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E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 08-31-2008, 03:20 PM
faviolosky faviolosky is offline
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How do you know if the fuel pressure regulator is going bad

ok so i disconnected the vacuum hose for the FPR and it barely did anything it reved up maybe 50 rpm, not 500 but 50, and previous times i had taken the vacuum hose off and that thing would growl at me as if i was taking the food away or something
so back to my original question, is there a way to know if the fuel pressure regulator is bad
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  #2  
Old 08-31-2008, 06:06 PM
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drivinfaster drivinfaster is offline
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fuel pressure regulators will sometimes leak fuel past a ruptured diaphram to allow extra fuel into the intake. this usually results in poor performance, fouled plugs, and saturated engine oil. however, sometimes they don't leak. rather, they 'plug up'.

in order to verify this, you need to take a fuel pressure reading. (not sure if yours has a schrader valve or not) check your reading while engine is idling, then rev the engine. the pressure should increase a few psi, then return to normal. then remove the vacuum line and your fuel pressure should go up about 10 psi and stay there. if there is no change to fuel pressure (and it is in spec) then suspect a stuck fuel pressure regulator.

if you do not have a schrader valve on the fuel rail, then you will need to tee into the fuel line at the filter with some hose and adaptors. everything that you will need should be available from a parts store.

i'm not saying this is going to be an easy job, as fuel will be under pressure and could cause severe injury. wear safety glasses and depressurize the fuel system to reduce the fuel from spraying all over everything if you have to tee in to the line at the filter. (read how to do a fuel filter replacement if you are not familiar with this sort of thing first to see if you feel comfortable in doing this proceedure)

hope this helps, and good luck.

df
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  #3  
Old 08-31-2008, 06:44 PM
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downhiller downhiller is offline
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Originally Posted by drivinfaster View Post
i'm not saying this is going to be an easy job, as fuel will be under pressure and could cause severe injury.
im still waiting to see how you get injured in this job other than stabbing your finger with the screwdriver. about the worst i got was some spray in the mouth, and fuel doesnt taste all the best.
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Old 08-31-2008, 07:03 PM
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drivinfaster drivinfaster is offline
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you obviously have never had the pleasure of taking a fellow employee to the er because he got a face full of fuel sprayed into his eyes and was almost blinded.
suffered 'exposure consitent with 1st degree burns' (chemical burn, i believe) on his entire face. and yes, he was wearing glasses, which is probably what saved his eyes.

and yes, you can poke yourself with a screwdriver, pinch your fingers, and a bunch of other 'stupid' injuries. however, you only have 1 pair of eyes. blame my caution on my grandfather who taught me tool safety, knife safety, and gun safety. i don't know what his skill level would be, nor do i know what the fuel pressure will be. in the case of my co-worker, the fpr was malfunctioning, internal failure of the spring, which caused the needle of the metering rod to remain fully on the seat, essentially deadheading the fuel pump. the fuel pressure was reading 100psi. is this common?? no. probably very rare. however, the very next day another employee got sprayed in the face and also had to be taken to the er because he *did* get fuel into his eyes. he was not wearing glasses, and the fuel pressure on this particular vehicle (4.3 v6 astro tbi injected) was only 14psi.

so, you tell me. am i nuts to caution someone about the (potential) dangers of working on a fuel system?? i am assuming that 90% (or more) of the posters here are not ase master technicians, with emissions repair certifications, and 15 years experience turning wrenches. otherwise, he wouldn't need to post his questions.

and if people were as smart as you think the are, warning labels would be obsolete, wouldn't they??

df
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  #5  
Old 08-31-2008, 07:13 PM
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downhiller downhiller is offline
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Originally Posted by drivinfaster View Post
you obviously have never had the pleasure of taking a fellow employee to the er because he got a face full of fuel sprayed into his eyes and was almost blinded.
suffered 'exposure consitent with 1st degree burns' (chemical burn, i believe) on his entire face. and yes, he was wearing glasses, which is probably what saved his eyes.

