fuel pressure regulator vacuum diagram..

[jaimster]

hey Guys ,
so I have been chasing high negative numbers on LTFT both banks around - 18 % I think I m dealing with a Rich conditon - decided to test the fuel pressure

getting fuel pressure numbers with car off 48 psi , car running 58 psi also I m trying to test the fuel pressure regulator and vacuum hose problem is CAN NOT DETERMINE exactly where the vacuum hose goes for sure at the moment it is connected to what I think it may some kind of switch

wondering if anybody can help me with a diagram and are the fuel pressures correct and pressure regulator testing procedure ??

this relates to a 2001 boxster 2.7 manual transmission believe vacuum lines might be different than automatic !!

[78F350]

On a 2001 model the vacuum hose for the fuel pressure regulator should go directly from the rubber boot on the intake cross-tube to the regulator on the fuel rail.





It sounds like you may have the vacuum lines on incorrectly. The diagram above is for a 2001 2.7L manual. There is more discussion of it here: https://986forum.com/forums/boxster-general-discussions/64576-vacuum-line-clarification.html#post518618

[jaimster]

Originally Posted by 78F350

On a 2001 model the vacuum hose for the fuel pressure regulator should go directly from the rubber boot on the intake cross-tube to the regulator on the fuel rail.





It sounds like you may have the vacuum lines on incorrectly. The diagram above is for a 2001 2.7L manual. There is more discussion of it here: https://986forum.com/forums/boxster-general-discussions/64576-vacuum-line-clarification.html#post518618

I have seen this before .
are you sure this applies to 2.7 manual transmission?

cause my FPR seems to be coming from top of "J" change over electric valve and other end of electric valve goes to a the Flapper valve !



thanks for all your help.

[78F350]

I'm sure that diagram is for a 2.7L with Manual. The connection for the fuel pressure regulator should be direct from that rubber boot. Change over valve (J) should only be connected to vacuum source on one end and resonance flapper valve (K) on the other end.

[jaimster]

that makes sense NOT sure why previous owner had it like that ! where else would the FPR get any vacuum otherwise !!

I disconnected the hose going to the FPR there was no change at all almost no PSI at all thought that was weird then now it makes sense

i m gonna correct that as soon as possible . wanted to replaced some of these small OD vacuum hose any idea where I could buy those ?

thanks for verifying the diagram believe I m ON to the real cause of my high negative LTFT issues now..

thanks again

[jaimster]

do you know if these 2 items :
SAI: Vacuum source -> electric change-over valve (E) -> change-over valve (D).
are located next to the vacuum reservoir ? I'm debating whether I should pull the
intake to get to it ( hate to mess with these intakes) although maybe I should change the gaskets on both sides too

I can't get to these items if they are underneath the intake which most likely they are !! unless the vacuum intake is removed

[78F350]

Yes, they are in a difficult to reach spot, forward from the vacuum reservoir. I have reached it by removing the alternator instead of the intake, but having the intake off gives better access. I have a couple engines in the garage and can get some pics tonight if that helps.

[jaimster]

Originally Posted by 78F350

Yes, they are in a difficult to reach spot, forward from the vacuum reservoir. I have reached it by removing the alternator instead of the intake, but having the intake off gives better access. I have a couple engines in the garage and can get some pics tonight if that helps.

if you have some pictures that will be great
at least I know now where to look at removing alternator one last question
where did you get your vacuum hoses ? or do you remember the sizes the rigid smaller black hose and the larger rubber material hose ?

thanks again

[78F350]

Hope this helps visualize...

Originally Posted by 78F350

In regard to the vacuum connections, here's that diagram, created with actual parts from a scrapped 2001 2.7L.

Notes:
-This picture shows what connections have to be made, the actual order of connections to the Y fittings (I) and (G) are not critical.
-The Tiptronic cars will have a 4-way connection at (I) or (G) with a line running to a changeover valve on the transmission.

