base fuel pressure question

Topic: base fuel pressure question (Read 2081 times) previous topic - next topic

base fuel pressure question

August 26, 2011, 10:40:21 AM

My base fuel pressure, vac line unhooked and plugged, is 45lbs. That seems kinda high. Should I get an adjustable FPR and bring it down to 39-40lbs.

It seems like it is kinda loading up at idle and low rpms, but could be my imagination. It does smell rich, but I have no cats on it ????????:D

Most of my other Mustangs we set at around 40 lbs.

base fuel pressure question

Reply #1 – August 26, 2011, 12:20:40 PM

Seems a bit high but it's near spec (40 psi). Do you have the stock regulator or an adjustable one?

base fuel pressure question

Reply #2 – August 26, 2011, 06:52:48 PM

Sometimes you will get them this high. Its ok actually because injector flow is based on 43.5 PSI

If your injectors are 19 LBS @ 40 PSI (stock) and you are running 45 LBS of pressure your new flow rate will be 20.15

base fuel pressure question

Reply #3 – August 26, 2011, 11:28:17 PM

A stock computer will also compensate for the higher pressure using your O2's. Shouldn't be a problem.

base fuel pressure question

Reply #4 – August 27, 2011, 12:13:58 AM

Quote from: Haystack;366127

A stock computer will also compensate for the higher pressure using your O2's. Shouldn't be a problem.

Yep. The EEC automatically tunes any increase in fuel pressure out. I'm running 24s with the stock FPR no problem.

base fuel pressure question

Reply #5 – August 29, 2011, 08:59:38 AM

Quote

Yep. The EEC automatically tunes any increase in fuel pressure out

TO a certain point. 42 pound injectors would be a problem. 36's would be as well....

base fuel pressure question

Reply #6 – August 29, 2011, 09:13:08 AM

Right now it is a stock FPR with 14'lb injectors.

I was wondering if 5lbs of pressure was too much for the comp to compensate. Sounds like its not.

base fuel pressure question

Reply #7 – August 29, 2011, 09:27:29 AM

To the best of my knowledge Ford injectors for a port system are rated at 39psi, other mfgrs and aftermarket do use different pressure ratings... At 45psi you are no doubt on the edge of what the computer can compensate...

What did the pressure read with the vac line on the regulator???

base fuel pressure question

Reply #8 – August 29, 2011, 10:08:40 PM

What kinda of mileage are you getting out of it, 5.0?

I have swapped out the fpr around 200k and things felt better and reved quicker. Didn't change the performance of gas mileage. The diaphram could be ripped or something letting pressure get high.

base fuel pressure question

Reply #9 – September 12, 2011, 06:46:57 PM

Quote from: mcb82gt;366279

Right now it is a stock FPR with 14'lb injectors.

I was wondering if 5lbs of pressure was too much for the comp to compensate. Sounds like its not.

Adjusting a 14 pound injector from 39 PSI to 45 PSI would effectively make it act as a 14.65 pound injector. The EEC- will compensate when needed by adjusting pulse width....

base fuel pressure question

Reply #10 – September 12, 2011, 06:58:39 PM

base fuel pressure question

Reply #11 – September 12, 2011, 09:12:50 PM

Thanks guys, just wondering if the computer could adjust enough at idle. Overly rich smell.

base fuel pressure question

Reply #12 – September 14, 2011, 01:35:20 PM

Are you sure it's not in constant open loop/FMEM and it is in fact reading the o2 sensors?

Also, are all emissions components in place?

base fuel pressure question

Reply #13 – September 14, 2011, 06:06:59 PM

Quote from: V8Demon;367641

Are you sure it's not in constant open loop/FMEM and it is in fact reading the o2 sensors?

?

How could I verify that??

base fuel pressure question

Reply #14 – September 15, 2011, 09:54:48 PM

Constant open loop will set a code.

65) Never went to closed loop fuel (C)

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