difference in fuel psi
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I have been told anything under 40psi you are losing performance. Anything under 15psi you are doing damage to the injector.
So dropping from 64psi-52psi at WOT should be no big deal. That is what my truck is doing with the B codes.
So dropping from 64psi-52psi at WOT should be no big deal. That is what my truck is doing with the B codes.
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13,503 Posts
dropping from 50-30 would be a huge loss. 70 psi is generally a tad high for any injector. i have tried almost everything and anything from 55-72 you're good. losing psi with your hybrids means you need a fuel system. losing psi with ur b cods means your fuel system needs help. mine doesnt budge ever. most boring gauge ever!!
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1,781 Posts
Yeah, my fuel system does need help...or just a new pump. It's so sporadic when it decides to drop pressure, the only thing I can figure it beign is the pump. Until I can find a pump option that suites me (which may be soon), I'm just taking it easy and hoping this pump doesn't totally quit. Mine didn't used to budge, and I'd sometimes wonder if the gauge was even working properly. LOL.
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7,730 Posts
I turned mine down from 68 to 59-60 recently and the truck smoked less and ran noticably cleaner and crisper.
This only further prompted me to do away with the flow through the head design because of the probable fuel aeration being created at the entrance to the heads being worsened by the increased pressure ahead of these two ports making the pressure drop across them worse leading to an even bigger aeration issue.
This is all speculative at this point, but the idea that these ports are aerating the fuel upon it's entry to the head is also shared by Aeromotive's lead tech who actually posed this issue to me initially. Only after reviewing the facts over and over again did I realize that it makes perfect sense. (To me and him at least)
By bypassing both heads entirely with the return fuel flow and using all 4 ports to feed fuel to both ends of the heads you drop the demand on those ports an unbelievable amount. Less than 1/4 of the demand. They only have to flow what the engine needs, not everything the pump produces, whether at idle or full throttle 24-7.
With the topic of fuel pressure at hand, I think it's important to note the serious pressure fluctuations dependent on where you take your measurement.
Then there is the obvious issue of killing electric pumps with too much pressure.
I might go ahead and swap over the fuel feed and regulation before I go to the belt pump just to go ahead and see if it effects anything significantly.
If I get a chance to do that I will post the results as always.
This only further prompted me to do away with the flow through the head design because of the probable fuel aeration being created at the entrance to the heads being worsened by the increased pressure ahead of these two ports making the pressure drop across them worse leading to an even bigger aeration issue.
This is all speculative at this point, but the idea that these ports are aerating the fuel upon it's entry to the head is also shared by Aeromotive's lead tech who actually posed this issue to me initially. Only after reviewing the facts over and over again did I realize that it makes perfect sense. (To me and him at least)
By bypassing both heads entirely with the return fuel flow and using all 4 ports to feed fuel to both ends of the heads you drop the demand on those ports an unbelievable amount. Less than 1/4 of the demand. They only have to flow what the engine needs, not everything the pump produces, whether at idle or full throttle 24-7.
With the topic of fuel pressure at hand, I think it's important to note the serious pressure fluctuations dependent on where you take your measurement.
Then there is the obvious issue of killing electric pumps with too much pressure.
I might go ahead and swap over the fuel feed and regulation before I go to the belt pump just to go ahead and see if it effects anything significantly.
If I get a chance to do that I will post the results as always.
I am running fuel pressure at 65. At WOT It drops to around 55lbs. This along with non-shimmed pumps and tunes calling for extreme icp are causing my truck to fall off at WOT. Putting the shims in and installing an Airdog to correct the issue. Hope this helps you.
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1,781 Posts
Charles, I for one would like to see you go ahead and rearrange your fuel system before you put the belt pump on. You've got me thinking about that arrangement, but I wouldn't go the route of a belt pump, and it would be interesting to see the results gained by those of us sticking with electric pumps.
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13,503 Posts
i dont think 3-4 lbs at WOT is a problem.
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1,132 Posts
During the fall of '02 Mike Halas was looking at the DI regulated return system in my truck and stated that feed was very restrictive and he was feeding both heads directly into the fuel rails with a custom made fitting that did not use the OEM feed. I have not looked closely at this but IIRC, the fuel rail is drilled in the head and then plugged at the rear. I believe he left the OEM plugs used by most aftermarket fuel systems in place and modified the heads to accept his custom feed. Of course, the heads had to come off to make this happen whereas the JnB and DI kits did not.
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