/197kaa6 View: https://www.reddit.com/r/FiestaST/comments/197kaa6/beware_of_the_low_side_fuel_pressure_sensor/


I had a P008B code recently, and fixed it by replacing that sensor. Similar to you, my car would sputter and then die occasionally before I replaced it. However, my car would still start before I replaced the sensor, and just periodically die while driving.

TyphoonFiST has a good guide on replacing the sensor, as you may have seen already. Though I am not sure if that sensor would be the culprit in your case.

 

[Yoyofatboy]

This person on Reddit had the P006C code you have, and replacing the low pressure sensor seemed to fix it for him: https://www.reddit.com/r/FiestaST/comments/197kaa6 View: https://www.reddit.com/r/FiestaST/comments/197kaa6/beware_of_the_low_side_fuel_pressure_sensor/


I had a P008B code recently, and fixed it by replacing that sensor. Similar to you, my car would sputter and then die occasionally before I replaced it. However, my car would still start before I replaced the sensor, and just periodically die while driving.

TyphoonFiST has a good guide on replacing the sensor, as you may have seen already. Though I am not sure if that sensor would be the culprit in your case.

Thanks for that information, I saw a lot of videos about that sensor and the one on the rail. All the threads/videos I saw had their cars still running, just stumbling/dying. Mine doesn't start at all due to the pressure so I figured I could rule out a sensor fault. Though im about to hit 90k miles so it might be a great "while-youre-in-there" thing to get done as well.

 

[Yoyofatboy]

New fuel pump did not resolve the issue, still seeing the same fuel pressure levels. What else would cause it not to fire??? Are the sensors really that detrimental to starting the car? Lost now

 

[ShakenCoffee]

New fuel pump did not resolve the issue, still seeing the same fuel pressure levels. What else would cause it not to fire??? Are the sensors really that detrimental to starting the car? Lost now

You could give replacing the low side sensor a try. They seem to be a relatively common issue with the Fiesta STs. I'm not sure how many miles are on your car, but I am about ~85,000 miles I think, and had the issue with that sensor somewhat recently.

This is where I bought mine:
https://www.fordpartsgiant.com/part...bmodel=&extra1=&extra2=&filter=()&location=pd:,

It's very easy to replace, and not terribly expensive. Definitely take a look at TyphoonFiST's guide. One thing I noticed when replacing mine, is that the line where it screws into moves a fair amount while you are trying to loosen and tighten the sensor. It was helpful to have another person there to hold the line in place, just to potentially avoid anything further down/up the line from being stressed unnecessarily.

 

[Yoyofatboy]

You could give replacing the low side sensor a try. They seem to be a relatively common issue with the Fiesta STs. I'm not sure how many miles are on your car, but I am about ~85,000 miles I think, and had the issue with that sensor somewhat recently.

This is where I bought mine:
https://www.fordpartsgiant.com/part...bmodel=&extra1=&extra2=&filter=()&location=pd:,

It's very easy to replace, and not terribly expensive. Definitely take a look at TyphoonFiST's guide. One thing I noticed when replacing mine, is that the line where it screws into moves a fair amount while you are trying to loosen and tighten the sensor. It was helpful to have another person there to hold the line in place, just to potentially avoid anything further down/up the line from being stressed unnecessarily.

Just replaced the Low side sensor. picked up a Dorman OE Sensor from O-Reilly's. Still same pressure readings, though goes up to 11-12psi when cranking.

At this point its got a new Low Pressure Fuel Pump, and new Low Pressure Fuel sensor but still unable to reach good rail pressure. I have a Purge Valve assembly in the mail from two weeks ago when i was troubleshooting the failure to purge CEL, but otherwise I'm stumped.

While I enjoy dailying my 944 again, I'd really like to get this car back up and running.

Thoughts on a clogged line somewhere? Whats the likelihood there?

Could a bad fuel pump relay still allow it to run but not at full capacity?

 

[Yoyofatboy]

Swapped Relay47 (Fuel Pump) with Relay52 (Blower Motor), did not resolve

 

[TyphoonFiST]

Does It have spark? Do you have a Cobb AP3?

 

[Yoyofatboy]

Does It have spark? Do you have a Cobb AP3?

I can definitely test for spark, but I replaced the plugs and co three months ago with woosh motorsports coils. What’s the easiest way to test on these cars? I have a spark tester light but unsure of how to fit it on.

No Cobb tuner available but I can get basic readouts on my scanner. Any readouts I should look for besides fuel pressure?

Gameplan for tomorrow is:
1. Try resetting the fuel system per manual
2. Starter fluid
3. Test for spark

 

[Yoyofatboy]

Got it started on starter fluid. Had no power but enough to get it into my driveway and out of the street. Died after 60-80 seconds of running so its getting fuel, just not enough.

My High Pressure Fuel Sensor comes in on Thursday but I'm not sure if that will fix.

Fuel rail pressure read 910kPa or 131psi when it stalled out, Fuel Level input at 31%.

Edit for clarification: It does not start back up unless starter fluid is present.

 

[TyphoonFiST]

It does have fuel in it? Even though it shows about 1/4 ful*

 

[Yoyofatboy]

It does have fuel in it? Even though it shows about 1/4 ful*

Yes plenty of fuel in the tank, verified when I replaced LPFP.

Can someone clarify when the HPFP is engaged? I read it only comes alive at higher RPMs, so I ruled it out on my issue, but that and the associated sensor is all that’s left on this fuel system that could be bad. Of course, assuming no lines are clogged.

 

[Yoyofatboy]

So the HPFS did not resolve the issue as expected so I really dug into the fuel system tonight. I decided to removed the HPFP and bench test it. When applying 12V it clicks once but nothing more. I’m thinking it’s locked up or not functional.

I also decided to test fuel flow from the lines as seen in the picture below. Fuel flows nice, smooth, and steady, which only leaves the HPFP as the final obstacle to the rail.

Picked one up to install from AutoZone and will post results. Attaching fuel rail pressure numbers for prosperity. The car will start after 8-10 seconds of cranking but sputter out immediately, as seen as the drop in pressure.

 

[Yoyofatboy]

ITS ALIVE! (Sort of)

Today I learned a failed High Pressure Fuel Pump can cause a no-start due to low pressure. Everywhere I read states the HPFP only activates under load. But, the $250 replacement HPFP from AutoZone resolved my fuel pressure problem and I was able to get it running.

The vehicle starts and idles great, until about 30 seconds it stumbles and dies unless throttle is applied. A dip in fuel pressure can be seen in attached image when it dies. It’s throwing a generic P0001 code for a stuck open sensor or something similar. I believe it’s one of the cheapy sensors I replaced during troubleshooting (HPFS notably).

I’m satisfied for tonight, got to drive it again and pull into my garage.

Will be putting back in my old High Pressure Fuel Sensor tomorrow to troubleshoot stalling problem.