DUAL STOCK CP3 Question

[max57]

I have a stock valley and a stock cp3 on belt, Question is I have 2-pumps and Injectors all into the original line near turbo and going to the original van cooler on ward to the tank. Will it screw things up if there is to much return pressure on the system?
As some of you know my fuel is giving me fluctuation problems. At Idle around 6000-7000psi I get a little up and down as much as 100psi on Actual Rail Pressure and i noticed if I command 23,000psi at idle I see it as well as much as 900psi . At idle and with rpms. Lift pump on or off.
Im thinking of pinching fuel supply off to the valley pump and see if it does it on just belt pump. Then remove Belt and try on just Valley cp3 to see If I can narrow it to a pump. What do you think? Is there a better way?

 

[ZeroGravity58]

Fuel pressure is never going to stay perfect. It's is always going to fluctuate a couple hundred psi actual vs desired. Also don't pinch off the fuel lines. No fuel = no lubrication

 

[max57]

Fuel pressure is never going to stay perfect. It's is always going to fluctuate a couple hundred psi actual vs desired. Also don't pinch off the fuel lines. No fuel = no lubrication

I am see every once in a while as much as 900-1000psi just above an Idle. No Load. I see 2000 psi fluctuate at WOT full load.
I know I would not want to loose fuel supply to it very long , seem like 10 seconds i could get away with it . Im sure not the best but see no other way to see if one of them, or either are fluctuating.
Im getting real close to just putting a 12mm Or 14mm pump in valley. do I need a new tune if get rid of twins, i do not think so.

 

[max57]

New tune has taken a way Lope at Idle and all surging in the engine but did not fix this fuel pressure. Tune no where near the power the old one was though.

 

[Bdsankey]

Just an FYI, I would keep the posts/threads you have going VS creating new posts. It makes it difficult to follow and see other's recommendations.


As for pinching off a fuel supply, I'd urge you not to do that. If you're attempting to see if the problem is restriction in the return circuit why don't you then just run the return lines to a jug? That is a much smarter move than pinching off the supply. You could also put a gauge somewhere in the return circuit and see the pressure it builds.


Also, as for your new tune not having the power of your old tune, have you told your new tuner? Have you asked for more? Have you sent them a datalog and given them the opportunity to try and tune it out? It may be something as simple as they don't think your setup should be given anything else be it for smoke control, egt control, drivability etc.

 

[2004LB7]

When I ran duel cp3s I had the venturi nozzle on the tank pickup pop out. Thinking it was from the increased return flow.

As others have said above, dont restrict any return or supply fuel in an attempt to "solve" a problem

I would bet your fluctuations could be fixed with tuning

 

[max57]

Just an FYI, I would keep the posts/threads you have going VS creating new posts. It makes it difficult to follow and see other's recommendations.


As for pinching off a fuel supply, I'd urge you not to do that. If you're attempting to see if the problem is restriction in the return circuit why don't you then just run the return lines to a jug? That is a much smarter move than pinching off the supply. You could also put a gauge somewhere in the return circuit and see the pressure it builds.
No, I want to test each pump to see if I can limit one of them as my fluctuation in High pressure. Was just curious if anyone was had return restriction problems. Is there a Maximum return pressure?? Do you run yours through a cooler?


Also, as for your new tune not having the power of your old tune, have you told your new tuner? Have you asked for more? Have you sent them a datalog and given them the opportunity to try and tune it out? It may be something as simple as they don't think your setup should be given anything else be it for smoke control, egt control, drivability etc.

No, I want to test each pump to see if I can limit one of them as my fluctuation in High pressure. I know its not the best way. Not sure how else to do it though.
Was just curious if anyone was had return restriction problems. Is there a Maximum return pressure?? Do you run yours through a cooler or straight to the tank??

I am getting a Street tune and then a Race tune , They are getting Data logs each time they send a new Version of the Street tune. Once we get that tune right tuner will move on to Race tune. I was just stating that New tune has taken a way Lope at Idle and all surging in the engine but did not fix this fuel pressure completely. It is suppose to have less power. It is in 57 Chevy wagon, so no polution control needed.

 

[Bdsankey]

No, I want to test each pump to see if I can limit one of them as my fluctuation in High pressure. I know its not the best way. Not sure how else to do it though.
Was just curious if anyone was had return restriction problems. Is there a Maximum return pressure?? Do you run yours through a cooler or straight to the tank??

I am getting a Street tune and then a Race tune , They are getting Data logs each time they send a new Version of the Street tune. Once we get that tune right tuner will move on to Race tune. I was just stating that New tune has taken a way Lope at Idle and all surging in the engine but did not fix this fuel pressure completely. It is suppose to have less power. It is in 57 Chevy wagon, so no polution control needed.

I am running nothing that is reminiscent of a factory system. I have all of my returns (2x pumps, 2x injector banks, relief valve) plumbed to a manifold then going to a single 1/2" return back to tank (no cooler). What ever you do, DO NOT pinch off either of the pumps feed or return lines as that is a quick way to kill a pump. I do not know what a reasonable return circuit pressure is but I'd imagine as low as possible is preferred. I would doubt your issue is high return pressure as many people run standard dual pump kits where you "T" into the feed and return lines.


Has the rail pressure deviation at WOT been getting better with tune revisions? What has your tuner said about it?

 

[2004LB7]

The only way I can see you isolating one pump is to pull the belt and put the stock belt back on and see if the problem persists. That will tell you if the stock pump is good or not.

