Tank transfer problem siphon pump failure fuel system problems convoluted tube issue.
11-03-2008, 05:57 PM
#1
Le Mans Master
Thread Starter
Tank transfer problem siphon pump failure fuel system problems convoluted tube issue.
Sorry for the convoluted title but I hope it makes someone's search a little easier if they run into the problem(s) I have while building a C6Z fuel system. (I would imagine this is applicable to a standard (non C6Z) as well but I'm not certain. I really can't imagine the OEM fuel systems being any different between a Z06 and non-Z06 car.)
The C5 and C6 fuel systems ARE DIFFERENT! This does not apply to a C5 system!
I've put together a couple of fuel systems for the C6Z's now so I wanted to share a little tidbit that will hopefully save folks MANY hours in troubleshooting if you encounter the same issues I did.
Here is the toughest problem that I had:
After building a fuel system utilizing the stock canister and dual aftermarket in-tank pumps I was only able to use one fuel tank. IE: The passenger's tank was always full and never transferred over to the driver's side tank. This is obviously bad for a number of reasons.
If you are reading this then you probably know (or will soon find out) that you have to drop the entire rear subframe in order to drop both the fuel tanks. This sucks immensely. (I was able to drop them once with the rear subframe still in the car but I had to cut an access panel behind the driver's seat when I tried to reinstall them in order to get the convoluted tube reconnected - this route is NOT recommended! Go ahead and drop the rear subframe! It's much easier in the end!)
My new fuel system consisted of two large in-tank pumps, two -6 lines up to the fuel rails/regulator, and I utilized the OEM feed line as the return line to the driver's side tank.
Bulkheads were attached to the stock plastic canister for wiring and fuel connections. (make sure these bulkheads seal properly or fuel WILL leak out around them when you fill the tanks up at a gas station!)
This setup works very well - but as mentioned above, I was only utilizing one tank and the other always stayed full.
I literally pulled the tanks twice, connected them up (with transfer lines to simulate the convoluted tube) and powered the pumps up. I simulated the actual fuel system of the car - and it worked both times!!! Fuel flowed between the tanks and equalized just as it was supposed to! What the heck was going on????????
The ONLY difference in my external test was that I didn't have a fuel pressure regulator connected for the test so the fuel pressure was very high.
This was the big clue... After a little more research I found that the siphon pump in the passenger's tank has a 56 PSI regulator on it. Meaning, if fuel pressure is at 56 PSI or less, then the siphon pump simply doesn't run! (this is so that the motor doesn't lean out if the fuel pressure drops. This is pretty smart on GM's part, actually.)
Guess what I set the static fuel pressure at on my car when I built the fuel system and tuned it? 50 PSI...
DOH!
I've adjusted the static fuel pressure to 58 PSI (where it should be from the factory) and now the siphon pump works like a champ!
It probably took me 50-60 hours of dropping the tanks/testing before I figured this out. Hopefully this thread will save you some effort!
The C5 and C6 fuel systems ARE DIFFERENT! This does not apply to a C5 system!
I've put together a couple of fuel systems for the C6Z's now so I wanted to share a little tidbit that will hopefully save folks MANY hours in troubleshooting if you encounter the same issues I did.
Here is the toughest problem that I had:
After building a fuel system utilizing the stock canister and dual aftermarket in-tank pumps I was only able to use one fuel tank. IE: The passenger's tank was always full and never transferred over to the driver's side tank. This is obviously bad for a number of reasons.
If you are reading this then you probably know (or will soon find out) that you have to drop the entire rear subframe in order to drop both the fuel tanks. This sucks immensely. (I was able to drop them once with the rear subframe still in the car but I had to cut an access panel behind the driver's seat when I tried to reinstall them in order to get the convoluted tube reconnected - this route is NOT recommended! Go ahead and drop the rear subframe! It's much easier in the end!)
My new fuel system consisted of two large in-tank pumps, two -6 lines up to the fuel rails/regulator, and I utilized the OEM feed line as the return line to the driver's side tank.
Bulkheads were attached to the stock plastic canister for wiring and fuel connections. (make sure these bulkheads seal properly or fuel WILL leak out around them when you fill the tanks up at a gas station!)
This setup works very well - but as mentioned above, I was only utilizing one tank and the other always stayed full.
I literally pulled the tanks twice, connected them up (with transfer lines to simulate the convoluted tube) and powered the pumps up. I simulated the actual fuel system of the car - and it worked both times!!! Fuel flowed between the tanks and equalized just as it was supposed to! What the heck was going on????????
The ONLY difference in my external test was that I didn't have a fuel pressure regulator connected for the test so the fuel pressure was very high.
