Blizare

Hey Everyone, my first post here.

1990 300e

This car runs beautifully, starts up cold no problem and has no idle issues.

BUT

I have a bad stalling problem that now occurs at anytime the throttle is pressed, OR the transmission in shifted into 2 or 3rd gear (automatic) . It will drive perfectly fine down the road , accelerate and shift and cruise at a very slight throttle pressure, but as soon as you ask for more it 'cut's out' basically.

Been through almost everything,

New fuel pumps x2
fuel tank screen removed and cleaned
fuel filter
spark plugs
Wires check out,
injectors removed and cleaned
a/f adjusted to 50%
Distributor rotor is Mercedes/bosch part. Beru cap Replaced rotor bracket.
Have spare EZL and MAS and ECU with no differences noted with any parts

Any suggestions? Something that has to do with the transmission being in a certain gear? thats the part I don't understand. ugh.

Blizare

I've read every post that comes up when searching for stalling but nothing specific to the throttle pedal

optimusprime m1

Replace the OVP relay ,and it will solve this problem .

Blizare

I;ve got a new OVP in there now and no change. I have a fuel pressure gauge attached as well and am noticing the pressure dropping when the stalling occurs , it goes from a steady 70 psi and then fluctuates between 50-60 and then as soon as you ask for more throttle it stalls.

I've retested the accumulator and it is operational, no dripping out of the line when engine running. it feels like something gets blocked inside the fuel filter and stops flow.

optimusprime m1

Have you the two fuel pump set up? .
/

optimusprime m1

I think you need to look at the fuel pressure regulator. Pull the vacumm pipe off .Do you see any pettrol? from the pipe . if you do the diaphram is split.And needs replacing .

Blizare

FP regulator checks out, no fuel in the pipe running to the intake. Also, pressure is steady at the beginning. I can drive a few blocks and then it will start jumping around.

optimusprime m1

This is fir the early type but idea is just the same , only yours will be in an other place under the cover ..see picture

Blizare

yes 2 pumps. both are new, and I have a new spare as well. The top one seemed to be making more noise than usual so I swapped it thinking maybe it was no good out of the box but still the problem persists. 1 Pump gets louder after a few minutes of running.

optimusprime m1

Fuel pressure regulator is in the engine depot .The acumulator is next to the fuel filter. Next thing i would try is the fuel pressure relay. Thats by the ovp these can be a problem .And would your engine have a potentiometer on the side of the throttle body ? Its a black box with a coill inside and the carbon wears off in time as it is moved along the contacts by the linkage for engine speed.It as 2 screws holding it to the throttle body.What is your engine is it a m104.?

optimusprime m1

.As you put your foot on the gas it operates the butterfly in the throttle body electronicaly .If this part is not working right it will give these symptoms. A stall or flat spot. You need some one inside on the gas pedal ,then you look at this part and view if the butterfly opens , but should not shut in any possition when you they have thier foot on the gas pedal,,, unles they take thier foot off the gas ...Make sure it in park hand brake on fully, dont stand in front but to the side of the car. Keep safety in mind allways i will get a picture to show you ..

optimusprime m1

The first one is M103 2 black boxes side by side.
The second one is M104 Its the top half of the throttle air meter

The M103 is an easy fix if thats the problem see pic for m103
But the M104 is expensive to replace and needs to be sent away to be serviced . You need to get the readings to test the m104 out .I can see the fault with the M103 after its been removed. Just remove screws.to inspect it .See picture for wear on the carbon track.

optimusprime m1

Can you say what engine you have so i need to focus on one instead of both M103 , and the m104.. Thanks . Now going back to what i said, and as the contacts travels over the carbon track it comes to a part thats worn out ,this is were you loose throttle response.and flat spot, or stall will happen. By the way you fuel pressure is fine anything over 40 psi is fine but if its 35psi its faulty

optimusprime m1

I will see how you get on, our time frame is not the same .Over in the uk its 8.30pm in the evening. Time that i had a rest .

optimusprime m1

Please let us know if you have sorted it out.

royzell

pardon my ignorance...what is the / an ovp?

optimusprime m1

Royzell Your not ignorant , its just a lack of information . The OVP is at the rear of the battery ,you need to pull out the plastic cover to get to it ..On top it will have 1 or 2 fuses ,check them .But i dont think it is the problem but worth looking at to eliminate it .But it may be bad fuse in the fuse box or vacuum leaks .It could be a host of things you need to go through them all . But Blizar as another problem .

RA6523

Blizare, did you ever get the problem solved?
I describe my e420 the stalling problem as, when trying to accelerate, serious hesitation, sputtering, followed by missing. As best we've been able to determine, there has been evidence of arc-ing inside the dist. caps. Initially thought it was caused by condensation, but after replacing caps with Beru caps, it appears the condensation is more like an oil based film.

Blizare

Problem ended up being inside the fuel tank. A lot of rust deposits kept causing the problem. Tank got pulled and dipped at a local radiator shop and has been running great ever since