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Thread: Fuel pressure question
06-26-2017, 09:27 PM #1
Fuel pressure question
I took my truck out for its first drive in almost two years. My goal was a few "light throttle" cruising datalogs for my tuner. Made it a few miles then it began running lean and chugging. AFR was pegged lean, fuel pressure dropped to 19psi... I got it in my garage and pulled both fuel pump fuses, installed them one at a time and cycled the key. Pressure was 19psi koeo for both pumps. Started the truck and adjusted base fuel pressure back up to 40psi. Tested both pumps again. Koeo both went to 29psi. Base fuel pressure is rock steady at 40psi now. Haven't driven it since.
I worked with my tuner over the winter to get the startup and idle figured out. Base fuel pressure was set at that time to 40psi. I haven't touched the regulator since. Logs show voltage at 14 so I know that checks out.
Opened the regulator tonight and found scoring on the seat. I would think this would only affect pressure bleed off when engine is off
Not sure why this 21psi fuel pressure drop happened. Any ideas? Last thing I need is fueling issues on my fresh build.
System consists of:
**Dual Walbro 465 pumps # F90000267 (1k miles use)
**Dedicated 10ga wiring to each pump
**Id1300 injectors (new)
**8an ptfe feed
6an ptfe return
**13101 Aeromotive regulator
**Division-x 10 micron stainless filter
For those that are curious...
Truck is a lowered F150 4x4
Tubular control arms
custom drop knuckles
Super duty transfer case
Built 5.4 2V
Etc, etc, etc
Bumper cover is not installed yet
Last edited by painlessauto; 06-27-2017 at 06:52 AM.
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06-27-2017, 04:54 AM #2
Matt, did you mean dual F90000269 or F90000267 pumps. That series of pump from Ti Auto is a monster. Each one flows 450 lph or better. The xxxx67 pumps are the lower blow off pressure relief and the xxxx74 pumps are the higher blow off pressure relief. Not that you asked but, a -10 feed and return line would probably work well.
The fact that you have such a large fuel system and drive it on the street means that the regulator needs to bypass a huge volume of fuel back to the tank whenever you are not at WOT. The process of bypassing that much fuel may make the regulator vibrate or chatter as it does its work. The vibration is usually the check valve (frequently a ball bearing) opening and closing rapidly against its seat in the regulator. The regulator diaphragm can also sing and possibly contact some part of the interior of the regulator body.
I think going to larger feed and return lines could possible help. Best fix for the regulator is to use one with a ceramic / metallic or ceramic / ceramic ball and seat relief valve. Aluminum is soft enough that it can get beat up in short order if the regulator misbehaves.
06-27-2017, 06:07 AM #3
I just verified my Walbro pump part numbers are F90000267.
What brand regulator do you recommend? I agree that a stainless ball seating on aluminum is not a good idea. I just emailed magnafuel asking what materials they use.
On a side note, I ran this exact setup 2 years ago with 60lb injectors for 1k miles without issues running 18# boost. Only thing that changed between then and now is the addition of id1300 injectors.
Last edited by painlessauto; 06-27-2017 at 07:56 AM.
06-27-2017, 09:50 AM #4
Got this response from magnafuel.
"Our regulators use a brass valve and a stainless-steel seat. Both are replaceable. Usually we only see excessive wear or chatter marks when there is cavitation or large amounts of air running through the regulator. If you have any other questions let us know or give us a call."
Looks like the problem is...
The pumps were sucking air into the system from aerated fuel. This would explain my lean AFR at idle when I got home and bumped my base pressure back to 40psi.
Last edited by painlessauto; 06-27-2017 at 10:07 AM.
06-27-2017, 11:11 AM #5
At this point Matt I am reading the tea leaves similar to you. The thing that I struggle with is the aeration of the fuel. Was the tank fuel level low enough to uncover the pickup(s) or perhaps the pumps needed better fuel control baskets to prevent uncovering the pickup going around corners or accelerating. I suspect there is still a hidden bad actor in here somewhere but I am not certain what or where it is yet.
While it wold be nice to have a stainless valve or better a ceramic valve / seat instead of the brass equivalent, if the brass valve shows no signs of wear it should be working properly ???
06-27-2017, 04:06 PM #6
The pumps have a pretty good pickup basket in the tank. Fuel level was low, guess I underestimated just how low it was. I am thinking that the fuel returning to the tank was splashing and creating bubbles? I was not driving spirited, just poking along checking everything out.
Hoping the weather holds out so I can drive it tonight.
Who offers a ceramic valve/seat FPR with 1:1 boost reference? Can't seem to find one anywhere.
Last edited by painlessauto; 06-27-2017 at 04:11 PM.
06-27-2017, 04:45 PM #7
The only thing I can gather is perhaps the fuel level got low enough to uncover a pickup, Matt. How much fuel did you have when the problem occurred?
In regards to the regulator, if I remember correctly, the Fore F4i regulator uses ceramic / stainless valving. Justin's pricing is not cheap but the regulator is very high quality, is safe with all fuels and does come with a lifetime warranty.
06-27-2017, 04:59 PM #8
Fuel level was pretty low. Didn't have plans to drive it far that day. Fuel light came on when I was almost to my driveway.
I'll look into the fore FPR. Thanks
06-28-2017, 02:36 AM #9
I think you are most likely right about the under estimate of fuel being the bad guy, Matt. Justin Fore's stuff is pretty impressive quality. If you choose to go that route I am confident you will be pleased with his regulator.
06-28-2017, 10:15 PM #10
Looks like I am torn between the Magnafuel and Fore F2i regulators. Both are very nice pieces. I like how the Magnafuel valve tapers and centers itself in the seat. Magnafuel is brass/stainless. Fore is ceramic/stainless. Both are the same price. Decisions decisions....
06-29-2017, 12:32 AM #11
Quite similar, Matt. Both appear to be high quality. At the same price point I would opt for the ceramic / stainless solution.
06-29-2017, 05:48 AM #12
I agree Ed
Pulled the trigger on the Fore unit
07-06-2017, 08:54 PM #13
Looks great in my engine bay. You were right Ed, very nice piece!
07-06-2017, 11:48 PM #14
Justin works hard to produce high quality pieces, Matt. I have always been impressed with his products. Although they are not the least expensive, I consistently use them for their fit, function and quality. IMO they are easily the best.
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