Serious Fuel Pressure Problems - Please help
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TECH Enthusiast
Joined: Dec 2001
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From: Columbia, MD
Serious Fuel Pressure Problems - Please help I searched all the way back to 2002, but I couldn't find a specific answer to my particular problem.
I have the Walboro 340 in-tank pump AND the T-Rex in-line pump, but the fuel pressure now drops to 40PSI at WOT in 3rd, 4th, and 5th gear. The fuel pressure did NOT drop this much when I had the stock in-tank with the T-Rex, ONLY since the Walboro 340. I know that with bigger and better fuel pumps, or in my case TWO strong fuel pumps, the fuel pressure will be lower than a stock setup, but this low?
Black LS1 T/A and Harlan, you guys seemed to know the most in the other posts I searched through. Can you help me with this one, or anybody else?
BTW, on Monday, we are switching over to 50# injectors, hopefully this will help.
Thanks. I appreciate any responses.
Randy.
Correction: Fuel pressure now drops to as low as 20PSI at full throttle over 6000RPMs.
I have the Walboro 340 in-tank pump AND the T-Rex in-line pump, but the fuel pressure now drops to 40PSI at WOT in 3rd, 4th, and 5th gear. The fuel pressure did NOT drop this much when I had the stock in-tank with the T-Rex, ONLY since the Walboro 340. I know that with bigger and better fuel pumps, or in my case TWO strong fuel pumps, the fuel pressure will be lower than a stock setup, but this low?
Black LS1 T/A and Harlan, you guys seemed to know the most in the other posts I searched through. Can you help me with this one, or anybody else?
BTW, on Monday, we are switching over to 50# injectors, hopefully this will help.
Thanks. I appreciate any responses.
Randy.
Correction: Fuel pressure now drops to as low as 20PSI at full throttle over 6000RPMs.
TECH Fanatic
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From: Las Cruces, NM
Re: Serious Fuel Pressure Problems - Please help You did not mention what you were using for a fuel pressure regulator? I hope its not the stock one. The stock one does not do well with the increased volume, plus you would want one that is boost referenced, if you don't already have one.
Gary
Gary
Re: Serious Fuel Pressure Problems - Please help i had the same problem , i had the intank walbro and the inline aeromotive.
i turned out to be that when i put in the intank unit i didn't tighten the hose coming from the pump to the top of sending unit enough( it has to be on pretty tight). what would happen is that when ever i got on the car the fule pressure would gradually drop .
the best wat to test this is to unplug the power to your t-rex pump and take the car for a spin ( no wot runs just part throttle), if the pressure still drops as it did before then that could be a good indicator you have a leaking hose on the pump.
hope this helps
i turned out to be that when i put in the intank unit i didn't tighten the hose coming from the pump to the top of sending unit enough( it has to be on pretty tight). what would happen is that when ever i got on the car the fule pressure would gradually drop .
the best wat to test this is to unplug the power to your t-rex pump and take the car for a spin ( no wot runs just part throttle), if the pressure still drops as it did before then that could be a good indicator you have a leaking hose on the pump.
hope this helps
Re: Serious Fuel Pressure Problems - Please help yo im having the same problems, i have a t-rex inline, and tried adding the walbro intank pump. i know have worse fuel pressure then before. i even put another fuel pump housing in the tank and it still drops bad. does yours drop sitting in park? just revving the gas? mine goes from 62 to 50 just reving it. It seems if you own a 99 up you need to do a complete fuel system because of the stupid intank fuel pressure regulator. I am looking for a 97 corvette fuel rail, and im gonna use 6cyl fuel lines so i can have an aftermarket fuel pressure regulator on the rail. I just hope we didnt screw up the t-rex by putting a larger pump behind it. looks like im not alone.
TECH Fanatic
Joined: Nov 2001
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From: Las Cruces, NM
Re: Serious Fuel Pressure Problems - Please help If your pressure is dropping just sitting there at idle with a little blip then its most likely not the pump. The regulator is what controls your pressure to the engine. I would replace that with an external unit.
Gary
Gary
Re: Serious Fuel Pressure Problems - Please help redws699 the problem with a 99 up car is the regulator is in the tank. there is one fuel line. it t's off at the back. so there is no way to put an aftermarket regualtor unless you change the entire fuel system. im just wondering if the intank regualtor doesnt work with the external pumps.
Thread Starter
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From: Columbia, MD
Re: Serious Fuel Pressure Problems - Please help I did not perform the installation of the supercharger or any of the fuel components. But I'm pretty sure that a fuel pressure regulator was not in that list. All we put in was the Vortech V9 kit AS IS out of the box, plus the Walboro 340 in-tank pump, heads and cam, and LS1-Edit tuning. I never saw a "fuel pressure regulator" on any list of parts, nor did I order one. I didn't know I needed that!!
What do I do now? Where can I get one and how fast can I get it? Or do I need a whole new fuel system like Mike said? Tom Byrne was running this exact same setup last year, and I don't remember him saying anything about a regulator (but his car WAS a 1998).
I'm lost.
What do I do now? Where can I get one and how fast can I get it? Or do I need a whole new fuel system like Mike said? Tom Byrne was running this exact same setup last year, and I don't remember him saying anything about a regulator (but his car WAS a 1998).
I'm lost.
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Thread Starter
TECH Enthusiast
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From: Columbia, MD
Re: Serious Fuel Pressure Problems - Please help
yo im having the same problems, i have a t-rex inline, and tried adding the walbro intank pump. i now have worse fuel pressure then before. i even put another fuel pump housing in the tank and it still drops bad. does yours drop sitting in park? just revving the gas?
