Airlocked injectors?

[emegg]

I have a 2002 gmc 2500hd. I got very low on fuel, got 6 gallons at the Exxon, drove out of the station and died, it has not started since. I pumped the primer pump (probably about a thousand times or more) with the bleed screw open and never got any fuel out. I replaced the filter, primed some more and still nothing. Finally I found out I needed to crack the injectors and crank the engine. The only tow injectors I can get at are the rear one on the passenger side and the front one on the drivers side. Cracked the rear one, and it sprayed diesel. The front one just keeps bubbling. I have cranked it alot, but still just bubbles. Any suggestions? (this is my first diesel-just got it licensed the day before).

[DmaxMaverick]

DO NOT try to bleed the injectors like the old IDI's. You risk a very bad condition of contaminating the fuel and junking the injectors. The Duramax injectors can not airlock, but the pump can. Loosening the injector lines won't change the way it primes. You got some baaaad advice.

If you got a slug of air into it, the pump will lose prime, and it is not self priming. If you change the filter, it can take more than 100 pump cycles (by hand/thumb) to get fuel to show up at the bleeder screw. If it just dies from running out of fuel, you should be able to get'er going by pumping the primer with the bleeder closed. Just pump away until the primer gets hard to pump. Repeat as necessary until the engine stays running. The engine may lope/surge until the air is purged, which should be no more than about 15 seconds. When changing the filter, I've had better results pumping with the bleeder closed, and opening it after about 20 pump cycles at a time until the fuel comes out. The primer check valve may not be completely efficient on some, allowing air to be sucked back in on the primer upstroke when there is no resistance on it. Loosening the fuel filler cap during this helps in some situations.

This may sound silly.......
Are you absolutely sure you pumped Exxon #2 into the tank? If you didn't, stranger things have happened.

BTW....
Welcome to the Forums! Wish it were under different circumstances.

[emegg]

Thanks for the reply. Actually, making sure I pumped the right fuel was my first fear. I was actually just out of the station lot when it died so I rechecked my receipt and even went to the pump to re-check the one I used. Sooo, unless the station filled their tank wrong, I got the right fuel. I took the new filter off last night (I had used a strap wrench and had REALLY tightened it). I thought possibly I had caused an air leak there so put the old filter back on (the wrench destroyed the new one getting it off). I will try your suggestions tonight. I had been pumping with the bleeder screw open. Is there a way to pressurerized the system to force the fuel to the pump?

[DmaxMaverick]

To pressurize the suction side of the fuel system, you can add an electric fuel pump ahead of the tank. You can modify (sacrifice) a fuel cap by installing a tire valve into it. With a valve stem in the cap, you can use LOW PRESSURE (2-3 PSI) shop air to pressurize the tank, forcing fuel up to the filter. Otherwise, you'll have to depend on the primer pump to draw fuel up from the tank.

At any rate, you should not be having problems getting the fuel to pump up to the filter. If it just never happens, suspect a bad filter head. They do fail, but it is rare. You should be able to confirm its pumping ability by pumping with the bleeder closed. After 20-40 pumps, opening the bleeder should produce a pretty good rush of air (and/or fuel) as you loosen it. If you get no escaping air, the primer is shot, or you have a leak between the filter and HP pump (doubtful, but possible).

You need to eliminate the possibilities, one at a time. Try the closed bleeder pumping first. My guess is you just haven't pumped enough.

Greg Landuyt at www.lubricationspecialist.com sells a nice bleeder valve to replace the bleeder screw. It's about $20, but the kit is complete and completely eliminates fuel mess at the top of the filter assy with a tubing. It will also prevent a very bad situation of damaging the plastic screw, and leave you with no way to get fuel up to the pump. I have the tubing routed through a fender liner hole into the wheel well. You could put together a similar bleeder valve with parts from the hardware store, but you will be missing the adapter for the unique threads of the bleeder hole. Don't waste your time trying to find one locally. I searced invane, but the threads are truly unique in the hardware world. He also sells a SS bleeder screw, but if you're going that far, just get the valve. Greg is a member here, and TDP Supporter (http://www.thedieselpage.com/vendors/main.htm).

