I have had an uneven lopey idle for several week now. It's kinda like a gasser with a big cam. It seems to come and go but mostly when cold. Got in my truck yesterday, fired her up and she died. Fired her back up and she sputtered and died again. Tried again and ran bad for a few seconds and finally picked up and ran. Thought I might have gotten a bad load of fuel so I drained and changed the filter. Tried again this morning and still the same problem. It seems to happen mainly when cold or sitting for awhile. I have also notice lately a lot of smoke under heavy load. I have 56k and no mods.


Are these symptoms of a bad lift pump?

Going to the dealer Monday for a check up.

 

You need to install a fuel pressure guage, then you would know what is going on with the LP.

 

Silver Goat, next time just bump the starter but don't start the engine. This will allow the lift pump to run for about 30 seconds. Should be able to hear it.

MikeyB

 

I hear the pump start running when the key turns. Gauges are on my wish list. Just wish the 03 had the srader valve like the 02 did. I have a manual fuel gauge but no where to plug it into. It acts like its loosing pressure and need to catch up when the motor starts up.

 

If the filter canister was drained and the lift pump was done would it even start at all? How did the system get primed?

 

That's a good question. I never thought about it. I drained the can, bumped the starter 3 times like normal and it ran after a seconds of sputtering. I am not sure if it's the LP or not. Just doing alot of guessing at this point. That was my first thought because or the history with the LP's on these trucks. It does seem to be somewhere in the fuel system. When it happens it acts like it's not getting fuel.

I was hoping a member here with much more knowledge than me on these things could give me a direction to look at. Got in it this morning and she fired right up missing for a few seconds and then ran ok.

Scheduled to go to the dealer on Monday and wanted to point them in a direction to start looking at. I did not want to get the truck back $100 and 3 days later with that same old story about how they could not duplicate the problem.

 

Make sure the High Pressure Connector Nuts are properly torqued to the cylinder head. Especially if they look wet.

With a new filter, the High pressure pump should be able to pull the fuel through (like the Duramax) until about 1/2 tank. Make sure your tank if full (with good fuel).

Do you have any fault codes? If so, what are they.

 

So is it only people with less than half a tank that are getting starnded?

 

UPDATE:

Got to the dealer. Truck sits a full day and dealer say's it starts it right up for them. They scan for codes and do what they call fuel volume test, power cycle test. Ticket says all tests passed within normal parameters and no codes available. Possible fuel quality issue.

Got the truck back home and it has not shown any other problems other than the eneven idle. I have been using 3 different sources for fuel and have never had any problems except for the idle.

Got to get some gagues to really see whats going on I guess.

 

I can check that but I don't see and signs of fuel leaking or seepage.

 

I have been having a similar problem.
About a month ago, I went to start the truck (let the plugs cycle, turned the key--like normal) and she started up fine and ran for about 10 seconds and then quit. Then every attempt at starting after that it would only run for about 5 seconds or so and then quit. I had it towed to the dealer, where it of course ran just fine for them. They checked codes and found nothing.

So, this morning, the same thing happened again. It finally started about an hour later after trying dozens of times unsuccessfully and having to leave to regain my composure.

This is in 35-42 degree weather in Georgia.

Any more info on your problem? I'd like to be able to tell the dealer something. The only thing different from your description is that I didn't have an uneven idle leading up to either of these episodes.

HELP!!

2003 Cummins HO

 

Plugged fuel filter?

Even if the lift pump is failed, if the tank is full it should run. What's the fuel gauge say?

 

Fuel gauge reads full.
The truck is parked outside. And it did get below freezing last night.
Is it possible that water in the fuel froze and clogged the hoses?
My drain filter light never came on, but . . . .

 

I have run several tanks of fuel with Power Service fuel conditioner thru mine and changed the filter again and it seems better. I am not sure it the cold is a major issue for you. 35-40 degrees is really not that cold for these trucks and mine started up at 26 degrees the other morming with no problem.

It seems to me that fuel quality is more of an issue for the 3rd gen than for the 2nd gens. My 02 did not seem to care where the fuel came from but it seems the 03 does not like certain brands from some of the places I was fueling up. I have started using a single source for fuel and my issues seem better now. I have always had good power and only having problems with noise, uneven idle, and hard starting when cold. Now that I am using one brand from the same source my truck seem to be much happier. Guess we need to be more selective about where you fuel up these days.

Not sure if this helps you. I will continue to watch mine but for now all seems to be ok.

goat

 

fuel will not go thru transfer pump if it quits, pump uses fuel to cool, the pump is a big POS i have 11k km and had 2 replaced so far, and we cant keep them in stock fast enough for as many dead cummins getting towed in.