60lb injectors, low fuel pressure

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06-22-2010, 12:09 PM
sliverado rst

60lb injectors, low fuel pressure

ive been after a low fuel pressure/ lean issue for a while now, i used to only have a about 38lbs of pressure at an idle, and then when the truck started making boost (magnacharger) my pressure would drop way down and the truck would run lean. so i upgraded to 60lb injectors, gutted out the stock sending unit and put a walbro 255 pump in the tank witch brings me to around 48 psi, then i disconnected the fuel pressure regulator and brought me around 52-54psi at an idle, but when i start making boost im almost down at 20psi, and the things kinda of slug. so im thinking i need to change my in line pump, im not sure witch pump it is its the one that comes from mangacharger, i just don't know what i should run for an inline pump to feed those injectors. any suggestions?
06-22-2010, 01:31 PM
Atomic

Might want to upgrade the wiring to the pump. I have a walbro 255 in take and 60lb injectors and have around 50 at idle and cruise, but down to about 45 at high rpm WOT.
06-22-2010, 01:35 PM
oleshifty

honestly, get rid of the 'magnacharger' pump, and have the computer tuned for charger/injectors.

Depending on boost, you may want a dual 255 setup in tank, I would avoid an 'inline' setup.
06-22-2010, 02:11 PM
sliverado rst

well i currently have a nelson tune, and Ive never seen a dual in tank pump setup for a truck, do you have to make it?
06-22-2010, 04:16 PM
oleshifty

ya, several guys here are running them. Sure someone has a pic / howto laying around
06-22-2010, 07:52 PM
Mangled03gmc

What kinda power are you making?? I agree, check all the wires to and from the pump.A faulty or loose connection will def drop amp/volts.. Hook or put a new FPR back on the truck. Then make sure the tune is spot on for the size injectors that you are using. A 255 pump is good to 500 whp.. Their is a guy making like 800 hp using a single 255, it is keeping up fine
06-22-2010, 08:04 PM
danger_ranger83

http://www.ls1tech.com/forums/fuelin...l#post13504876
06-22-2010, 08:07 PM
sliverado rst

well the pump that's in the tank now is spliced into the factory pump/sender unit were it was originally, and it still uses the factory harness that it did before and it did have power when i installed it, however i think when the old pump in the tank was weak it may have been straining my inline pump, my inline pump i can still here it when i the turn the key and it primes itself, but it really don't sound very good.
06-22-2010, 08:23 PM
Mangled03gmc

Ok so you have a intank walbro, one inline?? That is kinda unclear.. If the one inline is going south that might be the problem, remove it, see what happens. As the inline can draw through another pump, but one can't push through a weak or dead one.. If you decide to do a intank, save alot of hassle imo and do a single BOSCH 044.. Here is a write up I did when I did mine.. Have about 270 buks in it, you might have a lil more if you decide to get factory connectors..

http://www.performancetrucks.net/for...d.php?t=428535
06-22-2010, 08:28 PM
sliverado rst

wow man i thought everybody was running 1intank and 1 inline pump, i guess i was wrong, ill have to see if i can bypass it hopefully without replacing a line, thanks for the link.
06-22-2010, 08:31 PM
Mangled03gmc

Like I said what kinda power are you making?? lol That single bosch will handle alot. But what ever you do next time around, you need to upgrade and run larger wire and a relay, so you don't exp voltage/amp drop when the pump is working under hard load. It will, does happen.. I say pull that inline out and see what happens :D
06-22-2010, 08:50 PM
sliverado rst

well i really have no idea what im making for power now, ever scene Ive swaped from an lq9 to an lq4 ( with the same heads, cam, supercharger ) ive been making less boost and having fuel issues. towards the end of the lq9s life i did already start having a fuel pressure issue
06-22-2010, 09:49 PM
Atomic

How much boost? I am just guessing but near 500 to the wheels.
06-22-2010, 11:42 PM
RedHeartbeat

Quote:

Originally Posted by Mangled03gmc

Ok so you have a intank walbro, one inline?? That is kinda unclear.. If the one inline is going south that might be the problem, remove it, see what happens. As the inline can draw through another pump, but one can't push through a weak or dead one.. If you decide to do a intank, save alot of hassle imo and do a single BOSCH 044.. Here is a write up I did when I did mine.. Have about 270 buks in it, you might have a lil more if you decide to get factory connectors..

http://www.performancetrucks.net/for...d.php?t=428535

What filter is that in the Bosch? I didn't see it listed anywhere in the post.
06-22-2010, 11:53 PM
Mangled03gmc

Quote:

Originally Posted by RedHeartbeat

What filter is that in the Bosch? I didn't see it listed anywhere in the post.

