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Self Bleeding Diesel Fuel System

4532 Views 6 Replies 4 Participants Last post by  rdavisinva
Have had lots more questions about diesel fuel line routing.
Here are a few pictures of an Isuzu 4JB1-T setup, but the same for any diesel install.

Routing = tank, sedimenter, 12V fuel pump, engine lift pump, Fuel Filter, IP, return line back to tank.
Pump wiring from 12V relay =
86 - ignition circuit - white (+) when key is on
85 - ground (-)
30 - Positive (+) from battery (usually taken off main starter lead)
87 - (+) when key is on

No need to ever worry about bleeding the system.
If you run out of fuel or you change the filter, simply switch on the key, wait a few minutes, start the engine, and drive away.

If you get a bad batch of fuel, note the drain screw on the sedimenter.
Drain as many times as necessary until you purge all the smeckley and then drive away.


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Any reason not to put the 12v fuel pump closer to the lift pump to shorten the electrical runs?
Robert - any particular fuel line you like to use?

I am thinking of running the fuel line and return down the left hand side of the new build - IP, pump, filter of the OM617 is on that side. And I think I can keep the sedimenter on the outside of the left hand frame rail for easy viewing.
Think I saw another thread where you stated to not use the included filter on the 12v pump. I see in your picture there is a fitting there instead? What fitting do you use in place of the 12v pump pre-filter?
It depends on the pump, but if you're referring to the E8012S Universal Electric Fuel Pump that I started using after this thread was posted, there is a prefilter circled in red included with the pump that you simply leave off. Note the 2 pump fittings circled in green.
The reason for leaving the pump pre-filter off is because if it clogs, you don't know where to look to clear the clog and you don't need a 12V pump pre-filter with a sedimenter and proper fuel filter.
click to enlarge

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You'll need a 1/8" NPT to 5/16" (8mm) barb like the one in the post 5 picture.
Be careful, those plastic pump housings are fragile.
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