fuel pressure for my combo

stanger8172 · 02-12-2002, 11:15 AM

Should I be running about 40-43psi of fuel press? I put my buddies gauge on the fuel line and it stays about 38.

I am wondering if I should because of my heads, valves and exhaust. The only other mod I have that isn't listed is the K&N panel with no silencer. Stock intake, injectors, fuel rails, press reg.

It sounds really good when I start it cold but maybe sounds like it's choking or running a little lean when the car's warmed up.

Rebel79 · 02-12-2002, 04:53 PM

An adjustable fuel pressure regulator is not a bad idea at all. I'd try 42psi and go from there. You want it to have the most power without pinging. So install your FPR, set the FP, go on a bonzai run, pull over and stop, and pull a plug to see if you are detonating. If not, lower the FP until you do and then up it 1 or 2 psi.

gtsr515 · 02-12-2002, 09:59 PM

Pump is more important than the regulator, you really don't need much more pressure considering your package.

Rebel79 · 02-13-2002, 02:27 AM

Quote:

Originally posted by gtsr515
Pump is more important than the regulator, you really don't need much more pressure considering your package.

Yeah but he thinks he is running lean! If he gets a bigger pump, his fuel pressure will rise, yet he won't be able to adjust it! He could end up loosing power because his motor is too rich!

gtsr515 · 02-14-2002, 07:25 PM

He thinks he's running lean, but, i doubt he is. A larger pump will not increase pressure, only volume, pressure is the regulators job, he needs both, reg and pump.

stanger8172 · 02-14-2002, 07:39 PM

I'll just keep the timing where it should be for now by turning the distributor. Maybe I can turn it up alot with more fuel pressure.

Isn't it true on a cold start that the motor is in a warm up phase and the computer makes more spark advance and fuel pressure than normal?

Thanx!

jimberg · 02-14-2002, 08:19 PM

The computer does not control fuel pressure at all. The computer operates in open-loop mode when the engine is warming up. This means that the computer opens the fuel injectors based only on the air moving past the MAF sensor and lookup tables and does not use the oxygen sensors. The reason for this is that the aif/fuel mix must be rich to warm up the car. So rich that it is outside the range of the oxygen sensors' ability to measure.

gtsr515 · 02-14-2002, 08:23 PM

Hey Stanger, when you adjust your timing, are you removing the spout connector?, also raising fuel pressure has no bearing on ignition timing adjustments. Also, when adjusting fuel pressure, you need to remove the vacuum line, adjust, replace line. I hope you know that.

02-12-2002, 11:15 AM	#1
stanger8172 Registered Member Join Date: Nov 2000 Location: Milwaukee,Wisconsin Posts: 380	fuel pressure for my combo Should I be running about 40-43psi of fuel press? I put my buddies gauge on the fuel line and it stays about 38. I am wondering if I should because of my heads, valves and exhaust. The only other mod I have that isn't listed is the K&N panel with no silencer. Stock intake, injectors, fuel rails, press reg. It sounds really good when I start it cold but maybe sounds like it's choking or running a little lean when the car's warmed up. __________________ '91 LX convertible , T-5, Centerforce Dual Friction, MSD Blaster Coil, FR 9MM wires, 13* timing, 1.6rr, ported/polished/milled stock heads, 1.94/1.60 stainless valves, March Performance Pulleys, K&N panel, 1"spacer, BBK shorties, 2 1/2" off road H, Summit 2 1/2" catback

02-12-2002, 04:53 PM	#2
Rebel79 News Editor Join Date: Apr 1999 Location: Concord, CA Posts: 2,101	An adjustable fuel pressure regulator is not a bad idea at all. I'd try 42psi and go from there. You want it to have the most power without pinging. So install your FPR, set the FP, go on a bonzai run, pull over and stop, and pull a plug to see if you are detonating. If not, lower the FP until you do and then up it 1 or 2 psi. __________________ Scott Halihan, News Editor The MustangWorks Magazine 1994 Supercharged Mustang Cobra Rebel Racing. Home of Bay Area Mustangs

02-12-2002, 09:59 PM	#3
gtsr515 Registered Member Join Date: Nov 2001 Location: Sunny, Hot, Sebring, Florida Posts: 725	Pump is more important than the regulator, you really don't need much more pressure considering your package. __________________ Remember...2nd place is 1st place for losers!

02-14-2002, 07:25 PM	#5
gtsr515 Registered Member Join Date: Nov 2001 Location: Sunny, Hot, Sebring, Florida Posts: 725	He thinks he's running lean, but, i doubt he is. A larger pump will not increase pressure, only volume, pressure is the regulators job, he needs both, reg and pump. __________________ Remember...2nd place is 1st place for losers!

02-14-2002, 07:39 PM	#6
stanger8172 Registered Member Join Date: Nov 2000 Location: Milwaukee,Wisconsin Posts: 380	I'll just keep the timing where it should be for now by turning the distributor. Maybe I can turn it up alot with more fuel pressure. Isn't it true on a cold start that the motor is in a warm up phase and the computer makes more spark advance and fuel pressure than normal? Thanx! __________________ '91 LX convertible , T-5, Centerforce Dual Friction, MSD Blaster Coil, FR 9MM wires, 13* timing, 1.6rr, ported/polished/milled stock heads, 1.94/1.60 stainless valves, March Performance Pulleys, K&N panel, 1"spacer, BBK shorties, 2 1/2" off road H, Summit 2 1/2" catback

02-14-2002, 08:19 PM	#7
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	The computer does not control fuel pressure at all. The computer operates in open-loop mode when the engine is warming up. This means that the computer opens the fuel injectors based only on the air moving past the MAF sensor and lookup tables and does not use the oxygen sensors. The reason for this is that the aif/fuel mix must be rich to warm up the car. So rich that it is outside the range of the oxygen sensors' ability to measure. __________________ 351W 89 Mustang GT Convertible

02-14-2002, 08:23 PM	#8
gtsr515 Registered Member Join Date: Nov 2001 Location: Sunny, Hot, Sebring, Florida Posts: 725	Hey Stanger, when you adjust your timing, are you removing the spout connector?, also raising fuel pressure has no bearing on ignition timing adjustments. Also, when adjusting fuel pressure, you need to remove the vacuum line, adjust, replace line. I hope you know that. __________________ Remember...2nd place is 1st place for losers!

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Fuel Pump Pressure?	Swarzkopf1	Windsor Power	3	08-31-2004 02:07 PM
fuel pressure issues	mustang98gt	Modular Madness	3	07-05-2003 10:43 PM
Rising Fuel Pressure with Rising RPM?	StreetStang37	Windsor Power	1	05-21-2002 03:49 AM
Fuel pressure at high altitude. etc...	Dark_5.0	Windsor Power	5	04-19-2002 07:52 AM
fuel pressure for my combo?	stanger8172	Windsor Power	3	09-02-2001 02:55 PM