help with fuel pressure numbers

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Jan 25, 2010 | 03:01 PM

britt

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help with fuel pressure numbers

Guys, my 2000 v-10 has been going thru a lot of gas lateley

, had a friend scan iot...said it was pushing too much fuel thru. i got a actron fuiel pressure tester to double check it going by info from a post from Art Krewat. At idle,engine running, should see 28-30....i have 45 psi. with engine off,key on,should see 38-40...i have 38. couldnt test with engine running and vacuum disconnected from fuel regulator (and plugged)...so i went to next step...pedal to floor should be above 35 , i have 40+ couldn't really see guage from cab as well as i thought. could this point to a fuel regulator problem? thanks guys....Britt

Jan 27, 2010 | 01:51 PM

krewat

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with engine idling and vacuum connected to the fuel regulator, it should be 28-30 pounds. If it's 45, there's something wrong with the regulator, I'd think.

Jan 27, 2010 | 06:01 PM

britt

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Art,thanks for chiming in...i went out a few minutes ago and checked the fuel pressure with the regulator vaccum line disconnected and line plugged. the fuel pressure was 50 psi. i spoke with a parts guy at the local ford dealership. He said that if the fuel pressure reg was going out, the truck would be nearly un-driveable. I dont know what the symptoms are of this problem, my friend who scanned it told me that it seemed to be pushing too much fuel thru....the only issue ive got with the truck aside from this is its started to go thru oil a little more than usual. normally i'll go thru a 1/2 to 3/4 quart between changes....last week its gone thru a quart. pvc is clear....it rattles....and both pvc and elbow was changed out in last year. also recently did the sct3 87 economy tune from mike at 5 star. only picked up 0.10 mpg increase

last mpg check figured at 8 mpg, have been averaging around 11.7....thanks for any ideas Britt

Jan 28, 2010 | 08:52 AM

krewat

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OK, 50 is TOO HIGH. 45 at idle with the vacuum connected is TOO HIGH.

Connect a hose to that vacuum nipple on the regulator, apply vacuum, and watch the fuel pressure. It should drop as you apply vacuum. If it doesn't, and certainly doesn't go below 45, something is wrong with the regulator.

Before 2002, the OBD-I systems wouldn't really complain about fuel mix until it gets WAY out of whack (+-40%) https://www.ford-trucks.com/forums/5...t-come-on.html

With the system running in closed-loop even at WOT, it'll monitor the O2 sensors and trim the mix up to a point, making up for the increased fuel pressure. I bet if you had a scan tool and watched the fuel trims, they'd be way into the (-) direction as far as they can go.

And for the oil consumption, a rich mix will wash the oil from the cylinder walls, and burn off the oil.

Again, if you have 50 psi with no vacuum, and 45 with, that's way too high.

Jan 28, 2010 | 01:16 PM

britt

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Art, just got your reply....thanks,picked up a new regulator today,will try the vaccum trick as soon as i can find my vaccum pump

.....gotta clean my garage out!!! will have time to swap it out this weekend. i'll get back to you then....this has probably been an issue for a while, just wont throw a code with obd-1 system. thanks again Britt

Jan 28, 2010 | 07:43 PM

britt

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Art...an update...found my vac gauge. hooked it to pressure reg. pulled vaccum down to 40 and it held...that was with engine running. however with the engine off and key on had 22 pounds pressure i applied vaccum and the pressure slowly dropped to 20 pounds. i've probably got this all screwed up... i also checked my tailpipe for gas residue,it was wet with gassy oil residue. should i check with engine off or running? I appreciate the advise, does this still point to bad regulator? Thanks Britt

Jan 28, 2010 | 08:40 PM

britt

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Art, forget the above numbers....didn't have the guage screwed tight

. with engine running, i've got 50 psi. I unplugged and capped the line to the pressure reg. then hooked my vaccume guage to the nipple pulled 15 pounds of vaccum on the guage and the fuel pressure dropped from 50 to 45 psi. there was a little fluctuation on the guage. exaust is still gassey....thanks

Feb 9, 2010 | 01:18 PM

britt

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Guys, update...fuel pressure reg swapped out.truck drives better. before i swapped it out i had fuel pressures up to +35 (useing a friends data logger scanner) now fuel pressures are in range of -3 to + 1 fuel mileage seems to be a little better to. thanks

Feb 9, 2010 | 04:12 PM

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krewat

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Britt, do you mean "fuel pressures" of +35 or "fuel trims" of +35?

Thankfully, you got it fixed, and if it's "fuel trims" that you mean, that sounds about right, now.

Feb 10, 2010 | 05:23 AM

#11

britt

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Art...thats "trim"....oops,he's reading it to me as we were driving. should i unhook the battery to reset the computer to clear it out? btw, i'll try the vac. test on my 4x4 today. i'll let you know, thanks