Please Explain the 0087 Code

[Drholliday]

Tim, did you ever get to data log it to see what your desired vs. actual fuel rail pressure looks like when the 0087 happens? I had my truck throwing the code when it was tuned with out a lift pump and the logs showed that it was the FPRV popping. We logged it at a tractor pull and desired stayed at 26,000 psi actual went from 26,000 and dropped instantly to 14,000 about half way through the pull, it stayed there for about a second then it started to build back up to 26,000 psi again.

When you did the bottle test did you get the truck to throw the 0087 code?

 

[JoshH]

If your FPRV pops open, it won't close until you shut the truck off.

 

[Drholliday]

If your FPRV pops open, it won't close until you shut the truck off.

What would have caused what I saw in the log then? There are no electronics in the FPRV so they could all be different. Its just a spring, when it gets to a certian pressure the spring compresses, when it goes back down enough the spring will close the valve again. Thats why the shim works, it just makes the spring tighter.

 

[JoshH]

What would have caused what I saw in the log then? There are no electronics in the FPRV so they could all be different. Its just a spring, when it gets to a certian pressure the spring compresses, when it goes back down enough the spring will close the valve again. Thats why the shim works, it just makes the spring tighter.

You're right. There is nothing electronic that will make it stay open, and if the pressure drops enough, the valve will close itself. However, it has been my experience that the pressure has to drop well below 14,000 for the valve to close, and once you have popped the valve open the engine will be in limp mode and will not be able to go above about 2200 RPM. The way the valve is designed it has a very small surface area that the fuel pushes against when it is closed, but it it quite large when it is open. That allows it to stay closed without having to have a huge spring, but keeps it open until the pressure drops well below the safe range upper limit. It sounds to me like what you experienced was just too much fuel for the CP3 to keep up with.

 

[LBZ]

If you have a gauge you can make an adapter to screw it into the bleed screw hole in the filter housing......

FWIW, if you have an electrical boost pressure sensor, you can remove it and thread into the filter housing with the appropriate adapter fittings to read the lift pump fuel pressure while in the cab-instead of rigging up a new gauge and a bunch of other stuff.

Did you guys do your bottle tests or check fuel pressure yet? One thing I know is that once the FPRV goes, it gets easier and easier to pop the more often it happens.

 

[Alligator]

You need a M10 x 1.5 pitch male by 1/8" npt female adapter. The install looks like this:

 

[LBZ]

Yup-exactly what I was talking about Chad-thanks for the pic.

 

[Alligator]

Glad to help:hug:

 

[Krazykid]

This is great information guys. I still seen to be having some fuel rail pressure issues I think, (need to do a bottle test). Anyway my question is this: Is it more benificial to know the Lift pump PSI or the rail pressure with the use of the gauge?

 

[LBZ]

This is great information guys. I still seen to be having some fuel rail pressure issues I think, (need to do a bottle test). Anyway my question is this: Is it more benificial to know the Lift pump PSI or the rail pressure with the use of the gauge?

RP needs to be checked with a special high pressure gauge or by monitoring with EFI Live or similar datalogging software. It cannot be checked with a simple gauge (26 000 psi!!)

To answer your question, it depends on the problem you are having as to what you want to watch. If you suspect a bad lift pump because you have the 87 code even with a moderate PW tune then you want to check it at the filter housing.

If it's a problem that happens on WOT runs only, then you will want to know what is going on with the rail pressure and see if it is just a problem of draining rail because your PW is too high and the lift pump can't keep up, or if it's a possible bad FPRV, worn out CP3, etc.

Both places give good information when troubleshooting the 87 code so both are just as important. I personally would monitor both along with the bottle test to rule out the FPRV.

 

[TIM Z]

Great Info and Pics Guys, Thanks!!

As soon as im healed up i'll be attacking the code again.:baby:

 

[Drholliday]

What would have caused what I saw in the log then? There are no electronics in the FPRV so they could all be different. Its just a spring, when it gets to a certian pressure the spring compresses, when it goes back down enough the spring will close the valve again. Thats why the shim works, it just makes the spring tighter.