It looks like a mess of tubes and parts, but in function it is fairly simple.
This shows 3 vacuum powered components: SAI, Resonance Flapper, and Fuel Pressure Regulator. Brake booster vacuum system is not shown.
SAI: Vacuum source -> electric change-over valve (E) -> change-over valve (D).
Resonance Flapper: Vacuum source -> electric change-over valve (J) -> vacuum unit (K).
Fuel Pressure Regulator: Vacuum source (B) -> Pressure regulator (C) -> injector valves (A).

Rubber sleeves (L) and (B) are the source of vacuum from the intake. (H) is a check valve. (F) is the vacuum reservoir.

From the right rear of the engine looking forward under the intake:


Looking down to the right side of the engine with the front cross-tube removed:


From the front of the engine looking back under the intake:


I buy this with a 3.5 or 3 mm ID and use it on a wide variety of cars with fittings from a local auto parts store to connect them or cut scraps from old tubing to connect.

[jaimster]

great .
I actually ended up removing the intake wanted to get a better view on things !!

found all the small vacuum hoses broken from reservoir, change over valve, injection check valve a mess all over pretty much .. lol

also, found some hoses at Oreilly's small plastic hose and large one I m thinking of using it fits great into the " Y" connections.

list of parts to getting :

long AOS vacuum hose to PVC found broken connection or NOT sure if I broke it ! anyways Im buying a new long hose found it at AutohauzAZ.com for 32.00
. Intake gaskets (3) 23.00
.check valve 15.00

parts from europarts.com change over valve 28.00
fuel injector lower O rings $ 3.0 or SHOULD I GET THE KITS ??

SHOULD I GET THESE PARTS ??: vacuum reservoir 21.00 , air injection check valve 135.00 these parts are right there underneath next to each other...

your thoughts ??

[78F350]

My thought is that while you are in there it's a good idea to replace those 20+ year old plastic parts now rather than deal with it again 6 months from now.

Double check the wires that go to the knock sensor too. If the car has ever sat where rodents can get to it, they chew that particular wire for some reason. Usually the car won't throw a code and will run fine with the wires chewed through.

[jaimster]

so many thanks to 78F350
have been able to redo the vacuum system all new hoses , new check valve , one new changeover valve , new vacuum reservoir
new passenger side intake gaskets ..
soon after it appears fuel trims numbers were GOOD not so fast ! after several driving cycles now its up to

- 14.0 bank1 LTFT B 2 - 15.0 LTFT short ones fluctuates up and down

so this afternoon tested again the FPR seems to react right when disconnecting the vacuum line pressure goes up to 60 psi

listened to the fuel injectors with a headset stethoscope seem to be working right ..

02 sensors on both banks seem to move up/dowm on voltage (maybe have to pay closer attention to those numbers )

interesting enough all my emission components now are completed ready (7 of them )

I m NOW getting the P1130 code oxygen sensing on BANK 2 ???

guess car wont pass inspection due to the code even though components are completed ???

what am I missing looking at NEXT ??

[Makrilli]

You have split this issue into 3 threads and it's hard to keep track of it.

What were your maf readings at idle with ac on and off?
Have you tried to disconnect the maf and see if the fuel trims change?

[jaimster]

I know .,, its just being really frustrating still have not been able to figure this out .

gotten 2 new MAF sensors and the old BOSH one currently have a new BOSH and the Old one swapp those out from time to time DONT MAKE MUCH OF A DIFFERENCE ..

If I disconnect the MAF today I believe the might only indicate if its bad or NOT . correct ?

HAVE NOT DONE THAT ..

I will follow your advise ac on and off reading on the MAF and check the fuel trims numbers today ?

NOT sure if I mentioned this before have an after market air filter hose and filter ( actually was having issues even before this was put in DESTROYED THE OLD ONE GETTING IT REMOVED ) otherwise I would put it back on just to see if it makes a difference...

thanks

[78F350]

Reading about the air filter hose and swapping different MAFs in makes me wonder if the wire harness or connector for the MAF is damaged.
Any potential air leaks between the MAF and throttle body?

