Hi C6 side.
I have a late '03 C5Z (C6 Fuel System) that I LSA Swapped. It has an ECS stage 1 Fuel system in it. I am having Fuel Pressure problems when I go into boost. It is making my tuner crazy. Here's what's going on....
I have a gauge but can't data log FP. The gauge reads a solid 59# all the time. When It goes into boost the Hobbs kicks in (4# boost) and lights up Pump 2 - It goes as high as 65# for a second. Then, as I stay 'into it' the FP drops - I've seen as low as 38# and get all kinds of lean spikes in my logs. I've talked to ECS and they say 'there's hundreds of these out there running just fine', etc, etc. There is a check valve on the outlet of Pump 2. My GUT feeling is that I need another on the tank side of the T that came with the kit. I think pump 2 is overpowering the In-Tank pump and regulator - they are playing Tug-O-War. There's nothing to tell the T which way to route the fuel. So it goes both directions. Just a hunch.
I'm asking on THIS side of the isle hoping that there's more experience with the C6 ECS system. I might have to plumb it as a true retune system this winter but I'd like to get it running without doing that.
Does anyone have an opinion on this dilemma? I did all the work on the car so If you need more Info, Fire Away
Thanks for any help - Here's a pic of the project. I do have a practice hood on it at this point. I want the lid to show - that's why I PD'd it body color.

 

It would be helpful if you posted a diagram of your fuel systeml, include pump models an include AN hose sizes.
Note I also have a late model 2003 Z06 also yellow. I am running a boost referenced system with 17lbs boost with an RHS 427 block 900+ to the wheels

 

Thanks for the reply - this is from ECS's site...
ECS Stage 1 Fuel System:
The ECS Stage 1 fuel System incorporates your standard intake pump, and adds a secondary AEM 380lph pump that is only used when fuel demands exceed “normal” levels. The Secondary pump is activated via a hobbs switch that recognizes vacuum and boost pressure and activating the secondary pump and increasing both fuel pressure and flow.
Thanks to the custom machined ECS Fuel Block and fittings, the ECS Stage I fuel system cleanly ties into your factory fuel lines and continues to use factory fuel rails and pressure regulator. All ECS stage 1 fuel systems come with pre-made high pressure PTFE Fragola hoses, pressure tested and ready for install…that is an industry first and exclusive to ECS!!
The ECS Stage 1 fuel system has proven to be stable to 800 rwhp and is easily upgraded should your HP grow at a later date.
This ECS Stage I Fuel System is designed for mid 2003 and later C5 & C6 Corvettes. For earlier systems refer to ECS Stage I Fuel Systems for 1997-2003 Corvettes. ECS Fuel Systems DO NOT come with injectors.

It's all -8 from Pump 2 then it hooks to the OEM system with a 'T' and goes forward to the stock LSA Rails. And here is a pic of my install...



Pump 2 from ECS

I think this 'T' is part of the problem. Pump 2 may be Back Feeding Into the tank

 

you have the external pump mounted too high. it is not being gravity fed.... it is having to work too hard to suck the fuel from the tank. the fuel line is making it worse being way too long. I can imagine it probably is hardly working at all like this

 

Thanks for the reply Russ472. I've thought about that. The pump is mounted just about where ECS's instructions put it. I had to move it a bit and make that loop in order to keep my brake cooling duct - they said to 'just remove it'. The 'T' on a C5 is much higher than on a C6 and the hoses were WAY too short. We went Round & Round till they made me correct length hoses - that 'kit' ain't cheap!. They have pictures of my entire install because of that - one would THINK that those experts would say something about 'gravity'.
I'd have to look into the pump's abilities. If Gravity is a big deal then that loop might be an issue. I've jumpered the Hobbs to force the pump to run and it doesn't seem to have trouble making pressure instantly. Interesting.