You're right. There is nothing electronic that will make it stay open, and if the pressure drops enough, the valve will close itself. However, it has been my experience that the pressure has to drop well below 14,000 for the valve to close, and once you have popped the valve open the engine will be in limp mode and will not be able to go above about 2200 RPM. The way the valve is designed it has a very small surface area that the fuel pushes against when it is closed, but it it quite large when it is open. That allows it to stay closed without having to have a huge spring, but keeps it open until the pressure drops well below the safe range upper limit. It sounds to me like what you experienced was just too much fuel for the CP3 to keep up with.

Mine might have been a freakishly strong FPRV spring. The reason I don't think it was too much PW in my case is b/c the truck was requesting 26,000 and holding right at 26,000 then the line dropped almost perfectly strait down to 14,000 held 14,000 for a little while and then started to climb back up steeply back to 26,000 all at the same PW. As for not limiting the truck to 2200 rpms, it was one of Dustin's very first LBZ tunes and I don't know what limiting tables he had changed.

I wish I had access to the video over here so I could link it. Dustin Video'd the truck on that pull and you could here it in the middle of the pull it sounded like it lost some power then you could hear it come back, it was really weird.

I was just asking Tim if he got the 0087 code when he was doing the bottle test to remove the FPRV from the equation.

 

[LBZ]

Sounds to me like it could be two things on your case-Either the FPRV let go and then closed, or for some reason, your Fuel Pressure regulator commanded less fuel-whether it be something in the tune or a wiring issue. If you were logging RP current, RP commanded and RP actual and the commanded dropped then it's something your tune. If everything stayed constant and just the RP dropped, then likely the FPRV let go.

 

[JoshH]

Mine might have been a freakishly strong FPRV spring. The reason I don't think it was too much PW in my case is b/c the truck was requesting 26,000 and holding right at 26,000 then the line dropped almost perfectly strait down to 14,000 held 14,000 for a little while and then started to climb back up steeply back to 26,000 all at the same PW. As for not limiting the truck to 2200 rpms, it was one of Dustin's very first LBZ tunes and I don't know what limiting tables he had changed.

I wish I had access to the video over here so I could link it. Dustin Video'd the truck on that pull and you could here it in the middle of the pull it sounded like it lost some power then you could hear it come back, it was really weird.

I was just asking Tim if he got the 0087 code when he was doing the bottle test to remove the FPRV from the equation.

Did you happen to notice a rail pressure spike right before it dropped all of a sudden? If so, that may be what happened.

 

[othrgrl]

Looking at the log from the pull Chris is talking about it held 26,071 before popping the FPRV open. Demanded and actual stay very close to the same on the way up. After about a second of being at 26,071 actual drops suddenly to 19,000 then slowly drops to 14,400 before slowly building back up to 26,000 again by the end of the pull. Throughout the pull RPM stayed above 3000 most of the time; and the PW was around 2600 the whole time. IMO it was most definately the FPRV popping open then finally closing when pressure was drained low enough.

 

[JoshH]

LBZs and LMMs read up to 29007 without doing anything to the tune.

 

[othrgrl]

LBZs and LMMs read up to 29007 without doing anything to the tune.

Good call, I actually should have spent a few more seconds looking at it and I would have seen that actual got up to 26,459 at the end of the pull - it's wierd how dead flat it is at that 26,071 area before the FPRV popped open though - made me think it was at the sensor's limit.

 

[x MadMAX DIESEL]

figure things out Tim? ive been having issues aswell. i even have my LP turned up ALL the way and i still can get that code at WOT

 

[JoshH]

What kind of pulse are you guys running? I've recently two different trucks, one LBZ one LMM, that both hold 2800 uS without dropping rail pressure in 4th and 5th gear, and they don't even have lift pumps.

 

[x MadMAX DIESEL]

What kind of pulse are you guys running? I've recently two different trucks, one LBZ one LMM, that both hold 2800 uS without dropping rail pressure in 4th and 5th gear, and they don't even have lift pumps.

if that was directed me, i havent got a clue