92-300 ce won't rev over 4500 rpm - PeachParts Mercedes-Benz Forum

92-300ce · #1 10-28-2002, 03:24 PM

Hi all,
I have a problem with my girlfriends '92 300 CE with 124k km's on the clock,actually,it's a couple of things that are not normal:
-It won't rev more than 4500 rpm,after that it feels like a governor kicks in (engine cut's out,hesitates).
-I have to start it with the trottle pushed in half way,without it fires and dies instantly.
-Bad fuel economy,can't tell exactly the MPG but it's using a lot of gas.

At first I suspected the OVP-relay,replaced it with another from a 500 SEC,but problems stayed.Then I replaced the fuel-pump relay(after I fried it while measuring power on the 2 fuel pumps underneath) for a new one,still the same symptoms.
Also I checked the sparkplugs,they were ok,and the distributor and rotor,ok too.

I asked 2 local Mercedes mechanics what they think that could be the problem,but they don't have a clue,other than to check the above mensioned parts.
Could it be the fuel filter? Or any other suggestions?

Thanks in advance for helping me with this problem.

Greets,
Jan
The Netherlands.

#2 10-28-2002, 04:25 PM

When was the last time you replaced the fuel filter?

Good luck,

downsmith · #3 10-28-2002, 05:16 PM

I had a similar problem with the solution being the fuel pump.

There are two tests to look at fuel pump fitness: Fuel pressure and fuel volume. Could be your pump is delivering adaquate pressure but cannot keep up with demand.

92-300ce · #4 10-28-2002, 06:53 PM

Ehm,fuel filter is still the original,I'm gonna replace it tomorrow,if that doesn't fix the problem I will bring it to the shop for testing the fuelpumps.Thanks for the quick replies !

Jan

dakota · #5 10-28-2002, 07:51 PM

I was going to suggest maybe the cat was plugged, but I don't think you have those on the European cars, eh?

G-Benz · #6 10-29-2002, 09:54 AM

Sounds more like the fuel pressure regulator...truthfully, in a fuel-injected system, pressing on the pedal while starting really does nothing...it works because there may be some fuel left that hasn't been backwashed into the system by the regulator.

As far as not being able to rev past 4500 rpms. Are you doing this while in "Park"? This IS a MB design, and the engine management system shuts down a couple of cylinders to prevent overreving the engine with no load...my M104 does the same thing.

pentoman · #7 10-29-2002, 07:30 PM

Quote:

Originally posted by dakota
I was going to suggest maybe the cat was plugged, but I don't think you have those on the European cars, eh?

In the UK, we do from.. I think, 1991.

92-300ce · #8 10-29-2002, 07:35 PM

@ G-Benz:
Sorry I didn't mention this before,the car has a 5 speed manual transmission.Fuel pressure regulator,where can I find that part ?

Today I got the fuel-filter,tomorrow I'm gonna install it,tonight I found out that while driving,as in every gear,it cuts out at 4500-4600 rpm,that's 169 kms/h top speed (wow)...but when I go from 5th to 3th it easily shows more than that,so the car is able to rev up more.More tomorrow,after the fuel filter installment.
By the way,just as an interesting thing:I payed (converted to us $) 143 for the fuelpumprelay and 35 for the filter,after discount but with tax.Same price in USA or ?

Jan
The Netherlands

92-300ce · #9 10-29-2002, 07:42 PM

@dakota

This one has a cat,actually,I saw two of them right in the beginning of the exhaust.(Those small units after the exhaust manifold).If that's the case I take them out,since this car has been Aircared today with these catalystic converters on it :-)

Should give it a nice roar out of the tailpipe too...

92-300ce · #10 10-30-2002, 07:59 PM

Ok,I replaced the fuelfilter this morning,but the problems are still there.I noticed at first after I put the key on the ignition stand for 4 times to fill up the filter with gas,that after I started the car it started smooth and after it warmed up a bit I got at least 5500-600 revs easily,so I took it out for a testdrive and that was that.
4500 rpm,and it cuts out.
So I'm gonna make an appointment at the local Mercedes dealership and they can play with it,see if they find the problem.
BTW,what's that thing besides the fuelfilter with a membrane(right word?) in it,a Bosch part,it has a line straight from the fueltank-then the thing- and then on to the filter,any ideas?

Jan
The Netherlands

#11 10-30-2002, 08:42 PM

Just a thought ---

Are any of the indicator/warning lamps on? I think when something in the ABS system has failed, the revs are limited to 4500 RPMs. Pushing past 4500 RPMs and it feels like a governor kicks in and keeps the car from passing 4500 RPMs no matter how much gas you give it.

In my E420 it turned out to be a blown fuse in the black box with 4 allen screws (on the passenger side by the firewall). This had the 4500 RPM limitation you're talking about, and the cruise control didn't work, and the ASR dash light came on.

I suggest checking those fuses; you'd hate to have the dealer tell you is was just a fuse and charge you 1 hr diagnostic time! That's what my benovolent dealer did!

amg280 · #12 10-30-2002, 09:22 PM

Sounds like an electrical glitch or sensor that tells the car is moving, and is not stationary, and can rev past the neutral governed 4500 RPM. Its most likely on the transmission itself.

dakota · #13 10-31-2002, 01:13 AM

My E-Class Bible says:

Problem-
M104 Hesitates, cuts out or is difficult to start.

Possible cause, suggested repair-
a) KLIMA circuitry defective due to moisture/corrosion

b) Defective tach. Disconnect tach to check.

c) Ign spark jumps to grnd inside caps(s). Check for burn marks.

d) Loose eng coolant temp sensor connector. replace.

e) Faulty eng managment grnd connections. trace and repair.

f) Loose connections on CIS-E harness. check and repair. if harness checks ok, CIS-E contol module.

g) Loose fuel pmp gnd connection in trunk. check and repair.

You'll have to decide if this described problem is close to your problem.

BTW, that's probably the fuel accumulator next to the fuel filter and 2 pumps.

Also, like John, I'd suggest you replace those fuses with NEW fuses...even if they look good.

92-300ce · #14 11-05-2003, 12:15 PM

A year later:problem is still there,I left it this way last year because the car passed the emissions(because they didn't check:) and I replaced already so many parts that I got tired of looking at it.Also found out that somebody else(Mercedes shop) already played with it before my girlfriend bought the car already,but couldn't find it either.
But this year it failed emmisions:co of more then 10(!) where the book says 0,5 %.
BTW:Car is a 92- 300 ce U9 m103 with 5 speed manual gearbox,no airco,KE-jetronic.

Yesterday warmed up the car,shut it off,put the ignition 5 times on (for 2 seconds),full throttle,started and yes ! :7000 rpm for a second,then it went back to the dreadful 4500 rpm and hesitate again.Lot's of black smoke,bad mpg but it drives ok and starts fine.
So in my opinion it has to do with not enough fuel or fuel pressure.Last year I replaced already the filter,both the pumps are working,I tested this with some sort of stetiscope and heared them both ,although one had a slightly lower tone.

Since I don't have the tools to measure the fuel pressure is there another way to determine if the pumps are the fault or that the fuel pressure regulator is the problem?

Any other suggestions are very welcome too,since my girlfriend drives now a bike and doesn't feel too happy.

Thanks in advance and
greets,Jan

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