Fuel Pump

[taylork057]

EMS has full control over it correct?

Running into fuel pressure problems with this setup-

DCR option b-
race port head
BC 3 cams
inline walbro
intake walbro
return system.

At 5000 every time it starts shooting lean. On low boost tuning it was fine, no fuel problems. Come back and turn the boost up a little(10 to 15) and it cant keep up. Its not even making 500 yet and its dropping from 55-60 down to below 30. The inline fuel pump is very loud.

With the EMS it runs a constant voltage, none of the variable stuff like the stock ecu does?

[d_fl8ted1]

do you have both pumps running off the same relay or do you have a relay for the external as well...? are you sure the intank pump is working

[taylork057]

with the KOEO and grounding the relay, it primes, then i can hear cavitation, and the fuel pressure jumps around from 50-59.

[d_fl8ted1]

how much fuel you have in your tank... less then a 1/2 and this will happen... the fuel sloshes away from the intank pump..

did you just install the return line as well... if you did make sure you have fill the stock regulator hole very well... any type of air getting into the tank will cause flucuating fuel pressure as well

[nutz]

have you tried using an external power source, for a constant voltage (IE: rewire)

[never2muchboost]

problem #1= not enough info on the setup

you say in tank and inline pump however you dont mention if the in tank is feeding the inline. you cant use a pump to feed a pump without having an accumalator tank. however if you are using a y-block and the second pump is on a natural gravity feed then that is ok.even if the second pump is slightly weaker than the first pump it will surely cavitate.

problem#2 = describe the return portion of the fuel system. what regulator are you using? is it the standard -6 in -4 back? if you have restriction on the return you can deadhead fp and kill the pumps quick.

the first thing i woul do is remove the second pump and see if you still run out of fuel.

second thing is fix your feed issues and dont run both pumps all the time. there really is no need to do that. you can control the second pump with the ems to only come on in load. this will make tuning driveability a whole bunch easier.another problem running two pumps all the time will be a bottleneck in the return that wont allow you to drop fuel pressure below a certain psi.it will also cause fuel pressure to bounce around at its lower settings

[d_fl8ted1]

You are correct on the button jay... i had mine up where the intake would feed the external because that is the way AMS installed it when i was on the dyno when they wouldnt believe i had a low pressure walbro instead of the high pressure walbro

so i changed mine up where i put a bung on the center back of the tank and fed a line to the external and allowed both pumps to y into one line and go to the rail

I am going to be switching my pumps around though like you said with the aem controlling the second pump.. Can you give me the pin out to use to control the second pump?

I am also going to switch the power wire from the fuse box stud to the back of the altenator so the second pump gets full power

[taylork057]

Thanks for the replys

I took the feed line off from the tank and turned the pumps on, it was barley flowing, and not a steady stream. So i took that pump out, put in a new walbro, with the -6 feed and bulk head fitting mod. Its cleared it up now!

Its a 255 intake, with a bosch 44 inline -8(from the 44) and -6 return. Thanks

[never2muchboost]

Quote: Originally Posted by d_fl8ted1

You are correct on the button jay... i had mine up where the intake would feed the external because that is the way AMS installed it when i was on the dyno when they wouldnt believe i had a low pressure walbro instead of the high pressure walbro

so i changed mine up where i put a bung on the center back of the tank and fed a line to the external and allowed both pumps to y into one line and go to the rail

I am going to be switching my pumps around though like you said with the aem controlling the second pump.. Can you give me the pin out to use to control the second pump?

I am also going to switch the power wire from the fuse box stud to the back of the altenator so the second pump gets full power

shit you couldnt ask something simple right...hang on

use a seperate relay for the pump and run a 10ga. wire to pin 30 of the relay
run a 10ga from pin 87 of the relay to the pump.
10 gauge ground from the pump - to chassis ground
then run a fused b+ 16 ga to pin 85 of the relay
run a 16 gauge from pin 86 of the relay and run that to the pcm and it will go into connector c2 pin 15(low side driver #9)

thats how to wire it up

then go into the ems and follow the path
options>configure outputs
on the drop down menu select ls9 and name it secondary fuel pump
check basic activation and i would suggest putting your parameters as follows
coolant at least 140*
load at least 5 psi
rpm at least 3000
tps at least 75%
road speed at least 10 mph

make sure you have the parameters set right and it shows at least and not less than..double click it to change it

like that you will only have your second fuel pump come on in boost at wot only

[never2muchboost]

btw i would also put a fuse on the pump 10 ga wire too...thats a high current draw

[d_fl8ted1]

thanks jay... will be doing that today along with some grounding tricks darrell told me to do... since this aem is very picky on grounds..

[never2muchboost]

i usually take the pcm sensor grounds and run them directly to the negative terminal on the battery