Sixpack73

ok i've had my 392 installed for a few months now and have been living with the fact that below a half a tank when coming to a stop, all the fuel sloshes to the front of the tank. This is apparently putting air into the fuel lines, dropping fuel pressure to 0 psi (sometimes killing the truck). In fact it stranded me last month (in my business work clothes) when I forgot and let it get down to a 1/4 tank and it died when i came to a stop. I had to crawl under the truck, disconnect the fuel line, and bleed the air out with a hand-siphon to get her going again. I was not happy, and had to cancel a meeting I was headed to.

anyway, what i'm looking to do this weekend is drop the tank again and relocate the bottom portion of the pick-up tube to see if that would help (ie point it more toward the front of the tank), but I've also been thinking about hooking up the stock LP and using it to feed into the walbro, in series in other words.

the only thing with doing that is i'm wondering if the stock LP would be a flow restriction, meaning the walbro would be straining, trying to pull fuel thru the stock pump. I could also wire in the stock LP in parallel with the walbro so that both pumps would run at the same time, but I still think the walbro would be pulling through a restriction. (might overload the electrical relay too?)

Does anyone have any other suggestions on how I can get rid of this problem? It is really an annoyance and kinda limits the distance you can go on a full tank.

gator6

it seems like you guys with the newer trucks have alot of problems with the intank fuel pickup. i was wondering what the main difference in the newer and 03-04 tanks are? would it be possible to put the pickup/fuel guage assembly out of an 03-04 in the newer tank and add an 03-04 aftermarket lift pump assembly? or get an 03/04 fuel tank and put it in the newer truck?

trx

hey six pack that sucks, do you know if others have had this problem? Is your pick up as low as possible? Also i have read that trying to pull fuel through stock pump is a great restriction.

vzdude

Last I checked, the GDP kit didn't come with a different pickup. Whose did you use? Rich at GDP says he has guys running some pretty high HP on factory pickup tubes ! Good enough for what I plan on doing! He also advised of the trouble you are describing!

skynyrd

sounds like you might have cut the pick up tube a to great of an angle or to short. mine start sucking air when fuel sloshes at about 1/16th of a tank but i cut the pick up tube at a 20 degree angle and made sure it was really close to the bottom of the tank.

trx

correct me if i am wrong but this was on their website

GFS Competition kits for the '05-'07 application now come with our new, flexible pick-up tube assembly! No more worries of punctured tanks or rub thru due to rigid pick-up pipes. Our new pick-up tubes curve towards the center of the tank to keep your system fed from the lowest point possible at all times.

sid325

I'm with skynyrd. I have not had a problem unless I let the fuel level drop below a 1/16th of a tank. I usually fill around a 1/8th.

Jacob

vzdude

My bad! I have an 03 with the engine mounted lift pump. You HAD to use a pickup tube to bet past the OE lift pump in the tank. I should think more! I would say the tube is either flexed or curved up for some reason, or cut too short. One or the other.

Sixpack73

yeah i've heard of it happening to several guys, just never heard of any real solutions.

since i have the in-tank stock LP, the only way to use the stock fuel lines is to pull fuel through the stock LP. and it sounds like the consensus is that it would be pretty restrictive?

Maybe I can relocate the pickup tube somewhere more towards the center of the tank then. this is gonna be fun...

vzdude

I kinda like the Vulcan draw straw myself. Granted, after talking to Richard @ GDP, I don't need one, but it looks to make a very clean install using the factory hole in the sending unit. Also has provisions for the return line! It keeps the pickup in the sending unit where it has some "reserve" to avoid the sloshing problem. Check it out. It might be just what the DR. ordered.

Snoxracer

When I first installed my GDP pump I ran it in line with the factory in tank pump. Which seemed to work for a little while, but then started to notice hard (long crank time) starts, when less than 1/4 tank of fuel. Also noticed pressure drop during WOT runs. So I ended up getting the plastic draw tube from Rich and mounting it so the straw is just behind the factory pump in the tank. I cut the straw at a little angle and it pretty much rest next to the molded hump in the tank that holds the factory pump etc. Since this I have had no problems and never have any long starts now.

Plus now on WOT runs fuel pressure goes from 22psi down to 18psi and never wavers.

RamNu2

Mine was the same way Talked to Rich several times about it. We ended up not knowing what the problem was. He rold me then that the stock lift pump should flow around 95-100 gph. I hooked them up in line (i.e. both pumps pumping and most of the problems went away. Now if I get below 3/16 tank it has low fuel pressure until start up and long crank times but alot better than dieing at quick stops at intersection. All the stuff needed to do this minus a couple wire connectors was sent with my kit and easy to do except dropping the tank by myself.

Sixpack73

well I relocated my pick up tube to the same place as 8mpg did in his write up: https://www.dieseltruckresource.com/...walbro+install, which was pretty much where i had it to begin with, but I did trim some length off of it and made sure it was flat against the bottom of the tank with a slight angle cut in the tip to prevent it from suctioning to the bottom.

so...took it for a test run, and I still have the same problem!! with fuel just below a 1/2 tank (as in about 3/8 full) it still drops to 0psi when coming to a stop. depending on how long the red light is, it usually comes back up to 22psi before the light turns green though. so evidently the fuel is still sloshing forward and causing air to get into the pick up tube and killing the siphoning effect. I can see it doing this below a 1/4 tank, but at 3/8ths? thats not right! and depending on how hard I have to stop, it will occassionally get enough air in the lines to kill the truck. which means i have to crawl under it, disconnect a hose, and taste some diesel to get it siphoning again.

so here's my next idea... i wonder (if I can find a way) to put the pick up tube into the yellow cup that the stock LP pulls from, if that would solve the sloshing problem, and avoid the low pressure problems you guys mentioned if i were to run them in series.

thoughts? anyone done this before?

vzdude

O.K. here is a link to what I described earlier. I think this will fix all of the sloshing issues. Read the entire description as to where it goes, and why it goes there.

http://www.vulcanperformance.com/ser...2%84%A2/Detail

vzdude

Re- read the dang thing. only works up to '04. Give them a call. maybe they have something for the '04.5 and up?