Fuel problem, code P0190

Black GT

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Sep 8, 2018
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Jacksonville, Florida
About a week ago I came home and my car sat for maybe 5 minutes. When I got back in the car and started it, it started sputtering like it was starving for fuel and stalled out. I turned the key to the off position and back to start and the car started right up and ran fine.Since that time I have put maybe 200 miles on the car with no problems. Today I was at the drive thru and turned the car off while waiting for my food. The car had been running good before this. When I started the car it sputtered for a couple of seconds and stalled out. I turned the ignition to the off position and started it again and again it sputtered and stalled. This happened 3 times. On the 4th off to start cycle the car started and ran normal on the 6 mile ride home. On the ride home I noticed the service engine light was on. The code is P0190 fuel rail pressure sensor. I turned the car off when I got home and immediately started it and it ran fine. The only other issue I have noticed is when idling in heavy traffic or in drive thru lines every couple of minutes the idle will drop to around 400 rpm's but will immediately recover.Since the car runs great other than the times mentioned I do not think it could be a clogged fuel filter. I am thinking it is probably the fuel pump going bad. About a month ago The car would not start at all. I traced that to the fuel pump shut off switch. I fixed that problem by bypassing the switch and connecting the wires together. I don't think that problem was related to the problem I am having now. The car would not even sputter when the switch was bad it would just keep turning over. Any input on this is appreciated.
 
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Black GT

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Sep 8, 2018
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After doing some research going to check the wiring and connectors to the FRPS in the morning. Seem weird though, All the post I have read the posters cars would not start at all. Can not find anyone that was having the same problem I am.
 

wmburns

SN Certified Technician
Aug 14, 2009
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Houston Texas
The FRPS is a "no start" sensor. That is IF the PCM is missing a valid FRPS signal it should be expected the motor will not start.

Anytime the DTC calls out a "circuit malfunction" it means there is something sooooooooo wrong with the circuit that the PCM is unable to perform any diagnosis. Think:
  • Totally failed sensor
  • dirty/loose connector
  • wiring fault
  • short to ground or short to power
If this were my car I would start with a through visual inspection of the wiring to/from the FRPS.

>>>
P0190 - Fuel Rail Pressure Sensor Circuit Malfunction (FRP)

  • VREF open in harness.
  • VREF open in sensor.
  • VREF open in PCM
Verify VREF voltage between 4.0 and 6.0V.
 
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Black GT

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Not meaning to sound dumb, but what is VREF short for? This is the freeze frame data my obd2 scanner had stored from the p0190 code. Fuel sys.1-OL, Fuel sys..2-n/a ,Calc Load-20.8%, ECT-208 degrees, stft b1-5.5%, ltft b1-1.6%, stft b2-5.5%, ltft b2-24.2%, Fuel pressure-17.0, RPM-753, SPEED-0. Don't know if anything can be deciphered from this.
 

Black GT

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Just did a visual check and all wire look in good condition, connectors and plugs are all tight, Battery terminals are clean and tight and all grounds appear good. All vacuum lines look almost new and are hooked up and tight. I almost wish this was not a intermediate problem. It would be easier to find.
 

wmburns

SN Certified Technician
Aug 14, 2009
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Houston Texas
VREF=Voltage reference. Normally the 5 volt PCM reference but could be a 12 volt reference.

On your freeze frame check out the reported fuel pressure at 17 (PSI?). Also look at the fuel system 1 value of "open loop".

Note: IF the FRPS value is accurate then look at a problem with the fuel pump as 17 PSI is WAY too low (should be 40 PSI).

Note2: an ODB2 scanner with graphing capabilities could make the trouble shooting easier. Consider that graphing the FRPS over time could reveal where the problem is.
 
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Black GT

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I used the graphing mode on my scanner today monitoring fuel pressure. Here are some pictures. The first one is at start up. The others are at idle. Of coarse the problem was not happening. I turned the car off and started it back up 7 times but could not create the problem.
IMG_0753.jpg
IMG_0753.jpg
IMG_0756.jpg
IMG_0758.jpg
 

Black GT

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Sep 8, 2018
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I have gone out every day and started the car actually hoping it would act up so I may be able to trace the problem. The car starts right up and runs great. I even took it around the block yesterday but I am afraid to drive the car anywhere . I am scared it will shut off and not start back up. I don't think it would do any good to run any test since the problem is not there right now. I am very tempted to buy a new fuel pump and install it in hopes that will end the sometimes problem but hate to waste the money if the fuel pump is not the problem. A fuel pump is $200. I really do miss driving the car though.
 

