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Hot Topic (More than 10 Replies) fuel pressure falls off... (Read 313 times)
 
MikeP
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Re: fuel pressure falls off...
Reply #15 - 08/16/19 at 07:16:00
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so ive been following/reading this post and my advice (complete novice but still can figure out crap Smiley )would be to start from the original setup of the jeep as in no fancy pumps and different carbs etc and that way you can rule out stuff by having the original setup and then re add items that you want to it and try to recreate your issue also there may be a likely chance your carb could be malfunctioning in some way whether its clogged or something not lifting or releasing etc
  

1950 willys cj3a
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aboyandhisdog
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Re: fuel pressure falls off...
Reply #16 - 08/16/19 at 16:32:45
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Okay, I think I discovered the issue.  On an M38 tank the pick up is in the top of the tank and goes down 73/4" to the bottom of the tank.  At the bottom of the pick up is an in line filter.  Last spring I changed this filter and just used what I had in the garage which was one of those plastic see through filters.  I liked that you can see what is inside it.  Trouble is it has a slightly tapered body so it doesn't secure squarely in the bracket that holds it in place. 

As is my practice to over tighten things, I secured it so it wouldn't shift.  Wouldn't you know, it had a small crack in it as a result and I believe it was probably sucking air in when the fuel would slosh around or especially when the level was low and on hills.  I'm guessing a little bit of air entering the line would be just enough for my pump to lose it's prime.  Anyway, everything is back together and filled with fuel and now to see if we have victory.

Thanks to you all for your ideas...fingers crossed...
  

Tom

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Bob W
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Re: fuel pressure falls off...
Reply #17 - 08/16/19 at 19:35:32
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athawk11 wrote on 08/10/19 at 22:17:14:
Here is a specific write up on a 3A cap.  I'm not sure how the M38 cap works in comparison.

http://www.cj3a.info/tech/gascap.html


Original M-38 fuel caps are unvented. Later M series caps have a valve inside so they can be changed between vented and unvented. Many M-38s ended up with later fuel caps on them. The venting on an M-38 fuel tank is in the assembly where the external vent line attaches to the tank. There are check valves in there very similar to what is inside and original CJ-3A fuel cap.
  

Bob W
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