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Discussion Starter #1
So my recently new to me truck truned on the cel last week. Came up as a P0089 which is fuel regulator performance. Cleared it, and it returned later that night. I did some searching and investigating today. Most of the diesel forum guys coincide this with a surging idle, comparable to a big cam in a gas engine. If anything I noticed a very slight occassional stumble at idle while wating at stoplights. I never thought too much of it until the CEL came on. Looks like sawpping the regulator out is a little over $200 in parts (bosch) and anywhere from 3-8 hrs of my time.
I was curious about the location and cost of that pressure sensor, since I'm not noticing a big driveability problem. There is also a bulletin about some bad terminals on that plug as well. Anyone been through this? I hate to spend the $200 and more importantly time chasing down a gremlin.
 

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bobbing for fries
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What version of the Dmax is it? LB7, LLY, etc...

The idle lope only happens when fuel pressure is actually too high. There is a video of this in the diesel rice thread. Kid wired in a switch to raise fuel pressure at idle, and sound cool:homer:. But a bad regulator can do this as well.

Usually with a p0089 and a stock engine, you will hear a slight idle surge, if anything.

If yours is a LB7, the terminal fix is to install an LLY harness.

Pressure sensor location varies, depending on model.
 

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bobbing for fries
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Check the regulator wiring first, its easy to get to. Regulator is on the back side of the fuel pump, located in the engine valley.

Fuel pressure sensor is on the drivers fuel rail behind the a/c compressor.
 

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Discussion Starter #5
So it's possible to disconnect the plug without all of the disassembly required to change the regulator?

The cel went out almost immediately after I started pulling a 7000# load and returned within a few miles of disconnecting
 

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bobbing for fries
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The engine runs higher fuel pressure when loaded. Seems like a sticky regulator from what you are saying, but check the wiring just to be sure. I would replace the connector anyway if you replace the regulator.

You should be able to unplug the regulator with a long pick. Look behind and to the left of the thermostat housing. Fuzzy cell phone pic is of an LLY, but will be similar to yours. The connector may be on the back of the regulator, not on top like this one. It will still have one yellow and one purple wire.
 

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