Petrol Diagnostics

Post a Response

Mercedes Sprinter 2.7 2003 - Fuel pressure reading #

Posted by Andy Broomhead on February 6, 2015, 8:40 pm

Year of Manufacture *: 2003
Engine Size and Code *: 2.7
( Optional ) Scanner Used: Modis
( Optional) Fault Codes: None

This was towed to a local garage with suspected run out of fuel. Garage put in a couple of gallon and changed the fuel filter, owner had been trying to bleed it at injector 1 and (luckily) found no fuel pressure
I had about 10 codes with low pressure, injectors open, cmp open circuit, ckp/cmp coherence, glow plugs etc. Most look like they have been created by owner over the last week of "checking stuff"
All clear except glow plug cylinder 3, and here is where it gets odd
Live data all looks good on cranking except rail pressure reading is VERY high. It switches between 416 and 922 Bar on ignition and rises to 2010 on cranking.
I know this is not possible so check scanner is set to Bar and not PSI, it isnt. I put a meter on sensor and on ignition it is reading .5volt which is about correct. live data says between 416 and 922. Out of interest I put on a signal generator at 1.2Vand crank. Live data says stupid pressure and engine doesnt fire.
But in all of this the ECU has not flagged one code for over pressure??
I would like to put on a different scanner but it has the round diag socket and I only have a Modis that will connect to that
Snapon dont know of any problems with this engine software and the Modis
Any thoughts

Re: Merc Sprinter Fuel pressure reading Sorry Wrong location!

Posted by aidan birley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on February 6, 2015, 9:31 pm, in reply to "Merc Sprinter Fuel pressure reading Sorry Wrong location!"
Aidan Birley

Hi

This does sound like a scanner issue, possibly wrong system (i think there is a choice on that year)?? is all other live data OK ?

You need to get this on another scanner, but hat is the voltage on FRP sensor when cranking ?

what happens if you give it a sniff of easy start ?

Cheers Aidan

Re: Merc Sprinter Fuel pressure reading Sorry Wrong location!

Posted by Andrew Pethig on February 7, 2015, 8:35 pm, in reply to "Merc Sprinter Fuel pressure reading Sorry Wrong location!"
Edited by board administrator February 10, 2015, 1:01 pm

0.5 volt is the correct voltage for a non running engine, when you crank it the voltage should rise as the pressure does, if the computer does not see the correct pressure it will not fire the injectors.
You can not trust your scanner so i would go back to basics and make sure the fuel filter is full up and make sure the fuel line to the pump is also full, not sure if the merc has a low side pump in the tank some do some do not, i like to look at wiring diagrames to establish this if it has got a pump in the tank you can power the fuse or jump the relay to make sure you have fuel in the line or . use a electric pump on the fuel line to the pump and suck up the fuel from the tank , and once you have a full filter and a solid supply to the filter , the low side pump in the engine bay will be able to do its job ( if its got one).

do this and a few whiffs if easy start will get a diesel that has run out of fuel started right up, if thats the only problem.

« Back to index

[ Petrol Diagnostics ]