Need Help?

1994 Mercedes-Benz 300 Series Base 4dr Sedan 3.2L Auto

1994 Mercedes-Benz 300 Series
Do you own this car?
Estimated Mileage
 Miles
Enter current mileage for most
accurate info about this vehicle


Track Your Service Records
Get Recall Alerts
Get Updated Value Estimates on Your Car.

back to question list

Ask the Community

Ask Our Auto Mechanics


June 14, 2011, 10:38 am

Albert C
 

Question: Ignition ON vs CRANCK

E.
I disconnected fuel line fron entry point injector house and stuck line into bottle......
turned ignition ON (did not cranck) and fule pump BUZZES 5 seconds and a small amount fuel fills bottle during buzing period.
Again its a small amount not under a lot of pressure..............
if I cranck engine a few rotattions, then would see what you describe Copious amounts
screaming into my bottle ???
At least this test has proven no clog in the line.....now if cranck should determine pressure bulids up as expected ???
Tx
Albert


June 15, 2011, 11:38 am

Elizabeth K
Expert Mechanic

Yes, you don't get the pressure in ON that you would in CRANK. Here's a website with a great description of how to test your fuel system, scroll down to the paragraph that starts with "Checking the pump is simple." (and don't worry that it is describing an L-jetronic system, for the basic fuel pressure, it's close enough):
http://www.hiperformancestore.com/Ljetronic.htm


1/1 users found this helpful.

June 16, 2011, 11:42 am

Albert C
 

E.
Thanx for reply.
In fact I tested first ON and then CRANCK.....with same result....
there is no obvious increase pressure......
so from clog...would point to defective fuel accumulator..
from quick checking, accumulator in this K jettronic in fact critical to create the pressure required to push through injection distributor till flows out injectors in to pistons....
would you agree my conclusion...???
will check website you indicate.
Tx
Albert


0/0 users found this helpful.

June 16, 2011, 2:03 pm

Elizabeth K
Expert Mechanic

If the fuel pump comes on, but the pressure is not sufficient, then it sounds like the fuel pressure regulator or the fuel pump are bad, not the accumulator.


1/1 users found this helpful.

June 23, 2011, 3:05 pm

Albert C
 

Hie E
Tx
Checked that website hoping would tell me how to measure proper voltage for pumps...
does not.
this model 300te has dual pumps,,,,one next to tank...other floating rack mid under chassis next to filter and accumulator (regulator)

pump has two wires...one brown skiny other thick multicolor...
which would i disconnect and with voltmeter (key ON position) check voltage ??

is it voltage feeding in to pump I am measuring or voltage pump is receiving in order to operate properly ??
tX
aLBERT


0/0 users found this helpful.

June 23, 2011, 4:00 pm

Albert C
 

Hie
update
I checked both pumps...at least make sure running....
both upon turning contact ON....they HUM few seconds and had hand touching them....felt vibration while hum lasted.....

what is causing low pressure yet to figure out........


0/0 users found this helpful.

1 2 
Ask our panel of certified auto mechanics a question. We pay for their advice so you don't have to



My Auto Score

See the free AutoCheck score

Meet The Experts
Kim Perrin
Kim Perrin is our resident mechanic here at DriverSide. Kim worked as…
Tyler Orr
Tyler Orr is an expert in German and Japanese cars and has been a mechanic …
Elizabeth Kriesten
Elizabeth Kriesten worked as an automotive technician for several years at Dodge…
Tips on Servicing

Car Brakes: How Do You Know When to Change Them?

By Zach Bowman For those who suffer a daily commute through heavy traffic, your vehicle's braking system can bring thousands of pounds of metal, plastic and empty Starbucks cups to a stop hundreds of times before you get to work. It goes without saying that these pieces wear out, but they do so slowly, meaning you may not notice they need attention until ...

Read more…