New e85 car voltage drop to 12v at 4500 rpm

[kccobra1]

Ok need some help, I have a e85 car that was just converted and it is dropping 1.5 volts at 4500 rpm. Talk to me people. I think its the alternator but my tuner isnt sure. Just put new 465 pumps in and my pressure is 60 psi till I hit 4600 rpm and it drops to 40 psi. Have a 1400hp lethal return system on it and regulator is set at 43lbs at idle.

help me

 

[da28fan]

Run e85 and dual 465lph walbros (just replaced the 255s). Fuel pressure is set at 38/39 at idle. At WOT, it drops to 29. I'm hearing more and more that Lethal's fuel systems do drop pressure at higher RPMs. My tuner indicates current is fine. Just that we're losing pressure. Using 10an supply line. Tuner is wondering if it is the design of the fuel hat that 's the culprit, and recommends if I upgrade from my 2.2 KB to a 3.4 whipple or 2.9 KB that I look into a sump fuel system, especially if sticking with e85.

 

[nanastymach1]

Mannnn i knew there were going to be draw backs to this e85 shit....i did research for the while year of 12 and i made the switch and I'm experiencing the same shit with my lethal 1200 system fml

 

[MaximumVelocity]

Voltage drop where? If you are monitoring the voltage at the PCM, battery or alternator terminals, it will be a charging issue.
If voltage is dropping at the (+) terminal on the pump, you likely have a wiring issue. Have you done a wiring upgrade with good quality amp wire to the relays, and kept the relays close to the pumps (relays should be rated for at least 30A)? Do a voltage drop test...from battery to pos terminal, from terminal to relay, from relay to pump (+), from relay (-) to ground , and from pump (-) to ground. If any of these differ by more than 0.3V then you have found the issue.

 

[sabotage]

According to my tuner oem cobra alternators completely stop charging at wot.....it sounds like those huge fuel pumps drain to many amps and the stock 100amp alternator can't keep up. It's a charging system problem check the voltage at the pumps at 4500 and see what it does. Your best bet is the the voltage is dropping ie fuel pressure dropping as well.....and specially if you guys have different lowers with the stock alt pulley. ....

 

[gaspasr]

Think I had a similar problem and my mechanic fixed it with a PA performance 160amp.
Also did the wire upgrade and alt pulley

 

[da28fan]

Think I had a similar problem and my mechanic fixed it with a PA performance 160amp.
Also did the wire upgrade and alt pulley

Wire upgrade? Is there a kit somewhere for this, or a link?

 

[gaspasr]

Search Results - We Carry Most Ford and GM Applications

 

[black03]

Run e85 and dual 465lph walbros (just replaced the 255s). Fuel pressure is set at 38/39 at idle. At WOT, it drops to 29. I'm hearing more and more that Lethal's fuel systems do drop pressure at higher RPMs. My tuner indicates current is fine. Just that we're losing pressure. Using 10an supply line. Tuner is wondering if it is the design of the fuel hat that 's the culprit, and recommends if I upgrade from my 2.2 KB to a 3.4 whipple or 2.9 KB that I look into a sump fuel system, especially if sticking with e85.

Where have you heard about our systems dropping pressure?

Our system is a simple mechanical fuel system just like any other return system. Pumps run full time at full voltage and pressure gets regulated by the 1:1 boost reference regulator. It's not abnormal to see a small pressure drop on a return system. 2-3psi at high RPM's is pretty normal. Higher pressure drops can be caused by several things and should be addressed immediately.

If you're running our system and having higher pressure drops then 2-3psi then I would check.

Pump install height- If the pumps weren't installed to the correct height in the hat they may be bottoming out on the floor of the fuel tank. This will definitely cause a pressure drop as the pumps will starve for fuel when the pre-filters are pinched together. It's also common that the bottom of the fuel tank is bent in from being jacked up in the center of it at a previous date. So even if the pumps are installed to the correct height the bent tank will still press on the pre-filters choking the pumps.

Voltage- A bad alternator or wiring will also cause pressure drops. The 03-04 cobra are notorious for this. You need to verify that your pumps are seeing constant 13-13.5V. If you're seeing less than that at any point as the voltage drops so will fuel pressure.