 

I agree with this, I have a similar setup with probably only 1/3 of the length that you have. When you dynoed your car, did you have at least 1/2 tank of gas,this would be an almost full drivers side tank.
It would be interesting to check your fuel pressure with the Hobb switch on with cold car and also after a long drive. I hav e a Bosch 44 in tank and a Walboro 255 that is on full time, no Hobbs

 

Thanks GlennD. I have not had the car on a Dyno yet - all street tuning with a remote guy that know what he's doing. I WILL try the Full tank experiment though. Worth a shot. My goal is to NOT drop the tanks - ROYAL PITA with this system - But you all know that. I'll look into the specs on the pump to see if head pressure is important - you guys might be onto something. Even without the loop the pump will still be higher than the tank - no way around it.
When I bought mine it was $900 - It's $1200 now! 'Just eliminate the brake duct' was not an option. How 'bout designing it better? Believe it or not, I'm not president of the ECS Fan Club - once they get your $$ they seem to forget about 'service after the sale' - in MY case anyway. Because I was the guy that pointed out that, even though the Late 03+ has the C6 system, the hoses aren't correct they wanted to see what I did. They told me they would use MY set up in their instructions for anyone using this on a C5. They knew that loop was there and said nothing so I assumed it wasn't an issue. Just for fun, Look up the origin of 'Blowing Smoke up you A$$ - Kinda funny.
End of Rant.

 

I'm sorry you are withdrawing your application to be the president of our fan club, we were hoping to hang your picture on the wall. lol (I'm just kidding with you)

OK, so as others have asked, is there a difference from a full tank of gas to near empty? I hate giving the "there are 100's of these kits on the road" answer, but there are, so lets try and figure out what's going on here. The brake duct can be reinstalled with the pump lower if you notch the pump into it. I also think the hose is ran in a way that is causing a restriction, I would try and get that upward loop out of it.

 

Thanks for that reply Doug - Glad You chimed in here. I will fill up and run it. It is below 1/2 so all the remaining fuel is now in the D-Side tank. Hopefully, it is as simple as moving the pump and changing the hose.
Do you have any pics of this system on a C6? Maybe an install YOU did in your shop? There isn't really a way to get the pump below the tank - maybe a little lower than where I have it but... 10# of Poo in a (C) 5# bag. Why do you spec a 120* fitting at the inlet of the pump if it's not supposed to run Uphill? That's how it was shown in the instructions. That document also shows the check valve on the T vs on the top of the pump - would THAT matter here? Mine is on the pump.
Thanks again - I'll try to get back on board with the Fan Club.

 

I think you may be onto something here. I just took a data log drive - filled it up as full as I could get it. FP did not go below 61# at all. I WOT'd it a few times too. I still have a burble but no lean spikes / pressure drops. I guess that loop is part of the problem.?
This whole thing is about the ECS system - are there any pics of how others have it installed. I'm still struggling with the fitting choices in the kit. Unless you can lay the pump flat why are there 120's & 90's?
Looks like I have another thing to do this winter...
Thanks - Pics please??

 

Check the diaphragm on your fuel regulator your running one, seen this cause all kinds of problems.

 

Thanks I30 - The regulator is IN THE TANK- I don't want to got there, yet. Last Resort
The C6 fuel system is WAY over engineered, complicated and un-friendly. Just the way it is.

 

I’m the tuner. I’ll just say tuning SD with the FP all over the map is very difficult.

The ECS setup is unregulated. And just feeds to the main fuel line in parallel. The hobs switch activates at around 135 kpa. The pressure jumps 6 psi.

This is where I think having a pressure gauge you can log is invaluable.

The fact that the stock pump and Reg in the tank sags to the 30’s pre boost says there is an issue there.

Best scenario here is fix that. Then convert this setup to a boost referenced system with a good regulator at the fuel rail. The ECS setup has a provision for a return. And no “T” in the system. A Y fitting at least keeps the fuel flowing in the same direction. When in doubt, put a good check valve after each pump.

Jumbo is a great guy. Doing my best to help from across the country.

I’ll add, fuel is set rich, timing at 8 degrees. I certainly don’t want to hurt it during this process.

