Fuel pressure regulator

[grease lightnig]

How do I know when the fuel pressure regulator has gone bad? The symtoms are it will not idle without a really bad shake and it runs in limp mode and gives me a P0087 code. And it dies if you give it to much fuel/throttle. The fuel pump works because I have a fuel pressure gauge mounted after the fuel filter (new) going into the engine.

If it is bad do I have to replace the whole rail? How much is that part I bet it is very expensive? I have 172,000 miles on this car. I am taking it in to my trusted mechanic on Wed. today is Sunday.

[qwerty]

Originally Posted by grease lightnig

How do I know when the fuel pressure regulator has gone bad?

The fuel pressure will be too high or too low.

[grease lightnig]

Did I mention that is was a 2005 E320 CDI with a common rail. Is there a way to check the pressure after the rail?

[scotty68]

do I have to replace the whole rail?

dont want to make a new post but, do you? I've read in the past you cant just buy the fpr itself.......

[Diesel911]

Originally Posted by scotty68

do I have to replace the whole rail?

dont want to make a new post but, do you? I've read in the past you cant just buy the fpr itself.......

You could try that and hope it works.

I would do a regular internet search to see if anyone has had the issue before and look on YouTube to see if there is a video with troubleshooting.

Not a diesel but this gives some idea on what you think might not be cause. This is on a chevy gasser that has a high-pressure fuel pump. It was taken to a shop, and they replaced the fuel pump, but it was still throwing a low-pressure code, and they called in another person with better scanners. He verified that yes, the pressure was too low.

He removed the new fuel pump and eventually pulled out the tappet and roller that actuated the fuel pump and found out that the roller and the tappet were badly worn, and neither were allowing the tappet to move as far as it was supposed to.

When those were replaced the new fuel pump worked fine and the pressure was normal.

For low fuel pressure you would think anything from the fuel tank venting system from the tank screen, any fuel pumps in-between the high-pressure pump, restricted filters on into the high-pressure pump and that regulator you mentioned could all cause the issue or any combination of them.

If you had a manual that covered that there should be a fuel feed pressure up to the high-pressure pump and of course a reading on what the fuel pressure relief does.

[engatwork]

The only thing I've seen fail on one of these was, IIRC the sensor at the rear of the fuel rail. I don't remember the specifics but you have an electrical device at each end of the fuel rail. One of those has probably failed based on mileage in my opinion.

[scotty68]

Originally Posted by Diesel911

You could try that and hope it works.

I would do a regular internet search to see if anyone has had the issue before and look on YouTube to see if there is a video with troubleshooting.

Not a diesel but this gives some idea on what you think might not be cause. This is on a chevy gasser that has a high-pressure fuel pump. It was taken to a shop, and they replaced the fuel pump, but it was still throwing a low-pressure code, and they called in another person with better scanners. He verified that yes, the pressure was too low.

He removed the new fuel pump and eventually pulled out the tappet and roller that actuated the fuel pump and found out that the roller and the tappet were badly worn, and neither were allowing the tappet to move as far as it was supposed to.

When those were replaced the new fuel pump worked fine and the pressure was normal.

For low fuel pressure you would think anything from the fuel tank venting system from the tank screen, any fuel pumps in-between the high-pressure pump, restricted filters on into the high-pressure pump and that regulator you mentioned could all cause the issue or any combination of them.

If you had a manual that covered that there should be a fuel feed pressure up to the high-pressure pump and of course a reading on what the fuel pressure relief does.

I have looked all over and only found one person said they replaced it but never said how it went. my rail has high pressure and believe thats the the problem.