Just put those pumps in too. You running a Hobbs switch with them?
2.9 and 3.4 whipple owners in here
- Thread starter spray'n mach 1
- Start date
Ummmm no, should I be?
Those pumps move so much fuel you can get by with just one till about midway through 3rd gear at WOT. So some like to stage the pumps to reduce fuel flow in normal cruise.
Personally I was one of them. I built an electronic module even that monitors MAF and works out fuel consumption and only turns the second pump on when it's needed and then latches it on for 60 seconds or as long as it sees aggressive driving demanding the second pump. It prevented the second pump snapping on and off all the time like a hobs switch would do since these cars show boost so easily and even under light partial throttle load.
The issue I found is the fuel pressure regulator doesn't behave the way I'd like. So with a both pumps running at idle with vacuum pulled on the regulator I set it to 39 PSI. Everything in my tune is set to work with a base of 39 PSI. The problem I ran into is now I turn off one of the pumps and suddenly I'm at a base pressure of 36 PSI. That throws off my AF just a bit and causes the computer to start adjusting short term fuel trims to correct it in closed loop driving. Then that second pump kicks in and throws everything off again and the ECU starts trying to compensate the other way and so forth.
I'm not sure the best solution to this yet... so while I think about it some more I've left both pumps on. I don't have a temp gauge in my fuel lines but just grabbing the fuel lines by hand all along the underside of the car and checking all over I can't tell a difference at all between staged pumps and both running all the time. Either way those lines are really warm. I've read some say that pumps put out so much heat they are heating the fuel but I'm not buying it. I actually have a set of 405 pumps laying in the garage and I think I'll do some testing by placing them in a 5 gallon container of fuel and run them for a while and see what if any heat I can measure them adding to the fuel.
I say 99.9% of the heating of the fuel is happening in the engine bay. The return system is pumping the fuel up to the engine, through the aluminum rails just absorbing heat at a tremendous rate from the hot engine heating up the fuel and then back to the tank and continuously circulating it all. Eventually the entire tank is going to get hot.
MalcolmV8, what's your hp/tq currently? Are you on e85? My mods are in my sig. My changes I'm doing are 3.25 upper pulley, Metco 4# lower kit, Id1000's, twin Walbro 465's, e85 compatible fuel filter, TR6's at .28. Also looking at installing an AEM wideband failsafe gauge. I think I should be around 25# boost on e85. I'm guessing around 725hp, maybe 750hp. Planned on running both pumps at the same time.
I had never dropped my tank till a couple weekends ago. It takes all of about 20 minutes. Cake
No idea what it makes. I street tuned it myself. E85 is a pain to get with hardly any pumps around and a long drive. So I run 91 pump and water/meth injection.
I'm also on the 3.5" upper pulley but will be switching to the 3.0. I'll probably put it on in a few weeks when I get some time. I also plan on trying E85 just for fun. Probably won't run it much due to the PITA of getting it.
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