This post is actually a compilation of some emails I wrote to a couple of other GMCers while the process was going on. Sometimes things are repeated but I did try to update a subject each time I mentioned [updates in brackets like these] it but it might still seem a little scattered. Sorry.
When we went to the GMCSJ rally at Tombstone we got the opportunity to talk to Jerry Work and see his FiTech EFI system. I took photos of his Fuel Command Center mounted on the passenger side of the radiator and then shot some photos of the throttle body with views of linkage and hoses. Those photos and one of the underside of my engine hatch are just below:
The following are separate sections, divided by day, that describe my progress.
I ordered my FiTech system soon after the Tombstone rally but the Fuel Command Center was backordered until March 15th. They did send it on that day.
On March 23rd I wrote the following:
I got the Fuel Command Center installed right where Jerry installed his. I used 1″ aluminum angle to attach the FiTech-supplied brackets to the radiator housing instead of the white plastic panel in the photo of Jerry’s. But, installing the Command Center is as far as I got before I had to install 130 feet of baseboard in a rental house and the visiting grandkids arrived. The kids just left this morning. I have to finish the baseboards in the rest of the house – another 150 – 200 feet – this week while hosting Carol’s Mom’s 90th birthday party on Thursday. After those things are done I hope to install the EFI and then drive it to the Marana Bluegrass event on 4/8-4/10 [didn’t make that date]. If I don’t make that I will have to fit it in with my son’s visit a few days later. I definitely will have it in so we can drive to the GMCWS rally in Temecula.
The instructions look pretty easy except for drilling a hole in the exhaust pipe although Jerry said that was a piece of cake [it was. Just jacked up the right front side a couple of inches and removed the fender liner]. The instructions say that you cannot run the engine with the O2 sensor installed and no EFI working – it will damage the sensor. I confirmed that with the FiTech people. That means, if I want to be able to drive it, I have to be sure everything else is ready before cutting the hole or I will have to install a plug instead of the sensor if still using the carb.
On April 3rd I wrote:
I have the fuel “Command Center” installed and have the vent and fuel supply hoses installed on it and in place on top of the engine. I have run the wires from the six-wire harness to the places they go but they are not soldered in yet. I have run the display cable up under the dash but not in place – they supply a suction-cup stand to hold the display but I don’t know if the cable is long enough to use it. [I since moved the cable so it enters in the center of the dash and it is long enough for that].
I removed the carb and tried fitting the TBI onto the manifold but it turns out the general purpose throttle connection lever sticks down below the level of the manifold. Jerry Work said he cut it off but didn’t say how – my only option is a grinder. I sent a message to FiTech asking for advice if any. [Their advice was to use a spacer – I cut it with a grinder].
I also will be needing an adapter plate of some kind. They suggest a Summit Racing (SUM-G1420) which is only 1/8″ thick while Jerry Work used a 1/2″ thick adapter he bought at NAPA and then had to modify his hatch to accommodate it. I had hoped to get away with just the thick gasket I had under the carb but now I will be ordering the adapter after I verify that 1/8″ will work. [It turns out that I needed 3 adapters stacked with 8 gaskets – 2 from FiTech and 6 from Summit].
Some hardware for connecting the throttle and cruise control cables is also needed. Jerry got his at NAPA so Merle’s should have it too [They did not but I did find them on Amazon]. The numbers Jerry gave me for this are Manifold to throttle body adapter – NAPA 735-4930 [this adapter was too tall for my coach], Carb linkage bushing 1/2 to 1/4” – Mr. Gasket 6026 from NAPA, Carb linkage 1/4” stud kit (bolts through bushing on throttle body linkage to accept stock GMC throttle cable) – Holley 20-38 from NAPA. [I used the stud kit but it was too short to use both sides of the linkage bushing so I just used the back of it with the stud.]
I put the carb back on and now plan to get the TBI installed the week of the 11th so I can drive it a little before going to the GMCWS rally three weeks later. [Didn’t make that date either].
On April 13th I wrote:
I finally got back to working on the FiTech installation yesterday (Tuesday) and immediately found out that the FiTech guy who told me that I didn’t need an adapter plate was wrong – it was not even close. I started calling around and found one at Autozone but it was too thick – with gaskets it would be almost an inch thick. I called Don’s Hot Rod and they had one that was the same thickness. I had the NAPA number from Jerry Work for the one he bought so I called them and they said they could have it by 8:00am today so I said go.
