Check your FP on the dyno and at full load. I say this because if you find it possible to dial out the increased idle pressure with an adjustable FP in an attempt to compensate at idle, you just may set yourself up for less than a rising rate of 1:1 under load. And of course, there is no way to know this unless one can view the FP with respect to boost pressure under load.


None that you can see anyway. If you check things with a meter against the voltage in your charging system, you'll find that you are not getting full voltage to the pumps. Getting full voltage to the pumps requires a better power feed, and a better ground as well.

 

if you call full blown they will tell you that they had a recall with there sending units

 

Don't worry. I've had to stand in front of a car many times watching the FPR's gauge while it makes a pass on the dyno. Something I'm quite used to doing. I just wish more people had electronic ones that can log instead of the mechanical ones.

 

Factory wiring is used only to trigger the relay that powers up the pumps. We're running 8ga. wire from the battery, in the trunk, to the relay and then 12ga to the pumps. We made a quik-disconnect using a a trailer light harness Pumps are GSS342's.
I would have thought it impossible that fuel could flow in reverse through another pump but for whatever reason it was the case on this car.

 

Where did you find that info? We never had a recall on our stuff. The problem with the fuel pressure was dued to the factory siphon be restrictive. We just never had an oppertunity to test drilling out the factory siphon. So we reccomend guys run a hobbs switch or AEM to trigger the second pump. Buschurs kit has the same problem because of the factory siphon. If im correct, I think he uses a hobbs switch as well. I talked to Ted on the phone and he offered to do the testing for us to TedB. I need to revise the install instructions thanks to TedB. LJ

 

Use extreme caution when drilling the siphon tube. You need to drill straight as an arrow and make sure to remove all the chips from it when your done. If you break through the side of the internal siphon, it will not work and you will end up loading the opposite side of the saddle tank with fuel. Chips not cleaned out completely will also do this.

 

We have NO problems with our double pumpers, thank you very much. This is in response to Full Blowns comment.

Yes, we use a Hobb switch, actually of course we use a Hobb switch. Some cars with AEM's we use the AEM to trigger the pump. I sell atleast 2 double pumpers a week, some weeks up to 5 of them. I have not had a single switch fail, I'd say the worries of a switch failure is pretty low. Running both pumps all the time to me is dumb.

 

Dan, i think you read it wrong. I was not referring to the problem of a failed switch. I was referring to the problem of base pressure not being able to go below 60psi due to the siphon. Im not here trying to bash on anyone, just simply stating that we use a hobbs switch to overcome the problem of the fuel pressure being too high because of the stock siphon. LJ

 

Please lets not turn this into a negative thread. I just wanted to state why the hobbs switch was used and the fact that it is used in buschurs kit as well. My intentions were not about his double pumper having issues. LJ

 

I have both pumps running all the time as well and drilling out the siphon + using a -6AN return dropped the idle fuel pressure like a charm...thanks Ted for the tip!

 

So far, so good in my case. Everything is working just fine - no Hobbs switch, no additional wiring, no pressure lines, and noticeably less noise during normal driving than a single pump. I am 100% satisfied.

 

I had a similar issue with a buschur setup that came with 1 defective pump. Dave replaced it without blinking. but I didnt want to use the hobbs switch he supplied, I wanted both pumps on all the time. So I installed an Aeromotive regulator and rail. That solved my problem

 

aeromotive a1000 reg, ams rail, and -8feed -6return here. Can't get below 60psi base with both pumps on.

Therfore, I just use the EMS to switch the second pump.

 

I would be more concerned if you could get less than 60psi. That would seem to indicate that there isn't enough fuel to overrun the factory return restrictor.

With a standalone, running an electronic trigger is certainly an option, and IMO preferrable to a Hobbs switch. For those without one or who don't want to configure that, a 9/64 drill bit is all that's needed to fix it.

 

I've tested various drill sizes for the eductor, indeed 3mm was not enough, i had to go 3,5mm but just touching the unit with a drill caused the suction from the right tank-side to drop dramatically. Enough to eventually run out of fuel? I dont know I just stated that this is the case and that it could cause problems on the racetrack.

This is how I would connect my dual walbro if I wanted to avoid drilling the eductor.



This will set the pumps in a low speed mode until desired boost is acheived.

The resistors have to be able to handle at least 200w each.