How the wiring was done- We recommend installing our wire harness by connecting the trigger wire to the green/yellow wire pre-FPDM. This will trigger the pumps to run full time and see a constant 13-13.5V once the key is turned to the on position. So whether you actually start the car or just turn the key on the pumps will have full voltage and run full time. There have been others on this forum who have chosen to trigger the relays with the POST FPDM wire. That works as well but needs to be tuned for. If not the signal to the relays will see variable voltage and will not provide a full constant 13-13.5V to the pumps. Tuners will typically tell the car to run 100% duty cycle when wiring their cars this way.

Hope that helps.

Jared

 

[da28fan]

Hi Jared. I have read about dropping fuel pressure some here on the boards and my tuner has said he's seen it before. Now I do like the fuel system, no question. To address my drop, my tank is not dented in, but can see how this would hurt it. I just put in your 465lph Walbros. On the height question, there is only one way these babies go in. Without modding anything, they are taller and the fuel hat will not seal against the top of tank due to height, even after pushing them all the way in. We had to actually trim some of the plastic grommet on the pumps that goes into the little rubber hose on the hat. So the pumps are in as far as they will go. So it is indeed possible the filter bags could be restricted some.

I've also been advised that cavitating could be occurring as the returning fuel could be "aimed" near the pickup (filter bags), so another person recommended changing where that fuel goes upon return. Don't recall exactly, but I'm guessing there is a way to connect some type of hose to the underside of the hat to cause the returning fuel to be returned outside of that main chamber/sump.

Tuner says I am not dropping current, even though I have stock alternator, but if I could confirm that was the issue, would not hesitate in upgrading it.

I would be interested in if you're hearing how any others have mounted the 465s since they are taller pumps. Thank you.

 

[black03]

Hi Jared. I have read about dropping fuel pressure some here on the boards and my tuner has said he's seen it before. Now I do like the fuel system, no question. To address my drop, my tank is not dented in, but can see how this would hurt it. I just put in your 465lph Walbros. On the height question, there is only one way these babies go in. Without modding anything, they are taller and the fuel hat will not seal against the top of tank due to height, even after pushing them all the way in. We had to actually trim some of the plastic grommet on the pumps that goes into the little rubber hose on the hat. So the pumps are in as far as they will go. So it is indeed possible the filter bags could be restricted some.

I've also been advised that cavitating could be occurring as the returning fuel could be "aimed" near the pickup (filter bags), so another person recommended changing where that fuel goes upon return. Don't recall exactly, but I'm guessing there is a way to connect some type of hose to the underside of the hat to cause the returning fuel to be returned outside of that main chamber/sump.

Tuner says I am not dropping current, even though I have stock alternator, but if I could confirm that was the issue, would not hesitate in upgrading it.

I would be interested in if you're hearing how any others have mounted the 465s since they are taller pumps. Thank you.

Who is your tuner?

What color wire are you using to trigger the relays?

My best guess is that you're pumps are either bottomed out on the bottom of the tank, you have a voltage drop due to a bad alternator or you've got the relays hooked up to the post FPDM wire which see's variable voltage.

The 465's are indeed taller and don't fit in previous version fuel hats without modification. If you have an earlier version fuel hat you'll need to trim the outlet of the pump just below the 2nd barb leaving no barbs once modified. This will allow you to push the pump all the way into the hose without hitting the fitting on the underside of the hat. You'll know the pump is at the correct height if the bell portion of the pump is right against the bottom of the basket that houses the pumps. If the bell portion of the pump hangs lower than that you may end up crushing the pre-filter causing a fuel starvation issue.

The new V4 fuel hats from DX use a lower profile fitting on the underside of the hat so no modification to the pump is needed.

As far as the return port goes it's located in the same position as it was when the first hats from Fore were offered over 5 years ago. We've never seen an issue with it in that location and have sold hundreds upon hundreds of their hats and the DX ones since. If it was an issue I'm sure we would see more problems from others by now.

