Fuel Return
Update-
Tentative success!
Spent more time than I wanted to searching manuals and the Interweb and wading through mounds of irrelevant information, and came up with this.
In the '75 FSM, I have this:
So, the filter's vapor return is supposed to have a .060 orifice/restrictor. No sign of it in the Wix.
Found a couple old threads on the B and E body sites, seems even then there were issues with some filters coming through with oversized or no restrictors, QC was a problem or the filter lineups were being homogenized or whatever, and it was causing issues ranging from fuel delivery to lean idle misfires.
As a temporary test of what I think I found, I took a scrap of 1/4" hard line and drove a piece of lead shot into one end.
Then, using a drift punch inserted into each end of the line, I hammered the lead in place so it was solidly in place and wouldn't move.
Then I drilled the correct size orifice in the lead plug.
I installed my makeshift orifice in the return line coming off of the filter.
Fired up the engine- issue is gone.
I'll come up with something a little cleaner for a permanent fix, I'm thinking a 1/4" brass connector barb either soldered closed and drilled, or maybe tap it's inside diameter for an appropriately sized carb jet...
This way I won't have to worry about whether the filter I get has the proper restrictor or not- if it doesn't, I'm still good to go. If it does, then my added restrictor just becomes redundant and doesn't hurt anything.
Maybe this can help someone else who's about ready to throw a match in the gas tank and walk away.
Update-
Tentative success!
Spent more time than I wanted to searching manuals and the Interweb and wading through mounds of irrelevant information, and came up with this.
In the '75 FSM, I have this:
So, the filter's vapor return is supposed to have a .060 orifice/restrictor. No sign of it in the Wix.
Found a couple old threads on the B and E body sites, seems even then there were issues with some filters coming through with oversized or no restrictors, QC was a problem or the filter lineups were being homogenized or whatever, and it was causing issues ranging from fuel delivery to lean idle misfires.
As a temporary test of what I think I found, I took a scrap of 1/4" hard line and drove a piece of lead shot into one end.
Then, using a drift punch inserted into each end of the line, I hammered the lead in place so it was solidly in place and wouldn't move.
Then I drilled the correct size orifice in the lead plug.
I installed my makeshift orifice in the return line coming off of the filter.
Fired up the engine- issue is gone.
I'll come up with something a little cleaner for a permanent fix, I'm thinking a 1/4" brass connector barb either soldered closed and drilled, or maybe tap it's inside diameter for an appropriately sized carb jet...
This way I won't have to worry about whether the filter I get has the proper restrictor or not- if it doesn't, I'm still good to go. If it does, then my added restrictor just becomes redundant and doesn't hurt anything.
Maybe this can help someone else who's about ready to throw a match in the gas tank and walk away.