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From: Raleigh, NC
Re: Serious Fuel Pressure Problems - Please help This is my experience:
With the In-line pump, idle and cruise fuel pressure is less than stock pressure because the inline is a restriction until it is running. Aeromotive's pump regulator can cure this by letting the pump spin slowly at lower rpms (without heating the fuel unneccesarily with a 2nd pump running at full speed) and turn on full at WOT.
I took the Aeromotive off and put two Walbro's in. I still have the stock regulator.
I have about 59.5 to 60 PSI at Idle and cruise, about 58 or 59 at part-throttle. The D1SC and 422 with 55 PSI injectors sucks it down to about 54 or 55 lbs at the rail at WOT. I have the 2nd Walbro come on with a Hobbs switch and relay that senses when I go to boost.
Hope that helps.
With the In-line pump, idle and cruise fuel pressure is less than stock pressure because the inline is a restriction until it is running. Aeromotive's pump regulator can cure this by letting the pump spin slowly at lower rpms (without heating the fuel unneccesarily with a 2nd pump running at full speed) and turn on full at WOT.
I took the Aeromotive off and put two Walbro's in. I still have the stock regulator.
I have about 59.5 to 60 PSI at Idle and cruise, about 58 or 59 at part-throttle. The D1SC and 422 with 55 PSI injectors sucks it down to about 54 or 55 lbs at the rail at WOT. I have the 2nd Walbro come on with a Hobbs switch and relay that senses when I go to boost.
Hope that helps.
Re: Serious Fuel Pressure Problems - Please help
...it t's off at the back. so there is no way to put an aftermarket regualtor unless you change the entire fuel system.
Thread Starter
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From: Columbia, MD
Re: Serious Fuel Pressure Problems - Please help
This is my experience:
With the In-line pump, idle and cruise fuel pressure is less than stock pressure because ....
With the In-line pump, idle and cruise fuel pressure is less than stock pressure because ....
I think your problem was a little different than mine. My fuel pressure drops to 20PSI(??!!!) at full throttle in 3rd, 4th, and 5th gear. I was better off with just the T-Rex and the stock in-tank! At least then it only dropped to 56PSI.
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Re: Serious Fuel Pressure Problems - Please help
My fuel pressure drops to 20PSI(??!!!) at full throttle in 3rd, 4th, and 5th gear.
SC-
Thread Starter
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From: Columbia, MD
Re: Serious Fuel Pressure Problems - Please help
Stupid question. Are you POSITIVE that the inline is running? Could the walbro install have netted a loose connection on the inline pump? It sounds like a HUGE restriction is afflicting your system.
SC-
SC-
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From: Las Cruces, NM
Re: Serious Fuel Pressure Problems - Please help I also have an Incon kit, its actually quite easy to put an external in. The difficult part is getting the right adapters for the plastic quick connects. The return line tees off just after the filter it then goes back in the tank. You remove the intank regulator and put in the new one. Its not as good as putting one at the engine but it works. Also the 98 f-body had the same setup for the regulator. The 97 corvette had the regulator were our pulse damper is.
Gary
Gary
Thread Starter
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From: Columbia, MD
Re: Serious Fuel Pressure Problems - Please help So...
1. Check the T-Rex inline pump, make SURE its working. And if it is, then..
2. Order the Aeromotive fuel pressure regulator.
I saw in another thread that there were a couple of models. Which one is the best for the 1999-2002 F-bodies? And who sells these?
1. Check the T-Rex inline pump, make SURE its working. And if it is, then..
2. Order the Aeromotive fuel pressure regulator.
I saw in another thread that there were a couple of models. Which one is the best for the 1999-2002 F-bodies? And who sells these?
Thread Starter
TECH Enthusiast
Joined: Dec 2001
Posts: 553
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From: Columbia, MD
Re: Serious Fuel Pressure Problems - Please help
it turned out to be that when i put in the intank unit i didn't tighten the hose coming from the pump to the top of sending unit enough( it has to be on pretty tight). what would happen is that when ever i got on the car the fule pressure would gradually drop.
Thanks.
Thread Starter
TECH Enthusiast
Joined: Dec 2001
Posts: 553
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From: Columbia, MD
Re: Serious Fuel Pressure Problems - Please help
i turned out to be that when i put in the intank unit i didn't tighten the hose coming from the pump to the top of sending unit enough( it has to be on pretty tight). what would happen is that when ever i got on the car the fule pressure would gradually drop .
Looks like the same exact problem, the hose came loose.
Thank you for your quick responses everyone. Gotta love the folks on LS1Tech.com!
TECH Apprentice
Joined: May 2002
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From: Jacksonville
Re: Serious Fuel Pressure Problems - Please help Oh Hell yeah!.. that's awesome news!.. Man you had me worried about mine.. I still haven't gotten a FP Gauge after I recently installed a Walbro.
What's your FP holding at now?
What's your FP holding at now?
Re: Serious Fuel Pressure Problems - Please help
redws699 the problem with a 99 up car is the regulator is in the tank. there is one fuel line. it t's off at the back. so there is no way to put an aftermarket regualtor unless you change the entire fuel system. im just wondering if the intank regualtor doesnt work with the external pumps.
The better way (how I "should" have done it) is to purchase the V6 lines and use them (hard and soft lines). The V6s have the regulator on the engine and as such have three hard lines instead of two.
Chris