and yes, you can poke yourself with a screwdriver, pinch your fingers, and a bunch of other 'stupid' injuries. however, you only have 1 pair of eyes. blame my caution on my grandfather who taught me tool safety, knife safety, and gun safety. i don't know what his skill level would be, nor do i know what the fuel pressure will be. in the case of my co-worker, the fpr was malfunctioning, internal failure of the spring, which caused the needle of the metering rod to remain fully on the seat, essentially deadheading the fuel pump. the fuel pressure was reading 100psi. is this common?? no. probably very rare. however, the very next day another employee got sprayed in the face and also had to be taken to the er because he *did* get fuel into his eyes. he was not wearing glasses, and the fuel pressure on this particular vehicle (4.3 v6 astro tbi injected) was only 14psi.

so, you tell me. am i nuts to caution someone about the (potential) dangers of working on a fuel system?? i am assuming that 90% (or more) of the posters here are not ase master technicians, with emissions repair certifications, and 15 years experience turning wrenches. otherwise, he wouldn't need to post his questions.

and if people were as smart as you think the are, warning labels would be obsolete, wouldn't they??

df
i never personally had an issue nor heard of one til i read this. everything i heard was fire related (i did have a couple of those).

but i didnt mean to offend on what i stated, its been a long day and the roomy is kinda p!ssy. so im having a hard time controlling my manners and my "does it look like i care" mood.
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  #6  
Old 08-31-2008, 08:49 PM
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drivinfaster drivinfaster is offline
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no offense taken. i didn't mean to sound alarmist, either.

df
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  #7  
Old 08-31-2008, 08:53 PM
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downhiller downhiller is offline
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no offense taken. i didn't mean to sound alarmist, either.

df
no hard feelings man. i blame the lateness, and holiday parties
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  #8  
Old 08-31-2008, 10:16 PM
Ryan M Ryan M is offline
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The fuel pump supplies the pressure to your fuel rail, and the pressure regulator is what maintains this pressure. Common symptoms of a bad regulator are too high of fuel pressure, and little or no fuel pressure after shut down. The fuel pressure regulator holds fuel pressure in the system to aid in quicker starts. Like another poster mentioned above, you need to get a fuel pressure gauge and do a pressure test and residual test. Cycle the key on and off and read what the pressure is. Then come back in an hour or so and read the pressure again. It should be virtually the same. If it has dropped out of spec, it is most likely faulty.
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  #9  
Old 08-31-2008, 11:04 PM
faviolosky faviolosky is offline
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ok so this is what i got,

but i dont know where to connect the pressure reader or gauge, you mentioned something about T connection at the fuel filter, but i thought u would connect it somewhere near the regulator, or is it just anywhere

or what kind of pressure reader or gauge to get
also my external fuel pump is going bad, so i ordered one so it should be coming in soon, also what i tried was taking the vaccum hose off to see if it had any effect on the idling and it did not do a thing, not even flinch, and i would expect it to at least change rpms a little. but nope, so do you think that by far it my be a bad one
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Last edited by faviolosky; 09-02-2008 at 08:09 PM.
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  #10  
Old 07-15-2013, 08:59 AM
strangedaddy strangedaddy is offline
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Great info guys. Appreciate it. On the '94 325i, do you know if the FPR is under the inlet manifold in the back by the firewall?
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  #11  
Old 07-15-2013, 09:58 PM
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hornhospital hornhospital is offline
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The FPR on your M50 engine is on the back of the fuel rail, under the cover, part #6 in the illustration...and you're in the wrong forum. Wander over to the E36 forum for more help with your '94 325i.
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Last edited by hornhospital; 07-15-2013 at 10:02 PM.
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  #12  
Old 07-16-2013, 04:13 AM
strangedaddy strangedaddy is offline
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Thanks Horn! Not quite sure how I got over here in E30, but thanks.
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