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Discussion Starter · #1 ·
Hey All,

So I'm a Duramax newbie with all this so y'all bear with me please. It has 175K on it.

I read a few threads concerning priming and air in the fuel lines, but I need a bit more understanding. I had an '88 F250 International and most of its issues were fuel related (Either no fuel or no air, or air in fuel, diesels are pretty basic). Anyway that was a much older engine than today's technology.

So went out to my truck to take the wife to dinner last nite. Noticed the dash lights were dim but was able to get her fired up for about 2 seconds (engine not the wife!) Then it died. Tried starting again and no go. Threw a charger on the batteries and went to dinner. BTW, batteries are Bosch and only 10 months old. Came back two hours later, starter was much happier but it still would not fire up.

To me I have two issues: 1) Find what is draining the batteries, 2) find why the engine isn't getting fuel??

The truck had a new filter ass'y installed last year. I understand it has a small fuel lift motor. Where do I start? Am I on the right track?

Thanks in advance!
 

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Your on the right track alright. Remove the black screw in the top of the filter head. Then pump the primer bulb on top. (The BIG round metal button) If fuel does not come out on the first pump or two then you do have air in the lines. Pump the primer till fuel comes out then install the black plug again. Then prime until it gets hard. Try to start. Then repeat the process of priming till it gets hard again and start. If you have a liftpump that is not a "flow through" design and it has failed then it will block the fuel from flowing to the motor.
 

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When my 01 did the same thing. Had it towed to dealership. It was dirty fuel filter. Learned about all the crap that can grow in dirty untreated fuel tank.
 

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Discussion Starter · #4 ·
Thanks Guys. I pumped the fuel prime while the nut was open and fuel did come out. HOWEVER, the bleeder nut cracked and when I removed the broken threads, it looks like it had been cracked and could be sucking in air. Seems strange though that all of a sudden it just won't start. it has been driving perfect since I've owned it-1 mo.

Anyway, I'm curious if you will hear a whirring from a fuel pump somewhere when the key is turned to the start position (like in a car). I hear nothing. Is this normal? I've had car fuel pumps die like this with the same symptom.

Anyone know where I can get a replacement bleeder nut? Brass instead of plastic maybe?

Thanks again
 

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There is no fuel pump on a Duramax-- the injection pump pulls fuem from the fuel tank-- SO any small leak will allow air in the fuel line and may not start.

The bleeder screw is plastic- after you get it replaced pump the primer button until fuel comes out, close it [careful-- plastic] pump it until firm-- crank -- repeat. Go to a good hardware store and get a short metric screw cannot remember the size-- also a o-ring for the seal. It does not have to be very tight- the o-ring does the seal.

If the engine does not turn over, you may have a battery problem-- best to have them tested-- be sure they isolate the one being tested because they are connected together to make one big battery.
 

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Discussion Starter · #6 ·
Awesome advice everyone. Ok, so I went to the hardware store and got a nylon bolt with a o-ring. Its a 3/8" 18 thread. I cut it down and put it on with the o-ring. Pumped it up till the plunger was hard. Cranked the engine for about 20 sec and it fired up.

Now that I know the CP3 injection pump is the only way fuel gets to the filter, I will definitely invest in a FASS unit. Seems pretty ridiculous that there is no other electric delivery pump to get the fuel from the tank to the CP3. Poor design in my opinion.

So this story ends happily. I'm changing the engine oil and filter as its due.

thanks again guys. without your help, I wouldn't be smiling right now :)
 

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Now that I know the CP3 injection pump is the only way fuel gets to the filter, I will definitely invest in a FASS unit. Seems pretty ridiculous that there is no other electric delivery pump to get the fuel from the tank to the CP3. Poor design in my opinion.
There is nothing wrong with the design. It is perfectly capable of the job as designed.
 

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