Also if you search for the P1130 you will find some threads where it was a problem with the evap purge valve: https://986forum.com/forums/boxster-general-discussions/67910-fault-code-p1130.html
Also check again for more vacuum leaks - Brake booster vacuum hose, oil cap and fuel cap, hoses connected to the AOS.

[Makrilli]

I have a strong suspicion the new intake might have something to do with the problem, perhaps the diameter of the MAF tube is somehow smaller than stock.

I also had a problem with my boxster running rich.
It was very frustating and among other things I bought durametric, two new MAF sensors, replaced O2 sensors and checked fuel pressures.
In the end I read a forum post suggesting to check the mesh just before the MAF which seems to collect trash thanks to the bad design of stock air box.
I had small pieces of leafs stuck around the edge of said mesh impacting airflow, but not on front of the MAF so the readings were normal.

Your problem shouldn't be the same I had but disconnecting the MAF might help pinpoint the problem, even if it's not the MAF sensor itself.

[jaimster]

Originally Posted by 78F350

Reading about the air filter hose and swapping different MAFs in makes me wonder if the wire harness or connector for the MAF is damaged.
Any potential air leaks between the MAF and throttle body?

Also if you search for the P1130 you will find some threads where it was a problem with the evap purge valve: https://986forum.com/forums/boxster-general-discussions/67910-fault-code-p1130.html
Also check again for more vacuum leaks - Brake booster vacuum hose, oil cap and fuel cap, hoses connected to the AOS.

MAF's connectors wires bad ! I would think it would truly affect it and run rough ?

I have an audio stethoscopes planning to use it maybe I can hear any leaks and another smoke TEST on the plans .
will check those other items too .. fuel cap too

I had also read the tread on "evap purge valve " disconnect it and blow on it

the car has 7 emissions components ready completed - wouldn't this keep it from completing if there was an issue with the EVAP PURGE VALVE ???

should have a chance later today .. will report on it

[blue62]

Originally Posted by jaimster

MAF's connectors wires bad ! I would think it would truly affect it and run rough ?

I have an audio stethoscopes planning to use it maybe I can hear any leaks and another smoke TEST on the plans .
will check those other items too .. fuel cap too

I had also read the tread on "evap purge valve " disconnect it and blow on it

should have a chance later today .. will report on it

A few things that could cause your issue........
Bad MAF or MAF wires...and or connections.
Leaking Fuel Injectors.
Bad seal on the Oil Fill Tube Cap
Bad Fuel pressure regulator
Bad Evap Purge Valve under the intake manifold
Exhaust leak ahead of the Pre Cat 02 sensor.

[Starter986]

Originally Posted by blue62

A few things that could cause your issue........
Bad MAF or MAF wires...and or connections.
Leaking Fuel Injectors.
Bad seal on the Oil Fill Tube Cap
Bad Fuel pressure regulator
Bad Evap Purge Valve under the intake manifold
Exhaust leak ahead of the Pre Cat 02 sensor.

Blue... question...

Would having a Durametric at one's disposal eliminate a lot of "chasing"? I'm halfway familiar with the product, have never used it, but I believe you can see in the app the fuel pressure... bad connections... etc. No?

I ask because I've been considering the enthusiast version. I'm still working on a fuel smell... and that darned P0455 popped again. I've been unable to crawl under the car due to a bad back.

Thank you.

[JFP in PA]

Originally Posted by Starter986

Blue... question...

Would having a Durametric at one's disposal eliminate a lot of "chasing"? I'm halfway familiar with the product, have never used it, but I believe you can see in the app the fuel pressure... bad connections... etc. No?

I ask because I've been considering the enthusiast version. I'm still working on a fuel smell... and that darned P0455 popped again. I've been unable to crawl under the car due to a bad back.

Thank you.

No electronic diagnostic tool, even the almighty PIWIS, can see fuel pressure and delivery, both require a mechanical test with a fuel pressure test gauge.