GMCforum
For enthusiast of the Classic GMC Motorhome built from 1973 to 1978. A web-based mirror of the GMCnet mailing list.

Home » Public Forums » GMCnet » [GMCnet] FITECH Mystery solved
[GMCnet] FITECH Mystery solved [message #328471] Sun, 21 January 2018 18:51 Go to next message
glwgmc is currently offline  glwgmc   United States
Messages: 1014
Registered: June 2004
Karma: 10
Senior Member
Some of you will remember that the new owners of our Clasco experienced a no start issue following refueling south of Denver last summer on their way back to Alaska. They reverted to the carb and made the rest of the trip. At the time there was much speculation on this forum as to the root cause issue. Many speculated that it might have been too much heat for the throttle body mounted ECM, others that the high pressure fuel,pump inside the fuel command center might be bad, etc.

We are in Quartzite, AZ for the day and it turns out the new owners are as well and found us. It turns out the issue was an intermittent failure of a connection inside the main factory wire harness plug. He said he called the factory when they got back to AK and asked the FITECH guys what the problem might be with the throttle body. They had him reinstall the FITECH throttle body and it fired right up so the mystery remained. Later he said they experienced another failure after fueling. That time he rooted around under the hood and while moving things around heard a click. The FITECH fired right up again. He then could replicate the issue by squeezing that connector, one wire crimp was faulty inside the plug. No issues since.

Who would ever have thought a factory crimp could fail intermittently inside a factory plug.........

Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com


_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org



Jerry & Sharon Work
78 Royale
Kerby, OR
Re: [GMCnet] FITECH Mystery solved [message #328477 is a reply to message #328471] Sun, 21 January 2018 21:01 Go to previous messageGo to next message
Larry is currently offline  Larry   United States
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
Senior Member
glwgmc wrote on Sun, 21 January 2018 18:51
Some of you will remember that the new owners of our Clasco experienced a no start issue following refueling south of Denver last summer on their way back to Alaska. They reverted to the carb and made the rest of the trip. At the time there was much speculation on this forum as to the root cause issue. Many speculated that it might have been too much heat for the throttle body mounted ECM, others that the high pressure fuel,pump inside the fuel command center might be bad, etc.

We are in Quartzite, AZ for the day and it turns out the new owners are as well and found us. It turns out the issue was an intermittent failure of a connection inside the main factory wire harness plug. He said he called the factory when they got back to AK and asked the FITECH guys what the problem might be with the throttle body. They had him reinstall the FITECH throttle body and it fired right up so the mystery remained. Later he said they experienced another failure after fueling. That time he rooted around under the hood and while moving things around heard a click. The FITECH fired right up again. He then could replicate the issue by squeezing that connector, one wire crimp was faulty inside the plug. No issues since.

Who would ever have thought a factory crimp could fail intermittently inside a factory plug.........

Jerry Work




With my FiTech, I have high pressure pumps in the tanks feeding a pressure regulator and dead heading to the Fitech. I was having trouble with no start after a hot run stopping for fuel. Hooked up a fuel pressure gauge and found that on shut off, the pressure burried the needle on the gauge. If I released the pressure, I got immediate start. I'm speculating that the pressure got so high that it held the injectors closed for a no start. Releasing the pressure allows for the pump to pressurize at normal 58lbs and allows a normal start. Currently thinking about adding another Fuel pressure regulator at the output side of the FiTech to bleed pressure in excess of 70lbs or so, back to the fuel filler pipe. I did this when I had the same trouble with my EBL system. Eliminated the no start issue. Just what I think.



Larry Smile
78 Royale w/500 Caddy
Menomonie, WI.
Re: [GMCnet] FITECH Mystery solved [message #328512 is a reply to message #328477] Mon, 22 January 2018 18:41 Go to previous messageGo to next message
Justin Brady is currently offline  Justin Brady   United States
Messages: 769
Registered: April 2015
Location: Bell Buckle, TN
Karma: 11
Senior Member
Good to know Jerry thanks for the update.

Larry, why would the pressure build past the regulator? The fitech already has a built in regulator, and you've added another. Curious where the spike in pressure is coming from. Boiling fuel from heat soak?


Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455
Re: [GMCnet] FITECH Mystery solved [message #328539 is a reply to message #328512] Tue, 23 January 2018 10:40 Go to previous message
Larry is currently offline  Larry   United States
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
Senior Member
SONICJK wrote on Mon, 22 January 2018 18:41
Good to know Jerry thanks for the update.

Larry, why would the pressure build past the regulator? The fitech already has a built in regulator, and you've added another. Curious where the spike in pressure is coming from. Boiling fuel from heat soak?



I have not added another regulator YET. Just considering putting another in because it worked so good with the MPI system I had. Yes, the Fitech has a built in regulator. It works with the Fuel Command Center, regulating and returning fuel to that FCC. My Fitech is dead headed. The regulator is located back at the tank and regulates and returns fuel before it goes to the TB. Boiling fuel from a heat soak builds pressure and since the TB is dead headed, (no return line from the TB) and the engine is not running to relieve the head soak pressure, the pressure has no where to go, so builds to a point that it holds the injector pintles closed, and no start for lack of fuel. Cracking open the plug on the TB relieves the pressure and allows the pintles to open and engine to start. By putting another FPR on the output side of the TB set to 15 or 20lbs higher than the running pressure, it allow s the engine to run normally. When heat soak occurs and the pressure gets to 70lbs or so, the return regulator bleeds off excess pressure allowing the pintles to open and engine to start. It worked on my old system, should work on this. I've talked to tech support at FiTech and they concur. Just my theory on what's happening here.


Larry Smile
78 Royale w/500 Caddy
Menomonie, WI.
Previous Topic: Re: [GMCnet] Ken. Can we have new windshields installed in Amana Iowa in September.
Next Topic: Need plumbing advice, please?
Goto Forum:
  


Current Time: Thu Mar 28 21:24:57 CDT 2024

Total time taken to generate the page: 0.01244 seconds