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Fuel Pressure Regulator question

I made some changes to my EFI conversion; including changing to a bigger injectors (from 525cc to 750cc ones) and have since been having a severe misfire whenever I get to high boost & high RPM (>4000 RPM) situations. And when that happens, my AFR has gone WAY lean (>15).

Took me a while but I finally noticed that my fuel pressure is dropping as my AFR starts to climb. So this leads me to the question...

I am using a stock 3.2 set up for intake, fuel rails and regulators. Could replacing the fuel regulator to an aftermarket one be the answer? Some suggested that its best to stay with a 1:1 ratio one as I can always change the fuel table to provide more fuel.

I was looking at a Bosch type adjustable one that Turbo Kraft has on their website (I couldn't find any from our host ) - thinking that I can start with higher pressure and it can lock into stock position (no fabrication). Does this sound like a good choice?

thanks!

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Old 10-06-2014, 06:43 AM
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Hmmm... Sounds more like a supply problem to me.

Also, keep in mind that the wide range is just reading O2. If you have a full misfire, the oxygen is not burned and is measured by the sensor. This makes a misfire look like a lean A/F.

The small Aeromotive regulator is very popular if you want to modify your setup, otherwise the Bosch one will have to do.
Old 10-06-2014, 07:24 AM
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+1 on the aeromotive unit. no stories
Old 10-06-2014, 07:56 AM
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Thanks for the input guys...

One question about the comment on "seems like supply problem" - I was thinking same. If that's the case, would the regulator solves the issue? I am going to hook up EGT - if its truly lean then I should see a spike. If its blow out with lots of fuel left then I should see EGT drops?

Re:aeromotive unit, is this (Aeromotive 13101 - A1000-10 EFI Fuel Pressure Regulator DIYAutoTune.com) the one to get? What's the difference between this & the Bosch?
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Old 10-06-2014, 08:02 AM
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Hobieboy, Thats the same FPR that I use on my build (Aeromotive). I have set my base pressure at 50PSI, and I have it hooked to MAP. (to get the 1:1 boost ref). I am running ID1000 injectors (1000cc at 43PSI)
It is a great FPR, however I have all custom fuel rails. I do not know what you would need to do to use it with a factory fuel rail setup. (FYI, the factory rail setup is good for high HP applications)

I also am running dual 044 motorsport pumps in parallel.

What pump(s) are you running? What duty cycle are your injectors seeing when the problem occurs?
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Old 10-06-2014, 08:57 AM
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I had the exact same issues with a high end aftermarket regulator in place. It took a new 044 fuel pump to deliver enough volume to feed the 1000cc injectors to bring the AFRs into line.
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Old 10-06-2014, 09:50 AM
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Quote:
Originally Posted by turbobrat930 View Post
What pump(s) are you running? What duty cycle are your injectors seeing when the problem occurs?
I am running stock dual Bosch pump in series on config. The rear pump is new. I am using ID725cc injectors and the max duty cycle I saw is ~48%.

To be clear, the FPR seems to be doing its job - pressure rises as boost builds; to about ~60psi. But, It doesn't rise about that nor can it stay flat. Fuel pressure starts to drop by the time RPM reaches ~4200.

I'll post a picture of the data log shortly.
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Old 10-06-2014, 01:28 PM
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Quote:
Originally Posted by tailwind22 View Post
I had the exact same issues with a high end aftermarket regulator in place. It took a new 044 fuel pump to deliver enough volume to feed the 1000cc injectors to bring the AFRs into line.
umm... looks like I may indeed need a new 044 pump

Would running a higher pressure help?

What I don't understand is: unless I need to adjust the baseline pressure to something other than stock (~45psi), how would an aftermarket FPR help.
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Old 10-08-2014, 06:24 AM
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Quote:
Originally Posted by hobieboy View Post
umm... looks like I may indeed need a new 044 pump

Would running a higher pressure help?

