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Is there a way to purge air from my 6.2 diesel by myself without someone turning the engine over?

On my Cummins I popped the top off the relay in the fuse box for the starter and would manually operate the relay.
 
There are several ways that could be done..

Some have used low pressure compressed air introduced into the fuel tank by a modified gas cap (one that has had a tire valve stem added to it and the pressure/vacuum guts removed),or some other method..but you risk creating a leak in the tank if its weak in a spot with rust ,it may not withstand the 15 psi or so needed to push the fuel all the way thru the system,while you crank it over..

Some use a gas soaked rag help over the intake to get it to start and run long enough,to get it to prime itself..or use starting fluid..which on a 6.2 is equal to using a stick of TNT if not done a certain way..overall starting fluid is a bad idea,you also should have the engine whipping over full tilt with the glow plugs deactivated before spraying,or it'll just bind up and possibly bend a rod,crack a piston..

It's best to have a helper to crank it over,or you can rig up a remote starter button to the purple wire on the starter solenoid and battery positive to crank it yourself from under the hood..(remember to turn on the ignition to "run" too!)..

I've seen a few guys use a Mighty-Vac tool or vacuum pump on the injector pump's return line fitting to suck all the air out..one guy I know rigged up a "squeeze bulb" primer from a boat gas tank onto his injector pump to prime the fuel system..

Usually if you fill up the new fuel filter full first,and wait to ensure its really full (the element soaks up some of the fuel),then it shouldn't take too long of cranking it over to get it to self bleed..but they can be stubborn...dont go nuts cranking it over 30 seconds,it'll kill the starter,and the batteries..best to have two fully charged ones at the start too..

I clamp off the fuel lines to the filter with vise grips before I replace the spin on filter on my truck,so as little air gets in as possible..the ones with the square "clip on" firewall filter are often a mother to get to bleed,they also get cracks in the mounting base that lets air sneak in while its sitting..

Others here may have more & better-er ideas than mine..
 
Crack the fuel lines at 2 of the injectors. If you have the square fuel filter crack the bleed valve on top. Remember, it's recommended not to crank these for more than 30 seconds at a time. Gotta let the starter cool down a couple of minutes in between....
 
Big Ray said:
Crack the fuel lines at 2 of the injectors. If you have the square fuel filter crack the bleed valve on top. Remember, it's recommended not to crank these for more than 30 seconds at a time. Gotta let the starter cool down a couple of minutes in between....
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So it will be ok if I am cranking it myself and then checking to see if the fuel is coming out of the injectors? No fire danger there?
 
I just found an extra fuel line hose and I don't know where it goes. lol I have had been working on the fuel tank and painting the undercarriage so haven't put it back together for a long time. It's about 6-8" long and it's a hardened rubber hose. It looks similar to the hose that comes out of the bottom of the mechanical fuel pump to the hard line to the fuel tank. Anyone know where this goes??
 
Diesel equipped trucks had a third hose on the sending unit that goes rearward ,to a water drain valve located in the frame,on my pickup the valve is located in the center of the opening of the spring hanger ,the front most hanger,for the rear leaf spring..

They did this to make draining any water out of the fuel easier..you could put a hove on the valve's other barb fitting and open it,and it would (hopefully) siphon out the water,however it may take a bit of suction to get the siphon action to begin..(use something like a turkey baster,not your mouth!)..

The sending unit on diesel fuel tanks differ not only due to the "extra" hose nipple,there is also a "water in fuel" sensor to operate the dash idiot light should it detect water...
 
I went through this just yesterday. I changed my spin on filter, filled the new one with fuel, waited a few minutes, topped it off again and started the engine thinking I was all good. Even though that has worked before on different trucks. It didn’t work on that truck yesterday. I should have done what the manual says. Open the bleeder valve, pull the pink wire from the injection pump and crank the engine for at least 10 seconds. Instead I tried a less messy way and had to do the crank for 30 seconds, wait a few minutes repeat process.

I have had at least 2 6.2 or 6.5 vehicles on the road just about daily for the last 10 years. There are two different systems to purge air from. The low pressure fuel system from the fuel tank to the solenoid inside the injection pump. This can be bled by an electric fuel pump, air in through the fuel cap and all the other ways mentioned in this thread.

