how much vacuum.???

[bcredliner]

Since you don't have year and model X5 you have in your signature and I don't see where you have mentioned what you have I don't know what vehicle you have.

That said, Upallnight's post is correct. Vacuum decreases as throttle increases. To eliminate a vacuum leak have a smoke test done.

[1iwilly]

it says it on post#3 02 x5 3.0i
yes i know how the engine theory works as you rev up vacuum decreases.
but this is at idle.

Originally Posted by bcredliner

Since you don't have year and model X5 you have in your signature and I don't see where you have mentioned what you have I don't know what vehicle you have.

That said, Upallnight's post is correct. Vacuum decreases as throttle increases. To eliminate a vacuum leak have a smoke test done.

[bcredliner]

What I am saying is that at idle the vacuum line to the fuel filter/ fuel pressure regulator should be at the maximum vacuum the engine produces. If the proper vacuum is not there the engine will run rich. As engine vacuum decreases the FPR adds fuel. That would explain why the problem is only at an idle. A vacuum leak could be in the line to the engine or it could be a vacuum leak at some other location that is reducing/eliminating vacuum to the FPR. If you haven't already carefully checked the entire length of the fuel filter vacuum line I would do so. One way to do that is to disconnect the line at the engine and see if there is vacuum at the connection point. If you have done so I would have a smoke test done to eliminate a vacuum leak as the root cause.

[1iwilly]

ok i already check the line going to the fuel filter regulator.line is fine
if you look at the pix on the hose for the brake booster has a y. where the 3/8 hose has vacuum all the time and it also go to the elbow so there is vacuum present even if there was a minute leak some where else so i'm still puzzle as to why there is no vacuum to the skinny hose when there is vacuum from the 3/8 hose which are almost touching each other. now mind you if you put your hand actually on any car car where the throttle body is while running and you give it gas it starts to suck your hand in.any way i move the hose to temp vacuum port on the intake and notice i have better throttle respond and no hicup between 2200/3000

Originally Posted by bcredliner

What I am saying is that at idle the vacuum line to the fuel filter/ fuel pressure regulator should be at the maximum vacuum the engine produces. If the proper vacuum is not there the engine will run rich. As engine vacuum decreases the FPR adds fuel. That would explain why the problem is only at an idle. A vacuum leak could be in the line to the engine or it could be a vacuum leak at some other location that is reducing/eliminating vacuum to the FPR. If you haven't already carefully checked the entire length of the fuel filter vacuum line I would do so. One way to do that is to disconnect the line at the engine and see if there is vacuum at the connection point. If you have done so I would have a smoke test done to eliminate a vacuum leak as the root cause.

[bcredliner]

If I understand you correctly you have disconnected both hose at Y connector which connects directly to the source of the vacuum. You are not checking for fuel regulator vacuum at the fuel filter.

With both hoses connected to the same source for vacuum the only reason I can think of where one arm of the Y has vacuum and the other does not is that the fuel regulator side of that Y is plugged.

[upallnight]

You could also have a collapse hose.

[1iwilly]

no i already check it out yesterday. i took down the cover under the truck to access fuel filter.disconnect hose from front of truck use a air hose connected to it then block it at the end where it goes to the filter found no issues. connected back to constant vacuum got back under the truck and it had good suction at fuel filter end.but again where the vacuum suppose to be coming from at elbow part it is not.

Originally Posted by bcredliner

If I understand you correctly you have disconnected both hose at Y connector which connects directly to the source of the vacuum. You are not checking for fuel regulator vacuum at the fuel filter.

With both hoses connected to the same source for vacuum the only reason I can think of where one arm of the Y has vacuum and the other does not is that the fuel regulator side of that Y is plugged.