We just bought an 03 cummins 305hp 6spd with 95,000 miles. It will not start with the key, it will just keep cranking and cranking. It will start with a very small shot of ether, and runs excellent after its running. It will also pop start by being towed and fire right up. It had had new injectors on it, its got 2 fuel pumps on the tank and other things have been done to try to fix it b4 we got it. There are no DTC's or CEL's. We really could use some help before we end up sending it to Cummins. If u need anymore info ill try to get it for u.

 

We just bought an 03 cummins 305hp 6spd with 95,000 miles. It will not start with the key, it will just keep cranking and cranking. It will start with a very small shot of ether, and runs excellent after its running. It will also pop start by being towed and fire right up. It had had new injectors on it, its got 2 fuel pumps on the tank and other things have been done to try to fix it b4 we got it. There are no DTC's or CEL's. We really could use some help before we end up sending it to Cummins. If u need anymore info ill try to get it for u.

 

did any one replace the pressure flow valve on it. not thre right name for it but cant think of it. it will allow the pressure to bleed off if its bad since you have new injectors i would guess it mite be the problem

 

we tried doing the bypass trick on the banjo bolt today with the plug or whatever we read about and that didnt work either if thats what u mean. It looks fairly new. If we take off the banjo bolt and look down theres fuel sitting there. if we crank it fuel runs out...

What the heck would cause it to pop start easy as pie, but not start at all without ether using key???

 

Sounds like you have a leaky injecter, & or rail pressure relief valve. It will leak off your rail pressure faster than the pump can build it @ cranking speeds. If you don't have the equipment, & understanding of the system you should bring it to someone who does. A real quick fix may be to double check the torque on all the injecter transfer pipes. That is the most common leak point. Good luck.

 

I just answered that question in your other thread. You should read it. Good Luck.

 

Just bought an '03? Batteries are already over 5 years old and may not deliver the needed voltage to the puter. You can test by measuring voltage at the battery as someone cranks over the motor. If it drops too much, get a new pair of batteries.

The reason it pull/push starts is there is enough voltage to run the puter because it is not being used to run the starter. If the puter doesn't have enough voltage, it can't tell the sticks to spit fuel.

It could also be poor battery cables and/or connections, but at 5 years, I'm betting batteries.
Back to my evening adult beverage. . .

 

thanks alot FMB. we will definetly check the battery voltage with the multimeter. we are a heavy truck and car garage so we know what we are doing. just we are stumped ourselves on this. What should be the lowest voltage needed to give it enough to start on each battery while cranking??

But why would it crank over really really fast. i mean this thing cranks really fast like its not a weak battery you know.

 

I don't recall the exact voltage, maybe someone on here can pipe up what the minimum ECM Voltage would be. Maybe around 11.5 or so (guessing).
It takes less voltage to turn over the engine than run the ECM. (Don't confuse Voltage with Power though, as the crankin takes a lot more power than the puter)

 

does it start fine when it is cold, if so probably still bad injectors, mine I had to replace all 6

 

Dirty MAP, MAF or MAT sensors might cause the problem.

 

it doesnt start at all cold or hot doesnt matter. you can have it running all day if u leave it idling runs beautiful. if u turn it off quick and try cranking it over fast to see if itll restart, nothing....

when im cranking do i measure the voltage at the battery or at the ECM?

 

Battery Post. If that is good, check for a voltage drop across your cables and connections (make sure they have clean connections on both ends, both cables, both batteries)

 

I had this same problem on a Ferd one time, sounded like it was turning over fast but turned out to be bad battery cable that was all burnt up under the insulation where you couldn't see it.

 

cgoff,
I think it sounds like injectors. Change your fuel filter 1st then check your cov(Cascade overflow valve). Pull the cov and clean it real good 1 little spec of dirt can keep your truck from starting but once it starts it will run great. Make sure you clean around the cov before you pull it and after you have the cov out be sure that you blow out the port that the cov goes into.
Good luck,
Topper