Airlock in Fuel System

[atom_c]

I changed my fuel filter and filter housing the other day and did not bleed the new filter long enough and sucked air into my fuel system. I did not have a good visual on my bleeder line because of the catch tub I was using and thought I had sufficiently bled the filter.
I tried to start the truck and it wouldn't fire so then I realized my mistake and bleed the filter until I had a visual on fuel flowing out as I ran the lift pump.
The truck still wouldn't start so I verified that fuel was getting to the injection pump intake from the filter housing when I ran the lift pump. It was.
I loosened up the 19mm nuts on 6 of the injectors (excluding the two under the turbo) and cranked. I did not get any fuel dribbling out.
I disconnected the fuel return line and directed it into a jar and did have fuel coming through when I cranked it over.
So what to do now? The truck had been starting and running fine.
When I have the injector fuel lines cracked by loosening the 19mm nut I should have some fuel dribbling out when I crank???
Do I need to keep cranking with fuel lines cracked on injectors? Is it critical that I get all 8 lines cracked open?
Thanks in advance for any suggestions.

Adam
1995 k2500
Bumper mounted pmd

[atom_c]

Now I am wondering if I might have damaged the injector pump when I sucked air into it. I bought the truck with 92,000 on it and now it is at 175,000. As far as I know it is the original pump.

Is it likely or even possible that my injector pump is now the issue (beyond being just air locked)?

Thanks in advance,
Adam

[atom_c]

I pried back the tin at the turbo and managed to crack loose the last two injector lines. After cranking 3 more times for 10-15 seconds I still don't have a drip of diesel out of any of my injector lines.

The only thing I had changed was the fuel filter housing as my old one was rusted out at the base and seeping some fuel.

Would a bad connector on the fuel filter assembly cause my injector pump to quit?
I wouldn't think so but I am a bit stumped here.

Any suggestions?

Thanks,
Adam

[a5150nut]

Is the Fuel Shutoff solenoid working properly? If so then, make sure the batteries are up to full charge. These motors have to see 100 rpm cranking before the computer will let them have fuel.

Its a PITA but remove all glow plugs. Then loosen one injector line at a time and crank until you have fuel. Once all injectors have fuel replace the glow pugs and it should fire up. If its still missing crack one injector at a time to remove any remaining air. Its a lot easier on the starter this way.

[atom_c]

I will check the fuel solenoid and go through the process one injector at a time. Not looking forward to the glow plugs but I have taken them out before.
I didn't realize this could be such a stubborn issue.

Thanks,
Adam

[Warren96]

You might want to try plugging in the heater for a couple of hours and then try it. Mine was airlocked and i tried everything. I had to have it towed home were I plugged it in and after that, it started like a clock! a5150 touched on it when he said that these engines need a good spin from the starter.

[Robyn]

Once the IP is full of air it's a real beotch to clear.

BEST and easiest on the PATIENCE, BATTERIES, STARTER ETC.

Yank the glow plugs.

With the plugs out the engine will spin like the wind and the IP does not have to fight the air in the lines, injectors etc.

Left side plugs are easy.

Right side is not bad either.

Pull the FRONT wheel (block rig)
Remove rubber splash shield on inner fender and you have great access to the plugs except #8

Don't sweat it as 7 of them out will get it done.

Spin the engine until fuel mist blows out big time.

Replace the plugs and it should fire right up.

May run rough for a few moments but at this point it will clear right out.

Good luck

[atom_c]

I am still buggered. And the worst part is it was purely my own fault!

I have now removed 7 glow plugs for easier cranking. I might take the last out if I don't resolve this soon.

I had tested power to the shutoff solenoid with key on. Just recently I took the solenoid out and tested for actuation with 12 volts on it, and it worked fine. There was a puddle of fuel in the pump when I removed the solenoid. At least there is fuel in there somewhere!

I have cranked with all the injectors cracked and then one at a time and then all of them cracked again.

I will give it a few more crank sessions soon and then maybe try having only one injector line cracked at a time and work around in circles a couple of times.

PITA

Thanks for all the suggestions.

I assume Warren was referring to the block heater not somehow the fuel filter heater element? It is in the 90's today so I don't see how temp should be an issue.

Thanks,
Adam

[DmaxMaverick]

The temperature (above freezing) has nothing to do with it not moving fuel.

Even at 90F, good glow plugs are needed to fire off most 6.5's. It never made much sense to me, as all my 6.5's need GP's in the summer, while all my 6.2's will start at 90F+ without any GP heat, at all.

[atom_c]

Yesterday I took out the last glow plug and then went around alternately opening/closing one injector line at a time. I would crank about 15-20 seconds with each one open. I was still not really getting any fuel out the injector lines.

After a couple go arounds I opened all the lines again and cranked a few times that way. I started to get an ooze of fuel out most of the lines. If I rubbed my finger under the injector line nut I would get some fuel on my finger. I got a couple drips out of the #1 line.

I am assuming that when the air lock is cleared I should be getting enough fuel that it would be dripping out and down the side of the engine.

How much fuel should I be seeing?

Thanks,
Adam

[DmaxMaverick]

It's best described as "wetness", or weeping. The fuel volume is measured at a few milliliters per 1000 revolutions, and during start cycle, it's at a minimum. It will eventually "drip", but don't count on it immediately, especially after an airlock episode. The purpose of bleeding is to get enough fuel in the system so it will start. Once started, the air will bleed more completely for a while during some rough running. If you are getting "any" fuel, you're almost there. Tighten all the line nuts and crank. You should see some mist from the GP holes. To fully bleed the air, the system must be pressurized, meaning the injector lines must be secure, and the injectors must pop. If you are seeing some wetness at the line nuts, they should be tightened, followed by a few cranking sessions. Once fuel mist is present at a couple/few GP holes, it's ready to button up and attempt a start.

[atom_c]

Thanks!

Looks like I might be there now. I will tighten up the lines that are drooling.

Hope to have it all stitched up today.

Adam

[DmaxMaverick]

If you have some lines that are "drooling" (which is well past weeping), I'd tighten them all, spin it a couple times, install the GP's and go for it. It bleeds MUCH faster while it's running, even if rough.

[atom_c]

Problem resolved. Truck is running.

I have to give myself an "F" for diagnostic work though

It turned out in the end that I had stepped on my PMD wire harness mounted in the bumper. My toe must have caught the wire as I used the handy "toe holes" provided and unplugged it sometime in the air bleeding process.

Started right up with PMD plugged back in!

Thanks for all the responses.
This forum is awesome!

Adam

[a5150nut]

Note to Adam,

Get some zip ties and fix that wire!

Crazy when its something simple.

[DieselDavy]

Adam,
Don't feel too bad.... I think we've all suffered from self inflicted wounds before! Glad you got it started!
Dave

[atom_c]

I changed out my PMD about 3 months ago and must not tied up the wire as it was before.

Will do it now!

Adam

[rustyk]

I would revisit the lift pump/fuel filter. With zero compression on the cylinders, the IP should produce fuel at the loosened lines (note that it's really very little). With what you've done, air should have been cleared.

I'm skeptical the IP is getting fuel.

[arveetek]

I would revisit the lift pump/fuel filter. With zero compression on the cylinders, the IP should produce fuel at the loosened lines (note that it's really very little). With what you've done, air should have been cleared.

I'm skeptical the IP is getting fuel.

Hee hee... look at post # 14 above! :D

Casey