Onesick99GT

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Nov 20, 2018
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My old ride a (2000 ford ranger) did this exact thing. It went on for 6 months. Replaced fuel pump and it never did it again. How many miles are on the car? My guess would be the fuel pump. I would also change the fuel filter at the same time. Fuel pressure drop would definitely lead me to a fuel pump failing. Sounds like it needs replaced. There isn't much to diagnose and replace when talking about your fuel delivery system. An injector failing wouldn't cause this issue unless all fuel injectors were failing at the same time. A clogged fuel filter would read low fuel pressure and cause very bad drivability. Like it was miss-firing when a spark plug goes bad. A fuel leak could be the issue but it would stay consistent and not leak no occasion plus fuel would be everywhere. Replace the fuel filter if you went over your wiring. You could also inspect the wiring to your fuel pump if you have a lift. Did you notice these problems occurring when it rained or were you driving it on sunny days?
 

Black GT

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The car has 213k miles on it. The engine was rebuilt about 30k miles ago, but I am not sure if the fuel pump has ever been replaced. The car has been very well taken care of all its life and even has original paint on it. It was not raining when the problems occurred. The weather was nice when it acted up. Every time its happened the car was running great and I turned the car off. Then within 5 minutes I started the car back up and it sputtered and stalled after a few seconds. Its like the fuel pump is not working and the car sputters off the fuel that is in the fuel rails. Each time it has happened so far after turning the key off and then back to start a few times its like the fuel pump starts working and the car runs great again.
IMG_0517 (1).jpg
IMG_0519.jpg
 

Onesick99GT

Active Member
Nov 20, 2018
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Dayton, Ohio
If you choose to wait on replacing the fuel pump I'd suggest you keep your obd with you in the car in case the same situation happens you can datalog. When this happens again try having someone turn the key forward, and listen for your fuel pump to kick on. You should hear a humming sound for 1 to 2 seconds. If you don't your fuel pump isn't working. Whenever you are driving if you notice any hesitation when giving it gas like cuts on and off or just doesn't go when throttling is another sign of a failing fuel pump. if it were me I'd replace the fuel pump before it quits and then you have a tow bill and the hassle.
 
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Black GT

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Going to order one tomorrow. I can get one manufactured by walbro for $160. From what I have heard they are a pretty good brand. I have not experienced any hesitation while accelerating but have experienced a momentary drop in RPM's while idling, but it catches and goes back to normal idle. Thanks for the advice and help.
 

Black GT

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Will do, I ordered the fuel pump but it has not arrived yet. I am going out of town this weekend so will probably be middle of next week before I get it installed. I took the car around the block yesterday but afraid to go any further than that. lol. Thank goodness I have another car to drive while the mustang is down.
 

Black GT

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Well after I bought the Walbro I read several articles that walbro fuel pumps are not good to use with returnless fuel systems. So I did not install the walbro. Yesterday I went and bought a delphi from autozone. Don't really know about that brand but it does come with a lifetime warranty. In the reviews a guy stated he has had one in his truck for 6 years with no problems. The car has gotten now to where it will not start. There is no fuel pump sound when the key is in the run position. I also depressed the schrader valve after turning the engine over and no fuel whatsoever came out. I then unplugged the fuel pump harness and with the key in the run position I have power at the plug. So I am confident it is the fuel pump. I was going to replace it today but it is raining and the car is not under cover so it becomes tomorrows job.
 
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Black GT

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I went ahead and did the job today. Car started right up when I was done and seems to be more responsive. The walpro pump I bought I think it said it was a gerotor pump or something like that. I think walbro makes turbine pumps that work fine with returnless . But to be honest, I am only going on what I read and there is a lot of wrong information on the internet. Anyway I used the delphi pump.
 
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