702_MJ Posted July 25, 2012 Share Posted July 25, 2012 I got an 86 MJ with a 4.0L, the fuel pump just crapped out and I'm assuming its the original by the looks of it and since my dad said he never changed it. Jeep has been running fine for years. BUT I was thinking if it would be a better idea to swap in a pump for a 91-92 4.0 instead of getting another 4cyl? I bought a pump today and tried to get it to match the original but no luck in fitment in the sending unit. But I also have this Bosch pump from another jeep sending unit...I'm assuming cherokee. But don't know the year, Part # 9580810019 on the side of the pump. I can get that one to work by just swapping the top holder from the other sending unit. Any thoughts or suggestions? Thanks Link to comment Share on other sites More sharing options...
ComancheKid45 Posted July 25, 2012 Share Posted July 25, 2012 Alright I'm confused here. the truck is currently a 2.5l 4 cylinder or a 4.0 6 cylinder? Anyway a 2.5 pump will bolt into a 4.0 sending unit (afaik) but it will NOT supply enough pressure for the engine to run properly. Link to comment Share on other sites More sharing options...
702_MJ Posted July 25, 2012 Author Share Posted July 25, 2012 its a 4.0L now. I ended up getting a pump for the 2.5L, specs said its rated at 65psi so the reg on the rail should bring it down to what the 4.0L needs. Funny thing is the jeep has ran fine the whole time with the original 2.5L pump. If I remember correctly when I tested the pressure at the rail years ago it was in the high 30s. So it should be fine I guess. Thanks anyway. Link to comment Share on other sites More sharing options...
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