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Where is the fuel pressure regulator?

Tiny
, DUSTY M
  • MEMBER
  • 2005 VOLVO C70
  • 2.0L
  • 5 CYL
  • 2WD
  • AUTOMATIC
  • 80,000 MILES
Car won't start when warm nor first thing when its warm outside. Have replaced fuel pump, fuel relay, coolant temperature sensor and cleaned the MAF. Also replaced pcv. Now think its the FPR but can't locate it. It is not on or under the injector rail, or near the steering. Don't know if its a mechanical FPR or electronic. Could it be on the fuel tank?
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Saturday, June 19th, 2021 AT 2:30 PM

10 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Your engine does not have a separate fuel pressure regulator, it is part of the engine control module. Basically it monitors and regulates the fuel pressure and then will set a code if there is an issue.

If you have no codes then I would just check the fuel pressure when this is acting up and find out if that is the issue.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Also, this could be a crank sensor issue so we need to check if the RPM is moving when the engine is cranking. Here is a guide that talks about possible issues from a crank sensor:

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

This info will help us get started. Please let us know if you have questions and what you find with this. Thanks
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Monday, June 21st, 2021 AT 5:57 PM
Tiny
, DUSTY M
  • MEMBER
  • 7 POSTS
Thank you very much for your reply. The RPM was not moving when cranking and the OBD indicated no engine revolution data was available to the ECU. So I replaced the crank shaft sensor. Good news! The car started but it stopped after two miles. I had to be towed to my local garage who have now replaced the cam shaft sensor as well. Same thing happened - started then stopped and the OBD saying still no engine revolution data is available to the ECU. The garage have reached to end of their diagnostic expertise and advised me it's the ECU and to go to a specialist garage. That means getting the car transported there (you couldn't drive it as it's too risky) ( 50/ 60) plus a fee of  83 for the initial diagnostics and any repairs would be on top. Add on tax (VAT) and I will have pretty much spent what it costs to have the ECU tested and repaired off the car. So it's either the ECU or a connection between the sensors and ECU which is faulty. Is it worth paying another  133 minimum to confirm whether it is the ECU or just take a chance and get the ECU tested and if necessary repaired off the car - about  200?
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Monday, June 28th, 2021 AT 12:22 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Did they pull the sensor out and make sure it is not contacting the tone wheel?

The fact that is runs for a short time and then shuts off and not to restart points to an issue with the sensor again. Just changing the sensor would not cause the PCM to suddenly see the signal again. This points more to the sensor.

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

The ECM can be repaired off the vehicle but this depends on what is wrong with it.

Again, if the sensor is changed and it causes the engine to start again, I suspect it is either faulty sensors or something causing the sensors to fail.

Please run through this material and let us know what you find. Thanks
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Monday, June 28th, 2021 AT 8:32 PM
Tiny
, DUSTY M
  • MEMBER
  • 7 POSTS
Thank you for your advice. I am a bit stuck to be honest regarding the sensors. I have read the attachments and I don't see there is anything in them which helps. Both are new a few days ago and been fitted properly by a local mechanic - they have just one bolt to hold them. I am not in a position to test them and I assume they must work because the car does run. I have brought the car back to my drive from the nearby local garage as they say they can do no more to help. It runs for 10 minutes then cuts out. So the problem must be heat related but finding out exactly what seems damned near impossible. Next step is testing the ECU or selling the car as is for someone else to fix. You need a special tool to get the ECU out which I haven't got so I will get back to it next week.
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Wednesday, June 30th, 2021 AT 5:40 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. I am just hooked on the idea that the crank sensor had an issue and then you replaced it and it started. Now when it gets hot it cuts off again. That points to a crank sensor as well. If you look at the one guide for crankshaft sensor symptoms, you will see that this is a symptom of them. The reason for this is they are called hall effect sensors and when they are faulty and get hot they go to an open circuit and that will cut the engine off as it doesn't know the position any more.

I understand that these are new sensors but this site is full of posts where the new part failed and caused a failure similar or the exact same as it was before.

This always throws us off because we assume that it was replaced so it must be something else.

After it cuts off when it is hot, does it restart right away or does it crank and not start until it cools down again? Again, that is a sign of a crank sensor.
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Thursday, July 1st, 2021 AT 6:33 PM
Tiny
, DUSTY M
  • MEMBER
  • 7 POSTS
Thank you for your reply. It doesn't start until it cools down again. I will clean the crank sensor connector with contact cleaning spray and see if that helps. Then try a second new crank sensor. Can they be tested?
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Saturday, July 10th, 2021 AT 4:21 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
They can be tested but they require a lab scope to watch the pattern. Otherwise you will just see various voltage readings from the meter and they won't mean anything. A failed sensor normally still produces voltage but it is the incorrect pattern so the PCM doesn't recognize it so it doesn't allow the start.

Thanks for the update. Please let us know how it turns out.
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Saturday, July 10th, 2021 AT 5:16 PM
Tiny
, DUSTY M
  • MEMBER
  • 7 POSTS
Thank you for your speedy follow up. I have trusted your advice/take on this and ordered a second new crankshaft sensor which should arrive in a couple of days. I will let you know if the new one solves the problem, or not!
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Sunday, July 11th, 2021 AT 6:40 AM
Tiny
, DUSTY M
  • MEMBER
  • 7 POSTS
KASEKENNY, you were right! 12 out of 10 and 5 gold stars! Fitted a second new crankshaft sensor to replace what I now know is a faulty new one and the car is fixed! I have gradually extended my drives in it and it has not cut out and started straight away when hot. After weeks of head scratching and frustration it's great to have the car 'back'. Thank you very much for your help which I really appreciate.
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Monday, July 19th, 2021 AT 8:43 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
That is great news. Thanks so much for coming back and updating us. That info will surely help others that are in the same position.

Unfortunately, I have only learned to not trust new parts by getting burned over and over. Thanks again for using 2CarPros. Please come back. Thanks
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Tuesday, July 20th, 2021 AT 8:25 AM

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