Hard Cold Start

[glmoore001]

I have a very hard start even when temps are sitting at 34 degrees. My "Wait To Start" light comes on and goes off but it will still not start on the first crank unless I give it extra fuel. Even then it stumbles and barely runs for the first few seconds then blasts out a cloud of non burnt fuel. My last diesel would do this in extreme temps but not in mild.
I had the grid heater off when I rebuilt the vacuum pump and I noticed that there are 2 ground nuts that I could hook the ground from the top of the plenum. I am hooked to the bottom nut. Is there supposed to be a jumper between these connections?
Would the WTS light even cycle if the grid heater or relay was not working? Is the IAT sensor what triggers the WTS light? I saw mentioned in another post that this could sometimes need cleaning.
I can take the wire off and check for continuity on the grid heater, but the wire in the grid heater looked intact when I had it off.
I can also take a reading from the wires to ground to check for voltage when the WTS light cycles.
I have not done either of those things at this point, trying to first understand the system. Thanks. Gary

 

[KATOOM]

A diesel has to crank over at speeds fast enough to create the proper combustion chamber temps, so bad/weak batteries and/or dragging starters can slow the cranking RPM down and hard start.

Other than that, the grid heater system isnt too difficult to diagnose but here's a link to help: http://dodgeram.org/tech/dsl/troubleshooting/Maniford_htr.htm

That said, if the grid heater isnt working as it should then usually it will generate a code letting you know that there's an intake heater problem.

 

[BDaugherty]

Copied from Bluechip’s webpage
https://www.bluechipdiesel.com/troubleshooting-quick-reference

Hard Start, Cold

This is typically due to a cracked or broken diaphragm inside the Injection Pump. To test for this try disconnecting the electrical power from the Lift Pump BEFORE turning the key on, and see if it starts better. This happens because the electric lift pump pushes air which is always in the fuel chamber inside the VP44 pump, through the crack or break in the diaphragm, into the mechanical high pressure pump and it becomes air-bound until it rotates enough times to bleed out the air. If it starts better without an electric Lift Pump, it is because the electric Lift Pump hasn’t forced air into the mechanical high pressure pump through the crack or break in the diaphragm, which is what separates the fuel chamber from the high pressure pump. This failure requires a VP44 replacement to fix the problem.

 

[glmoore001]

I had that issue on my last truck, that truck cranked and cranked with nothing... I had it rigged so I could disconnect the power to the lift pump momentarily so it would start. This is different. It hits every time, it just stumbles the whole time till you give it fuel.
Not quite convinced it is a VP44 at this point..

 

[KATOOM]

Its not a VP issue... Hard "hot" starting from a torn diaphragm was a false diagnosis as the diaphragm doesn't tear. For that matter, the diaphragm was replaced a long long time ago with a metal covered plastic disc.

Hard hot starting is generally from an aftermarket fuel pump pumping too much pressure during engine cranking which hydro-locks the timing ring and fuel solenoid. This isnt whats going on here...

This is a cold engine starting issue in cold weather which was addressed in my previous post.

 

[glmoore001]

Its not a VP issue... Hard "hot" starting from a torn diaphragm was a false diagnosis as the diaphragm doesn't tear. For that matter, the diaphragm was replaced a long long time ago with a metal covered plastic disc.

Hard hot starting is generally from an aftermarket fuel pump pumping too much pressure during engine cranking which hydro-locks the timing ring and fuel solenoid. This isnt whats going on here...

This is a cold engine starting issue in cold weather which was addressed in my previous post.

I will go out this coming weekend and try to figure out what is going on. Reading the repair manual and the page you linked
me to helped a lot Katoom.. Thanks for the info.. Gary

 

[glmoore001]

Figured out the problem of my hard starts on cold mornings., boy is my face red
Early last summer I replaced the batteries and all the cables. Went with military style battery terminals, I replaced it all.
When I hooked all the wires back to the terminals, I installed the fusible link cables that feed the intake heater grid solenoids to the negative side of the battery. That might cause a cold start issue, huh?
These black cables now are adorned with red shrink tube.
Thanks for all the help.. Gary

 

[glmoore001]

I do wonder why the IAT sensor does not throw a code if it sees no change in manifold temperature after running the grid heater.