Diesel question


I have a 2001 GMC 3500 Duramax Diesel with 80k miles on it (bought it new). About 2 years ago, it refused to start after sitting for more than one day. Called the dealer, and they told me to manually pump fuel into the engine using the pump under the hood. I then took it in, they held it for a few days but couldn’t find anything wrong. They said it might be something on the gas line that got flushed out. It ran smooth for 2 years, then last week it started doing it again, this time more often: if I leave it overnight, it’ll do it.

Before I take it back for repair, I would like to know if there’s anything I should tell the dealer, who’ll probably say it’s nothing again…

Thank you very much,


Do you do regular fuel filter maintenance? It sounds to me like you’ve got water in the fuel, and the fact that it’s winter makes that seem more likely. When you take it in to the garage, ask them if it is a water in fuel situation, and ask about draining it from the water separator yourself. I don’t know much about the Duramax fuel system, but purging the fuel line from the tank to the high-pressure pump, and from the pump to the injectors is a royal pain on some rigs, and not that bad on others. Have them clue you in on what they’re doing.

While I would not lean towards the water in the fuel theory, it is possible. If you have not changed the fuel filter and it is near or passed scheduled time, do it now.

I would suggest a possible very slow fuel leak that is allowing air to get in the line. You may get very little fuel leaking out, but just enough air leaking in to cause problems. It also could be a fuel pump issue, that should be checked if it was not checked well.

since your dealership cant figure this one out, why not find a decent local mechanic who specializes in diesel and take it to their shop, and start making a relationship with a independent shop instead of a dealership??

your engine has two fuel pumps, a tank mounted low pressure pump, and a mechanical high pressure pump.

first; i cant guesstimate exactly where the problem lies, but as mentioned the fuel filter would be the first place to start. (actually i CAN guestimate that by having to use the manual pump the high pressure pump is failing (why i dont know) and you are having to charge the fuel rail to the injectors to get the thing running.) why this would happen when cold starting is hard to guess.

secondly a good mechanic can put a gauge on the fuel rack and on the fuel line to check what the pressures are to start finding the problem.

since your dealership has been unable to get this far find a new mechanic.

I really appreciate your feedback, I now have something to start with. You guys are great!

Thanks again!