[michael_d]

My 96 reg cab 4x4 nv4500 has always started like a champ. I mean it fired up fast every time. Lately that has changed and I have been working to fix this issue for a while now. The cold snap we are experiencing is exacerbating the symptoms to the extent that I am worried it will not start one of these mornings. Thus far, it has not failed to start. Keep in mind this issue is not ambient temperature related. It began when it was still 70*F outside a few weeks ago. The cold has obviously made it worse but is not the cause.
SYMPTOMS:
*Slow to crank. The rrrr...rrr..rrrr.. that we all dread.

*Battery gauge on dash heads south when the key is turned on. It will be down in the range of 8 or 9 before the 'wait to start' indicator turns off.

My first thought was dirty connections. So I removed battery connections and cleaned all the terminals and connectors. No improvement. At that point I crawled under the truck to check connections on the starter to see if one was loose and not making solid contact. They were dirty but tight so I cleaned them up as well. From here I decided to check the alternator output to see if it was keeping the batteries charged. I had 14.1-14.2 on both batteries while the truck was running. Hmm. Ok, let's load test the batteries to see if one is bad. Nope, they load tested fine. . Now what? Ok, did some reading. I thought maybe the starter needed freshened up so I ordered LarryB's upgraded contact and plunger set for the starter. Pulled the starter and installed new parts with great anticipation but it was to no avail. I considered that the grid heater may have taken a dump on me so I disconnected the wires on top of the intake elbow which power the grid heater. That made zero difference thus eliminating that as a problem. For the hell of it, I put two brand new interstate 810 cca group 27 black tops in the truck. Again, no change.
I am down to thinking there is either a monster somewhere that I don't understand or that I need to replace my crossing positive cable between batteries.
Thoughts before I waste more time and money?

Thanks,
Michael

 

[zachu812]

I was having similar symptoms when one of the brush wires in my starter melted, the starter was basically running on half power and wouldn't spin the motor fast enough to fire up quickly. That could explain the cranking problem but not the voltage drop. Does the voltage gauge still drop really far after you put in the new batteries?

 

[michael_d]

Yes the voltage drop occurs with the brand new batteries. I had considered that the crossover cable was bad and not allowing voltage to both batteries. The only way I could come up with off the cuff to test this was to use my jumper cables as an auxiliary set of cables to connect both batteries together with a known good cable. It didn't make any difference.
So tell me, what energizes when the key is turned to the run position while the engine is off? I have ruled out the grid heater by disconnecting those wires and saw no change. Something is creating a tremendous amount of electrical draw when the key is first turned on (wait to start position).

 

[zfaylor]

Poor ground, starter is junk, or cables are corroded inside of the jacket. Bend the cables around and if there are any spots that bend extremely easy that usually points to corrosion inside of it. The crossover can be good and the juice going to the starter can be hindered by corrosion a poor connection. Check grounds for sure because a ground is as important at the connection on the hot side.

 

[Ravenhaven]

Try the fuel shutoff solenoid. When the starter is engaged this solenoid draws a large current. When the starter is disengaged( motor running) this solenoid draws a small current. Maybe it is stuck in high current mode? Maybe the fuel shutoff solenoid relay is at fault. Good news is these are inexpensive parts that you can replace. Good luck.

 

[zfaylor]

Try the fuel shutoff solenoid. When the starter is engaged this solenoid draws a large current. When the starter is disengaged( motor running) this solenoid draws a small current. Maybe it is stuck in high current mode? Maybe the fuel shutoff solenoid relay is at fault. Good news is these are inexpensive parts that you can replace. Good luck.

It is a possibility but usually if the "pull up" wire is hot for too long the solenoid cooks in a short amount of time.

 

[country_hick]

A worn starter does start much slower.

Batteries that are barely adequate will also turn over a good starter much slower.

 

[Loud Pedal]

Check that you have the correct starter. The PO replaced the starter with a gas version. Truck started good (but not great) for about 1 year. Then started turning over slower and slower. Narrowed it down to starter, took to shop for rebuild and found it was a gas starter. Replaced with correct starter and starts as a Cummins should. I found a local reliable rebuild shop (120 with swap). I also replaced the standard contacts with the larger ones while it was out.

 

[michael_d]

What I am trying to figure out is what draws amperage when the key is switched to the run position before the starter is engaged. I don't believe the shut off solenoid, were it the problem, would have lasted this long after the onset of issues. As stated, the batteries are brand new as of yesterday. Combined 1620 cold cranking amps. The starter is correct. I put it on when the original failed several years ago and just put new contacts and plunger in it. Does anything in the starter itself have a current draw when the key is in the run position? If so, I'll pull that sob in the morning and have it rebuilt. If not, then it isn't the issue.
Do these trucks have an in tank lift pump that could be going bad?

 

[country_hick]

What I am trying to figure out is what draws amperage when the key is switched to the run position before the starter is engaged. I don't believe the shut off solenoid, were it the problem, would have lasted this long after the onset of issues. As stated, the batteries are brand new as of yesterday. Combined 1620 cold cranking amps. The starter is correct. I put it on when the original failed several years ago and just put new contacts and plunger in it. Does anything in the starter itself have a current draw when the key is in the run position? If so, I'll pull that sob in the morning and have it rebuilt. If not, then it isn't the issue.
Do these trucks have an in tank lift pump that could be going bad?

The grid heaters draw massive amounts of voltage. They heat the intake air so the engine will start easier.

http://www.cumminsforum.com/forum/9...5-voltage-drop-lights-dimming-cold-start.html

 

[Common]

Edit, just read it was slow cranking.

 

[michael_d]

Country_hick, I have essentially eliminated the grid heater as a potential problem by unhooking the wires going to it but seeing zero effect on the starting issue.

 

[country_hick]

If your grid heater is eliminated the starter and batteries are likely culprits.

There is one other thing that can cause this kind of trouble. Corrosion. It could be on the battery terminals. Take the battery terminals off and clean them up.

You could also have corrosion on the wires that go to the starter. Take the wires off the starter and clean up the connectors. Even a slightly rusty nut can create electrical disruption and cause slower starting. I have even seen major corrosion where the wire that goes inside the starter was bolted to so much white corrosion that the starter would not tun over. Just a little bit of non-shiny on brass can also stop electrical flow.

 

[zfaylor]

Pull the cables and inspect them really well. While they are off clean the terminals on everything religiously. Pull the starter. If your local napa has a machine shop they can tear it apart and check everything out. It costs me nothing to have my napa tear down and inspect. Had an alternator that looked and tested good every time. Batteries kept going dead. Napa tore it down and found the brushes were just barely making contact enough to pass tests but not enough to charge. Cost me nothing to have it done.