i am starting to run out of fuel again on my setup. i am currently running 550/1600 injectors, power fc, supra pump with a boost a pump on it. at 14psi i am at 80% inj duty and at 18psi im at 90% injector duty. i am getting to the point of running out of fuel again. i want to run 22psi but dont want to hit 100% injector duty. i have an aeromotive fpr that is working correctly. i am running 45psi base pressure. i was wondering could my power fc be calculating my injector duty incorrectly? my sec. inj lag is set at .40 for the 1600s. i was thinking about running 55psi base fuel pressure to get me where i want to be for boost and still maintain low 90's for injector duty. any imput appreciated.

 

You could switch your 550's for 850's and keep the rest of the system the same...this should help you out greatly with minimal investment.

Raising the base pressure does help and it also atomizes the fuel better for when you are cruising but a change of 10psi will only provide a marginal improvement since you are already at 45...if you where at 35 and going to 55 then it would be a pretty nice change. And you don't want much above 55 because at 22psi you will be at 77psi of fuel already...and that is kinda pushing the pump IMO...

Good luck!

Chris

 

You're running out of pump at 18 psi. Upgrade the primary to 850cc and go with dual pumps or one Bosch 044 pump.

 

Thats what Im thinking. That single Denso just isnt enough.

 

Check these out.. http://www.injectordynamics.com/ID2000.html

 

/agree

 

thanks for the imput guys. i was thinking it was not the pump since i have the kenne bell boost a pump on there and usually they work very well. but is possible. ill give the injectors a shot and see how the 850s work. i just didnt want to have to redo the entire map.

 

How do you like the boost-a-pump? I have yet to install mine. Did you by chance use a fuel pump relay? I'm thinking of running one along with the boost-a-pump with the rx7.com fuel pump.

Thanks

Mike

 

yes i have the relay on there. i had originally ran my fuel pump direct and that didnt help enough. it did drop my inj duty by 10%. the boost a pump works well, i think i must be out of injector. the boost a pump paired with the supra fuel pump should flow lots of fuel at 16-17 volts.

 

I'm running twin FD pumps 550/1680, base pressure slightly higher then stock. With a large street port, t70 and 23 psi my duty cycle is in the mid 70's. No boost a pump, just a good rewire. Stock fuel lines with Y block in tank.

I'm surprised you're running out of fuel with the boost a pump added. You don't need to go to 850's, but your map will need to be redone either way regardless if you increase the fuel by pressure or more injector.

 

what about adding some a/i?

 

That would only help if it was meth injection. Water injection wouldn't change the afr's. Although it will help protect the engine at those high boost levels. My vote is to get a second supra pump, if that alone doesn't fix it, which it should then turn the base pressure up some more. While we're on the discussion when was the fuel filter changed out? Don't neglect the simple stuff

 

If you have the right supra pump and the boost a pump is wired up right you are NOT running out of pump...Howard Coleman ran way more power than a 35R with one.

 

When I removed the 3 ohm resitors from my PFC driven Bosch 1600s and used the FJO driver, I had to reduce my fuel which lowered the duty cycle by over 7%.

 

^ I'm using a 4ohm resistor. I really don't see why you're running out of fuel. Is the pump rewired? I will add this... before upping the boost I was still running the stock pump rewired, and my duty cycle was around 90%. The pressure held fine but once I added the second pump it made a huge difference. Obviously, since I'm seeing duty cycle in the 70's with considerably more boost. No changes with the injectors.

 

Since I recently added my FJO, I've been considering moving from 850's to 550's with my Denso pump. Mainly because I want a good idle and cruise AFRs again. I'm getting old and tired of smoking myself out.

 

back up with this thread. does anyone run bored out primary injectors? i was thinking of jumping up to 750cc. i was able to get to 22 psi with 93% injector duty after tuning. i kept the same fuel pressure at 45psi. i may either drop in a bosch 044 or up the fuel pressure. i picked up a new turbo setup billet 6265 so i am planing on upping the boost to 25psi. so i know i will need some sort of fuel upgrade at this point.