CEL- Low Fuel Pressure

[Bhollier]

Anyone here have a CEL for Low Fuel Pressure when in Tow/ Haul mode? The last 2 times I have been towing my trailer I have gotten a low fuel pressure CEL. Watching my fuel pressure gauge it is when the truck was in 10th gear going up a small hill is the only time this occurred. Other than these times I have had this happen one other time when we were first tuning the truck. Isn't a big concern of mine just found it odd and was wondering if anyone else had this issue.

 

[smurfslayer]

I thought tow/haul locked out the OD gears - or was supposed to...

 

[Bhollier]

I thought the same. I was thinking it would limit the truck to anything under 8th gear. It kept going into 10th when I was on flat/ semi flat ground then 7th and 8th up hills. The same light hill both coming and going to the location I was travelling I noticed that the truck stayed in 10th. It wasn't until my return trip I got a CEL for Low Fuel Pressure.

From what I can tell in tow/ haul me truck uses the gears to brake by downshifting when coming to a stop more aggressive than normal mode and tends to hold the rpm higher for longer. Also noticed that it holds a lot more boost than normal. Figured it is allow the truck to have more torque than under normal conditions. Noticed this trip my turbos making a lot more noise than on previous trips as well. The good kind of turbo noise, spooling up sounds great. My wife even noticed it over the music she was listening to.

 

[smurfslayer]

what are your RPMS when this is happening? I’d think 10th is a poor choice for towing a trailer, even if the transmission thinks so, especially as you describe going up a hill, unless you’re doing like... 80. even then, I’d think a downshift would be called for.

It sounds like you could work around this -until fixed- by locking out 10 while towing.

 

[Bhollier]

The RPM's were around 1900, no real load on the engine. Speed was 74 mph, cruise control was enabled. Once I got the CEL I did lock out 10th. I think I will keep doing this when I tow the trailer again.