Can you tell us the part numbers of the components replaced? I wonder if you have a batch of nasty fuel? These trucks don't have a problem starting in the cold. I haven't plugged mine in for 2 winters now, going into the 3rd. It starts like a car, even if i forget to run the pre-heaters. It was 6F yesterday and it popped right off as usual.

Andy

 

I will tll you tomorrow what they did, actually just received paper work today. I don't think its a bad batch of diesel. They flushed fuel system and its been through many tanks since original problem.

 

03 won't start cold once warm will start every time. They think it's pulling air into the system. I think that it would do it all the time not just when its cold though. If you were able to warm your pump and get it to start it sounds like something is not electrically right. If they changed pumps and still the same problem, then what is telling the pump what to do? Computer is telling the pump do the wrong thing. Sound like the exact problem this 03 is having so fix the computer or senser that is giving wrong info to get it to start.

 

Update,
They found that the #3 injector is bad. It was letting air in system, thats why hard to start and sometimes I had to purge system. Will see when get truck back.

 

I don't mean to be a smart *** or a know it all and I've already posted a lot of stuff today, but I think it is a mis diagnosis.

First of all, there isn't any place for the number 3 injector to pull air from. It sits in the head. The fuel rail stays full *UNLESS THE CP3 IS BACK LEAKING*. The return line from the injector goes back to the tank return where it is immersed in fuel. The CP3 would only back leak if there was a suction before it, say because it couldn't get fuel from the lift pump through the canister. (How clean are your fuel filters ? Is the fuel bowl heater working ?)

There is no place for the injector to get air from. Unless they think combustion gases where going into the injector when the engine was shut off, but that would only affect injector number 3 and only if piston number 3 ended at the top of its compression stroke, which would be a 1 in 6 chance.

There is a control valve at the top of each injector that would eliminate said air from contaminating the fuel system for the rest of the injectors. Even if there was an air leak in #3, the other 5 cylinders should have started the engine.

I'm not buying it.

You *might have* had a leaking #3 injector that wouldn't allow a CP3 at cranking RPMs to get the rail pressurized. That would have taken about 10 minutes to initially diagnose. One: crack the return line at the back of the head and put a cup under it. Two: put a scan too on the rail pressure sensor. Three: crank the engine. Watch the pressure and the leakage. If this was the case it had nothing to do with air.

The real problem ? I suspect your lift pump is shot and the CP3 was pulling vacuum.

I've got a tip for the shops that work on these things. When you test the lift pump, don't do it on a warm engine in your warm shop. Test them outside where they won't start. Cold. Not much fun, but that is where the problem occurs.

I'll honestly shut up now. I won't say another thing about CP3s, lift pumps and Dodge service for... a month. Starting now.


Oops... one more thing. The lift pump will purge the CP3. And there isn't anything after the CP3 to let air into the system. It wasn't air.

Even if it was air, after 30 seconds of cranking the CP3 would displace it and the engine would fire up.

I'm wondering if the rail pressure sensor is shot. That might explain the hair dryer trick starting the engine. The sensor won't work when its cold. Once again: Put a scan tool on the engine and watch rail pressure. Is it there or not ? How hard can this be ? The ECM has to see about 3500-4000 PSI before it will begin firing the injectors. No pressure, no fire.

I'll shut up now. I promise.

 

I've just started learning about these engines, but I'm interested that warming up the CP3 got the truck started. Isn't there a fuel heater in the full filter housing? Could this not working be part of the problem at the temperature you mentioned? (Sorry, I'm away from my home computer on an Aircard, and I don't have a copy of the manual with me.) Good luck with this.

 

https://www.dieseltruckresource.com/...ad.php?t=78702

 

I agree with mis-diagnosis (or your not getting the whole story from the dealer).

Actually, I think your not getting the whole story because of the misdiagnosis.

The injector drain back test is the second test performed when diagnosing problems with the fuel system.

1st test is lift pump flow (40ml/sec minimum to pass and no more than 6 in-Hg back vacuum.)
2nd test is an injector return flow test (180ml/min maximum to pass). Any more than that and you have a "leaky" injector.
3rd test is cp3 return flow (1000ml/min max). Any more and you have bad cp3.

You need to seperate the return flows to do these tests. There are special fittings.

 

They dealer said had to get two special fittings to test. They did the tests with them and all good. Then he did injector test and said # three injector was bad. This all I know of right now. The will be replaceing injector when it comes in and I will see if this was the problem. The injector pump is brand new.

Thankd
rob

 

Injector Test?

You mean he cut off fuel to each cylinder and listened for an audible change?

No change means the cylinder must not have been firing. An audible change means the injector must be good.

The most ridiculous test I have ever heard of.

Especially on a component that costs $600 ($3600 for all six).

You'd think someone could come up with a good way to test injectors.

 

He did not say anything about audible change test. If I remember correctly he did a bent test and said # thre injector was bad. I am no mechanic, just what I am told.

 

You mean a bench (not bent) test ?

 

Yes, my bad on spelling.