This was the big clue... After a little more research I found that the siphon pump in the passenger's tank has a 56 PSI regulator on it. Meaning, if fuel pressure is at 56 PSI or less, then the siphon pump simply doesn't run! (this is so that the motor doesn't lean out if the fuel pressure drops. This is pretty smart on GM's part, actually.)
Guess what I set the static fuel pressure at on my car when I built the fuel system and tuned it? 50 PSI...
DOH!
I've adjusted the static fuel pressure to 58 PSI (where it should be from the factory) and now the siphon pump works like a champ!
It probably took me 50-60 hours of dropping the tanks/testing before I figured this out. Hopefully this thread will save you some effort!
11-03-2008, 06:04 PM
#2
Former Vendor
http://www.lgmotorsports.com/catalog...oducts_id=1971
No dropping of tanks
No transfer issue
Run ANY base pressure you want
Run ANY fuel pump you want to
Sorry Ed, I had to
This fuel setup is the cats meow if you dont have the time, patience, or skill to build an all out fuel system
No dropping of tanks
No transfer issue
Run ANY base pressure you want
Run ANY fuel pump you want to
Sorry Ed, I had to
This fuel setup is the cats meow if you dont have the time, patience, or skill to build an all out fuel system
11-03-2008, 06:42 PM
#3
Melting Slicks
Sorry for the convoluted title but I hope it makes someone's search a little easier if they run into the problem(s) I have while building a C6Z fuel system. (I would imagine this is applicable to a standard (non C6Z) as well but I'm not certain. I really can't imagine the OEM fuel systems being any different between a Z06 and non-Z06 car.)
The C5 and C6 fuel systems ARE DIFFERENT! This does not apply to a C5 system!
I've put together a couple of fuel systems for the C6Z's now so I wanted to share a little tidbit that will hopefully save folks MANY hours in troubleshooting if you encounter the same issues I did.
Here is the toughest problem that I had:
After building a fuel system utilizing the stock canister and dual aftermarket in-tank pumps I was only able to use one fuel tank. IE: The passenger's tank was always full and never transferred over to the driver's side tank. This is obviously bad for a number of reasons.
If you are reading this then you probably know (or will soon find out) that you have to drop the entire rear subframe in order to drop both the fuel tanks. This sucks immensely. (I was able to drop them once with the rear subframe still in the car but I had to cut an access panel behind the driver's seat when I tried to reinstall them in order to get the convoluted tube reconnected - this route is NOT recommended! Go ahead and drop the rear subframe! It's much easier in the end!)
My new fuel system consisted of two large in-tank pumps, two -6 lines up to the fuel rails/regulator, and I utilized the OEM feed line as the return line to the driver's side tank.
Bulkheads were attached to the stock plastic canister for wiring and fuel connections. (make sure these bulkheads seal properly or fuel WILL leak out around them when you fill the tanks up at a gas station!)
This setup works very well - but as mentioned above, I was only utilizing one tank and the other always stayed full.
I literally pulled the tanks twice, connected them up (with transfer lines to simulate the convoluted tube) and powered the pumps up. I simulated the actual fuel system of the car - and it worked both times!!! Fuel flowed between the tanks and equalized just as it was supposed to! What the heck was going on????????
The ONLY difference in my external test was that I didn't have a fuel pressure regulator connected for the test so the fuel pressure was very high.
This was the big clue... After a little more research I found that the siphon pump in the passenger's tank has a 56 PSI regulator on it. Meaning, if fuel pressure is at 56 PSI or less, then the siphon pump simply doesn't run! (this is so that the motor doesn't lean out if the fuel pressure drops. This is pretty smart on GM's part, actually.)
Guess what I set the static fuel pressure at on my car when I built the fuel system and tuned it? 50 PSI...
DOH!
I've adjusted the static fuel pressure to 58 PSI (where it should be from the factory) and now the siphon pump works like a champ!
It probably took me 50-60 hours of dropping the tanks/testing before I figured this out. Hopefully this thread will save you some effort!
The C5 and C6 fuel systems ARE DIFFERENT! This does not apply to a C5 system!
I've put together a couple of fuel systems for the C6Z's now so I wanted to share a little tidbit that will hopefully save folks MANY hours in troubleshooting if you encounter the same issues I did.
Here is the toughest problem that I had:
After building a fuel system utilizing the stock canister and dual aftermarket in-tank pumps I was only able to use one fuel tank. IE: The passenger's tank was always full and never transferred over to the driver's side tank. This is obviously bad for a number of reasons.
If you are reading this then you probably know (or will soon find out) that you have to drop the entire rear subframe in order to drop both the fuel tanks. This sucks immensely. (I was able to drop them once with the rear subframe still in the car but I had to cut an access panel behind the driver's seat when I tried to reinstall them in order to get the convoluted tube reconnected - this route is NOT recommended! Go ahead and drop the rear subframe! It's much easier in the end!)
