Any diesel techs out there

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daredevil

daredevil

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When I go to start my 01 cummins it cranks forever before it hits and runs. i believe i have a injector line leaking and letting air in the system when it sits.Can I use air and pressure up the line at the filter and spray soapy water around the injectors and look for bubbles or is there another way? thanks DD
 
I'm no diesel mechanic, but with gas engines, there are two common problems when it comes to hard starting.

1. bad coolant temp sensor giving wrong temp to ECU.

2. low fuel pressure, due to bad pump, bad pressure regulator, clogged filter, poor ground connection at fuel pump, (I think your diesel uses a mechanical pump?) or leaking injector.
 
I'd say change the fuel filter if you had air getting in you would have fuel leaking all over when it was running. 99% of fuel related problems with a diesel is clogged filters.
 
Purple Haze said:
I'd say change the fuel filter if you had air getting in you would have fuel leaking all over when it was running. 99% of fuel related problems with a diesel is clogged filters.
Click to expand...

Agreed. At the very worst, you just performed routine maintnance. Not good to run a diesel with a clogged filter - hard on the injector pump. And on a 2001 that has spent the last two + years running on ULSD (which I don't believe the '01s were designed for) it's already not getting the lubrication it should.
 
blackbomber said:
Agreed. At the very worst, you just performed routine maintnance. Not good to run a diesel with a clogged filter - hard on the injector pump. And on a 2001 that has spent the last two + years running on ULSD (which I don't believe the '01s were designed for) it's already not getting the lubrication it should.
Click to expand...
I have the same truck, bi-pass the stock lift pump & replace it a FASS 95
 
I don't know if you can do the same thing as the gas cars. Pump smoke into the fuel tank and check for leaks along the lines, they do that to gas cars to see if there are cracks in the rubber lines somewhere.
 
What codes is it throwing do you have a fuel pressure guauge on it? These trucks like to burn out fuel transfer pumps than taken out the VP44 IP if you don't catch them in time.

The first thing is park downhill and see if starts normally. I fit does, there is a air leak into the return fuel circuit. On the Dodge, three frequent issues are:
Return line fitting (banjo bolt on Dodge) at back of cylinder head loose.
The 3 way fitting that cnnnects return from head and return from IP to tank.
Inspect closely for wetness at one or more Line fittings at head. Generally this indicated a connector tube O-ring leak. New O-ring required.
If nothing found, you didn't look hard enough. The rest of fittings on IP, filter, and LP are subject to leak. You might try pressure to fuel tank filler. No more than 3.5 psi (NO, not 35) and look for wetness to show up. Air will leak quicker than fuel because much smaller molucle. I have also heard of '01 Leaking Fuel Lines (sucking air) overnight from Deterioration of the lines.


Here's a nice link to a F.A.S.S. Filtration Systems Installation How To http://www.dieselpp.com/pdfs/mrpeal-howto.pdf
 
I would be looking at the fuel lines themselves, sounds to me like a leak in the line allowing the pressure bleed off. It seems to be a common discussion item on the diesel forums.

Secondly would be lift pump, like AZ340 says. Lift pump feeds the high presssure injection pump at engine, and weak lift pumps kill the VP44 injection pump (injection pumps do not like to draw fuel, they want it fed to them to pressurize). Replacement VP are VERY Expensive. FASS or AIR DOG are 2 vendors that by pass the weak stock lift pump, with a dual filter / water seperator systems, to give the injection pump all the fuel it can handle.
 
I'm sure the issue is fuel related, that is really all there is on a diesel. As stated check and change your filter first. There were issues with the stock lift pumps, There are retrofit kits from Mopar to put an electric pump in the tank like the newer ones have and bypass the stock lift pump. After that I'd be looking at the injection pump.

And I agree if you had a leak you would see it.
 
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