Supra Forums banner
1 - 5 of 5 Posts

· Newbe....I know nothing!
Joined
·
1,865 Posts
Discussion Starter · #1 ·
Hey Guys,

Its not often I need to post a thread for help but in this case I'm a bit stumped.

I am having fuel pressure drop on the dyno at about 466whp and 16psi.

My set up fuel wise is a Denso MKIV pump in tank to a stock fuel filter (bran new) and then to a -6 line to a Bosch 044 pump from there to a Bosch filter up front (brand new) to a t and twin -6 feeds to the rail. I'm running Simmens 83lbs inj. as well.

Problem is as I start to get into boost at 16psi the fuel pressure start to drop (58psi to 33psi) and we back out right away. I have a good boost reference and no problems with that for the FPR.

Ideas as to what the problem may be are 1) The sock in the tank is clogged 2) The hose from the Denso to the hanger is lose 3) pulling the basket in the tank dry (unlikly at 466whp) 4) restriction in the system some were.

I made 550whp at 24psi on my old 1jz set up and the Denso MKIV pump so I am loss as to what is going on now.

One last thing all the pumps are wired with 12 gage wire from there own relays.

Thanks,

Jeremy
 

· Vendor
Joined
·
4,627 Posts
What happens if you take the Bosch out of the equation?
 

· Newbe....I know nothing!
Joined
·
1,865 Posts
Discussion Starter · #3 ·
I had done that before and I was seeing fuel pressure drop at 11psi. I changed the factory fuel filter and installed the Bosch thinking that would solve the problem. Looks like it just moved it up to 16psi now.

I'm going to drop the tank tonight and see if there is anything messed up in there. Sean had said he had the line from the in tank pump to the hanger come lose once, so I am going to look at that. Everything from the tank outlet forward is new.
 

· Newbe....I know nothing!
Joined
·
1,865 Posts
Discussion Starter · #4 · (Edited)
I just worked on the car for a few hours and it looks like it was a bad diaphragm in the Aromotive FPR. I took off the vac line to it off and had a strong fuel smell, I then checked it for vacuum and it would not hold 15in for more than 2 sec.

I had a spare (brand new) and swapped it on in its place and did some tests. I can get the Fuel pressure to 95psi with no problem. I set the new FPR to 65psi static and gave it 30psi of air pressure. It held that constant for the full 30sec test.

I then took off the return line and tested it again at 95psi with the return going into a large jug. In 15sec I got 1 liter of fuel so 4L/min (240L/hr) sounds good to me.

I then tested it again at 65psi and got 1.2L in a 15sec test 4.8L/min (288L/hr).

Those numbers for flow sound good to me.

That was all done with both the MKIV pump and the 044 inline with it.

Trying to have enough fuel for 650whp on my 83lb/inj.
 
1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top