Fuel rail (preassembly) testing

sv51macross · 11-22-2010, 02:36 AM

Tomorrow (okay, this morning) I'm going to be reassembling Lucy's fuel system with four replacement injectors and all-new grommets/O-rings, and a replacement PD. Here is a photo as best as I could take of the primary rail.

http://sadpanda.us/images/285598-ER3BLVO.jpg

It seems that the fuel is leaking from the top of the leading injector and the wetness on the rest of the rail/PD is just 20 years of dust wicking and sticking the fuel. Obviously, I'm going to replace the injector and rubber seals, but is it wise to not replace the rail/PD? The engine only has about 80k on it, and the replacement rail/PD has 64k on it. If it is prudent not to replace the PD and keep it on hand as a spare, how should I store it so as to prevent further degradation of the internal rubber diaphragm?

Lastly, to make sure the PD is not leaking, I want to pressurize the fuel system. I was going to button the rails back together and use duct-tape to hold the injectors in their rail bosses. After that, plug the pump back in and hot the ignition. Is this a bad idea?

Grappler · 11-22-2010, 04:32 AM

I'm not really sure what you mean by button the rails back together or use duct tape...

Have you looked into using a banjo bolt at all? The rail itself should be fine its mainly the PD you should worry about.

Pete_89T2 · 11-22-2010, 06:29 AM

If your '7 still has the stock wiring harness, I would recommend installing both rails on the motor, jumper the yellow fuel pressure test connector (located by the passenger side strut tower). When you switch the key to run, you'll hear the fuel pump running and will know in a hurry if/where it's leaking from.

My5ABaby · 11-22-2010, 09:48 AM

I support putting in a banjo bolt where the PD is and eliminating that problem area all together.

C. Ludwig · 11-22-2010, 10:43 AM

That's an S5 primary rail. The PD is integral to the rail. This PD is not subject to the same failure (leaking) as the removable S4 PD and cannot be replaced with a banjo bolt. Clean it up and put it back together just as it is.

Install new o-ring on your injectors, just as you've said you're going to. Lube the o-rings before you try to insert the injectors in the rail It's very easy to nick the o-ring and ruin it when you try to insert the injectors into the rail without lube. I like to use assembly lube, motor oil works fine though. Just don't install them dry.

If this is a turbo car you can hook both rails and all the fuel lines up to the engine/manifold before installing the upper intake and pressure test the system that way. I would do that before trying to pressure test the system off the engine. If you do try to pressure test the system off the engine, use safety wire to hold the injectors tight in the rails. You need something very strong to hold the injectors. Tape will not work. You can use properly installed safety wire though to hold the injectors to the rails and jump the test terminal to run the pump just as you described. Doing this on the engine is a safer option though.

sv51macross · 11-22-2010, 12:09 PM

@ Ludwig,
I thought they were subject to the same failures, it was just harder and more expensive to replace. As my sig says though, Lucy breathes without the aid of a hairdryer, so probably different than what you're suggesting.

NoDOHC · 11-22-2010, 08:45 PM

Yeah, you can test the primary rail, but you have to have the secondary rail too, as it has the FPR on it. You can hold the injectors in with duct tape if you like, I prefer rubber bands. As an alternative, if you have extra fuel line, leave the fuel rail in the upper intake manifold and simply attach long line to test it.

I really like that fact that I can test my fuel system before installing the upper intake on my 4-port.

11-22-2010, 02:36 AM	#1
sv51macross Rotary Fan in Training Join Date: Oct 2010 Location: Ann Arbor, Mi Posts: 47 Rep Power: 0	Fuel rail (preassembly) testing Tomorrow (okay, this morning) I'm going to be reassembling Lucy's fuel system with four replacement injectors and all-new grommets/O-rings, and a replacement PD. Here is a photo as best as I could take of the primary rail. http://sadpanda.us/images/285598-ER3BLVO.jpg It seems that the fuel is leaking from the top of the leading injector and the wetness on the rest of the rail/PD is just 20 years of dust wicking and sticking the fuel. Obviously, I'm going to replace the injector and rubber seals, but is it wise to not replace the rail/PD? The engine only has about 80k on it, and the replacement rail/PD has 64k on it. If it is prudent not to replace the PD and keep it on hand as a spare, how should I store it so as to prevent further degradation of the internal rubber diaphragm? Lastly, to make sure the PD is not leaking, I want to pressurize the fuel system. I was going to button the rails back together and use duct-tape to hold the injectors in their rail bosses. After that, plug the pump back in and hot the ignition. Is this a bad idea? __________________ 1990 Mazda RX-7 NA; Lucy, after the main antagonist from Elfin Lied. Eventual plans? Something cyberpunk and spicy.

