502 MPI Vapor Lock Issues
#12
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Although the pump kits that Merc sells do solve the problem, they are $400 each. If you return the fuel to the tank, it will eliminate your problem for about $25 in parts per engine. It will also help to keep the fuel cooler when running, since the tank is acting as a cooler. It's pretty easy to do. That's what I prefer to do. Just my opinion.
Eddie
Eddie
#13
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^^^ Quick question. Run the return line from the "return" on the VST back to the tank. (plugging hole on the VST)
Or will this work?? Run a line form the vent on the VST back to the tank, with the removal of the diaphragm and plugging the nipple on the intake manifold...
Or will this work?? Run a line form the vent on the VST back to the tank, with the removal of the diaphragm and plugging the nipple on the intake manifold...
#14
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Join Date: Dec 2001
Location: Rapid City SD
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Run the return line from the "return" on the VST back to the tank. (plugging hole on the VST)
The return line comes from the fuel rail, so you need an inverted female flare to screw the line into, and route hose to fuel tank. I think I had to order it and probably got it from Summit.
The return line comes from the fuel rail, so you need an inverted female flare to screw the line into, and route hose to fuel tank. I think I had to order it and probably got it from Summit.
#15
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Or you can just cut the hose end off of the return line and use a hose mender (hose barb to hose barb) and extend the line so it reaches to the tank. You can just clamp the hose since there is very little pressure.
Eddie
Eddie
#16
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Thank you guys for the info!! Ill start looking for the parts tonight to redo my 502. Could I just put a "T" in the gas tank vent tube and tie the return line into it or dose it need it's own fitting into the tank?
Jsut thinking out loud......... Wouldn't running the vent line on the VST back to the gas tank render the same result with the diaphragm removed? Or is the vent to high on the VST?
Jsut thinking out loud......... Wouldn't running the vent line on the VST back to the gas tank render the same result with the diaphragm removed? Or is the vent to high on the VST?
Last edited by 92nsx; 07-27-2012 at 02:01 PM.
#17
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Well the vent tube on the VST goes to the intake/throttle body. The diaphram shuts off the ventalation so gas fumes don't go into the bilge, so I would not probably mess with that, but that might work also. Now that I think about it, I think there is a vacumm line that opens the diaphram and then a vent tube to the throttle body. Someone makes a connection that splices into the gas fill tube just for EFI return. http://www.cpperformance.com/c-500-f...s-returns.aspx