Twin Bosch 044 Strange Noises

[skylinekid]

ok heres how the story goes. ive got 2 bosch 044 pump feeding off a 4lt surge tank. they lead off to twin -8 lines then aare joined into one at a -8 y piece i then have -8 all the way to the front with an inline filter (earls screen type) which then joins onto another y piece then to twin -6 lines to each side of the rail.... hardline all the way till i reach the -6 area. now the problem is wen i have both pumps running i have this very strange like choof choof choof noise coming from sumwhere its very hard to locate as the pumps are so loud but as soon as i switch it back to one pump the noise goes away. im very worried that the pumps are fighting each other or sumthin at the y pieces or there is sumthin goin on with fuel pulsation or sumthin because i dont have a damper like the factory cars do. has neone had a similiar problem or neone know how i could resolve this issue?

[GT-RZ]

maybe. idealy if you have two 8mm lines going in to one line you would want that single line to be bigger? perfect setup would be two seperate lines? how much power are you making? is two necessary? maybe get one pump to supply it all? nismo?

just a thought... that noise is not heaps of fuel pouring through your surge tank overflow pipe? one pump would not be chucking as much fuel back in to your main tank?

[skylinekid]

i will be in the vacinity of 600hp maby more i could probably have run one pump but i wanted to run 2 just to have the extra bit there if its needed... on 1/2line should be plenty enough to do the job.... if it comes down to it im just gonna have to put in 2 3/8 lines. just means ive wasted alot of money on y fittings....

and no it wouldnt be the fuel pushing itself back into the surge its a 4lt surge so its gots plenty of juice to circulate.

[skylinekid]

can neone else shed sum light on this situation...........

[GT-RZ]

i will be in the vacinity of 600hp maby more i could probably have run one pump but i wanted to run 2 just to have the extra bit there if its needed... on 1/2line should be plenty enough to do the job.... if it comes down to it im just gonna have to put in 2 3/8 lines. just means ive wasted alot of money on y fittings....

and no it wouldnt be the fuel pushing itself back into the surge its a 4lt surge so its gots plenty of juice to circulate.

i never said fuel pumping back in to the surge. talking about fuel pourng from the surge in to the main tank... if you have wayy too much fuel coming up from the lifter pump and too much fuel pressure going down the line then the overflow pipe will be chucking it back in the main tank... maybe you should check it out.

i'm having a wild guess but it's all i can think off ?

Edited May 28, 2009 by GT-RZ

[skylinekid]

well yeh of course its gonna be puting fuel back into the main tank thats a given but for sum weird reason it makes the noises alos near the y fittings..... as if the colliding fuel is causing the noise..... im considering just runing one pump and leaving it at that for now and if i start running out of fuel lata which no doubt i probably will ill run another line and get the other pump working hopefully...... its just a very strange thing

[Swiper the Fox]

well yeh of course its gonna be puting fuel back into the main tank thats a given but for sum weird reason it makes the noises alos near the y fittings..... as if the colliding fuel is causing the noise..... im considering just runing one pump and leaving it at that for now and if i start running out of fuel lata which no doubt i probably will ill run another line and get the other pump working hopefully...... its just a very strange thing

if you are using a Vi-PEC you can program it to turn on the other pump at higher rpm or boost.

[skylinekid]

yes but wats the difference if its still gonna do the same thing..... ive been thinking and i thought maby the return back to the main tank isnt large enough to cope with the fuel flow coming in and out and maby its putting pressure into the surge tank which intail would be putting pressure on the wrong side of the fuel pump aswell..... just a thought....

[Marko R1]

im running the same setup with an 044 lift pump & 2 044's to my dual entry fuel rail.

what ive done is use the existing 'in' & 'return' lines as my 2 'in' lines & ive ran a new return line (as recommended by rips nz)

this should alleviate your problem & its an easy fix

[femno]

HAHA Youre using a 044 as a lift pump? Thats just stupid. Why? It will just heat the crap out of the fuel and cause major issues. I would use a specific lift type pump instead. haha.

Back on topic, it seems really silly to have 2 of everything then just joining it in the middle...im just day dreaming here but wouldnt this be the same scenario as a tuned length exhaust?

If the 2 pipes arent the same length it causes bad resonation and loss of power. In your case the choof choof choof maybe. Just guessing. I would run 1 -06 line from each of the pumps and put them into each end of the rail. Then to reg from middle of the rail and back to the tank from there. Simplest and easiest way IMO.

[Marko R1]

HAHA Youre using a 044 as a lift pump? Thats just stupid. Why? It will just heat the crap out of the fuel and cause major issues. I would use a specific lift type pump instead. haha.

these were my thoughts as i wanted to run the factory pump as a lift (seems over engineered this way TBO) BUT when i spoke to jim @ crd he said "stick with the 044, much more reliable"...i think he knows his stuff

[femno]

He does know his stuff, but thats really strange though running a 044 for a lift. Are you sure he suggested it as a lift pump and not as the main pump?

[rob82]

2x 044 pumps running continuously on a street car is a dumb idea. First off there are very few regulators that will return enough fuel back to the tank without causing a restiction; hence increasing fuel pressure. Then there is the additional heating of the fuel. If you must have a surge tank than at least switch one of the pumps on when you think it will be needed but dont forget to put a oneway vavle in front of both pumps.

Ohh 044 as a lift pumps is shit idea - dont care who said it.

Edited May 29, 2009 by rob82

[skylinekid]

keep on topic...... if u want a lift pump topic make a new thread......

[SirRacer]

If you want people to reply to your thread, you perhaps want to have a look at your attitude!

[skylinekid]

no attitude implied there mate..... but u want attitude pm me

[GT-RZ]

hah. well don't think this problem is going to be resolved very fast. one pump per line or work out some issues with fuel pressure and return.

[skylinekid]

i was told to put a fuel damper up the front because they reckon it could be fuel pulsations from the pumps im not sure if it would help but yeh

[MBS206]

2 pumps... No one way valve...

When you turn one pump off, you do realise fuel flows BACKWARDS through the second pump right?

In much the same fashion if one pump dies, it'll send fuel backwards out the dead pump, leaning your engine out?

Very VERY bad idea for a fuel setup...

Get ONE main pump. If it dies, at least the engine just turns off... It doesn't lean out.

[GTRNUR]

Ive seen this one before...

Fuel temperature. How hot are your pumps when they get noisy. Running two pumps circulates a lot of fuel and its all getting nicely heated up by cooling your fuel rail down. Check them when they are noisy. Warm is ok, but leaning towards hot certainly isnt. They start to cavitate as they boil the fuel internally. Then the sound like they are pumping gravel. The solution is to put a fuel cooler (small tranny cooler) on your return line at the back of the car. It makes your tune far more stable as well and lowers your over all fuel temps and minimises temp variations.

Also, if its an R33 Vspec or R34 gtr there is a fuel pump control module mounted under the drivers side parcel tray. There are two signal wires sent from the ECU that change the factory pump from low speed operation to high speed operation. This happens automatically at a specific load point around 3500-4000 rpm from memory. If you want to run one pump constantly, and switch in a second pump under high load, this is where you pickup the relay activation signal from. That combined with a 1 way valve on the switched pump would do the job just fine.

I see MBS206's point about a lean out, but I believe that a car tuned to the point where it has a need for twin 600hp pumps would also have a decent AFR system as well. Plus if you know your car you can feel when its running lean and if you have 1/2 a brain you dont try and drive through the "flat spot" that it feels like. You get off the throttle and make a few checks.