[Buck]

If you pump it with the bleed screw open your efforts are going out the screw hole. Yes, pump it with the screw closed, until you feel it getting hard, then open the screw a bit to let air out when air stops coming out close the screw and repeat until no air comes out. FYI, use a nut driver on the bleed screw instead of a screwdriver. DO NOT OVERTIGHTEN, it doesn't have to be that tight, just a bit over finger tight. The fuel filter shouldn't be that tight either, just snug.

[emegg]

Thanks all, it looks like I have a lot of pumping to do tonight:D . Thanks for the lead on the bleeder valve kit, I was just thinking about fabricating something like that to put a vacumn pump on. I will definatly be getting that.
This forum is great, I would have been lost without the help(actually I WAS lost).
Thanks again.

[emegg]

Ok, lots of pumping, no fuel, any further tricks/ideas?

[DieselMonk]

fuel sending unit plugged? Maybe you pumped some crap the last time you filled up. Had that happen a few times to me. So while you were pumping, did you have that bleeder valve closed? Did you have the fuel filter off and maybe pinched an O-ring creating an air leak. After all I would be very suspicious about that sending unit and fuel filter, cause you drove your tank just anbout empty. Maybe that loosened some dirt from the bottom of the tank while you were filling up.or you got crappy fuel.

[Buck]

emegg, where do you live? Maybe someone here can help.

If you pumped it with the bleed screw closed and no fuel, that would lead me to believe you have an air leak like the previous post. It would be kinda hard for something big enough to clog the fuel line to enter the fuel pickup in the tank, but......

You should take off the fuel filter and check the o-rings (for pinches or tears) on both ends;). I always use a little dielectric grease on the o-rings;). Remove your bleed screw and inspect it with good light for cracks. It may have be ovetightened at some point....it's just plastic.

[emegg]

I live in Baton Rouge, LA. I am going to by the bleeder adapter from lubrication specialist and try to pull a vacuum. I did pull the filter and checked for pinched/torn seals, did not seem to have one, but I am going to recheck anyway. I am learning alot about diesels, primarily that I do not know anything yet.

[DmaxMaverick]

Ok, lots of pumping, no fuel, any further tricks/ideas?

Definately check the filter assy and filter install for somthing amiss. It is possible for the nipple seal, the round rubber seal in the center of the filter top, to remain on the nipple when a filter is removed. It is possible for the new filter to thread on, even with this "double seal" in place, although very difficult. Did you account for the old one?

An air leak would have to be pretty big (relatively) for the primer to not pick up some fuel. Typically, a leaky O-ring will pump up, and cause problems later. Even a cracked filter assy will pump up. Something has to be really outa' wack, or the primer is shot.

If you get the bleeder valve, applying vacuum (or pressure) to the system will be very easy. The tubing can be attached to any vacuum source. Excellent suggestion for a diagnostic step.

Also, removing the filter inlet hose will allow you to blow shop air back to the tank. Be sure to remove the filler cap first.

[emegg]

I agree it is an excellent suggestion for a diagnostic step (and I believe it came from you:D )

[DmaxMaverick]

I agree it is an excellent suggestion for a diagnostic step (and I believe it came from you:D )

The vacuum at the bleeder was your idea. So, you get the credit.......or the blame:D

[emegg]

I got the bleeder valve today. I went to the auto parts store and bought a siphon pump, connected it to the bleeder valve and started pumping. Pumped about 50 times, finally got fuel. Took almost a gallon of fuel before no air. Closed the valve, pumped the primer pump and after doing what was advised above, everything is working as it is suppose to now. Of course, my batteries are too low to start, but I am closer. Charging the batteries overnight.
Thanks for all the help!

[emegg]

Charged the batteries all night, it started right up!