The high pressure part of the system which is inside the injection pump all the way to the injectors can only be bled one way. By turning the engine over with at least 5 psi of fuel coming into the injection pump. I have tried pushing fuel through an injection pump in a vice with up to 15 psi of fuel or air and the solenoid on. Nothing. Not even a hopeful drip.
 
I have a garden sprayer that I can pump fuel into the engine from the lines that come out of the canister fuel filter but I am wondering how to do the part that goes back to the fuel tank or if that is necessary if I pump the engine with fuel.

If I pump the engine with fuel will it send fuel back to the fuel tank since it is a circular system?
 
It is a circular system in that unused fuel goes back to the tank. However, air in the return lines doesn’t mean anything. The only time the return system can stop the engine from running is if it gets plugged up and builds pressure. Then your weakest return hose might pop off and cause a huge fuel leak. Or, if nothing breaks or pops off. The engine will turn off. You can test this by closing the hose coming off the top of the injection pump with the red squeeze clamp. Clamp it shut and the engine will stall in a second or so. I have often thought of looking for a spring loaded ball valve to mount in this line and use it as a cable operated shut off valve with the power solenoid bypassed in the run position.

The lift pump on the passenger front corner of the engine, through the fuel filter and to the injection pump is under positive pressure with the engine running. A leak in that part of the system if big will cause fuel to drip and is found easily. However since air molecules are smaller than fuel molecules. Normally your first indication of a leak in this area is the engine will start up like normal, run for 5-10 seconds, seem to accelerate just a bit and then die. This is very common with the stock square fuel filter because one of the sensors on the back will let air in with the engine off. The filter and lines will then drain back to the tank. Many of us have replaced the stock filter to a spin on type just to avoid this exact issue on some cold dark rainy night outside of cell range.

Unfortunately, the exact same symptoms will also happen if the hose connecting the lift pump to the fuel line at the frame, the hose connecting metal fuel line on the frame under the seat or the hose connecting the fuel line to the fuel pick up in the tank has a small air leak. Since all of those hoses are under vacuum with the engine running. There is almost never any visible evidence of a leak. Besides replacing all of the hoses in the entire system. Making note of how long it takes from start up to stall is about the only way to pin point this kind of leak. The longer it runs, the further toward the fuel tank your leak likely is.

Then there is the fuel tank pick up sock. If it is clogged, then fuel just won’t flow at all. Sometimes. Then other times it works just fine. Replacement of the fuel pickup/fuel level sender is the best fix for this. Remove the fuel cap, take the hose going to the frame off the lift pump and blow low pressure air toward the tank. You should hear bubbles at the filler cap.
 
I am thinking that the last time I started it from a bottle, because the tank was likely contaminated, that there is still fuel between the injection pump and the injectors. If I just try to start it as-is could it bleed the air on it's own?
 
If the lift pump to the filter to the injection pump is sealed and hasn’t been compromised since you last ran it. Then, yes. Get a clean supply to the lift pump and fire it up. There will be enough fuel in the filter to allow the lift pump start drawing fuel and fill the filter all the way up before it runs dry. Just don’t run it at wide open throttle.

I have tested many 6.2 or 6.5 engines in the military shipping cans with just a hose from the lift pump run into a Gerry can a few feet away.
 
Overlander said:
I am thinking that the last time I started it from a bottle, because the tank was likely contaminated, that there is still fuel between the injection pump and the injectors. If I just try to start it as-is could it bleed the air on it's own?
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If you think you have fuel between the IP and the injectors, but have air in the lift pump lines, purge the air out of the lift pump lines first. GM's method is to remove the pink wire from the fuel solenoid and crank the engine over until the air bubbles are gone. My method was to switch to an electric lift pump.

But either way, if you pump bubbles into the injector lines, you will be bleeding them the slow way. Crack open a few lines and crank until fuel comes out. Once you get enough lines purged to get the engine started, the rest will purge themselves. I have also done this on my 5-speed by towing the vehicle down the road in gear. As the engine windmills it will push the air out of the injector lines. Saves wear-n-tear on the starter, if you have a stick-shift and a tow rig.
 
campfire said:
If you think you have fuel between the IP and the injectors, but have air in the lift pump lines, purge the air out of the lift pump lines first. GM's method is to remove the pink wire from the fuel solenoid and crank the engine over until the air bubbles are gone. My method was to switch to an electric lift pump.

