The Stovebolt Site Forums The Shop Area Engine Shop Bleeding a GM 6.5 non turbo diesel

My donor truck (1993 P-30) has a 6.5 diesel. The P.O. stated that it was a good running truck. We tried to start it during a cold spell this winter and fried the starter and opened the fuel system. I replaced the starter today. It also has air in the fuel system. I am somewhat familiar with diesels, but would like some advise on bleeding the 6.5. I need to get this puppy home so I can rip it apart for the axles.

I am not familiar with a 6.5, but I think they have Roosa Master/Stanadyne injection system. There should be a primer pump at the injection pump. Pump it until you get fuel into the injection pump. Then crack the injector lines at each cylinder and crank it over a few times, let the starter cool, and then crank until fuel starts spurting at the injectors. As they start spurting, tighten the lines. It should start now. If it runs rough, crack the lines at the injectors one at a time to purge the remaining air.

Thanks crenwelge, It didn't have a hand pump on the injector pump and at this point I'm not even sure it's a 6.5. Could be a 6.2 as it has a mechanical lift pump. The research continues...

If it has a mechanical lift pump, it should prime itself to the injection pump. However, you will need to get rid of the air in the lines going to the injectors by cracking them at the injectors.

depending on how starved for fuel, you may have to take the fuel filter off the firewall, and fill with fuel and replace.

Yesterday I tried, cracking one of the lines at the injector, pouring some fuel into the intake, starting it. It fired on the fuel I poured in, then stalled. I repeated the process 3 times shutting the cracked line each time while I waited for the starter to cool. No fuel ever came out of the injector line. The PO thinks the mechanical pump is wasted. I'm not so confident of that as I can get fuel out of a bleeder on the top of the filter. He is going to change out the mech pump this weekend. The truck is 2 hours away from me so it's hard to play with. I will report after he trys his fix. Thanks again for the help

Have your tried either of these two sites???
I don't know anything about this place but it was the 1st place that popped up on a Google Search of "Bleeding a GM 6.2 non turbo diesel fuel system" and THIS SITE has been around for 14yrs.

It takes longer then you think to get fuel to the injectors. Loosen all the lines you can get to and keep on cranking. Fuel in the intake helps, and if it fires off on that its even better. Try pressurizing the fuel tank to force the fuel up in to the pump, that also helps and keep the fuel filters full.

Joe

just curious, why a duramax? no offense but they are the laughing stock of the diesel world.

Loosening any lines at all on a Roosa Master pump shuts it down completely. Putting any fuel into the intake will result in the engine trying to run backwards and probably bending some connecting rods. Definitely don't try starting fluid!

Just tighten everything down, and crank the engine until it fires off. Make sure the mechanical boost pump is flowing fuel to the injection pump, and don't fry ther starter! It will start, eventually.
Jerry

Hotrod, I agree that fuel should never be put in the intake and I don't care for starting fluid. However, If a system is completely dry, I don't know how you get the air out of the injector lines other than cracking the lines at the injector. In the mean time, I will continue to crack the injector lines to bleed the air on my engines with Roosa Master systems when my guys run them out of fuel. It has been working for me for 45 years. I figure it will continue working for me.

Zaboomafoo, I'm not planning on using the 6.5 in my truck (though I may tuck it into my 69 panel. they do lack power, but I can't get 23 MPG with the gas V-8s I have). At the moment I have a BT6cummins/NV4500 for the 36 1-1/2 ton.

The biggest reason to get it going is to drive the donor truck home.

http://i890.photobucket.com/albums/ac102/chiefbobber/36010a.jpg Here's a mock up of the 36

Everyone else WOW thanks. I forwarded a link to these posts to the PO. If nothing else he will be impressed with the support this site offers

The 6.5 is not a Duramax

I have a few tricks for Roosa Master pumps that might help you. When the ignition is on, make sure that there is 12 volts going to the pump whenever the ignition switch is on. The delivery valve inside these pumps will stick sometimes, especially if the engine has been sitting for quite a while (several months). If you have access to a mechanic's stethescope 'listen' to the pump in the area where the power wire hooks to the pump while someone turns on the key. You should hear a click, which means that the solenoid inside the pump is working and should be opening the delivery valve.

I am not sure where/how the transfer pump works on the 6.2/6.5 engine. Be absolutely sure that you are getting a good stream of fuel to the injection pump. It may help you to remove the glow plugs. This will let the engine spin over faster and takes some load off the starter. While you are at it (before you remove the glow plugs) ohm the glow plugs to make sure they are all good. There should be very little resistance (1-5 ohms) between the glow plug spade and ground. These engines WILL NOT start without at least some of the glow plugs operating.

If you are getting 12 volts to the pump but do not hear a click, remove the power wire from the pump and use an ohm meter to measure the resistance from the 12+ terminal on the pump to the case of the pump. I don't recall the exact resistance but 8-20 ohms sounds right. Open circuit=bad solenoid. This can be changed without removing the pump from the engine. If the solenoid checks, reattach the power wire and with the power switched on, use a small hammer and LIGHTLY tap around on the top cover area on the pump.

You really have to loosen the injection lines to get the air out of the system.

Something else, if you do get it to hit on one or more, stop cranking and let the glow plugs heat up a few times to get really hot, then crank again. It should take off running.

The 6.2/6.5 have a pick up pump very much like a sbc /bbc engine mounted in the same location as the gas engines. They go bad just like all the others, so check it for pressure or leaks.

Joe

Should be a Detroit. Had a turbo version on a 95 C2500. Good motor, just a little lacking on power. There is a bleed screw close to the upper thermostat housing-- crack it open, and crank till you get fuel, no bubbles. you don't have to bleed the injectors.
As for the Duramax being the laughing stock of diesels-- you have to be kidding. Go find a powersmoke that gets the same mileage and horsepower without using all aftermarket chips and such. As for the Cummins, great motor, nice milage, but really heavy and needs chips to make any decent power.

Well It runs. Thanks for all the help. The PO gave up on it two weeks ago and made me a very good offer to end his suffering. I contacted a local towing CO. and we drove on down there Thursday evening. 6 hours later we got back to my home with stories to tell. Today I finally got some time to spend on it and had it going in 30 minutes. The reason we couldn't get any fuel to the injectors was that the fuel shutoff solenoid wasn't getting power. As soon as I realized that I put a jumper on it from the battery. Then I cracked an injector connection, cranked it, and I'll be dipped if fuel didn't come out. I repeated this process (3 injectors) until the engine caught and ran. After about ten minutes it smoothed out and ran like a champ. Next I traced the wire back from the solenoid and it was tied into a circuit breaker for the onboard air system. Reset the breaker, did a driveway registration and took it out for a ride. Thanks again folks