Community Forums

Pirate_Jerry · 10-23-2020, 03:26 PM

Hi,

I've got a low power situation that I'm trying to diagnose with the help of the local Cummins shop. The problem doesn't occur except under a sustained heavy load which I discovered while pulling a trailer in Colorado. I live in Illinois and we just don't have those kinds of grades. The shop can't find anything wrong. No codes.

Is there a scan tool out there that will record 60 seconds of live data that isn't $3k?

2001 HR Scepter Cummins ISC

Ljwt330 · 10-23-2020, 06:50 PM

You might check out Blue Fire .

https://bluefire-llc.com/website

Don’t know about recording as the info is displayed via Bluetooth to a personal device like your phone, but you can witness the data in real time.

Pirate_Jerry · 10-23-2020, 10:08 PM

BlueFire might work. After looking at their website I dropped them a note with a couple questions.

Toribk · 10-24-2020, 04:21 AM

Can you give us a bit more information about the symptoms of the low power your experiencing.

Pulling a trailer in the Colorado mountain range with what Im assuming (by your year coach) with an ISB 5.9 or 6.7 could be a challenge without maintaining proper gear selection ascending steep grades.

Pirate_Jerry · 10-24-2020, 06:39 AM

2001 HR Scepter Cummins ISC 8.3

A low power issue manifests itself on a long uphill climb. After about 25 sec, the boost will drop from 25lbs to 10-15lbs and the coach starts slowing down. It’s just like someone flipped a switch. A friend in a similar coach with the same motor reports plenty of pedal and could easily pass me. The problem only presents under heavy sustained load and after 25 sec. Downshifting keeps the RPM’s up but if I hit the 25 second mark, boost and power drops.

Both fuel filters have been changed twice and I've been treating the tank for algae.

The local Cummins shop can’t find anything wrong but I’m not sure they tried very hard. I live in central Illinois and we don’t have the terrain that they do in other places so I’ve not been able to reproduce the problem. We’re headed to Kentucky in a week and I’d like to find a way to record this.

The key here is that I have good power for about 25 seconds and until that point I’m maintaining or can accelerate. My theory is that I’m losing fuel pressure and it takes that long to drop to the point that anything happens.

hypoxia · 10-24-2020, 08:00 AM

Quote:

Originally Posted by Pirate_Jerry

Is there a scan tool out there that will record 60 seconds of live data that isn't $3k?

2001 HR Scepter Cummins ISC

Bootleg Inline 6 adapter with Insite 7 & you can see and record everything Cummins can. I run it on the dash along with Silverleaf splitting a 15" laptop screen.

https://www.ebay.com/itm/Cummins-INL...IAAOSwIJlZ9U~7

Ljwt330 · 10-24-2020, 09:51 AM

Quote:

Originally Posted by Pirate_Jerry

2001 HR Scepter Cummins ISC 8.3

A low power issue manifests itself on a long uphill climb. After about 25 sec, the boost will drop from 25lbs to 10-15lbs and the coach starts slowing down. It’s just like someone flipped a switch. A friend in a similar coach with the same motor reports plenty of pedal and could easily pass me. The problem only presents under heavy sustained load and after 25 sec. Downshifting keeps the RPM’s up but if I hit the 25 second mark, boost and power drops.

Both fuel filters have been changed twice and I've been treating the tank for algae.

The local Cummins shop can’t find anything wrong but I’m not sure they tried very hard. I live in central Illinois and we don’t have the terrain that they do in other places so I’ve not been able to reproduce the problem. We’re headed to Kentucky in a week and I’d like to find a way to record this.

The key here is that I have good power for about 25 seconds and until that point I’m maintaining or can accelerate. My theory is that I’m losing fuel pressure and it takes that long to drop to the point that anything happens.

You have a CAPS injection system with lift pump. Your symptoms could well be from lack of fuel under specific circumstances, as you described. If you can install an electronic fuel pressure gauge between the primary filter and the main pump, you can monitor the fuel pressure under those conditions. The gauge should read negative pressures, ~-5 psi, under normal operation. If you discover that the negative pressure is less when under long climbing conditions, then you are starving the main pump of fuel, possibly from a leak in the lift pump or an obstruction in the line to the lift pump.

Roy1 · 10-24-2020, 01:12 PM

One of the best improvements you can do for your isc is to install a fass fuel pump . I added one to my coach that had less then 20,000 miles on it believe me climbing long mountain grades made a noticeable difference. I can now climb with out floor boarding and at a higher Rate of speed. Also by adding a fuel pressure gage you will be able to observe your fuel pressure as you drive which will be positive pressure rather then negative like you now have worth every nickel. My pressure gage is connected at the 2 nd filter before the fuel goes to the caps injection pump.