Fuel injector upgrade
04-09-2005, 08:22 PM
#1
Team Owner
Thread Starter
Fuel injector upgrade
I'm in the process of tuning the car using EFILive V7 with the FlashScan module and, with stage 2 heads cam and the VaraRam, I'm running quite lean in most of the part throttle fuel cells. I figured I'd install my FMS 30 lb./hr. fuel injectors to get the LTFT's closer to zero before going any further. My injector duty cycle was exceeding 90% in some cases as well so larger injectors would prevent premature failure.
Here's a shot of the FMS injectors. I got a good deal on these from a forum member a while back. Fuel delivery is at 36 lbs./hr. with the C5's 60 psi fuel pressure.
First pull off the FRC's. Next you need relieve the pressure in the rail. Unscrew the Schrader valve cap located at the front end of the driver's side fuel rail.
It's similar to a tire valve so you can relieve the pressure in the same fashion.
Using a small screwdriver or other appropriate tool, hold a rag over the valve while pushing in on the pin to relieve the fuel pressure. Be careful to protect your face from spraying fuel. If the car has been sitting for a couple of hours or more, the pressure will most likely be quite low.
Next, you'll need a fuel line disconnect tool similar to this one.
Arrange a rag to catch gasoline spillage around the fuel line before attempting removal. Place the disconnect tool over the line and push the prongs into the fuel line connector while pulling back on the braided line to pull it away from the tube. You'll need to do this twice if you have a '97 or '98 since there are two fuel lines connected to the fuel rail assembly.
I keep an assortment of cap plugs handy to cap off fuel, brake, coolant and other lines.
Now, remove the injector electrical connectors by pushing in on the metal wire clip and pulling up on the connector simultaneously.
Then remove the four studded fuel rail screws with a deepwell 10 mm socket. Using an 8 mm socket, loosen the intake manifold screw with the grounding strap on the passenger side so you can move it out of the rail's path when you're ready to remove it.
Here's a shot of the FMS injectors. I got a good deal on these from a forum member a while back. Fuel delivery is at 36 lbs./hr. with the C5's 60 psi fuel pressure.
First pull off the FRC's. Next you need relieve the pressure in the rail. Unscrew the Schrader valve cap located at the front end of the driver's side fuel rail.
It's similar to a tire valve so you can relieve the pressure in the same fashion.
Using a small screwdriver or other appropriate tool, hold a rag over the valve while pushing in on the pin to relieve the fuel pressure. Be careful to protect your face from spraying fuel. If the car has been sitting for a couple of hours or more, the pressure will most likely be quite low.
Next, you'll need a fuel line disconnect tool similar to this one.
Arrange a rag to catch gasoline spillage around the fuel line before attempting removal. Place the disconnect tool over the line and push the prongs into the fuel line connector while pulling back on the braided line to pull it away from the tube. You'll need to do this twice if you have a '97 or '98 since there are two fuel lines connected to the fuel rail assembly.
I keep an assortment of cap plugs handy to cap off fuel, brake, coolant and other lines.
Now, remove the injector electrical connectors by pushing in on the metal wire clip and pulling up on the connector simultaneously.
Then remove the four studded fuel rail screws with a deepwell 10 mm socket. Using an 8 mm socket, loosen the intake manifold screw with the grounding strap on the passenger side so you can move it out of the rail's path when you're ready to remove it.
Last edited by Patches; 04-10-2005 at 07:46 AM.
04-09-2005, 08:23 PM
#2
Team Owner
Thread Starter
Make sure all wiring harnesses and other obstructions are clear and pull up on the fuel rail assembly from both sides simultaneously. The injectors will pop out of the manifold. It may take some force so be careful and apply leverage judiciously.
The entire assembly with the injectors should come out as a unit. Here it is upside-down on the bench.
To remove the injectors, pull the retaining clip out and pull the injector out of the cup. It will require a bit of force as it's held in with an o-ring. Some fuel will probably spill out as you remove it as well so be ready with a rag.
Here's a side-by-side comparison of a stock '02 28 lb./hr. injector and the FMS injector.
A picture of one the injector ports in the manifold.
Make sure the cup is clean and free of debris.
Lubricate the injector o-ring with a small amount of fresh motor oil and firmly push the top straight into the cup until it seats. Then slide the retaining clip on until it snaps into place.
