| Re: [GMCnet] Jim Bounds interesting recent posts [message #325927 is a reply to message #325926] |
Fri, 10 November 2017 17:05  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
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Senior Member |
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FYI. I have been running a FiTech now for about 3K miles, and have had two issues, both of which were not really FiTech related. I post this only because if others run into the same symptoms, they will have a starting point on where to look.
Let me start with what I have. I am running a Cadillac 500 and have had it powered by a Qjet that was stock for the Cad engine, a Qjet that was altitude compensating, a Port EFI with EBL software, and now the FiTech. Best performance hands down is from the FiTech. My fuel system consists of 25gal fuel tanks. High pressure fuel pumps are in the tanks and controlled by a switch on the dashboard. Once activated by dash switch, fuel flows through a check valve located at each tank. Check valve keeps fuel from flowing into the nonactivated pump and into the other tank. Fuel continues to a "T" in the line allowing pressure to build at the Fuel Pressure Regulator. Once calibrated pressure is reached, excess fuel is dumped back into the front fuel tank, the "reserve" tank. Pressurized fuel then flows through another check valve which keeps fuel under pressure for "hot restart". Fuel then flows through an inline fuel filter and on to the "dead head" FiTech throttle body.
The system is designed this way with the pressure regulator located on the frame rail at the front tank to keep fuel from going to the engine, heated up by engine heat, and returned to the tank hot, thereby increasing the chances of vapor-lock.
Now that you know what I have, here are the two issues I delt with when I installed the FiTech. First issue...shortly after the install, the motor just suddenly started running VERY rich, like I mean AF ratios were in the low 11's, high 10's. Now that was averaging 10.8/1 FA. After looking at several things, decided to get a Fuel Pressure gauge and check to see that FP was at the spec'd 58lbs. So I let the engine run while I went looking for the gauge. When I got back I noticed that the FiTech TB was soaking wet with water, and ice cold to the touch. Also found the vacuum line going to the PCV valve was also cold and wet, as was the "T" in the line and hose that went to the vacuum canister. Disconnected the vacuum line going to the canister and plugged it. Instantly the engine smoothed out and AF went into the 14's. What I found was the Vapor separator (located in the left rear wheel well) had malfunctioned and was allowing a full fuel tank to bleed raw fuel through the canister and into the TB below the throttle plates. The change in physical state from liquid to vapor caused the cold TB and condensation on the TB. And most of all caused the excessively rich mixture as indicated by the AF readout. I now have replaced the Vapor separator and all is well. This issue, not the fault of the FiTech. Who KNEW!!
The second issue cropped up when I would stop for fuel after several hours traveling and a hot engine. The engine would not restart after refueling...not all of the time, just intermittently. When you turn the key on with the FItech, yours should hear a clicking sound coming from the TB. That is the software opening the throttle plates slightly and squirting some fuel into the intake manifold for a clean start. When I had the no start condition, I was not hearing the clicking and not seeing the throttles click briefly open. Apparently there is a sensor of some kind in the TB that sensed fuel presence. No fuel...no squirt. Somehow a bubble of air or maybe fuel vapor gets caught as a bubble in the TB and since it senses no fuel...no start. To start, I take a adjustable wrench, and crack open one of the fuel inlets to let the bubble out. Instant start and no issues until the no start happens again. I think this is a kind of vapor lock happening in the TB after a hot run. This may well be a result of not having a return line to the tank. When FP exceeds the 58lbs, there is no way to bleed off this pressure. So, I'm working on a solution to this..not sure what it will be.
Again, I post this so that it might help anyone experiencing these same symptoms and for people to take preventive measures. Hope this helps someone.
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
[Updated on: Wed, 15 November 2017 16:49] Report message to a moderator |
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