 

[Chevy1925]

I have a stock valley and a stock cp3 on belt, Question is I have 2-pumps and Injectors all into the original line near turbo and going to the original van cooler on ward to the tank. Will it screw things up if there is to much return pressure on the system?
As some of you know my fuel is giving me fluctuation problems. At Idle around 6000-7000psi I get a little up and down as much as 100psi on Actual Rail Pressure and i noticed if I command 23,000psi at idle I see it as well as much as 900psi . At idle and with rpms. Lift pump on or off.
Im thinking of pinching fuel supply off to the valley pump and see if it does it on just belt pump. Then remove Belt and try on just Valley cp3 to see If I can narrow it to a pump. What do you think? Is there a better way?

ive been running two stock pumps (one has 220k, other has 160k) on my truck for the last 8 years on both a factory LB7 return system and now a factory LLY return system. i run a large fuel cooler on the return side as well and have my lift pump return fuel prior to the cooler. the return isnt your issue.

ill bet you pull a pump and go drive it and it drives well on either pump. to do this, you need to make sure the rail pressure signal is not split into a box. in other words, get rid of the dual fueler box when hooking a single pump up. you will need to extend/make jumper wires for the belt pump. make sure the belt pump is not driven. the valley pump you cant single out/un-drive since it is gear driven so all you can do is check the valley pump in a single pump application. im currently running around on my valley pump with the second pump hooked up but no wheel and no electrical connections as im waiting on a custom wheel for it. Running a stock belt to do so.

based on the fact your turner has made changes that helped, ill bet this is more tuning related than anything. make sure either your lift pump pressure isnt too high or that FPR current is bumped up to account for the extra pressure from the lift pump. from there, the fuel pressure Direct and Time tables would need adjustment. being you have duals, fuel comes on faster and harder than stock, this can make for the stock tables here to cause problems making you over shoot and under shoot desired rail. Your tuner should know this and adjust for it. I ran into this issue specially on decel coasting to stop, part of it was lift pump pressure being high and the Direct/Time tables needing work. it helped smooth out the peaking i got when you jammed the throttle trying to get up to speed/power too.

logging the mA used on the FPR and the actul vs desired rail should help give the tuner a good idea on what to tweak.

 

[max57]

You are right, I do not want to starve the valley pump, was Thinking maybe it would be like a plugged filter and they live through it. But no the best idea. I wanted to compare the two pumps on the high side to see if one of them is giving me the trouble. .
I am getting another Tune version tomorrow and will see what that does. Log and send to them again, see if tune can fix it. yes I can rewire back to a single valley pump to see if it still does it. Commanding 23,000psi at idle . Thanks for the response guys.

 

[2004LB7]

I don't think you are going to learn much with commanding 23k psi at idle. The fuel quantity is too low to really see anything important with your problem. You will want to run it the same as you do when you have the issue.

Keep in mind, as mentioned earlier, the ramp up and down rate will be different with a single vs dual so there may be a different set of issues to deal with if your tune is still written for duels.

 

[max57]

Got the new Regulator on she holds 12psi WOT or Idle , does not matter. While adjusting things found the Airdog was pulsating fuel out the overflow return like the releif was kicking on and off. Jacked pressure up on airdog, run 5/8'' feed, 1/2'' return and Now the front Regulator takes care of pressure. Put ATP tune in and still surging, Lope Idle. Starlite tune and no surging, smooth idle but waiting for a Race tune from them to compare better, but looks like tune will fix it (fingers crossed!).

 

[Bdsankey]

Got the new Regulator on she holds 12psi WOT or Idle , does not matter. While adjusting things found the Airdog was pulsating fuel out the overflow return like the releif was kicking on and off. Jacked pressure up on airdog, run 5/8'' feed, 1/2'' return and Now the front Regulator takes care of pressure. Put ATP tune in and still surging, Lope Idle. Starlite tune and no surging, smooth idle but waiting for a Race tune from them to compare better, but looks like tune will fix it (fingers crossed!).

You haven’t addressed the problem. Did this help the delta or rail surge at WOT?

 

[max57]

You haven’t addressed the problem. Did this help the delta or rail surge at WOT?

The new tune has to help a lot, Much more stable High fuel pressure. Having a hard time getting the tune right now. have little throttle responce 0-20% , engine seems to labor, then 20% turbos whistle and full power. is better when above 2000rpms or maybe just because it has boost. If I could get Rob to adjust something so I had no surging in his tune, his has a ton of power. As soon as I install Robs it starts Loping at Idle like it has a big cam, and surging mid and WOT like it is loping up there as well. This is never ending.

 

[Chevy1925]

Nope, this is just part of the game we play for big power and still wanting it to run good besides wot lol

 

[max57]

I noticed my Calculated fuel rate is jumping from 8-12 constant.Average a 10. What would do that, bad injector? Have changed the FPR's.

 

[Chevy1925]

A lot of what’s going on here has me questioning tuning...

 

[max57]

3- tunes . Stock and new tune Jump about 10-12 and ATP 8-12 constant. New tune did get my rail pressure steady though, runs better tune wise. Having issues with 0-40% sluggish and 50-55% all out tire spinning , can not seem to get throttle to be normal, turbos lite and have to let off throttle a lot to keep under control.I think its more that it is say power lss at 0-40%. Would love to get it to run with ATP tune as well. Very progressive trottle. Thought maybe this would be fuel rate jumping would be a clue why it surges on atp tune?

 

[Chevy1925]

3- tunes . Stock and new tune Jump about 10-12 and ATP 8-12 constant. New tune did get my rail pressure steady though, runs better tune wise. Having issues with 0-40% sluggish and 50-55% all out tire spinning , can not seem to get throttle to be normal, turbos lite and have to let off throttle a lot to keep under control.I think its more that it is say power lss at 0-40%. Would love to get it to run with ATP tune as well. Very progressive trottle. Thought maybe this would be fuel rate jumping would be a clue why it surges on atp tune?

Nope, that tune needs alot of help.