Easy Bleed System for the 8V71 fuel System

[BlueScarecrow]

Had to replace my fuel pump about a year ago. It was a real hassle to try and bleed the system. I tried pressurizing the fuel tank to no avail. Then I thought, instead of trying to push the fuel, why not try and pull it. So I removed the 90 degree fitting on the fuel pump and replaced it with a "Tee" and installed a valve on the open end and reconnected the fuel line. I hooked up my AC vacuum pump through a clear hose through an in-out connection on a mason jar. I connected the clear hose to the new valve I had just installed and turned on the pump. Immediately, I had to turn off the pump. The fuel came so fast and furious that it scared me. It soared through the clear hose and filled up the jar in about 2 seconds. I closed the valve... disconnected the hose and started the bus, which came to life immediately and kept running. The idea worked like a charm. Should I ever need it again? The valve is still in place ready to be used again. I call it the "Easy Bleed System" Operators are standing by. LOL

[bevans6]

I have an in-line electric priming pump permanently installed in the line from the tank to the first fuel filter.  Flip a switch, you can listen as it pulls fuel from the tank, fills the first filter and primes the pump.  Works like a charm.  Does not restrict the flow of fuel when turned off.  Essentially the same idea as yours, pull fuel from the tank.

[chessie4905]

I installed an electric pump to do the same. No lines to disconnect or spilled fual mess.

[gumpy]

First time I trusted my fuel gauge and ran out, I happened to be across the street from a well known busnut in KY. He brought his vacuum pump over. We sucked on the fuel lines for an hour or two and could not get it to prime. We never did figure out why. It's such a simple concept, but it would not work on my bus, so I went and bought an electric pump. That worked like a charm and is now permanently installed in the system. I currently have a small leak somewhere and if I forget to turn off the fuel valve, it leaks back to the tank and I get to give the priming pump a workout. I had to replace the pump last year, and I'm not as happy with this one. Seems like it won't self prime if it goes dry. The last one worked great.

[TomC]

Sounds all well and good, but-you can blow the seals out on the engine fuel pump. When I lost a fuel line in Las Vegas, Don Fairchild drove up from Bakersfield (he wanted an excuse to go to Las Vegas anyway), made a new fuel line on the spot. Course by now we needed to bleed and prime everything. So how does a master Detroit mechanic like Don Fairchild prime the bus? First he opened the fuel lines one at a time and poured fuel into them allowing the air to escape. Then filled the fuel filters all the way. Try starting the engine, not yet. Don repeated this scenario of filling the fuel lines and refilling the fuel filters-which by my memory took about 4 repeat times. You think that after over 40 years of being a 2 stroke Detroit mechanic he'd have some sort of pump-whether it be vacuum or pressure? But no, he was the one that told me about possibly blowing the seals on the transfer pump.
So continue to do what you want with your pumps. I'm sticking with priming the non pump way.
When I change my fuel filters, I do them one at a time-and start the engine after each one. Never have lost a prime. Good Luck, TomC

[chessie4905]

Blowing the seals? An electric fuel pump doesn't make enough pressure and those seals aren't that fragile. I'd imagine that he has been doing it that way for so long, why change and it works. I like avoiding the mess when I'm in my tuxedo.😀

[Iceni John]

Maybe if you have an electric fuel pump for EFI engines you could possibly blow a seal somewhere, maybe?   That's why I bought a Facet-Purolator pump for carbureted engines  -  it makes only a few PSI, a lot less than EFI pumps, so no risk of blowing seals.   However, I'm skeptical about this whole seal-blowing thing at all.   My engine fuel pump produces about 65 PSI, so doesn't that means its own seals are able to withstand at least that much pressure?

John

[luvrbus]

Detroit has always sold electric and manual priming pumps for the Detroit I have a electric pump in a case from Detroit I bought in the 70's 

[Friday1]

I was a mechanic for a big city fire department for 30 years. It was common for fire trucks to run out at a big fire. Usually at 2 am and 10 degrees outside! My method for Detroit 2 strokes was: Put 10-15 gallons of fuel in the tank. Remove the pipe plug from the secondary filter and install a pipe nipple for 3/8 fuel line. Remove the rubber cap on the intake manifold from my gasoline powered service truck and connect the line. Start the service truck and watch for white smoke out the tailpipe. Disconnect the line. Reinstall the plug in the fuel filter and start the firetruck. If you are on the fireground, pouring diesel into filters or splashing it on the ground makes firemen really nervous.