GMC Motorhome, FiTech fuel delivery & final

Running a little late this morning…. blood work, you know all that fasting stuff…… I sucked down 2 Eggamuffins with a straw at 8AM!,,, just can’t wait that long for ice tea!

So now that we’re up on the lift… for you less fortunate get the coach off the ground unless you’re a horse jockey……. this thing is really low!  Fuel delivery for a fuel injection system is different that the ole ambient pressure carb system. 

While I will agree that the diameter of the hose (5/16) from the fuel/vapor separator up in the driver side rear well is woefully small but it IS positive ventilation from the carb through the vapor canister and we’re leaving that system in tact.  If your fuel vapor separator there is old or damaged I would replace it just cause    We have these for $89.  In that we had already dropped Marlin’s fuel tanks replacing all his hose with (30R) Ethanol resistant fuel hose ….. this is also something you really should address before installing the FiTech fuel injection.  The tanks need venting.

Likewise on the original tank fill hoses and the return to the neck should all be in operational condition.  If you don’t know…… break it all down.  It’s the only way to KNOW fuel delivery variables will not effect the system.

The FiTech throttle body has an inlet and oulet flare (AN-6) fitting.  We can make the hoses for you, put the fitting on one end of 2 high pressure 3/8″ hoses 15′ long each.  The other end will be cut to length and fitted to a barb fitting.   Route the inlet line to the carb to the feed line of the rear (main) tank. 

First route the inlet line through the frame to the outside of the rail,  We locate the electric fuel pump and it’s main filter there to make it easier to service    Why do this?  The highest failure rate components in electronics are motors and relays……. you should have purchased 2 of these hi pressure fuel pumps when you picked up the parts I listed.  This is because you will find having an extra pump with you will make your system more reliable.  Also mounting the pump and filter there no other in the frame components or hoses should need to be accessed on the road .  This will be the “main” tank.

Route the return line to the front tank feed line directly.  These 2 hoses can be disconnected from the original fuel tank solenoid.  BTW, take that selector valve out, you will no longer be using that.

Returning the fuel to the front tank will allow it to cool off before being used again.  Pressurizing fuel will heat it up, dumping the warm fuel back directly into the tank may cause a vapor lock in the tank from heat build up.  Connecting the drain openings on the bottom of the 2 tanks ties them together sharing the fuel in the 2 tanks, the warmer fuel will stay in the “accumulator” front tank cooling down as it makes it’s way throught either the fuel fill hoses or the drain hose 3/8″ steel line connection.  By the time the fuel mixes and makes it’s way to the rear main tank it’s temperature will have been reduced. 

Your original 2 fuel tanks tied together will act to delivering fuel as a 1 tank system…. with a 25 gallon “accumulator/cooler” tank before the main tank. 

If you have a Coachmen built Royale or another Transmode coach, be sure the take-off for the generator is not “T” connected to the main reat fuel outlet hose.  Some of them were.  If so, there is a barb fitting on the rear tank at the rear driver side corner on the top of the tank that should have the generator connection.  This outlet will go dry at 1/4 rear tank level to keep you from running yourself out of fuel with your generator.   Many of the Transmode builders didn’t know about and did not use the GM fitting put in for the generator feed line.

OK, with the electric fuel pump and filter installed as the pic above, the vent and return lines are good to go……. we’re done under here, lets go topside!

Kaitlyn and Phillip had already set in the reworked original intake manifold sealing it to the block with a fiber intake gasket set (Mr gasket 404 for a 455 motor, 405 for a 403 motor)    We put a light coat of Parmatex “Ultra-grey” RTV sealant on both sides of the intake gasket, a bead under and on top of the front and rear walls of the intake making sure the 4 corners get a good “blob”.  Some builders leave the cork gasket out…. you can do that I’m not gonna argue about that….

Vacuum routing

Reconnect your 3/8″ brake vacuum line at the back section of the intake.  Also reconnect the steel line going to the right side of the transmission to a vacuum port at the front of the intake.  These are THE 2 most important vacuum connections. 

Reinstall your water temp sender on the left side of the intake.  Remove the vacuum tree on the right front of the intake and install the FiTech water temp sender.  Do not use Tefon tape, for the sender to work it must be installed “dry”.    Of course they put MY sender on the left side…. whatever!

You have another thin plastic (capillary) line going to the dash heater control system, connect it where you can.  We pull out the original cruise control on restorations installing a no vacuum needed computer controlled cruise control.  If you are still using the original cruise system, reconnect it where you can.  The last vacuum line goes to the distributer advance diaphragm, this will be connected directly to the FiTech throttle body on the back side.  This vacuum line does not have vacuum during idle. (ported vacuum output) .