I personally believe the return tube should be located inside the baffle area as if it's not you'll most likely end up straining that area of fuel much quicker under load.

Let me know if you have any other questions.

Thanks, Jared

 

[kccobra1]

I replaced my alternator and my voltage is fine after that change. I have the top hat and system from lethal that is the older version you have to modify the pumps to fit. I have my pumps in the holder and sitting at 1.75 inches from the sock to bracket and I am getting 20lb pressure drop at 5k rpm with walbro 465 pumps that I just bought brand new. As for my return I first shortened up the tube and then just removed it. Same issue either way. This is E85.

 

[gaspasr]

I hope you find your problem. I replaced dead 400 walbro pumps for 465s and followed Lethal's instructions. I too have the older division x hat.

 

[kccobra1]

Here is what it is doing now with the pump setup.

 

[da28fan]

Here is what it is doing now with the pump setup.

I'm no expert, but 12.7 at high RPMs? That's what I was doing with the 255lph pumps. With the 465lph pumps, I'm 11.7/11.8. I'll prolly end up dropping the tank again to raise up the pumps as much as I can and look at redirecting the return fuel away from the bottom of the sump pit. Tuner says he has seen this in two other cars in the last week. If nothing else, at least I can rule this out as a possible problem. I am not dropping voltage, so rules that out.

 

[kccobra1]

I raised mine up to 1.75 inches as stated on lethals site.

The car I am working one has been a pile of shit since the day I got it. Over sold and under performed. I have read tons of threads with issue on the lethal fuel system so I am going to consider dumping it soon.

 

[black03]

I raised mine up to 1.75 inches as stated on lethals site.

The car I am working one has been a pile of shit since the day I got it. Over sold and under performed. I have read tons of threads with issue on the lethal fuel system so I am going to consider dumping it soon.

Could you please link me to the "tons" of threads where people have issues with their fuel systems from us? I'm curious as we rarely here of issues with our systems.

Besides the occasional person whose tank is dented in, the wiring was done wrong or they didn't follow the instructions about the pump install height or hose routing our systems seem to work perfect for the majority.

We currently run our systems in 3 of our shop cars which support all the way up to 1150rwhp on E85. Cars which not only get driven on the street but get beat on at the track. My 03 Cobra even with the 400lph walbros in E85 safely supports 870+rwhp with the 105lb injectors. Again no issues at all.

It's a simple mechanical system. The pumps stay on at constant voltage and pressure gets regulated by the mechanical regulator. There's really not much more to it than that.

I can understand your frustrations as I've been there before on several of my cars. But there's obviously something wrong and there needs some trouble shooting to find out what the issue is.

Simply blaming it on the fuel system isn't going to get you closer to figuring it out.

My suggestions would be this.

Triple check that your pumps aren't bottomed out on the bottom of the tank. Even though you have them at the proper height I've seen over and over tanks which have been jacked up from the bottom and cause the tank to pinch the pre-filters. I've had customers swear to me in the beginning that the tank is not dented later to find out after looking closer that it was.

Wiring- Make sure all of your wiring is correct. If you're tapped into the wrong wire for triggering the relays your system will not function properly.

Hose routing- Can you post a picture of how the feed line, rails and regulator are setup?

Pumps- Make sure each pump is running. You can do this by removing the fuse or relay for each pump individually.

Vacuum line to regulator- Make sure that it's not damaged or has a leak. If that line has a hole in it or damaged the regulator won't hold pressure properly.

Tune- Has your tuner properly set your tune up for a return style fuel system? Who is actually tuning the car? Also, How are you reading fuel pressure? The mechanical gauge on the rail/regulator or are you reading it off the FRPS?

Those are the first things I'd check to trouble shoot an issue that you're having.

Jared

 

[kccobra1]

Could you please link me to the "tons" of threads where people have issues with their fuel systems from us? I'm curious as we rarely here of issues with our systems.

Besides the occasional person whose tank is dented in, the wiring was done wrong or they didn't follow the instructions about the pump install height or hose routing our systems seem to work perfect for the majority.

