| Fitech Fail [message #357092] |
Wed, 22 July 2020 19:54  |
traveler1980
Messages: 24
Registered: September 2019
Location: Gettysburg, PA
Karma: 0
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Junior Member |
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Ok GMC brain trust. I need your opinion on an issue I’m facing with Fitech EFI. One of my worst nightmares came true earlier this week when my coach broke down in heavy traffic. The highway patrol had to tow me off the road while escorted by state police. It made an existing backup even worse. I ended up getting a Landoll tow (thank you AAA) to Ken Frey’s shop up in Quakertown.
My coach has a very custom EFI setup. There are two low pressure electric pumps and a relay under the coach (inaccessible without a jack) near the tanks and a Fuel Command Center up front that delivers fuel at high pressure to the throttle body. I think this Command Center component failed because the low pressure gauge on the FCC has a reading with the ignition turned on, but the high pressure gauge reads 0 when in the on position and when cranking the engine. I have 12v to the command center (Jim Bounds walked me thru some triage), but it looks like the pump inside the Command Center may have died.
So, my question is what to do about this. The EFI has several points of failure that cannot be easily fixed on the side of the road. Here are the options as I see them -
1- Buy a new Fuel Command Center (FCC2 or Fitech Force Fuel) and continue with the current configuration. This may be the quickest and most cost effective fix, but I could very easily end up on the side of the road again.
2- Modify the EFI configuration and replace the command center and low pressure pumps with 2 high pressure pumps that route thru the throttle body and return to the fuel fill tube. I think this is similar to what Jim does with his installs. This still leaves several points of failure - the throttle body itself and the pumps/relays.
3- Return the fuel system to stock mechanical configuration (QJet) and install an electric pump for use against vapor lock and to prime the system before starting. I don’t have any of the original parts, but it looks like Jim K has them. This is the most expensive option.
Thanks in advance for the feedback!
Jamie Sharp
South Central PA (Gettysburg area)
'76 Palm Beach, AKA "Grumble"
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| Re: Fitech Fail [message #357095 is a reply to message #357092] |
Wed, 22 July 2020 20:52  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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I do not have FiTech's command center. I have high pressure pumps located in the tanks, controlled by the fuel tank selection switch on the dash. All steel lines from the tank forward to the body behind the FiTech. (under the hatch) Small section of rubber hose from the body to the FiTech. Fuel is pumped out of tank and goes through a check valve, then to a "T". Check valves keep fuel from back flowing through the pump in the non operational tank pump. Fuel then goes to a "T" on the drivers side frame rail at the L front of the forward tank. One side of the "T" goes to the FiTech, the other side goes to a fuel pressure regulator located on the crossmember in front of the forward tank. Regulated fuel is then returned to the forward (Aux Tank) through the drain plug in that tank. That return in the tank is bent at a right angle so return fuel flows along the bottom of the tank, preventing a aerating geyser effect. Fuel going to the FiTech is regulated at 58psi. I had to put another return off of the return side of the Fitech to the filler pipe to bleed off excessive pressure when I shut down the engine for refueling. If you don't do this, I found that the pressure buildup in the FiTech from heat is enough pressure to hold the injectors shut so the engine will not start until a full cool down relieves the pressure. Have had this for two years now with no issues. JWID
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
[Updated on: Wed, 22 July 2020 21:15] Report message to a moderator |
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| Re: Fitech Fail [message #357097 is a reply to message #357095] |
Thu, 23 July 2020 01:20 |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
Karma: 14
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Senior Member |
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Redundancy is a wonderful thing. Reliability is a function of time to failure and time to repair. With redundant pumps (and filters) time to repair is less than a second if you have a changeover switch wired in. For the low pressure side, you're covered.
If you were worried about the relay, perhaps bypass switches at the pumps for redundancy.
For the high pressure side, here is a surge tank with fittings for two pumps...
http://rad-industries.com/pn-6-000-25st-dw-universal-2-5l-modular-surge-tank-fits-1-or-2-dw250il-fuel-pumps-pn-9-250/
Then carry a second FiTech throttle body.
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid November 2015.
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| Re: Fitech Fail [message #357101 is a reply to message #357097] |
Thu, 23 July 2020 06:19 |
traveler1980
Messages: 24
Registered: September 2019
Location: Gettysburg, PA
Karma: 0
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Junior Member |
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Yes, redundancy is exactly what I'm looking for. I want to minimize the risk of being on the side of the road with no options.
The two low pressure fuel pumps in the back are activated by the tank selector, so only 1 is active at any time.
For the relay, I may just have to live with the fact that the coach needs to go to a shop to replace it in the event that it fails. It would be a quick fix once the coach is off the ground a bit.
For Command Center/Force Fuel and throttle body redundancy, the only thing I can do is keep spares in the coach. $$$ proposition, but it would sure beat the hassle I went through to arrange a tow on a Landoll from the Eastern Shore of MD. AAA is worth its weight in gold. I don't want to see that bill.