My new fuel system consisted of two large in-tank pumps, two -6 lines up to the fuel rails/regulator, and I utilized the OEM feed line as the return line to the driver's side tank.
Bulkheads were attached to the stock plastic canister for wiring and fuel connections. (make sure these bulkheads seal properly or fuel WILL leak out around them when you fill the tanks up at a gas station!)
This setup works very well - but as mentioned above, I was only utilizing one tank and the other always stayed full.
I literally pulled the tanks twice, connected them up (with transfer lines to simulate the convoluted tube) and powered the pumps up. I simulated the actual fuel system of the car - and it worked both times!!! Fuel flowed between the tanks and equalized just as it was supposed to! What the heck was going on????????
The ONLY difference in my external test was that I didn't have a fuel pressure regulator connected for the test so the fuel pressure was very high.
This was the big clue... After a little more research I found that the siphon pump in the passenger's tank has a 56 PSI regulator on it. Meaning, if fuel pressure is at 56 PSI or less, then the siphon pump simply doesn't run! (this is so that the motor doesn't lean out if the fuel pressure drops. This is pretty smart on GM's part, actually.)
Guess what I set the static fuel pressure at on my car when I built the fuel system and tuned it? 50 PSI...
DOH!
I've adjusted the static fuel pressure to 58 PSI (where it should be from the factory) and now the siphon pump works like a champ!
It probably took me 50-60 hours of dropping the tanks/testing before I figured this out. Hopefully this thread will save you some effort!
That's what the forum is all about!!!!
Why did you set your fuel pressure so low at only 50psi? What size injectors are you running that can support 1300 WHP at only 50 psi? 120lbers?Dan
11-03-2008, 08:18 PM
#4
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MAN HAVE I BEEN THERE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! talk about a TOTAL PITA!!!!!!!!!!!!!!!!!!!!!!!!!!!
:w illy:
We could have an entire Opra show on this one...
:w illy:We could have an entire Opra show on this one...
11-03-2008, 09:07 PM
#5
Le Mans Master
Thread Starter
Dan,
Yes, I run 120's.
On the particular car that I had this problem with I had started out with 63 LBS/hr injectors but I maxxed them out right at 1,000 RWHP. So when I upgraded the injectors I decided to upgraded the in-tank pumps, too. (I had already added two walbro 255's and wanted something a little beefier - it was at this time that I dropped the pressure because of increased volume. My logic was, "why unnecessarily keep the FP way up?")
Louis,
I don't blame you - that fuel system of yours is absolutely ****... If I had it to do over again (and I probably will knowing how I go through cars!) I'd buy your setup in a heartbeat. It's very well thought out and quite functional!
Yes, I run 120's.
On the particular car that I had this problem with I had started out with 63 LBS/hr injectors but I maxxed them out right at 1,000 RWHP. So when I upgraded the injectors I decided to upgraded the in-tank pumps, too. (I had already added two walbro 255's and wanted something a little beefier - it was at this time that I dropped the pressure because of increased volume. My logic was, "why unnecessarily keep the FP way up?")
Louis,
I don't blame you - that fuel system of yours is absolutely ****... If I had it to do over again (and I probably will knowing how I go through cars!) I'd buy your setup in a heartbeat. It's very well thought out and quite functional!
Last edited by EdwardETraylorIII; 11-03-2008 at 11:44 PM.
11-03-2008, 10:55 PM
#6
Former Vendor
I started my tuning at 30 psi base. Im at 55 now. Sometimes its WAY easier to see where you need to be fueling wise by just tinkering with the regulator, and then going back in and adjusting your fueling. Flashing, and then reflashing gets old on initial base tuning.
Jeremy, is your opra episode TBC? or is it resolved?
Jeremy, is your opra episode TBC? or is it resolved?
11-04-2008, 02:54 AM
#7
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11-04-2008, 06:14 PM
#9
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I've adjusted the static fuel pressure to 58 PSI (where it should be from the factory) and now the siphon pump works like a champ!
My tank transfer works good "on the bench" at 55 psi, but of course as soon as I started the car the fuel pressure went to 46 psi with engine vacuum.
I assume I need to reset the fuel pressure so that it is at 55+psi with the engine running ? Of course I resist that because the higher fuel pressure the harder the pump works and now we are talking about 65+ fuel pressure at 0 vacuum and 80 psi under boost.
I haven't had time to test if the fuel transfer function is working yet, and I have an inter-tank slosh line that I was planning on removing so it would be nice to know exactly what this should be.
11-08-2008, 01:23 PM
#10
Le Mans Master
Thread Starter
I've heard that 55+psi figure before. Is that with the engine running and vacuum line connected or not ?
Please post back and let us know if this fixes your problem!