Ron

 

Thanks for the Kudos, Ron. I didn't want to 'out' you without permission.
I agree with a Y being a better choice - At least it encourages the fuel to go in the intended direction. I'm going to look for parts to put that together and keep the GM quick connects. I'd like to add a check valve too. Does anyone here know if that's a pre-made thing and where to get it?
In a perfect world I'd put a big fat pump in the tank and be done with it. Yes, a true Return Style would be nice. I just don't want to drop those tanks and I'm quickly running out of Corvette time in Central PA.
I have a lot of winter work planned. FP logging just got added to the list.
Doing the Full Tank Experiment was eye opening. I WILL find a way to lower the pump, get rid of that loop and keep my brake duct - I can now see that it's causing problems. If I can keep FP between 59 - 61 I think it'll make a difference that we can live with. That's up to the tuner though.
This is the kind of pic I was looking for. This is a C6 - the T on the output side is much higher on a C5. I might be able to get close to this routing if I put some thought into it.

Thanks for all the help here!!

 

That pump location looks good. The feed is below fuel level, that always helps!

 

Yeah Shrimp I ran an external pump setup very similar to there's for years on my C6's with a Hobbs switch and it worked great. Mine was mounted a little further forward like you moved yours and I put a #12 suction hose. Differences. I ran a separate supply line all the way to the rails (Aftermarket FR's) where I had a FPR a check valve in the line so when it wasn't running i didn't have any back flow issues. Don't know if that offers you any help. but I thought I'd throw that info at you. GL!

 

Thanks for that. I honestly might be easier to run a new line & Y it up front. There's not a lot of room in the back. C5's hook up is at the floor vs down low on the C6. Either way, it's a project and will take some time and thought to do it right.

 

I've given this a lot of thought, ordered some parts and gonna get started. I have 3 things to do.

1- Replace the Aeromotive T fitting form the ECS kit with a Y and a check valve. I still think the fuel from Pump 2 is going in both directions - just a gut feeling. It is LONG! I may have to cut the hard line going to the rails and use a compression to GM push-on adapter - I got one of those too. This is what's going in it's place. We'll see in a few hours - I'm starting there.



2- Lower the pump and re-do the hoses so I have a more direct, level feed into the Aux Pump. Good suggestions from Y'all. I think my routing is part of the problem - especially when I'm under 1/2 Full. That's happening after the Y block / Check valve. Hopefully I'll get to test these 3 things as each gets done. But...it Snowed here in Central PA and I might be screwed unless the weather co-operates a little. Doesn't look good though.

3 - Add a true return to my system. I Need advice here...
The ECS bulkhead fitting has a -6 port for a return - Good thinking! The way I understand the complicated, unfriendly C6 (and C5) system is that it pulls fuel from the Pass Side till it is empty then draws from the Dr Side. If I have both tanks full and I'm returning fuel to the Dr Side while the other tank is full - where does it go? It seems like I'll be OVER filling the Dr Side tank unless the system is smart enough to transfer it over to the Pass Side till THAT tanks is empty. Is it that smart? Am I over thinking this?

Let me know what you think
Thanks for all the wisdom...

 

Do you mean 13kpa or 135 kpa? 135 kpa is almost 20psi.

 

Hello Raj
It might be best for Ron to answer that. Depending on how you look at boost charts 135 KPA could either be 4# or 19.7 PSI. I have HPT logging a calculated boost and have never seen 20 in the logs.
What is your take on the return fuel going into the D-Side tank? That is really my question in the post.
I got into it yesterday but forgot about all the exhaust in the way. Had to drop the sway bar and one muffler before I could even SEE the T fitting. "It's always something". And because of the High location (not at all like a C6) the Quick Disconnect fittings are not at all quick. Also, It looks like I'll have to cut the main hard line going forward. My Y block and fittings are a mile long. I might just replace the whole line now with PTFE and get it over with. Project Creep! It haunts me.