Jamie Sharp
South Central PA (Gettysburg area)
'76 Palm Beach, AKA "Grumble"
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| Re: [GMCnet] Fitech Fail [message #357111 is a reply to message #357092] |
Thu, 23 July 2020 09:21 |
Margie Van Winkle
Messages: 51
Registered: March 2012
Karma: 0
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Option # 4. Eleminate FCC and go with two high pressure pumps near tanks,
replacing low pressure pumps. Would require plumbing return from TB to
fuel fill tube. ( accessible from hatch) and high pressure fuel lines from
pumps to TB
On Wed, Jul 22, 2020, 7:54 PM Jamie Sharp via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Ok GMC brain trust. I need your opinion on an issue I’m facing with
> Fitech EFI. One of my worst nightmares came true earlier this week when my
> coach broke down in heavy traffic. The highway patrol had to tow me off
> the road while escorted by state police. It made an existing backup even
> worse. I ended up getting a Landoll tow (thank you AAA) to Ken Frey’s
> shop up in Quakertown.
>
> My coach has a very custom EFI setup. There are two low pressure electric
> pumps and a relay under the coach (inaccessible without a jack) near the
> tanks and a Fuel Command Center up front that delivers fuel at high
> pressure to the throttle body. I think this Command Center component failed
> because the low pressure gauge on the FCC has a reading with the ignition
> turned on, but the high pressure gauge reads 0 when in the on position and
> when cranking the engine. I have 12v to the command center (Jim Bounds
> walked me thru some triage), but it looks like the pump inside the Command
> Center may have died.
>
> So, my question is what to do about this. The EFI has several points of
> failure that cannot be easily fixed on the side of the road. Here are the
> options as I see them -
>
> 1- Buy a new Fuel Command Center (FCC2 or Fitech Force Fuel) and continue
> with the current configuration. This may be the quickest and most cost
> effective fix, but I could very easily end up on the side of the road
> again.
>
> 2- Modify the EFI configuration and replace the command center and low
> pressure pumps with 2 high pressure pumps that route thru the throttle body
> and
> return to the fuel fill tube. I think this is similar to what Jim does
> with his installs. This still leaves several points of failure - the
> throttle
> body itself and the pumps/relays.
>
> 3- Return the fuel system to stock mechanical configuration (QJet) and
> install an electric pump for use against vapor lock and to prime the system
> before starting. I don’t have any of the original parts, but it looks
> like Jim K has them. This is the most expensive option.
>
> Thanks in advance for the feedback!
> --
> Jamie Sharp
> South Central PA (Gettysburg area)
> '76 Palm Beach, AKA "Grumble"
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] Fitech Fail [message #357122 is a reply to message #357111] |
Thu, 23 July 2020 12:05 |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
Karma: 14
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Senior Member |
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+1 for #4 if the 'Force Feed' or surge tank is not in the picture. A surge tank is supposed to help when a pickup in the tank gets uncovered. I haven't been running EFI that long.. is that a real problem with stock tanks?
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid November 2015.
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| Re: [GMCnet] Fitech Fail [message #357124 is a reply to message #357122] |
Thu, 23 July 2020 12:58 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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I can see it being a problem, if you run your tanks near empty. it is annoying not running the tanks down, but I think that is best practice. if that is a concern, then I can see maybe a surge tank situation, but that adds more parts and failure prone things, plus somewhere else for fuel to leak and cause a fire.
it is annoying, but I am only utilizing 2/3 of my fuel capacity. this last trip, the most I pumped in was 35 gallons and that was stressing me out being that low. I did not experience any fuel delivery problems over the 3100 miles. but when gas is down near 1/4 on the gauges, the needles move around alot depending on angle of the coach(seen one tank move to near empty while sitting nose up on an interstate exit)
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] Fitech Fail [message #357128 is a reply to message #357122] |
Thu, 23 July 2020 15:06 |
traveler1980
Messages: 24
Registered: September 2019
Location: Gettysburg, PA
Karma: 0
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Junior Member |
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Bill Van Vlack wrote on Thu, 23 July 2020 12:05+1 for #4 if the 'Force Feed' or surge tank is not in the picture. A surge tank is supposed to help when a pickup in the tank gets uncovered. I haven't been running EFI that long.. is that a real problem with stock tanks?
Yep, this was my option #2. It would eliminate the Command Center/Force Fuel, so one less potential component failure to worry about. A vent line is already plumbed from the old 1st gen Fuel Command Center to the fuel fill neck, but I'm not sure if it would need to be modified to handle the volume of fuel returned from the throttle body. Incidentally, the Force Fuel/FCC2 also requires a return since fuel is now allowed to flow through the sump and back to the tanks, so I will be looking at this return regardless. This wasn't the case in the FCC1 (it was supposed to be only a vent) and I understand caused many problems with leaking gas and pressure buildup in the FCC.
Jamie Sharp
South Central PA (Gettysburg area)
'76 Palm Beach, AKA "Grumble"
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