Fuel Pressure no longer adjustable after installing Hydra

mopwer · 06-30-2007, 10:00 AM

I set the fuel pressure before installing the Hydra. Now that I have it installed, the pressure won't go above 32psi no matter how much i adjust the FPR. I changed the rail to a center feed and installed the new injectors. All new HP hoses too. What happened?

ALSO, the fuel pump runs continuously with the key on and no jumper installed.

Greg

RickyB · 06-30-2007, 06:56 PM

The fuel pump should only run for two seconds when the power is turned on or when the engine is cranking or running. Otherwise, your jumpers are not set properly for the year engine harness you are using. See this page for details.

mopwer · 06-30-2007, 09:19 PM

Quote:

Originally Posted by RickyB

The fuel pump should only run for two seconds when the power is turned on or when the engine is cranking or running. Otherwise, your jumpers are not set properly for the year engine harness you are using. See this page for details.

Thanks, I'll check that out. Could this affect the voltage going to the fuel pump causing the pressure to remain at 32psi?

Greg

mopwer · 07-01-2007, 10:26 AM

Figured it out. Went in to check the jumpers and they were set up for a 91-92 not my 93. Also the #12 jumper was bent by the wires and actually fell off.

This brought the pressure up to where it should be and it only ran for 2 sec. before I put in the jumper. BUT, there is a little black box next to the resitor packs that sounded like it was screaming! It didn't do that before the Hydra, any idea what's wrong with that?? Thanks again.

Greg

RickyB · 07-01-2007, 01:07 PM

Are you saying that the fuel pump volume relay is buzzing? That is not proper operational behavior and suggests you might have a bad relay. I suggest that you bypass the fuel pump volume relay and eliminate it from the system so that the fuel pump is always at high voltage. You need to remove the relay and modify the body harness so that the two blue-black wires going to the relay connector are soldered or crimped together to make a permanent connection.

mopwer · 07-01-2007, 01:47 PM

Quote:

Originally Posted by RickyB

Are you saying that the fuel pump volume relay is buzzing? That is not proper operational behavior and suggests you might have a bad relay. I suggest that you bypass the fuel pump volume relay and eliminate it from the system so that the fuel pump is always at high voltage. You need to remove the relay and modify the body harness so that the two blue-black wires going to the relay connector are soldered or crimped together to make a permanent connection.

I imagine that is what it is. Its to the drivers side of the resistor packs. Do they go out often? Can I just replace it?

Greg

mopwer · 07-01-2007, 02:44 PM

Not wanting to cut up the wiring harness, I tore apart the relay and rigged it to always be on high voltage.

You can carefully pry the top cover off with a small screw driver. Then cut the wires to the coil so it won't activate. Just to be safe, I ripped the coil out completely (probably not necessary). This left the spring loaded contact always in the high voltage position (essentially connecting the two blue with black wires together). Then I'll seal the cover with some black RTV just to make sure no water gets in. Here are some pics! Make sense??

Greg

06-30-2007, 10:00 AM	#1 (permalink)
mopwer 933SGTE Join Date: Nov 2006 Location: Peoria, AZ Posts: 1,098 Thanks: 24 Thanked 13 Times in 13 Posts My Google Map iTrader Rating: (12/100% )	Fuel Pressure no longer adjustable after installing Hydra I set the fuel pressure before installing the Hydra. Now that I have it installed, the pressure won't go above 32psi no matter how much i adjust the FPR. I changed the rail to a center feed and installed the new injectors. All new HP hoses too. What happened? ALSO, the fuel pump runs continuously with the key on and no jumper installed. Greg Last edited by mopwer; 06-30-2007 at 11:19 PM.

07-01-2007, 02:44 PM	#7 (permalink)
mopwer 933SGTE Join Date: Nov 2006 Location: Peoria, AZ Posts: 1,098 Thanks: 24 Thanked 13 Times in 13 Posts My Google Map iTrader Rating: (12/100% )	Not wanting to cut up the wiring harness, I tore apart the relay and rigged it to always be on high voltage. You can carefully pry the top cover off with a small screw driver. Then cut the wires to the coil so it won't activate. Just to be safe, I ripped the coil out completely (probably not necessary). This left the spring loaded contact always in the high voltage position (essentially connecting the two blue with black wires together). Then I'll seal the cover with some black RTV just to make sure no water gets in. Here are some pics! Make sense?? Greg Attached Thumbnails Last edited by mopwer; 07-08-2007 at 02:39 PM.

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06-30-2007, 06:56 PM	#2 (permalink)
RickyB Automotive Cartographer Join Date: Dec 2005 Location: California Posts: 221 Thanks: 0 Thanked 114 Times in 33 Posts iTrader Rating: (0/0% )	The fuel pump should only run for two seconds when the power is turned on or when the engine is cranking or running. Otherwise, your jumpers are not set properly for the year engine harness you are using. See this page for details.

07-01-2007, 10:26 AM	#4 (permalink)
mopwer 933SGTE Join Date: Nov 2006 Location: Peoria, AZ Posts: 1,098 Thanks: 24 Thanked 13 Times in 13 Posts My Google Map iTrader Rating: (12/100% )	Figured it out. Went in to check the jumpers and they were set up for a 91-92 not my 93. Also the #12 jumper was bent by the wires and actually fell off. This brought the pressure up to where it should be and it only ran for 2 sec. before I put in the jumper. BUT, there is a little black box next to the resitor packs that sounded like it was screaming! It didn't do that before the Hydra, any idea what's wrong with that?? Thanks again. Greg

07-01-2007, 01:07 PM	#5 (permalink)
RickyB Automotive Cartographer Join Date: Dec 2005 Location: California Posts: 221 Thanks: 0 Thanked 114 Times in 33 Posts iTrader Rating: (0/0% )	Are you saying that the fuel pump volume relay is buzzing? That is not proper operational behavior and suggests you might have a bad relay. I suggest that you bypass the fuel pump volume relay and eliminate it from the system so that the fuel pump is always at high voltage. You need to remove the relay and modify the body harness so that the two blue-black wires going to the relay connector are soldered or crimped together to make a permanent connection.