Reinstall your distributer, on Marlin’s we reinstalled a carb on the motor, reconnected the distributer and had the motor run before starting the throttle body install.  This gives you less variables to get the fuel injection system interfaced.  One problem in the ignition or vacuum system will not allow the FiTech system to learn properly.  I would strongly recommend getting the motor in this condition and running before installing the FiTech system.  .

NOW, we’re ready to mount the throttle body. First install the ” 1/2 spread bore  adapter” you picked up    The 1/2″ is needed for the 4 butterfly valves to clear the original intake…. trust me u need it!

Open your main FiTech box and pull out the 2 harnesses.  Before the throttle body beds down, connect the rout the wiring.  Each wire is labelled on both ends, the large 2 wire connector goes to constant 12 volts and to the electric fuel pump.  If the FiTech senses the motor is not running it will shut down the electric fuel pump…. no safety switch needed.  The other connectors wires are labelled too.  Ignition power, water temp, there’s a separate connector for the O2 sensor.  The other wires on this plug will idle the motor up when the AC comes on…. if you like along with some other neat connections but none of that is necessary to run the system.  This is all the parts in your FiTech kit   The FiTech display has a cable with 2 plug in connections… easy peezy   We did modify (cut in half with a locator tab the throttle cable bracket

Now mount the throttle body with the 4 screws.  Connect the all barrels progressive linkage (all 4 work all the time).    …. hey, just connect it…. it’s all a simple mechanical connection.  Adjust it for good pedal response.  The original rubber and plastic throttle connections are all but gone,  what you see using a locknut works pretty well.   

OK, with the throttle body secured, vacuum routing. wiring and linkage done…. it’s time to fire that mother up!  From now on, other than maybe tightening a hose or something you can shut the hood.  The system will now be controlled by the control panel.  Turn on your ignition key (don’t try and start it) and push the big button on the panel.  This is what you will see   Scroll down to “Go-EFI initial set up”.  Press enter and select .  Here is your setup screen.  go to each line, insert the answer (copy this one if you like):o Cylinders—- 8
o  Engine CID—– 455 or 403

o  Cam—– 1 (mild)

o  Rev limit—– 5000 (or whatever you want)

0  Idle speed—– 950 rpm

o  Pump speed  —- 74.9%

Now press “send to ECU”  This will save your setting.  This is all you need to do to set this system up.  When you start the system leave it running for @ 5 minutes.  As it runs, you can hear and see the system adjusting to the motor.  When it’s done the motor will smooth out, idle will be 950…etc.

Press “back” and reach the main menu screen    With “dashboard” selected press “enter”.  You will see this screen with no numbers in the blocks (not running)   NOW, turn your key off, turn the ignition back on and start the motor.  It should take 3-5 revolutions of the motor and the motor should start.  DON’T TOUCH ANYTHING!  Let the computer do it’s thing and learn itself to your motor.

You are looking a 1 of 4 information screens, while it’s doing this, press “Next”, you will see this next screen of information    It’s amazing!  Hit “Next” again and you see this   press again and you see this screen of information   Look at that… even gives you barometric pressure!  Insane!!!!!  If there is any issues it will print out your codes too!

Now go back to the main menu and select “large gauges”.  You can select 4 bits of info to show up on a single screen in large like what I programmed I like to monitor Tach…..Air/fuel ratio….. Manifold vacuum —– water temp..  Select what you like……..  by now the FiTech system should have learned you motor enough to give you a smooth idle around 950 rpm. 

Lift the hood, look for anything leaking, anything loose and anything not where it should be…. the motor is still running… right?

OK, shut the hood and go for a drive.  The more you drive the more the FiTech system learns your coach and your driving habits.  Kinda ear hey!. 

Put together and install your air cleaner to look something like this As you can see we keep the crankcase vent hose and filter cap..

So Martin, here is your motor running  We will clean up the wiring a bit and get some miles on the system this weekend.

OK so that’s pretty much it… you can and we will making everything neat but that’s all up to you.  There’s so much more the system offers you, read the books that came with it.  You could consider this manual as a “specific vehicle quick ” installation guide.

I certainly hope this manual helps you with your FiTech installation.  If you have questions give us or FiTech a call, they have a great help line..  So back up the last couple of weeks, print out the posts with “FiTech” in the title….. this is the basic information to make up a manual.  Hope this helps, call me if you have a question,

Jim Bounds

PS: We are putting together the 2 hoses and the other bits to put this system in your coach.  If you appreciate we’re helping you with this install account, give us a call and we’ll send out the “care package” to go with the FiTech system.  How Much?  I’ll tell you Monday.  So go order it up, I’ll talk to you Monday.

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