AirDog 100 Woes.

[Wayne M.]

Drewhenry, where are you at with this now? Sounds like you don’t have a diagnosis or repair yet?

to leave a early 3gen fuel system stock isn’t the answer either.

 

[Drewhenry]

Drewhenry, where are you at with this now? Sounds like you don’t have a diagnosis or repair yet?

to leave a early 3gen fuel system stock isn’t the answer either.

The guys at PureFlow don't think its their pump. They suggested-at my expense-purchase a new harness, which I did along with new batteries.
Same damn problem. Fuse blows within 20 seconds of turning engine on. The new harness plugs into the ECM for the stock pump-the old harness did not. Also, with the new harness the low pressure light does not come on when the fuse blows, indicating the AirDog is no longer functioning.
Multimeter shows 12.5 volts from the batteries with the engine off and 14.6 with engine on. Dragged myself under the truck and checked the harness plug to the pump. 12.5/14.6 also.
Seems to me like just another case of a company not wanting to honor their warranty.

 

[Ozymandias]

12.5 seems low to me, no more then 50% charge.
Either your batterys need a good charge or replacement.

 

[Drewhenry]

12.5 seems low to me, no more then 50% charge.
Either your batterys need a good charge or replacement.

They are hooked up in parallel like damn near all other diesel pickups. Gives you more amps at the same voltage.
Try again.

 

[Wayne M.]

Drewhenry, precisely which fuse is blowing? What number/ location?

 

[Drewhenry]

Drewhenry, precisely which fuse is blowing? What number/ location?

The fuse on the AirDog harness.

 

[Wayne M.]

The fuse on the AirDog harness.

I am not familiar with the air dog, so I just downloaded the 30 page instruction sheet https://pureflowairdog.com/pdf/183993
I see that fuse.
To properly diagnose this, you’re going to need a pressure reading at the CP3. Summit racing has a small liquid filled gauge and a hose barb tee adapter. I strongly recommend plumbing that in to ensure a proper reading there. If the Air Dog regulator Is sticking, it’ll surely blow a fuse. Once you determine the regulator is working right, I would use a DVOM to measure the air dog’s amp draw on that fused circuit.
The way you describe how it blows the fuse under a certain condition leads me to a variable, and that could be the regulator or something that causes a condition change.

 

[Ozymandias]

They are hooked up in series like damn near all other diesel pickups. Gives you more amps at the same voltage.
Try again.

Actually it's parallel.

And 12.5 stays 12.5, that's not a good charge.

 

[Drewhenry]

Actually it's parallel.

And 12.5 stays 12.5, that's not a good charge.

Reference an post on 1-Aug-2007 by member jwc9 addressing this issue.

How is 12.5v on a 12v battery "not a good charge"?

 

[AH64ID]

How is 12.5v on a 12v battery "not a good charge"?

Assuming you have a standard LA automotive battery 12.7V is fully charged. 12.5V indicates only an ~80% charge. They should be higher with a good charge.

Something has drawn your batteries down, or they are old and not holding a charge.

If you have a good charger I would charge them and see what happens.

 

[Wayne M.]

Getting off track here. This has nothing to do with his issue- either that pump is locking up or dead heading causing the amp draw spike.

 

[JR]

12.58 is around 90% charged. Type and accuracy of voltmeter can make a real difference.

 

[Drewhenry]

12.58 is around 90% charged. Type and accuracy of voltmeter can make a real difference.

Using a RadioShack on-sale-special because I misplaced my FLUKE

 

[AH64ID]

Getting off track here. This has nothing to do with his issue- either that pump is locking up or dead heading causing the amp draw spike.

But it appears to be voltage related, which is odd since higher voltage means lower amp draw, but his isn’t doing that.

There is a good chance they are just low form lack of charge due to the issue.

 

[Wayne M.]

Drewhenry, here’s a link on how to measure amperage with any digital multimeter.

https://www.google.com/amp/s/www.hagerty.com/media/maintenance-and-tech/measuring-current/amp/

 

[Wayne M.]

But it appears to be voltage related, which is odd. Higher voltage means lower amp draw, but his isn’t doing that.

There is a good chance they are just low form lack of charge due to the issue.

Not impossible, but a long stretch.

 

[AH64ID]

Not impossible, but a long stretch.

But it’s still only blowing at running volts.

Could disconnect the alternator (control and hot wires) to see if the issue goes away, or run it off another battery.

 

[dieselshadow]

Centrifugal pumps (and similar non positive displacement pumps) typically draw more amps at full flow. When deadheaded, they draw less, such as no flow and/or relief valve lifting. A positive displacement pump pushes the same amount of fluid per revolution but amp draw will vary with pressure. More pressure all the way up to relief setting is max amps. Take this with a grain of salt as I am not familiar with the pump in questions design criteria or how the fuel is flowing in these different scenarios, key on/engine off vs engine running.

 

[TFucili]

Devise a way to isolate the pump from the truck electrically, and test.

 

[p-Bar]

pull it out of the truck and bench test it