11-08-2008, 05:00 PM
#11
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11-09-2008, 01:18 PM
#12
Le Mans Master
Thread Starter
Backchannel,
I'm not sure I understand your question.
I pull vacuum from the TV over to the Aeromotive Regulator in order to raise FP along with boost. Does this answer your question? If not, ask your question with a little more detail and I'll formulate an answer.
I'm not sure I understand your question.
I pull vacuum from the TV over to the Aeromotive Regulator in order to raise FP along with boost. Does this answer your question? If not, ask your question with a little more detail and I'll formulate an answer.
11-09-2008, 02:11 PM
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Backchannel,
I'm not sure I understand your question.
I pull vacuum from the TV over to the Aeromotive Regulator in order to raise FP along with boost. Does this answer your question? If not, ask your question with a little more detail and I'll formulate an answer.
I'm not sure I understand your question.
I pull vacuum from the TV over to the Aeromotive Regulator in order to raise FP along with boost. Does this answer your question? If not, ask your question with a little more detail and I'll formulate an answer.
11-09-2008, 05:09 PM
#14
Le Mans Master
Thread Starter
backchannel,
I better understand your question now. Sorry for the confusion.
Yes, when you reconnect the vacuum line to the regulator the fuel pressure drops due to the engines vacuum at idle. It's drops any from 7-11 PSI generally.
Hope that helps!
I better understand your question now. Sorry for the confusion.
Yes, when you reconnect the vacuum line to the regulator the fuel pressure drops due to the engines vacuum at idle. It's drops any from 7-11 PSI generally.
Hope that helps!
11-09-2008, 06:26 PM
#15
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I've connected both ways but did not go over 11psi boost because of trans issues[hurt it twice at only 816rwhp]
11-09-2008, 11:53 PM
#16
Le Mans Master
Thread Starter
backchannel,
I've never run a Fuel System any other way than a rising rate (1:1!!) regulator.
As an aside, I blew my second tranny in a year out tonight... First one was a T56 and this one was a T6060. Third went kaput. Calling RPM tomorrow for a new one!
I've never run a Fuel System any other way than a rising rate (1:1!!) regulator.
As an aside, I blew my second tranny in a year out tonight... First one was a T56 and this one was a T6060. Third went kaput. Calling RPM tomorrow for a new one!
11-10-2008, 12:35 AM
#17
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[QUOTE=EdwardETraylorIII;1567792375]backchannel,
I've never run a Fuel System any other way than a rising rate (1:1!!) regulator.
certainly linear with boost but my question is why connect to manifold vacuum[reducing idle pressure]vs. sensing before the throttle body so no affect on pressure until there is boost? Are you wanting to lower flow of bigger injectors at idle or some other effect?
I've never run a Fuel System any other way than a rising rate (1:1!!) regulator.
certainly linear with boost but my question is why connect to manifold vacuum[reducing idle pressure]vs. sensing before the throttle body so no affect on pressure until there is boost? Are you wanting to lower flow of bigger injectors at idle or some other effect?
11-10-2008, 12:17 PM
#18
Le Mans Master
Thread Starter
Tom,
I've never known any other way than connecting vacuum to a regulator.
When there is vacuum and the engine is at idle, yes, you want the fuel pressure to drop accordingly so the stoichiometric balance is perfect at any RPM vs. any load/TPS from idle to WOT at redline.
I've never known any other way than connecting vacuum to a regulator.
When there is vacuum and the engine is at idle, yes, you want the fuel pressure to drop accordingly so the stoichiometric balance is perfect at any RPM vs. any load/TPS from idle to WOT at redline.
11-10-2008, 01:31 PM
#19
Former Vendor
because the mechanics behind the regulator allow less pressure to defeat the spring. With boost on top of it, it takes more PSI to open the regulator. Vacuum takes less PSI to open it.
I like using vacuum/boost because it makes engine cal much easier. Trying to control a big injector at idle with 4 bar fuel pressure can be a task sometimes. Reduce it 10 psi, and you have effectively made your injector smaller, thus making it easier to tune.
I like using vacuum/boost because it makes engine cal much easier. Trying to control a big injector at idle with 4 bar fuel pressure can be a task sometimes. Reduce it 10 psi, and you have effectively made your injector smaller, thus making it easier to tune.
11-10-2008, 01:41 PM
#20
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Tom,
I've never known any other way than connecting vacuum to a regulator.
When there is vacuum and the engine is at idle, yes, you want the fuel pressure to drop accordingly so the stoichiometric balance is perfect at any RPM vs. any load/TPS from idle to WOT at redline.
I've never known any other way than connecting vacuum to a regulator.
When there is vacuum and the engine is at idle, yes, you want the fuel pressure to drop accordingly so the stoichiometric balance is perfect at any RPM vs. any load/TPS from idle to WOT at redline.