Mike Holmen

My truck takes a nose dive running a drag box and mach 6's after 2700 rpms. With the drag box my truck would stall after a wot blast. Dyno runs where tricky. I had to re-prime my injection box after the run. Yes, Don milks these VP as much and far as human can. Yes there you are at the maximum fuel delivery of the VP and your VP may not have enough fuel for them. For street driving I run the comp box, with none of issues are present any more. I've run lots of different injectors. Don's have made the most power yet and are the most drivable for a big HP truck. Not to many injector shop have guys running big sticks and driving them every day. But on the other hand there are guys going thru this barrier. I talked to a guy that making a special VP that has more fuel delivery than a HRVP. Everybody has this dream.

CTD2001

The mach 6s that i bought were new, when i drive around with the comp box on but only under normal drivng conditions, the truck runs awesome, could not ask for anything more, it is only once in a while, not every time that i hammer on it that i get that slight hesitation/defueling ect. Like yesterday afternoon i took it for a handful of test romps and it only showed the symptoms once and that was with it on 1x5. Honestly I like driving the truck around with the injectors only, still has tons of power.

Mike Holmen

How was your truck configured during your dyno run? You should try a set of twins? A mach 6 truck should be in the 600's rwhp area with enough air. A little single, your egt's would be crazy. My egt's are over 1500 deg's at 60psi. I would guess that my truck would put down a low 12sec quarter mile if I could ever find time to go to the track.

CTD2001

my old dyno number were with some bully dog stage 5 injectors that had some miles on them, i have yet to dyno the truck with the Mach 6 injectors. I will be putting it on the dyno this upcoming weekend in Indiana at IRP. I am hoping to be up in the 500 + hp range. I was talking to a guy tonight he had the same exact setup as i did and he made 544hp.

Clunk

I wiggled my pump wire to fix an occasional stumble, it's soldered now and no stumbles since.

Huff nPuff

The stock fuel module in the tank has an effetive area of a 1/4in fuel line coming out of the tank.You cannot possibly move enough fuel for that kind of power thru that restriction.Pressure is not the whole picture volume is key.At really high demand situations atmosphereic pressure cannot push enough fuel to your pumps thru the restriction so your pumps start cavitating and frothing the fuel you are actually pulling the colume of fuel apart.and sending pulses of fuel to the injection pump.If you do not fix this soon you will destroy your injection pump.

I SPEED

So, what can be done to right this situation?

Mike Holmen

Run a stock 12v mechanical pump and a cam with a pump lube on it. I would run a pressure regulator and set it for around 20 to 30 psi or run the fass system. I still have fuel even at wot, it never drops below 13psi. I have over 100000miles on mine, still works as good as it did when I bought it.

Clunk

Do you mean that 10 psi WOT lift pump pressure may not be liquid pressure but include foam too?

CTD2001

That is some very interesting information, i had no idea about the fuel lines coming out of the tank. As Nospin4me asked, how can i fix this, other than switching over to a 12v mechanical lift pump? Would a hotrod vp44 help the situation at all or would it just make it worse? Thanks for all of your guys time and suggestions.

Mike Holmen

I have a 1/2in line from the tank to the Fass pump and then 1/2 right to the injection pump. The return line is stock. The tank pick-up is stock. I've tried to remove the stuff inside and install a 3/4in pick-up tube but it causes to many issues on low fuel levels to be any use. There are guys running the stock 12v mechanical lift pump with no regulator. I've been just afraid of seal leaks to run the injection pump up to 50psi.

BigBlue

I'm not running near the power you are but I'm running -8 line from the tank to the vp and haven't had any problems with defueling. Even with 2 gallons in the tank.

francis212

I dont know if you resolved the problem yet but mine started acting the same way normal driving conditions fine at full throttle with comp off awsome constant pull with comp on, Feels like popping sputter hesitation shutter somethings not right....

CTD2001

I believe that the line from the tank to the fass pump is 1/2in, it is not stock. It is blue and it is what came with the Fass, then there is 1/2in line from the other side of the pump to the fuel filter canister, this also came with the Fass. From that point on, all the lines are stock. Does this sound right? Thanks again for the information

dzlfarmboy

Ive had good luck with this machanical MITUSA pump from a guy named opie, it's just like the Rasp but designed a little better. Has been one of the best investments for my peace of mind. The last thing im worried about is my lift pump which was always in the back pf my head before with a electronic pump. Just my oo cents