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Can you use a 12v pump AND the stock lift pump together?

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1.7K views 3 replies 4 participants last post by  FLChevy  
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#1 ·
First of all i did need new batteries, now with that out of the way i can get back to the real problem, which is an air leak. Problem is that i no longer use the stock 6.2 filter AND i have the lift pump pulling the fuel through both the diesel and veggie filters - so High Sierra's tricks for finding air leaks won't work. The other thing is that the air leak is so small and is only on the diesel side, no problems on veggie.
For the moment what is helping is i had an extra 12v facet lift pump around so i put that before the new diesel filter, pushing the fuel through it and to the stock lift pump underneath - and like this there are no problems at all starting or running. But i have been told this could be dangerous if the stock lift pump starts to leak, then the 12v pump will push fuel through the leak into the engine. My lift pump is new so i am not too worried about this for now - but does anyone else think this would be a problem? I just need to do it this way until i find the leak.
thanks,
Paul
 
#2 ·
No, it shouldn't hurt anything.

There are still ways of finding air leaks if your set up won't allow use of the method in the sticky, it is just that they are slightly more complex. What you must do is isolate certain sections of the fuel system and test them individually. Take a section from one component to another, unhook both ends of it, plug one end and hook the air hose to the other end, look for leaks, and move on to the next section. Takes about five minutes per section. It may be helpful if the leak is small to blow all the fuel out of the lines before you pressurize them and use soapy water to find the leak.

Hope this helps! :)
 
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S
#3 ·
This may or may not work.. Find a shop (automobile shop) that has an evap emissions leak tester. Basically for gas vehicles that pressurizes the evap emissions piping/fuel tank system to find leaks as small as .040 in size or smaller. The evap tester will blow a regulated pressured smoke through the lines (you will have to drain the line somehow). The pressure is regulated to less than 1psi i believe so it may not matter if the leak only shows up under neg pressure. Its worth a try, and when you see the smoke you've found a leak.. Works great on vacuum leaks on the engine and such as well.. One of those invaluable tools.
 
#4 ·
On my diesel system, I use both an electric pump in the back and the mechanical lift pump.
On my 2nd tank veggie system, I use two electric pumps in series.
If you think you have an air leak, you could always put one way check valves on your fuel lines. I thought I had an air leak on my diesel system, so I put a check valve between the filter and IP and then moved it to just before the lift pump to eleminate fuel drain back if there was a leak. After extensive leak troubleshooting, I bought a new INJ pump and it cured my hard to start/no idle conditions. I left the check valve in though.
When I thought I had an air leak, steps I took to isolate:
http://www.dieselplace.com/forum/showthread.php?t=100491
 
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