While I was taking my car to the dealership diagnose a problem with my low speed fan not coming on, the fuel pressure started acting up. I managed to crawl into the lot then she died on me. I shut her down then started her up again. Thinks came back on ok. So I asked them to check the fuel system too just in case. I thought maybe electrical gremlins were acting up. Today I stopped by to check on progress , this is what they tell me :
The External pump may be the reason. For installation I had provided them with the following link :
http://www.exoticperformanceplus.com...Car.php?car=40

One wierd thing though. I asked the tech to tell me exactly why he though that the pump was at fault he said that after it got warm the problem starts. Now my pump has always been a bit loud but I always thought that this was ok because of it being mounted behind the drivers side rear fender. The tech also said that the internal pump in the second tank the one near the pump has been bypassed when they did the install. I thought that was wierd since I was under the impression that the internal pump still needs to work and the new pump is spliced on to the harness. Can someone please elaborate on this ?

Note I also got PCM Code 1241. Does this have anything to do with the above ? What is it about ?

Help me out guys

 

I think newer ECS kits only activate 2nd pump when you go into boost so in-tank always runs. Diynoob was the first to do a demand (boost) based system and he noticed considerable temperature based improvement.

Also ECS lowered pump location some time ago to provide better suction head.

Oh by in-tank you mean drivers side?


Mike

 

I bought my kit from ECS this year but as you know there are no instructions. So I used the link to install. Yes I mean the driver side. I ASSUMED that the in-tank pump shouldn't be bypassed based on Diynoob's setup.Any install instructions for that setup ? What changes would be required ? Is that my problem ?

Thanks

 

The in-tank pump needs to run all the time because part of the flow is diverted to venturi pump in 2nd tank thus constantly topping off drivers side tank from passenger side tank.

I'm sure some owners of this system will comment. Also the link is for late 03-04 C5s.

In your climate I'd strongly suggest only running 2nd or external Bosch pump when you get into boost via hobbs switch and relay.


Mike

 

Mine is an 04. Ok to get this striaght ( pardon my ingnorance ) :

Passenger Side Pump Must Run all the time - This is happening.
Drivers Side intank Pump - Must it run or not ? Mine is not.
External pump - preferable running in boost only. Need more clearer Instructions .

 

The intank pump need to run as pointed out. For reasons also pointed out. The pump should not have been bypassed.

There were some changes made to the systems but if you bought it this year they are likely included in your system. Call ECS Monday and they will get you setup with a kit to modify your system if you need changes. If you need a replacement pump they can set you up with that as well.

ECS installs the systems with the second pump running all of the time. You can of course use a Hobbs switch to activate the pump when it sees a predetermined amount of boost. I have set them up both ways.

 

Passenger side pump is venturi or jet pump not a electric pump. It uses a small fraction of drivers side electric fuel pump output to run it or transfer fuel from passenger tank to drivers tank.

I don't have codes (PCM) on this computer but it sounds like you ran out of gas (passenger tank has fuel but drivers side tank is empty).


Mike

 

THANKS Guys. From what I read this is what I need to do :

1- Have the tank on again.
2- Fill up The car is on half a tank now.

I will call up Chris on Monday and check which kit I got. The pump seems to be fine for now since Fuel Pressure is fine so its pumping all right but once the tank runs out it stumbles.

I will check with the dealerchip tomm. and let you guys know.

Thanks again

 

You cannot bypass either of the factory pumps. The main pump (on the drivers side runs (or should 100% while the car is running) The pump in the passengers side only runs when more fuel is needed in the primary tank (drivers side).

The ECS fuel system can either run while in boost or run all the time. For me I would run it all the time...that way I would be able to detect a problem (by fuel pressure) early instead of when im in boost when its too late. Running the pump all the time though presents the potential for heat (cativation sp?) problems

 

Hi Nabil,
Sounds like it needs a little straightening out, shouldn't be a big deal. What is happening is that with the factory pump bypassed it is not draining the right tank like it should, plus you are not going to make proper pressure since they work in parallel.
The right tank does not have a pump in it, only a siphon tube that is fed from the factory pump, Y'd off of it shortly after it leaves the sending unit. So with yours not working, hence the right tank staying full.
Being that it is so hot where you are, using a hobbs switch on the secondary pump is not a bad idea to keep fuel temps down, plus they are very easy to wire in and inexpensive. But that is not your problem at the moment, it sounds to me like an improper installation that's all.

