Do i need a larger fuel pump?

[Bmxr152]

I was wondering if im over running STOCK my fuel pump. I am currently running 15 psi. I was running 10 but i was having too much knock so decided to run Alky injection and now i can hit 15 psi no problem. Also when i ran VP110 i could run safely about 21psi with no lnock. I was thinking maybie the reason im getting so much knock is becuase my motor isnt getting the fuel it needs. I do have a DSM link but am a noob and am trying to dial in my airflow right now. ITs weird because the link says my 720cc injectors are at almost 100% duty bet yet im only running 15psi on very low timing. Im sure the answer is going to be upgrade it and if so the 255, 255 HP, or 190?

 

[pooker]

Yeah you definately need to upgrade if your running stock pump, get a 255 with an afpr..

 

[TalonTsi31]

Yeah you definately need to upgrade if your running stock pump, get a 255 with an afpr..

i agree the walbro 255 is the way to go. and the stock fuelpump is only safe up to 16 psi.

 

[daren_p]

I saw 107% injector duty cycles with my evoIII at 15 psi, so more then likely your out of fuel. Have you atleast rewired your stock pump? If not this should be top on your list & even with a new larger pump you still want a rewire as pump flow is directly related to voltage & the voltage is low with the stock wiring. Which pump you needs depends on your goal, the 190 is fine for your current turbo, it good for around 400 hp. If you plan on making more power in the future you'll probably want to go 255 but remember you also need a proper FPR (fuel pressure regulator) to run one of these pumps as they will overrun the stock FPR, giving you tuning issues.

 

[Bmxr152]

i do have a Aeromotive AFPR kit from SBR but i just havnt had time to order the pump. Do you guys think that will solve some of my knock issues? Also how hard is it to setup the AFPR. I was told that it can take a lot of time to get the pressure all dialed in

 

[DJYoshaBYD]

wow... you should never increase the boost that much without a fuel pump... that is why you get knock...

 

[daren_p]

Can't be 100% sure it will solve your problem but it defently could be the source of the issue. Is a fpr hard to dial in?, no not at all. Run the car till its up to normal operating temp, disconnect the vacuum line, plug the vacuum line and adjust the FPR to read whatever you want to have your base fuel pressure at. 1g's are 38 psi base pressure from factory I believe & 2g's are 43.5. I believe some 1g guys set their base pressure at the 2g value of 43.5 as this is the industry std pressure & what most injectors are flow rated at. If you set your base pressure to 38 you aren't flowing the 720cc your injectors are rated at.

 

[BIGBLAZE79]

You might want to replace your fuel filter if you haven't done that yet. That could be restricting the flow of gas to your injectors.

 

[zippyshoe]

I was wondering if im over running STOCK my fuel pump. I am currently running 15 psi. I was running 10 but i was having too much knock so decided to run Alky injection and now i can hit 15 psi no problem. Also when i ran VP110 i could run safely about 21psi with no lnock. I was thinking maybie the reason im getting so much knock is becuase my motor isnt getting the fuel it needs. I do have a DSM link but am a noob and am trying to dial in my airflow right now. ITs weird because the link says my 720cc injectors are at almost 100% duty bet yet im only running 15psi on very low timing. Im sure the answer is going to be upgrade it and if so the 255, 255 HP, or 190?

I really wouldn't expect to see 100% duty cycle with 720cc injectors at only 15psi boost pressure. What you are describing sounds like a possible air metering issue (your ECU may be "seeing" more airflow than what is actually entering the engine). In DSMLink, do you have your global fuel values set correctly for 720cc injectors?

 

[Bmxr152]

I really wouldn't expect to see 100% duty cycle with 720cc injectors at only 15psi boost pressure. What you are describing sounds like a possible air metering issue (your ECU may be "seeing" more airflow than what is actually entering the engine). In DSMLink, do you have your global fuel values set correctly for 720cc injectors?

Ive been dialing in my MAFT setup and have it alot closer to actual boost than it was. Global value and everything else should be set right. I have the airflow meters As far as they will go to decrease the ammount the airflow the computer actual sees. like -20 on most of them. Is that normal

 

[zippyshoe]

Ive been dialing in my MAFT setup and have it alot closer to actual boost than it was. Global value and everything else should be set right. I have the airflow meters As far as they will go to decrease the ammount the airflow the computer actual sees. like -20 on most of them. Is that normal

Honestly, I'm not that familiar with the MAFT setups - you may want to post a message on the DSMLink forum. Regarding the global fuel setting, I believe this should be set to about 450/720 - 1 = -37.5% for 720cc injectors.

 

[Bmxr152]

Ok for some reason i though it was supposed to be at 405

 

[zippyshoe]

Can you post a DSMLink log here or on the DSMLink forum? A log would be very helpful in understanding this problem.