The entire assembly with the injectors should come out as a unit. Here it is upside-down on the bench.
To remove the injectors, pull the retaining clip out and pull the injector out of the cup. It will require a bit of force as it's held in with an o-ring. Some fuel will probably spill out as you remove it as well so be ready with a rag.
Here's a side-by-side comparison of a stock '02 28 lb./hr. injector and the FMS injector.
A picture of one the injector ports in the manifold.
Make sure the cup is clean and free of debris.
Lubricate the injector o-ring with a small amount of fresh motor oil and firmly push the top straight into the cup until it seats. Then slide the retaining clip on until it snaps into place.
04-09-2005, 08:24 PM
#3
Team Owner
Thread Starter
Be sure the clip has captured the lip of the cup so the injector can't pop out of the rail.
For future reference, I marked the stock injectors with their original locations with the cylinder position number.
Install the remainder of the injectors using the same technique. Lubricate the bottom o-rings with motor oil as well in preparation for installation.
Place the rail assembly carefully in place over the manifold, making sure each injector is sitting inside it's manifold port, and firmly push down on the rails to seat each injector. They should pop in solidly. You can tell if they are all seated by using a flashlight to inspect the ports. Also, the rail brackets should be completely seated on the manifold. Replace the screws and torque them to 89 in. lbs. Reconnect the injector connectors by snapping them down onto the injectors and replace the fuel line(s).
Double-check all connections. Put the key in the ignition and turn it to the ON position but don't start the engine. You should hear the fuel pump pressurize the system. Check for any sign of leaks in the engine bay.
Before going any further, most folks will need to scale the injector fuel rate table in the PCM for the proportional fuel flow increase these injectors provide. I didn't in my case because I was already running quite lean. When I scanned the car after the install, the fuel trims looked much better. They were now in the range where I would need to make smaller adjustments.
For future reference, I marked the stock injectors with their original locations with the cylinder position number.
Install the remainder of the injectors using the same technique. Lubricate the bottom o-rings with motor oil as well in preparation for installation.
Place the rail assembly carefully in place over the manifold, making sure each injector is sitting inside it's manifold port, and firmly push down on the rails to seat each injector. They should pop in solidly. You can tell if they are all seated by using a flashlight to inspect the ports. Also, the rail brackets should be completely seated on the manifold. Replace the screws and torque them to 89 in. lbs. Reconnect the injector connectors by snapping them down onto the injectors and replace the fuel line(s).
Double-check all connections. Put the key in the ignition and turn it to the ON position but don't start the engine. You should hear the fuel pump pressurize the system. Check for any sign of leaks in the engine bay.
Before going any further, most folks will need to scale the injector fuel rate table in the PCM for the proportional fuel flow increase these injectors provide. I didn't in my case because I was already running quite lean. When I scanned the car after the install, the fuel trims looked much better. They were now in the range where I would need to make smaller adjustments.
Last edited by Patches; 04-09-2005 at 10:26 PM.
04-09-2005, 08:37 PM
#4
Supporting Tuner
Awesome writeup and pics as usual, Patches 
Thanks!
EG
Thanks!
EG
04-09-2005, 08:51 PM
#7
Team Owner
That's a handy looking little tool....where'd you get it? What brand is it?
04-09-2005, 08:53 PM
#8
Team Owner
Member Since: Mar 2002
Location: Queens, New York Life begins at 183 mph....
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St. Jude Donor '08-'09
Excellent how-to Patches as usual!
You are a huge asset to this forum!
I'll be sure to bookmark this one!
You are a huge asset to this forum!
I'll be sure to bookmark this one!
04-10-2005, 07:43 AM
#12
Team Owner
Thread Starter
Originally Posted by 84zz4vette
That's a handy looking little tool....where'd you get it? What brand is it?
04-10-2005, 08:13 AM
#13
MONARTOR
I see no picture of the "I'm done" beer... 
your usual great write up
your usual great write up
04-11-2005, 06:17 PM
#17
Team Owner
Originally Posted by Patches
You can get these in practically any auto parts store. Just look for a 3/8" GM fuel disconnect tool.
04-15-2005, 11:10 PM
#20
Race Director
Originally Posted by lager99
Your hands...they look so delicate in the pictures...
Great write up, Patches....one would think you're one of them there engineers or somethin'!
