bonecrrusher

Hello everyone -

I have had my E-Force supercharger on my C6 for about 3 years now.

Car setup: LS2 block, LS9 cam, CNC ported LS3 heads, E-Force supercharger, Kooks headers, DSX E85 sensor and FIC1000 injectors. 3" Edelbrock pulley - the car made 650 RWHP on E85.

I installed the external fuel pump at the same time - it is an ECS style setup - using -8 PTFE hoses - and using the same inline 3/8 to -8 AN fitting that ECS uses: https://www.racetronix.biz/product.asp?ic=313-15121

I have a Deatschworks 350IL external pump as well.

The problem that I am running into - from a dig - or on the dyno - the car is dropping almost 20-30 psi when you step on the gas. From a stop - hit full throttle and it goes from 60+ psi down to 40 psi of fuel pressure.

When you are at speed - or on the highway and you floor it - the fuel pressure maintains 60+ psi without issue.

I have done my research here - and I saw a few "fixes" that I tried.

1. I installed the Racetronix fuel pump "hotwire" kit.
2. When I was installing the external pump kit - I somehow missed the fact that you need a check valve - I added a check valve after the fuel pump.
3. I replaced the external pump ground wire - with a wire that is 3x bigger - and I moved the ground location to a proper chassis ground.
4. I replaced the Hobbs switch as the tuner had noticed it had gone bad.
5. Installed a fuel pressure gauge so that I can verify what the fuel pressure at the rail is.
6. Verifed the External pump is receiving around 14 volts when activated - I also tested the ohm value of the ground wire that I replaced - and there was very little resistance drop.

I had done a few mods before this problem showed up:
1. 4" intake and cone filter from Vibrant
2. 2.75" pulley from Edelbrock
3. Russel -6AN Y Fuel Distribution block - and -6 PTFE hose to the back of the passenger side fuel rail.

I've done as much research as i can on this issue - hence why I am here - reaching out for some help.

Short of dropping the tank(s) - putting in the Lingenfelter FPR block off plates, adding an AFPR up front after the fuel rail, and adding a return line back to the tank - I am not sure what to do next and try and resolve this issue.

CHR89

Have you bypassed the hobbs switch to run the external fuel pump full time?

realcanuk

Just a guess really but maybe your external pump is overpowering the factory regulator.

bonecrrusher

No - the Hobbs switch is working fine - I did bypass it to verify that the pump is getting 14 volts - then I plugged the Hobbs switch back in. At speed - you can give it gas and see the fuel pressure increase from the second pump.

Yeah that issue had occurred to me - I have seen a number of threads where an AFPR was added + a return line - but the boost referenced regulator was adjusted to 58 psi and the boost reference port was left without a hose on it.

I've already been looking into getting the parts for that setup - but I just wanted to make sure I wasn't missing something obvious/stupid.

CHR89

Yeah I assumed the hobbs was working since you mentioned replacing it, I was just curious to see if it had similar issues when running it full time vs off the hobbs switch. I had similar issues running my external 044 off of the hobbs so I deleted it and just run it full time now.

realcanuk

That's exactly how min is set up now and its no issue. But now that I think about it I had an ECS stage 1 system with my eforce and never had an issue... so something is wrong somewhere.

realcanuk

Where is your external pump picking up from ?

bonecrrusher

That sounds dangerous - lol.

I have the pickup at the same spot where the ECS bulkhead picks up - I do not have the ECS bulkhead (its in my parts list for the return line - as I don't want to drill another hole in the tank).

Pic is below:

CHR89

How do you figure that would be dangerous?

CHR89

Also you don't really want your check valve on the inlet side, you want it as free of restriction as possible.

realcanuk

Try running the secondary pump full time. Maybe you are running out of pressure before it kicks in. What psi is the hobbs set to come in at ?

CHR89

That was my thought, not sure why he doesn't want to run it full time though. First thing I'd do though is get that check valve out of the inlet side especially with the pump pulling from essentially the bottom of the tank to the top.

bonecrrusher

Hobbs switch is set for 5 PSI.

I could try running the pump full time - and see what it does. That'll probably be the next thing that I do.

Could a weak alternator impact the fuel pumps?

Only reason I ask - is that both pumps run off of the alternator now - and I noticed it dipping into the 11 volt range yesterday when I was driving during lunch. It was 90* out and the AC was on. The car actually stalled out pulling up to a stop sign.

When I drove last night - it was in the 70's and the AC wasn't on and I didnt notice the charging issue that much.

I tested the battery - and it has 14 volts - also tested the alternator at idle and was producing 14 volts as well.

bonecrrusher

The check valve is on the outlet of the fuel pump (bottom of the DW pump) - the check valve looking thing near the tank is a -8 fuel filter.

CHR89

Sounds good, looked like a check valve. I would for sure look into your electrical issues though especially because your alt will be putting out the least amount of charge from a stop/idle. Running the secondary pump full time will help you figure that out as well. Interestingly enough when I had the same issue with my 044/eforce build I was having alt issues as well. I still just run both pumps full time on mine though, have done quite a few cars like this in the past but I am also on a return style setup now.

realcanuk

Low voltage will definitely effect the pumps. Make sure the belt isn't slipping or voltage dropping on hard acceleration.

bonecrrusher

What did you do to resolve the alternator issues? I am thinking of pulling mine and getting it load tested. After I do that I will run both pumps and see what happens.

Thank you - I will pursue both of those.

I don't think I have much belt slip as I have the bigger 90 or 100mm idler pulley (whatever size that upgrade was) and the updated bracket. The Gates HD Green belt was really difficult to put on.

CHR89

Mine ended up being just a bad alternator, I replaced it with a higher amp unit without the clutch on it (make sure to red loctite the nut if you do this). It could be your Alternator as it gets warm or your starter as it gets a little cooked by your headers. If your battery is up front you can always run a power wire from the battery directly to the lug on the alternator to rule out your starter being faulty.

My alternator died pretty quickly after running both pumps + my EMP pump for the coolant tank full time.

russ472

maybe I am wrong, but looking at your picture, it looks like the inlet line to the pump is on top of the pump.

CI GS

Yep, that’s the same thing I was thinking. It’s possible that the way it’s set up, it’s losing prime on the hit and the pump is cavitating. The first thing I would do is flip the pump over and try to keep the inlet on the pump as close to the bottom of the tank as possible.