1980 J25RCS hose replacement

[megacaver]

I am replacing old fuel hoses and started with the 2 large hoses from the line in to the pump and back to the carb using Shields A1 fuel hose. However there are also two smaller hoses, one leading from right above the fuel pump back up to the front of the crankcase and another above manifold back to the crankcase. My manual lists them as "92. By-pass cover to manifold hose" and "27. Manifold to crankcase hose". Are these vent hoses? What is the purpose of these? The factory service manual doesn't say. Just wondering if I should replace them along with the others if they see any contact with fuel.

One additional odd thing. The fittings for the hose from the fuel pump out, the carb fitting, and the line in fitting all require a ID 5/16 hose, but the fitting on the fuel pump in (circular one with the screen filter) is larger appearing to be ID 3/8. Is there a reason they would be different, it doesn't make sense to me why they would be. I can make it into the 5/16s but its much tighter. I have had this engine most of its life and am pretty sure no one has ever messed with the fuel pump.

Thanks All

 

[jasper60103]

Re: 1980 J25RCS hose replacement

I can't answer your other questions, but I recently replaced my fuel lines on my '81 j25hp. I don't recall the fuel pump/filter fittings being different sizes. I used 5/16" ID for both and the hoses went on easy and fit fine.

 

[ezeke]

Re: 1980 J25RCS hose replacement

Both hoses (92 & 27) were cut from 0321610, a 1/8" ID hose. That hose has been superseded by part # 0772570, ordered by the foot.

 

[megacaver]

Re: 1980 J25RCS hose replacement

So the ID size of the hoses Bypass/Crankcase and Manifold/Crankcase are 1/8 ID? That helps, but are the fuel related? If so i would think they need to be Type A1. The question I had above on size related to the fuel pump inlet cover fitting to hose that appears to be bigger then ID 5/16 (others all are 5/16).

 

[ezeke]

Re: 1980 J25RCS hose replacement

The cap on the original fuel pump (0385781) was supposed to be part #0322759, which was supposed to fit the 5/16 hose. That cap is superseded by 0433518.