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View Full Version : Low rail pressure, Lift pump not running


Magproapparel
01-26-2017, 10:20 PM
I have an 06 sprinter, the lift pump is not running. I can hook a hot wire to the lift pump, it will run, and the van will start. When the van starts, it shuts off 3 seconds later as if I turned the key off. It comes up with no codes when this happens. It only has P0087 when the hot wire is not hooked up to the lift pump. P0087 is low rail pressure. I have changed the fuel filter, crank sensor, cam sensor, and cleaned the egr and Mass airflow sensors. All fuses and relays are good. Does anyone have any clue what sensor controls this lift pump? Why does it shut off after 3 seconds?

It did start and run one time for 15 minutes and then shut off all of the sudden. After that, it would start, run for 3 seconds and shut off consistently.

Midwestdrifter
01-26-2017, 10:46 PM
I suspect you have a power supply issue. If your lift pump is not getting power, its possible other engine modules are not getting power either. This may explain the 3 second run time. The fuse block number 1 under the steering wheel has a history of bad connections. I would trace the pump power back through the harness to find where the problem lies.

abittenbinder
01-27-2017, 04:34 AM
When the van starts, it shuts off 3 seconds later as if I turned the key off. It comes up with no codes when this happens. It only has P0087 when the hot wire is not hooked up to the lift pump.

Your generic scan tool is only reading the fault code it has limited access to.

You will need the use of a factory grade diagnostic tool to reveal ALL fault codes, which may then give you more clues.

Conversely, lack of any fault codes when using a factory grade tool is a valuable clue in itself. You then can trust what the problem is not, with more certainty.

BTW, 3 second run time is roughly the 6 second delayed shut off time of the engine relay, after being de-energized, taking into account your ignition switch turn on and approx. cranking time.`

Doktor A

Magproapparel
01-27-2017, 03:28 PM
Thank you, what is the best alternative for a scan tool that doesn't cost 5 thousand dollars? I have done everything mechaincally that I know to do. From here it is surely an electrical problem. I just don't even know where to start! I guess this diagnostic scan tool is the first thing. Where do I get one, how much are they?

abittenbinder
01-27-2017, 05:00 PM
You don't need to buy one. You find someone nearby who has one and can help you. A group member perhaps?

Doktor A

misterbond10
01-27-2017, 11:33 PM
Sorry to hi-jack, but may I ask what led you to replace the crank sensor, & cam sensor? Also, how exactly did you go about cleaning the EGR?

I have an '06 as well

Magproapparel
01-28-2017, 04:43 PM
I've had diesel mechanics diagnose my problem both with and without a scanner. They all say it's a sensor somewhere, but no one has had any clue what it might be. I pulled the egr to clean the soot out of the valve, just for my own assurance. To the best of my knowledge, an egr wouldn't cause this problem, it would only reduce its power under driving conditions. The Mass air flow sensor would cause a vehicle to shut off immediately, I've had numerous vehicles with dirty sensors, simply cleaning them fixed them right up. Doktor A, thanks for the advice, I'll see if I can make a connection with someone, in the meantime I'll go back through the wiring harness in case I missed something.

lindenengineering
01-30-2017, 07:51 PM
I've had diesel mechanics diagnose my problem both with and without a scanner. They all say it's a sensor somewhere, but no one has had any clue what it might be. I pulled the egr to clean the soot out of the valve, just for my own assurance. To the best of my knowledge, an egr wouldn't cause this problem, it would only reduce its power under driving conditions. The Mass air flow sensor would cause a vehicle to shut off immediately, I've had numerous vehicles with dirty sensors, simply cleaning them fixed them right up. Doktor A, thanks for the advice, I'll see if I can make a connection with someone, in the meantime I'll go back through the wiring harness in case I missed something.

You will be looking for a needle in a haystack!
Methods of locating issues like this is basically refer to a decent scanner like a Snap On, with appropriate program and read and I mean READ live data!
If someone who has Sprinter repair familiarity is let loose on it I bet they will locate the problem within 30 minutes.
These are not difficult rigs to work on if you know Sprinters and have experience. So I recommend you find someone/shop to diagnose it. Cost will be about $135 to $150.
Then you can decide if you want to DIY it or have it fixed for you.
Dennis
Mechanic

Oilburner
01-31-2017, 01:11 AM
Mass air flow can be unplugged and enginr will run- for your information.

jazzbeast
04-23-2017, 02:12 PM
Magproapparel, did you get it figured out?