Chris.
Fuel pressure problem
Post Fiend
Joined: Sep 2003
Posts: 6,096
Likes: 26
From: Mesa AZ
I wonder about that myself. It sort of looks like the seal was pointing the correct way (bevel towards the bowl) when it began life but eventually smashed itself into the rim of the poppet valve so it looks backwards when I eventually pulled it out. I wasn't sure to be honest. When I put the new parts in from the rebuild kit, I assembled the seal per a photo that you sent me at one time. (see below). Did I do it correctly?
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
I wonder about that myself. It sort of looks like the seal was pointing the correct way (bevel towards the bowl) when it began life but eventually smashed itself into the rim of the poppet valve so it looks backwards when I eventually pulled it out. I wasn't sure to be honest. When I put the new parts in from the rebuild kit, I assembled the seal per a photo that you sent me at one time. (see below). Did I do it correctly?
The pic of my original seal shows how it wears when the seal is oriented properly.
Post Fiend
Joined: Sep 2003
Posts: 6,096
Likes: 26
From: Mesa AZ
You put it on right during rebuild but the pic of the deformed seal looks like it was put on backwards during a possible earlier rebuild, per my edit. Just looks like someone put it on wrong before you got to it.
The pic of my original seal shows how it wears when the seal is oriented properly.
The pic of my original seal shows how it wears when the seal is oriented properly.
Post Fiend
Joined: Sep 2006
Posts: 5,584
Likes: 0
From: Millbrook Alabama
Chris, did you replace the fuel pump? If so, was it by chance an airtex unit. When my FASS pump died back last fall I replaced it with a stock Airtex unit from Oriellys, and was suprised at the amount of pressure the new pump puts out. the pump itself is stamped with 110psi max output, and with NO orifice in my fuel system it will maintain 50psi, with an .0036 orifice (thats what came with my DFA kit) my truck sees 95psi, with only a 7#drop under WOT. Now of course I dont have a fuel bowl anymore so I dont have to worry about blowing out the o-ring on the lid and creating a leak, but my truck seems to like the higher fuel pressure.
Post Fiend
Joined: Sep 2003
Posts: 6,096
Likes: 26
From: Mesa AZ
Chris, did you replace the fuel pump? If so, was it by chance an airtex unit. When my FASS pump died back last fall I replaced it with a stock Airtex unit from Oriellys, and was suprised at the amount of pressure the new pump puts out. the pump itself is stamped with 110psi max output, and with NO orifice in my fuel system it will maintain 50psi, with an .0036 orifice (thats what came with my DFA kit) my truck sees 95psi, with only a 7#drop under WOT. Now of course I dont have a fuel bowl anymore so I dont have to worry about blowing out the o-ring on the lid and creating a leak, but my truck seems to like the higher fuel pressure.
Where is the orifice located on your truck? How does it increase pressure? I am not familiar with the fuel bowl delete systems and how they work so I am trying to learn a little bit myself here.
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Post Fiend
Joined: Sep 2006
Posts: 5,584
Likes: 0
From: Millbrook Alabama
1 feed line off the tank to (10micron) inline filter to fuel pump then to a 3micron spin on filter then1 feed line from 3micron filter to enigne bay that runs into a Tee fitting, and then 1 line off each side of the Tee to the back of each head. 1 line off the front of each head to another Tee fitting, Orifice on the outlet of the Tee fitting going to a single return line back to the tank.
by filling the heads from the lowest point any air is then sent out the return lines on the top(highest point)
unfortunatley i dont have a really good pic to post up that doesnt look like a bunch of random hoses..... so i hope you can follow my explanation.
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Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Yes, but about 3 years and over 100,000 miles ago so unless a failing pump suddenly causes a spike in pressure, I don't think that's it.
How long have you been running the higher pressure Brandon? I've heard it can be hard on injector internals, but that's just something I read on the internet.
Post Fiend
Joined: Sep 2006
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From: Millbrook Alabama
That varies. The fuel not being used by the engine goes out through the FPR back into the tank. When the truck is off and the key gets turned on, once pressure is up all the fuel goes out through the FPR. At idle the engine uses some, at WOT the engine uses more. I'll try and get a flow rate with engine off and at idle for you when I do this.
Yes, but about 3 years and over 100,000 miles ago so unless a failing pump suddenly causes a spike in pressure, I don't think that's it.
How long have you been running the higher pressure Brandon? I've heard it can be hard on injector internals, but that's just something I read on the internet.
Yes, but about 3 years and over 100,000 miles ago so unless a failing pump suddenly causes a spike in pressure, I don't think that's it.
How long have you been running the higher pressure Brandon? I've heard it can be hard on injector internals, but that's just something I read on the internet.
Post Fiend
Joined: Sep 2003
Posts: 6,096
Likes: 26
From: Mesa AZ
Greg, I'll try to explain it so you can get a picture.
1 feed line off the tank to (10micron) inline filter to fuel pump then to a 3micron spin on filter then1 feed line from 3micron filter to enigne bay that runs into a Tee fitting, and then 1 line off each side of the Tee to the back of each head. 1 line off the front of each head to another Tee fitting, Orifice on the outlet of the Tee fitting going to a single return line back to the tank.
by filling the heads from the lowest point any air is then sent out the return lines on the top(highest point)
unfortunatley i dont have a really good pic to post up that doesnt look like a bunch of random hoses..... so i hope you can follow my explanation.
1 feed line off the tank to (10micron) inline filter to fuel pump then to a 3micron spin on filter then1 feed line from 3micron filter to enigne bay that runs into a Tee fitting, and then 1 line off each side of the Tee to the back of each head. 1 line off the front of each head to another Tee fitting, Orifice on the outlet of the Tee fitting going to a single return line back to the tank.
by filling the heads from the lowest point any air is then sent out the return lines on the top(highest point)
unfortunatley i dont have a really good pic to post up that doesnt look like a bunch of random hoses..... so i hope you can follow my explanation.
I get it now. The orifice restricts the return flow, so that is why your pressure is so high. No orifice, no restriction and less pressure. Have you experimented with different orifice sizes?
Based on your readings, then it sounds like the return flow on Chris's truck is restricted as well...hence the similar fuel pressure readings. I suppose Chris could remove the spring from his FPR and see if his pressure falls to 40-50 psi range. That would highlight the FPR as the culprit. Correct?
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Post Fiend
Joined: Mar 2007
Posts: 26,966
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From: Texas
Mine suddenly stopped and went back to normal for no reason. I believe the above diagnosis is correct so I ordered a FPR rebuild kit from Bob and will install the parts when time allows since I'm no longer having any issues.
Lead Driver
Joined: Sep 2010
Posts: 7,793
Likes: 50
I can not find my "thread/post" about similar issue. My gauges reads 68/69 psi, all day long, but a few weeks back, i noticed at idle, from time/time, it would spike to 80psi. Once i needed fuel, went to chevron, and since 76, and that spikes' gone. The orig fuel in there was from Arco. Havnt gone back, think i'll pay the extra 5 cents per gal.
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