That is the filter that is used with it. Go to JAYRACING and look. I am not sure if it is made for it, or is universal style. I HAVE TO SHOUT.. WHEN YOU GET IT, PULL THE SOCK OFF THE FITTING, CUT A SMALL GROOVE AROUND THE FITTING, USE A EXTERNAL SNAP RING. The sock will slowly walk its way up, suk shut on the bottom of the fitting.. I fought FP issues for over a week trying to figure out why... :)
07-06-2010, 12:58 PM
sliverado rst

ive been super busy with work, sorry i haven't been on but removing the inline pump has helped me a great deal, my fuel pressure now drops only to 40psi instead of 25psi, so i do still have an issue but i am headed in the right direction.
07-10-2010, 10:47 AM
2boosted

Quote:

Originally Posted by sliverado rst

ive been super busy with work, sorry i haven't been on but removing the inline pump has helped me a great deal, my fuel pressure now drops only to 40psi instead of 25psi, so i do still have an issue but i am headed in the right direction.

I have an intank, and in line pump setup, 62 psi Idle, 60 psi Wot.

1st I had the OEM in tank, and a walbro 255HD inline, 50 psi Idle, 35 psi wot

2nd I had the OEM in tank, and a Bosch inline bigger Specs that the Walbro, 52 idle, 36 wot.

3rd I replace the intank with a walbro 255 and place the inline 255 walbro again.....voila...works till now.

I still have stock FS tubbing.
07-10-2010, 11:55 AM
farmtruc

1 Attachment(s)

We're building an 07 truck now that will require two pumps.

We tied two pumps together and routed the fuel outlets to a Y. I made the Y with some 3/8" metal tubing.
I looked all over and couldn't find a Y I liked, so making one was much easier and cheaper. There is limited room in the bucket, so an Aeromotive or Russel Y block wasn't a choice.
Here is a pic of the two pumps joined. If you're wondering if the hose will fall off, NO, I tig'd small bumps along the end of the tubing so the clamps and hose has something to grab onto.

For the wiring. We ran a 10g power wire fused to the alternator, then run it through a relay that is triggered by the stock fuel pump relay.
The stock bucket connector was disassembled and the stock 18g wires removed. We put in a some terminals that would accept the 10g wiring, then internally we discarded the stock wiring and installed 12g pairs.
A 10g ground was also ran the same way.
This allowed us to use the stock wiring connectors and drill NO hole in the bucket.

The stock feed line was used, but at the engine compartment an Aeromotive regulator is controlling fuel pressure now.
The stock evap line was used as a return line.
Routing: feed line into regulator, out the regulator, into the stock rails. The bottom port on the regulator goes to the evap line.

Both pumps will be running all the time.

The bucket was heavily modified to accept all this, but everything works just fine.

Truck is a new body w/ iron 5.7L, NP front mount, 80e swap (thanks RED), gonna push about 15psi.

We just did a camaro with the same mods, and fuel pressure was rock solid.
I have no doubt fuel pressure will stay constant, however, volume...
07-13-2010, 10:40 AM
sliverado rst

that 2pump in tank set up looks like its gonna flow nice, i wouldn't mind trying to use another 255 as an inline pump scene i still have wiring and a bracket for it, im assuming you have to make your own inline pump setup?
07-13-2010, 10:53 AM
farmtruc

Quote:

Originally Posted by sliverado rst

that 2pump in tank set up looks like its gonna flow nice, i wouldn't mind trying to use another 255 as an inline pump scene i still have wiring and a bracket for it, im assuming you have to make your own inline pump setup?

ya it actually does, we've been tuning this truck for a couple days, 08 sd 2bar is tricky, but coming along nicely.
it's setup for 10psi for now, fuel pressure doesn't move at all, we'll be increasing boost to 15psi today.

if you're gonna do two pumps in the tank, skip on the inline, it'll just slow things down. actually, with a walbro in the tank and one inline, there is no benefit.