11-22-2010, 09:48 AM	#4
My5ABaby Sigh..... Join Date: Feb 2008 Location: Murfreesboro, TN Posts: 2,377 Rep Power: 20	I support putting in a banjo bolt where the PD is and eliminating that problem area all together. __________________ 1986 Sport: 132k miles, 5A (Sapphire Blue Metallic), Tokico Blues, Racing Beat Springs, Custom LED tailights (only S4 LED tails in the world), SSR Mark II, Racing Beat exhaust, S5 black interior, Rotary Resurrection rebuild at 120k miles Community Service Manual RotorWiki "Imagination costs nothing; we could build square locomotives or fly to Mars" - Felix Wankel Yesterday is history, tomorrow is a mystery, but today is a gift. That is why it is called the "present."

11-22-2010, 10:43 AM	#5
C. Ludwig Rotary Masochist Join Date: May 2008 Location: Floyds Knobs, IN Posts: 494 Rep Power: 18	That's an S5 primary rail. The PD is integral to the rail. This PD is not subject to the same failure (leaking) as the removable S4 PD and cannot be replaced with a banjo bolt. Clean it up and put it back together just as it is. Install new o-ring on your injectors, just as you've said you're going to. Lube the o-rings before you try to insert the injectors in the rail It's very easy to nick the o-ring and ruin it when you try to insert the injectors into the rail without lube. I like to use assembly lube, motor oil works fine though. Just don't install them dry. If this is a turbo car you can hook both rails and all the fuel lines up to the engine/manifold before installing the upper intake and pressure test the system that way. I would do that before trying to pressure test the system off the engine. If you do try to pressure test the system off the engine, use safety wire to hold the injectors tight in the rails. You need something very strong to hold the injectors. Tape will not work. You can use properly installed safety wire though to hold the injectors to the rails and jump the test terminal to run the pump just as you described. Doing this on the engine is a safer option though. __________________ _______________________________________________ *One stop Haltech, AEM, Syvecs shopping. Installation and tuning.* http://www.lms-efi.com *Free support. Drop us an email.* chris@lms-efi.com 502-515-7482 Facebook @LMS-EFI

11-22-2010, 12:09 PM	#6
sv51macross Rotary Fan in Training Join Date: Oct 2010 Location: Ann Arbor, Mi Posts: 47 Rep Power: 0	@ Ludwig, I thought they were subject to the same failures, it was just harder and more expensive to replace. As my sig says though, Lucy breathes without the aid of a hairdryer, so probably different than what you're suggesting. __________________ 1990 Mazda RX-7 NA; Lucy, after the main antagonist from Elfin Lied. Eventual plans? Something cyberpunk and spicy.

11-22-2010, 08:45 PM	#7
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 18	Yeah, you can test the primary rail, but you have to have the secondary rail too, as it has the FPR on it. You can hold the injectors in with duct tape if you like, I prefer rubber bands. As an alternative, if you have extra fuel line, leave the fuel rail in the upper intake manifold and simply attach long line to test it. I really like that fact that I can test my fuel system before installing the upper intake on my 4-port. __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)

11-22-2010, 04:32 AM	#2
Grappler Rotary Fan in Training Join Date: Nov 2008 Posts: 31 Rep Power: 0	I'm not really sure what you mean by button the rails back together or use duct tape... Have you looked into using a banjo bolt at all? The rail itself should be fine its mainly the PD you should worry about.

11-22-2010, 06:29 AM	#3
Pete_89T2 Lifetime Rotorhead Join Date: Apr 2010 Location: Elkton, MD Posts: 874 Rep Power: 16	If your '7 still has the stock wiring harness, I would recommend installing both rails on the motor, jumper the yellow fuel pressure test connector (located by the passenger side strut tower). When you switch the key to run, you'll hear the fuel pump running and will know in a hurry if/where it's leaking from.