We currently run our systems in 3 of our shop cars which support all the way up to 1150rwhp on E85. Cars which not only get driven on the street but get beat on at the track. My 03 Cobra even with the 400lph walbros in E85 safely supports 870+rwhp with the 105lb injectors. Again no issues at all.

It's a simple mechanical system. The pumps stay on at constant voltage and pressure gets regulated by the mechanical regulator. There's really not much more to it than that.

I can understand your frustrations as I've been there before on several of my cars. But there's obviously something wrong and there needs some trouble shooting to find out what the issue is.

Simply blaming it on the fuel system isn't going to get you closer to figuring it out.

My suggestions would be this.

Triple check that your pumps aren't bottomed out on the bottom of the tank. Even though you have them at the proper height I've seen over and over tanks which have been jacked up from the bottom and cause the tank to pinch the pre-filters. I've had customers swear to me in the beginning that the tank is not dented later to find out after looking closer that it was.

Wiring- Make sure all of your wiring is correct. If you're tapped into the wrong wire for triggering the relays your system will not function properly.

Hose routing- Can you post a picture of how the feed line, rails and regulator are setup?

Pumps- Make sure each pump is running. You can do this by removing the fuse or relay for each pump individually.

Vacuum line to regulator- Make sure that it's not damaged or has a leak. If that line has a hole in it or damaged the regulator won't hold pressure properly.

Tune- Has your tuner properly set your tune up for a return style fuel system? Who is actually tuning the car? Also, How are you reading fuel pressure? The mechanical gauge on the rail/regulator or are you reading it off the FRPS?

Those are the first things I'd check to trouble shoot an issue that you're having.

Jared

Jared I have been fighting this issue and I am just pissed, the comment I made was mostly about the car not 100% the fuel system. Show me the pressure on your 2003 cobra like I just showed on the dyno sheet? I pretty much have the same setup as you minus the 4.0 SC. Showed you mine. Also I am using the hat LP sold around June of last year which is different. My tank is not dented, I looked with the plastic cover off.

I am using 3 different gauges and all around the same pressure.

 

[black03]

Jared I have been fighting this issue and I am just pissed, the comment I made was mostly about the car not 100% the fuel system. Show me the pressure on your 2003 cobra like I just showed on the dyno sheet? I pretty much have the same setup as you minus the 4.0 SC. Showed you mine. Also I am using the hat LP sold around June of last year which is different. My tank is not dented, I looked with the plastic cover off.

I am using 3 different gauges and all around the same pressure.

I don't believe I have a dyno sheet of my
03 showing fuel pressure. However if I did I'd be more than happy to share it with you. I'll ask Ken if he has one but I honestly don't think he even logs fuel pressure on these return setups unless the car is lean.

What about the other things I asked you above? Do you mind answering any of those questions? I asked them so that I could try and help you figure out what's going on with your car.

Thanks,
Jared

 

[kccobra1]

Wiring- Make sure all of your wiring is correct. If you're tapped into the wrong wire for triggering the relays your system will not function properly. This is 100% correct, I have checked and recheck. Ran 4 gauge off the battery both positive and negative. No help with the drop.

Hose routing- Can you post a picture of how the feed line, rails and regulator are setup? I will get these tomorrow. Pictures.

Pumps- Make sure each pump is running. You can do this by removing the fuse or relay for each pump individually. First thing I tested was this. I did notice a pressure drop from one to another running, but no drop with just ignition on, engine off.

Vacuum line to regulator- Make sure that it's not damaged or has a leak. If that line has a hole in it or damaged the regulator won't hold pressure properly. No leaks in this at all. Tested it.

Tune- Has your tuner properly set your tune up for a return style fuel system?
Yes, but this is still in progress, but the pumps drop 20 psi at wot .

Who is actually tuning the car? Dynosport

Also, How are you reading fuel pressure? Dyno, AEM, and the mechanical gauge that comes with the kit.

The mechanical gauge on the rail/regulator or are you reading it off the FRPS? mechanical gauge that comes with the kit.

Those are the first things I'd check to trouble shoot an issue that you're having.

Jared

Answered the questions. Will the updated top hat make a difference? What version you running?