When I picked it up I thought it looked a little thick but drove home anyway. I tried it on the coach – Jerry used it so it must work – but it ended up being about 3/4″ thick. It is actually closer to 3/4″ thick than it is to 1/2″. I put it back in the package and ordered 3 of the Summit Racing 1/8″ spacers that FiTech says work. My measurement of the space required for the butterflies on the TB is 3/8″ so three of them should work. I did think of making my own but, other than wood, I don’t know what material I could use. [It turns out that 3 of the Summit adapters was not quite enough but the addition of 4 extra gaskets that are included with the adapter plates and FiTech kit did the trick.]
I drilled a hole in my exhaust pipe for the O2 sensor yesterday and found that the clamps that came with the unit were way too big for my 2 1/2″ exhaust – they were too big for any normal exhaust pipe so I had to buy two more at Ace HW.
I have everything connected and even have the Fuel Command Center primed and ready. I even used my router to give the air cleaner another 1/2″ of space. As soon as I get the spacer thing fixed I will be able to start it up. My son is coming for a visit this weekend – arriving Friday – so I will not get to work on it again until Tuesday. Stay tuned.
On April 20th I wrote:
I ordered 3 of the Summit Racing adapter plates (SUM-G1420) that are 1/8″ thick each. I installed all three of them with one supplied gasket between each metal-to-metal joint and it was not quite enough so I added 4 extra gaskets (2 from adapter plates and two from FiTech) at the top and that did it. That did raise the air cleaner enough that I had to route out the forward portion of the engine hatch by 1/2″ deep and had to give it an extra inch forward. I bought 4 – 5/16-18 1 3/4″ bolts and torqued them to the 16 pounds specified.
On Saturday I installed the throttle body and connected all of the plugs and it started right up and ran nice and smooth. My son was visiting so I decided that was enough “fun” for the day and I shut if off. I locked up and turned the engine battery off and then thought about the installation instructions saying that constant battery power is required. That is so that the unit will have time to record its self-learning data. I turned it back on and went inside to look at the controller and, sure enough, it had been reset. I also noticed that the controller was on without the ignition key being on. I was informed by FiTech that this is normal and the alternative is to disconnect the controller connections (easy to do).
Besides starting the engine I was really anxious to see how the air cleaner and hatch cover fit. I immediately found that installing the fuel inlet at the rear left corner was a mistake – the air cleaner was hitting the inlet fitting. It turns out that the air cleaner has more room at the left front with the inlet pointing just aft of the alternator as usual and that fits fine. I left fixing the air cleaner for Tuesday when my son was leaving.
On Tuesday morning, after my son left, I finished making connections (the fuel vapor cannister hose is 1/4″ and the vacuum inlet is 3/8″) and moving the fuel inlet fitting. Now I installed the air cleaner – the FiTech unit requires a 5/16″ stud to hold the air cleaner and the top of my air cleaner had to be drilled out a little to allow it to fit. I just used a hex nut on the top, hand tightened. This is when I found out the the air cleaner is forward of the center of the recess in the hatch by about 1/2″. I had to enlarge that area and it now fits – I had to push down a little but I think that is due to the new weather stripping I installed at the same time. If necessary, I have a plan to add more space without a big lump in the middle of the floor. I hope I don’t have to use it.
Another problem I have identified is my fuel pump. I have only an electric pump installed just in front of the tank selector valve. A while ago, my mechanic noticed that the pump would not always turn on when the engine was started. I diagnosed it to be caused by the oil pressure switch which is there to shut the pump off if there is no oil pressure – i.e. the engine is not running. Gunning the engine a little just after starting was required. I noticed on the first start on Saturday that the electric pump was not running – the Command Center low pressure gauge was at zero. Given that the Command Center is holding somewhere between 1 and 2 quarts of fuel, a failed electric pump would take a while to notice. I bought a new switch and it seems to be working better.
I took it for a test drive today and I am impressed. When I first started driving there was a pretty familiar hesitation when going from no throttle to partial throttle but by the time I drove the two miles home via some stops and turns it was almost gone – self learning in action I assume. I then drove it to the NAPA store in Marana (to return the carburetor adaptor that Jerry Work used – too thick for my coach) and by the time I got back it was running great. Also, I will have to watch my speed on the highway because it wants to go faster than it used to – I love it. Now if my “vapors” problem is gone it will be worth the effort and money.
I had to buy 4 new bolts to bolt the TBI unit down to the manifold. I think they need to be 1 1/2″.
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