What I don't understand is: unless I need to adjust the baseline pressure to something other than stock (~45psi), how would an aftermarket FPR help.
In my case, whether the oem Bosch pump was bad or it's output inadequate, the move to the 044 corrected everything. Also, make sure that you are producing 14.2 volts to maximize injector output.
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Old 10-08-2014, 06:47 AM
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Just ordered a 044 pump. Will report back once I have a chance to test it. Really hope this is the problem.
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Old 10-09-2014, 04:12 PM
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Aeromotive a1000 pump and fpr. Works flawless with 1100 injectors and its e-85 friendly
Old 10-09-2014, 04:27 PM
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I have Metric fittings for the 044 fuel pump........



as well as "Direct Connect" hose fittings for AN -06 to M14......



If you are fitting aftermarket bits and are tight for space. These eliminate the need for costly adapters.

Len at Autosportengineering dot com

Old 10-10-2014, 06:22 AM
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+1 it sounds like a fuel delivery issue, not the regulator. Assuming:
(a) your fuel pressure is otherwise tracking with manifold pressure (good regulator, no vacuum or fuel leak), and
(b) you're measuring fuel pressure in the rails, ex: from the test port on the 3.2L Carrera's rail, and it's plumbed similar to factory,
then you're just not supplying enough fuel.

Check the voltage at your pumps. Original factory wiring + relays + fuses are all old enough to be suspect, and this wasn't Porsche's strong suit in the first place.

If good, check for flow restrictions between the tank and engine -- a kinked or pinched hose, clogged filter, etc. A new -044 pump won't help if you've got another restriction limiting flow.

TurboKraft Inc : Fuel Pump Adapter Fitting Front : Bosch 044 [999 620 993 TK] - $34.00
TurboKraft Inc : Fuel Pump Adapter Fitting Rear : Bosch 044 [999 620 930 TK] - $34.00
(Trying to get our host to start offering these.)
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Old 10-10-2014, 08:37 AM
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I was using 750cc injectors and 4 bosch pumps and ran out of fuel. I now use an aeromotive pump and -8 fuel lines and 1000cc injectors with gasoline. Years ago I found the stock fuel lines were too small and replaced them all from the front pumps to the rear pumps and up to the engine. The wide band is usually accurate as during tuning I started rich and worked my way back at fuel mixtures of 9-1 with gasoline. With methanol injection at full boost mixtures are usually 10.8-11.2
Old 10-10-2014, 09:37 AM
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Thanks for the suggestion Chris. I am using complete stock 3.2 rail setup & test port for pressure sensor. The fuse/relay are new - I converted to blade style setup with individual fuse for each pump; though wiring from fuse box to pump is original.

A question on the adapters though - I haven't dismantled the front (& its been a while), but do I need any with factory setup & 044 pump? I would have thought 044 pump has same inlet/outlet connections as factory stock pump?
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Old 10-11-2014, 04:06 AM
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Hobieboy,

You will need an 18MM hose barb adapter that you can get from Len or Chris for the pump inlet to the tank. Since your car is an 87', it already has a 12MM banjo fitting at the pump discharge. The 044 comes with an external 12MM check valve and should connect without issue. The only other thing to look at is the size of the wire connections, which I think are larger on the 044 pump. So you may have to enlarge the existing wire connections or replace the wire terminals with larger ones.
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Old 10-11-2014, 07:04 AM
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Correct, you have to change out the eyelets on the chassis wiring to one size larger, ex: 4mm /5mm to 5mm/6mm.

Highly recommended to split the power supply onto 2 separate circuits as the -044 fuel pumps draw more amps than the factory fuel pumps do.

The pumps also come with a spacer installed under the check valve which adds ~13mm to the length. This can be removed for a better fit.
However, use caution removing it; there's not a great way to hold onto the pump, nor is there a lot of room for a wrench. It is easy to break off a wiring terminal, rendering your new pump a paperweight.

Hose barb inlet adapter up front with a new copper crush ring, and replace the hose itself with a fresh piece of 12mm/0.5" ID fuel hose.

Threaded adapter in the back with new copper crush ring.

If you find the pumps noisy, rubber jackets are available.
The -044 pumps are *much* quieter than the Aeromotive A-series pumps (screamers).
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Old 10-11-2014, 07:43 AM
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My pump doesn't scream. It sounds more like an old norelco electric razor on a tin roof

Old 10-11-2014, 11:23 AM
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