Let me know if I can assist.

 

Thanks for the props Mike. Funny you mentioned the install and temperature data, I just finished digging out the old graph I made up and associated post a few hours ago for a thread over in C5 tech or gen.

Anyway, as posted above the OEM fuel pump needs to run all the time as it normally would. If you are running the Bosch pump all the time it's not surprising that you lose pressure once the car heats up. You are compressing (creating heat) fuel unnecessarily and furthermore, bringing it to the front of the car and into the aluminum heat sinks... I mean fuel rails only to send it back to the tank much hotter than it was to begin with.

There are plenty of people running both pumps all the time without issue, but now that summer is rolling around some people will start to see issues that weren't apparent before. And of course people in cool climates may not ever have an issue.

Either boost activate your second pump or put a nitrous pedal switch down there to activate it (or both). The thing I like about the pedal switch approach is that I can prime/test the pump before starting the car to make sure it hasn't completely died.



Regarding the bypass, it is possible to run the OEM pump but not feed it through the Y that feeds the passenger tank siphon pump. Doing so will result in fuel level gauge oddities as once the PCM sees the driver tank draining before the passenger tank, it will throw a code and show the tank empty (unless the code was disabled). In any case, you do need the OEM pump running and it does need to feed into the Y that goes over to the passenger tank.

 

Doug I tried looking for a hobbs switch that activates at 1 psi, however I only found the one KB sells which is 4psi. IMO that is way too late. I looked everywhere and their mothers for one and couldn't find one...any clue?

 

I found one somewhere, let me look on Monday and I'll pm you if I find it.

 

Here is a link that might help with the wiring in a Hobbs type switch

http://forums.corvetteforum.com/show....php?t=1627513

 

I have some that are set adjustable from 0.5 psi to 24psi. They are factory preset to 1psi.

They are $29 shipped. Let me know if you want one. Paypal to nick.steffens@usionline.net

I can ship it Monday.

 

Can you post a pic...

 

Seriously? It is a pressure switch with two prongs on it.

 

Thanks Doug & Guys. I just spoke to the guys at the "idiot"ship and told them to reconnect the internal pump. They said ok. After that is sorted out I will look into the Hobbs switch from BLOWNZ06. With my "climate" anything to keep fuel temps down is welcomed.
BTW this explains the problem I had a while back when I assumed my sending unit was going south. Seems it was this problem all along.

 

Update : Just got a call from the guys. The question they are asking is : After they reconnect the factory pump does it connect to the factory fuel rail directly ? or does it feed the external pump ?
If it connects directly then they will have to make a T into the fuel rail right ? Wouldn't that make fuel pressure a bit high ?

 

I don't think the instructions tell you to do this, but I set mine up to connect directly to the factory hard line and have that hard line go directly into the rails (yes, you need a T to do it this way, those are readily available at Aeroquip or from Summit, Jegs, etc.)

There was enough braided stainless hose in my kit that I could run an independent line for the auxillary pump up the rocker panel and T it to the OEM line up front. To be more precise, I actually have two Ts, one connected to the front of each rail. One leg of each the Ts connects the Ts together (to help maintain rail to rail balance and lessen negative hydraulic hammer effects) and the other leg of each T connects to either the OEM fuel system or the auxillary pump.

Again, the directions don't tell you to install it this way but this has worked flawlessly for me.

Fuel pressure MAY be affected slightly if running both pumps through the OEM hard line was restricting flow. Theoretically the regulator should take care of this, but I can tell you that my fuel pressure spikes 10psi when my aux pump activates -- so the regulator is not perfect.