All,
I have been struggling with troubleshooting my IC Pump problem. It's not the normal failed pump or fuse problem.

Symptoms

• The symptoms are identical to the IC Pump problem (have had this before and fixed it - I inadvertently caused this when I tested autocrossing it with the traction control disabled at the electrical block by the battery)
• When the car gets hot, after 3-4 pulls, the super charger stops engaging
• Pump is not on when car runs, even when hot, even when RPMS come above 2000

The Problem is Not

• The Pump
• The Impeller
• The ground
• The Fuse

I Know Because I Have Tested

• Connected a jumper wire directly to the battery to manually get power to the pump. When I do this, I can drive the car all day long and the SC never cuts out. As soon, as I disconnect the jumper wire, the water gets hot and the SC cuts out within three hard pulls. Happens like clockwork [1].
• Have done the relay jumper always on mod [4]. Wired pins 2 and 7 together on the N65 block, which causes the pump to come on and operate when the key is in the on position.
• Have logged intake air temps. The SC cuts out at ~205F and will come back on when intake air temps drop below `185F. With the pump hard wired, or the relay always on mod, the intake air temps are pegged at ~120F, which is exactly as expected if the pump is working and the impeller is in tact.
• Have done (temporarily) the fuse always on mod [2] (doesn't work because it's the relay).
• Have connected a 2 amp charger directly to the IC Pump wires and the pump comes on and pumps water when I squeeze hose (so I know the pump is good. Video for good measure [3].
• Tested power on both sides of fuse 13 (IC Pump fuse), so I know power is getting through the fuse, getting 14 volts on both sides of the fuse (also did the mod above just to make sure)
• Changed the fuse just to make sure
• Tried revving car about 2000 RPMs for a while to try and get the pump to come on
• Have been feeling the pump with my hand (so I am definitely sure when it is coming on and not coming on)

Open Questions

• Could it be the relay on the PBU?
• Should I take it to the dealership to try and troubleshoot? (I fear they will not come to the right conclusion)
• Should I just run a separate circuit to the pump?
• Has anybody else had this problem?
• How the heck do I test the relay?

Other Notes

• The IC pump is a Johnson CM30 and it is working fine [1]

Next Step

• Figure out how to replace the relay

I'm open to any and all ideas. My brain hurts, never seen this one before :-)

[1]: https://www.dropbox.com/sh/0p9r9m8ov...fa8flFvEa?dl=0
[2]: [3]: [4]: https://www.crossfireforum.org/forum...-question.html

 

A running pump means nothing, the impeller can break / crack and no pumping is gonna happen. Take the hose off the outlet and power the pump to see if it does anything for real. My gallery has many articles and photos when I did pump testing and evaluations. Enjoy Woody

 

The pump "isn't running" the pump "will run" when I put an external power source to it. AKA, it's not getting power from the car itself. I am going to connect an external source of power again, and feel the hose to make sure it is flowing. I am about 80% sure this is not the problem. The problem appears to be the relay. Any insight on the relay would be much appreciated.

 

For good measure I tested your theory. I wired it up with my battery charger, applied current, and watched it pumping coolant. It pumped with good pressure for a long time. It's impossible that the impeller exploded. Also, the noise is perfect - I can hear it perfectly because the car is not even on. Finally, I can hear the motor change speeds as I squeeze the main hose, essentially applying load to the impeller. This is enough data to conclude that the pump is working and in good condition. It's definitely the ECU/PBU or the relay. I suspect I burned it out somehow because about a week ago, I had a dead battery and connected the charger backwards to the battery (long story, but there was dirt and I thought he - was a +). Smoke came out of the charging cables, and the charger made a God awful noise. I quickly unplugged it, but alas, I am probably paying for that mistake. I have never done that in my entire life until now :-(

 

 

I like your idea of checking the codes. I didn't even think that the computer might be detecting something that I can't. That will be next on my list.

I just finished testing by jumpering the hot side of the pump directly to the positive side of the battery. This forces the pump on. When I do this, the car runs perfect and the SC never cuts out. I drove it around for 30 minutes after it warmed up this morning and it drives great. As soon as I disconnect the jumper wire to the IC pump, the SC will cut out after three or four hard pulls which engage the super charger (and of course heat up the coolant).

I am 99.9% sure it's the relay, or more specifically the computer not detecting that the water is getting hot and needs to come on. Either way, it's at the relay. The fuse is good, the pump is good, it's something in the computer or relay, so back to your initial suggestion, I am going to check for codes.

 

 

I just did some logging today with Torque. Long story short, the intake air and coolant temps are dead on. The super charger comes on as long as the intake air temp stays below ~205F. Once it goes above that, the SC cuts out until the temps come back down to below ~185F. Then, the SC will engage again, unitl the temps go above 205F. I did this test several times. Then, hard wired the pump, and the intake air temps PEGGED at ~120F. They would fluctuate a bit, up and down maybe 3 degrees depending on how hard I got on it.

Then, I did another test, and wired pins 2 and 7 on the N65 block together. The pump comes on like a champ, every time the key is in the on position. This leads me to believe it's definitely the relay. I am happy, now I just need to figure out what to replace. It "seems" like I might have to replace that whole part the the N65 block plugs into. Not sure about that yet...