FiTech Fuel Injection

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Bigtime53

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Well I got my A/C all lined out now after getting all of the extra oil out of the system but now I have a new problem. I have a 77 GMC with a 350 and I bought the FiTech fuel injection for it. I put it on last fall and I do not drive this truck much since the total rebuild of it but have been some now to get the a/c working properly. The truck is vapor locking and it really ticks me off. I followed the instructions to the letter and kept all of the fuel lines away from where there should not be a problem with heat. The only thing that is close to any heat is the command center which is on the drivers side of the radiator and not right up against it. My question is has anyone else have one of the systems and are you having this problem? What should I do to stop this?
 

4WDKC

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Are you sure its vapor lock and not a vacuum on the tank issue?
 

crazy4offroad

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Does the command center need a return line? If so dont use your vent line as a return. You may have to get a newer float assembly that has fuel, return and vent lines on the top. If it doesn't need a return line it sounds like your vent line is plugged, crimped or otherwise not working properly.
 

Bigtime53

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Are you sure its vapor lock and not a vacuum on the tank issue?
Well I don't think that is the problem. I have put close to 200 miles on this truck since I installed this setup and have not had a problem until it has been getting close to 100 everyday and then this started happening.
 

Bigtime53

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Does the command center need a return line? If so dont use your vent line as a return. You may have to get a newer float assembly that has fuel, return and vent lines on the top. If it doesn't need a return line it sounds like your vent line is plugged, crimped or otherwise not working properly.

I called fitech and they told me to use my orginal return line and that is what I have done. A friend of mine bought the same setup for his truck and his is vapor locking also. We both put the command center in the same location and I am wondering if it is getting to hot being by the radiator. Both trucks did not have a problem until it has got hot here and started running the a/c. I am going to put some insulation around it [command center] and try that and if that does not work then I will have to do something else.
 

crazy4offroad

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I dont think you're the first to complain of this with the command center. I think it runs out of gas in the little tank and the pump sucks air. Likely why many go with the in-tank fuel pump option.
 

1987 GMC Jimmy

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I’ve used this example before, but when GM kept getting complaint after complaint on P30 based motorhomes vapor locking, they put a fuel pump in the tank AND kept the mechanical one, which cured it. Of course, those had to have an external regulator on the frame rail, and yours is internally regulated. I’d consider doing an ‘87 tank or tanks depending on your setup, an ‘87 sender with that Walbro 255 (?) pump, and a standard five pin relay to control the pump properly. I understand that this is not a simple solution, and if this is not 100% the problem, you would have wasted your time and money, but this is the right way to go about any fuel delivery setup that’s not carbureted.
 

77 K20

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Kinda an apples or oranges thing- but I have something similar. I have the Edelbrock E-street EFI and it has the fuel sump kit also.

It is setup with the old mechanical fuel pump on the engine and now all it does if feed/fill up the Edelbrock fuel sump which is mounted on the passenger side of the radiator (where the old radiator overflow tank used to be). I've never had an issue with vapor lock and have run it at 90 degree days crawling up the side of a mountain to a fire lookout.

Do you still run the mechanical fuel pump also?
 

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can you route cool air to the system as a test?
 

Bigtime53

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Ok i googled fitech vapor locking and watched a video of how to fix the problem. Long story short seems like the pump that is in the command center gets the fuel to hot and the return line only sends vapor back to the fuel tank. They say to take the float out and where the filter is inside of the command center for the return line take it out and that way fuel will circulate and keep it cool and stop the vapor lock. That is what I will do and so far they say it fixes ti.
 

bluex

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Ok i googled fitech vapor locking and watched a video of how to fix the problem. Long story short seems like the pump that is in the command center gets the fuel to hot and the return line only sends vapor back to the fuel tank. They say to take the float out and where the filter is inside of the command center for the return line take it out and that way fuel will circulate and keep it cool and stop the vapor lock. That is what I will do and so far they say it fixes ti.

Glad you found that, I was just about to post that's what I've seen a lot of people with the command center do.
 

Brett77

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I have been told there are problems with the command center. Fitech rep at a show shared that info. Other than that how does the FI-Tech work?
 

77 K20

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Yes, I'm interested to know how it works also. With the Edelbrock system it like to surge (idle starts going up and down by 300-400 RPM) from time to time. But won't do it when it is in gear and idling.

Getting annoying- Especially when I'm idling using my air compressor to air up my tires after an off road trip.
 

Bigtime53

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Mine ran great all winter when I did drive it only to start having this vapor locking problem. I have been happy with it so far.
 

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