But either way, if you pump bubbles into the injector lines, you will be bleeding them the slow way. Crack open a few lines and crank until fuel comes out. Once you get enough lines purged to get the engine started, the rest will purge themselves. I have also done this on my 5-speed by towing the vehicle down the road in gear. As the engine windmills it will push the air out of the injector lines. Saves wear-n-tear on the starter, if you have a stick-shift and a tow rig.
Click to expand...

I tried to start it last night but it wouldn't turn over. My batteries weren't very charged because I have a manual battery charger and was afraid of over charging them. Because it wouldn't turn over at all and I thought my batteries were decent I thought it might be that the starter was bad or that the engine was seized up from sitting.

I took the batteries to the little battery shop where I bought them and they tested the batteries. Turned out one of them was bad and the guy told me how long to charge the other one. Once charged I just went for it to start it to see if it would at least turn over and see if it might start. It turned over really fast with the fully charged batteries and took about 2 or 3 times of cranking about 20 seconds each and it started firing. Fired for a few seconds then died. a few more times of this and it started and ran for like 30 seconds then died. Tried again and it fired up and ran. Then ran it for a few minutes revving it and it seemed good. Then shut it down.

I got out of the vehicle and looked underneath to see if there were any leaks in the fuel system. There was a large puddle on the left side of the vehicle. I am hoping it's just one of the injectors that isn't tightened down all the way. That loose injector or injectors might have helped purge air out of the system maybe?
 
Overlander said:
I tried to start it last night but it wouldn't turn over. My batteries weren't very charged because I have a manual battery charger and was afraid of over charging them. Because it wouldn't turn over at all and I thought my batteries were decent I thought it might be that the starter was bad or that the engine was seized up from sitting.

I took the batteries to the little battery shop where I bought them and they tested the batteries. Turned out one of them was bad and the guy told me how long to charge the other one. Once charged I just went for it to start it to see if it would at least turn over and see if it might start. It turned over really fast with the fully charged batteries and took about 2 or 3 times of cranking about 20 seconds each and it started firing. Fired for a few seconds then died. a few more times of this and it started and ran for like 30 seconds then died. Tried again and it fired up and ran. Then ran it for a few minutes revving it and it seemed good. Then shut it down.

I got out of the vehicle and looked underneath to see if there were any leaks in the fuel system. There was a large puddle on the left side of the vehicle. I am hoping it's just one of the injectors that isn't tightened down all the way. That loose injector or injectors might have helped purge air out of the system maybe?
Click to expand...

The sporadic firing is consistent with purging air out of the system. If you got it running smoothly, the air should all be purged out now. If it stumbles again next time you start I'd be looking for leaks in the fuel system.

The leak could also be a loose return line. Sniff around and see what you find.
 
campfire said:
The sporadic firing is consistent with purging air out of the system. If you got it running smoothly, the air should all be purged out now. If it stumbles again next time you start I'd be looking for leaks in the fuel system.

The leak could also be a loose return line. Sniff around and see what you find.
Click to expand...

Thanks!
 
A little late but my K5 has the later factory style rectagular filter on the firewall. The base has a hand turned bleeder valve on the top with a spigot on it. I clamped a section of rubber fuel hole onto that spigot and when I need to bleed it I put the hose into a water bottle or something to catch the fuel. Unplug the pink injector wire, crack open the bleeder, and go crank the engine a few times. Then I go and verify there is some fuel in the bottle. If no fuel go back and crank the engine a few more times. After doing this a few times I plug the injector wire back in, close the bleeder, and start the engine.
 
campfire said:
The sporadic firing is consistent with purging air out of the system. If you got it running smoothly, the air should all be purged out now. If it stumbles again next time you start I'd be looking for leaks in the fuel system.

The leak could also be a loose return line. Sniff around and see what you find.
Click to expand...

You know those little hoses around the injectors? On the one closest to the driver there's a hose missing on the bottom but I don't know what happened to it or where it would go.
 
Overlander said:
You know those little hoses around the injectors? On the one closest to the driver there's a hose missing on the bottom but I don't know what happened to it or where it would go.
Click to expand...

Aha. That would cause a puddle. Originally the last return line on each cylinder bank is capped off. As you said, it has nowhere to go. Alternatively the two dead ends can be connected together with a piece of hose, if you don't have a spare cap.

Badger Diesel sells a kit to replace all the return lines and both caps for about $25. It's a good idea if your lines are old. Stay away from cheap hose.
 
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