Fuel system help.

[Turbo Drifter]

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

 

[SupraClaou]

Re-check carefully your fuel system again.
I am going single in a month or two,and I have prepared my fuel system
allready for my 2jzgte. Sard fuel rail,850cc top feed injectors,dual 6AN
feed lines from the rail to a ' Y ' fitting (which is better for the fuel flow than a ' T ' fitting...I think so). I will use a 6AN return line to the AFPR and then
connect the return line to the stock line which ends up into the stock fuel tank.
Anyway...after the Y fitting there will be one and only inline high performance fuel filter (100 micron) with male fittings.Then one 8AN or 10AN line (feed/pressure line) to the stock modified (10AN fuel hunger) with two
255lph HP GSS341 Walbro fuel pumps.

I think you are having a flow restriction somewhere...and your pressure drops.
Also check the flow when using two inline back to back fuel pumps.Which are
also two different fuel pumps,where the one is much powerfull than the other
one. (Denso<Bosch 044)

 

[Turbo Drifter]

Re-check carefully your fuel system again.
I am going single in a month or two,and I have prepared my fuel system
allready for my 2jzgte. Sard fuel rail,850cc top feed injectors,dual 6AN
feed lines from the rail to a ' Y ' fitting (which is better for the fuel flow than a ' T ' fitting...I think so). I will use a 6AN return line to the AFPR and then
connect the return line to the stock line which ends up into the stock fuel tank.
Anyway...after the Y fitting there will be one and only inline high performance fuel filter (100 micron) with male fittings.Then one 8AN or 10AN line (feed/pressure line) to the stock modified (10AN fuel hunger) with two
255lph HP GSS341 Walbro fuel pumps.

I think you are having a flow restriction somewhere...and your pressure drops.
Also check the flow when using two inline back to back fuel pumps.Which are
also two different fuel pumps,where the one is much powerfull than the other
one. (Denso<Bosch 044)

You seem to think or make it sound like I have not done my research into fuel systems and what is needed. I know that the setup I have will support over 600whp.

I have gone over the full system 90% of it is brand new. I am going over the last 10% tonight.

Your set up its quite a bit different than mine and I need two filters as I have two pumps in line. I know I have a restriction somewhere as I am losing 30psi of fuel pressure.

I have a feeling my problem is in the tank some were I am dropping it tonight to see if I have plugged sock or lose feed line.

The 044 pump inline with the Denso will work as the Denso is pumping a high volume at a very low pressure. If the 044 pulls more fuel than the Denso can supply it will pull though the Denso pump.

If I cant find the problem I will just pull it all out and go with the twin in tank walbro shit.

 

[IJ.]

I run dual -6 from the pumps to the rail no issues ever on the dyno to 500+rwhp (I log fuel pressures)

 

[Turbo Drifter]

I run dual -6 from the pumps to the rail no issues ever on the dyno to 500+rwhp (I log fuel pressures)

I only have 1 -6 line from the inline 044 to the front were it T's off to the twin feed rail. I also log fuel pressure and that's how we cough the problem before damage was done.

 

[IJ.]

I'd be guessing it's just a volume restriction behind the 044, I look at it as too much isn't going to hurt anything hence the duals all the way.

 

[Turbo Drifter]

I'd be guessing it's just a volume restriction behind the 044, I look at it as too much isn't going to hurt anything hence the duals all the way.

That's what I was worried about. I had intended to run two 044's from a surge tank with twin -6 lines. I was told by a few respected people that would be over kill and one 044 in line would do the trick.

I guess I could put in the surge tank and just run one 044 from the surge tank to the rail.

 

[IJ.]

Does you car still have a CharCoal cannister?

 

[Turbo Drifter]

Does you car still have a CharCoal cannister?

Nope.

 

[IJ.]

Might just be as simple as you're out flowing the breather on the Vented cap.

To get xx fuel flow you need xx flow through the entire system, the stock setup actually builds + pressure in the tank through the CC to help move the fuel along.

You might be creating a vacuum in the tank due to the flow you need Vs the little flapper in the car not being able to breathe.

 

[Turbo Drifter]

Might just be as simple as you're out flowing the breather on the Vented cap.

To get xx fuel flow you need xx flow through the entire system, the stock setup actually builds + pressure in the tank through the CC to help move the fuel along.

You might be creating a vacuum in the tank due to the flow you need Vs the little flapper in the car not being able to breathe.

Hmm interesting idea, but with the line for the CC being open would that not be enough as well as the Cap?

 

[IJ.]

I would think so but there's a valve in the tank at the end of that line that could effect it.

Does it change it's behaviour dependant on fuel level?

 

[Turbo Drifter]

I would think so but there's a valve in the tank at the end of that line that could effect it.

Does it change it's behaviour dependant on fuel level?

Not sure to be honest, both times I have had it happen I have had about 1/2 a tank. One other thing we were thinking of is maybe the basket or baffle area in the tank is getting sucked out faster than the fuel can flow in.

Strange thing is that on my 1jz single I was able to hit 500+ whp with out any fuel pressure drop on just the MKIV pump and stock lines.

Would having a -6 feeding the 044 be a problem you think?

 

[IJ.]

The Labyrinth into the stock basket is HUGE I don't think that would be the cause.

The 044 from memory has a -10 inlet but I'd think the out flow from the Denso would be more than enough to keep up, I'm still inclined to think it's the stock filter and lines downstream.

I'm off to play with my car I'll check back in later on.

 

[Turbo Drifter]

The Labyrinth into the stock basket is HUGE I don't think that would be the cause.

The 044 from memory has a -10 inlet but I'd think the out flow from the Denso would be more than enough to keep up, I'm still inclined to think it's the stock filter and lines downstream.

I'm off to play with my car I'll check back in later on.

Well the only thing still stock in the fuel system is the tank hanger, line to the stock filter and filter. Out of the stock filter I have a -6 line going to the 044 Pump.

 

[IJ.]

Stock filter has a Banjo on one end doesn't it?

 

[Turbo Drifter]

Stock filter has a Banjo on one end doesn't it?

Yes on the one end it dose.

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.

Any input IJ?

Thanks for the help to BTW.

Jeremy

 

[CajunKenny]

My apologies for this newb question; but, how does one log Fuel Pressure?

 

[Turbo Drifter]

My apologies for this newb question; but, how does one log Fuel Pressure?

I have a 0-100psi sensor inline that is hooked up to my standalone via a 0-5V input.

I will also have mine set up to drop boost and invoke a lower rev limit if x fuel pressure is not made at x boost and RPM via a 4D map.

 

[CajunKenny]

Nice! I have a Maft Pro. I wonder if I could use one of the 0-5v 'Aux' inputs...? I'll do some research on that.

One last question: What inline sensor are you using? I like to use known good and field tested products.

Thanks!