Ok today car was running fine, then when I parked at a parking lot then started up again the car started right up but was continuously shaking (not vibrating). And if I gave it gas the shakes interval became shorter and the car shook according to rpms. I have recently replaces fan clutch, fan clutch bearing bracket, radiator, top timing cover seal. All of these projects have worked perfectly. I dont want to jinx it but I think I have solved my overheating problem. Now, back to this shaking problem. When i accelerate up to 100km/hr I cant feel the shakes, probably because of high rpms but when I slow down to 40-60km/hr the shaking continues.

The last time this happened was a few months back, my fuel filter started to leak gas and finally burst open. I replaced filter and some fuel lines. The problem went away. Also the shakes also occur in Park, so I know it has nothing to do with drivetrain etc. I remember using a carb cleaner additive, added it to the gas tank and the shakes seem to go away, this was before I replaced the filter.

Can the symptoms I have described occur because of a fuel pump thats not turning on sometimes and turning on other times.

I have also considered bad injectors, and a bad relay. Can anyone tell me the location of the fuel pump relay?

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190e 2.6 1990. 300,000 KM
C230 K 2000, 130,000 KM

Olde Timer First Rule: Be Ye Certain Thy Ignition Functioneth Before Ye Suspect Thy Fuel System.

Bad spark plug(s) wire(s) or rotor? If a cylinder 'misses' it will cause a shake, and ruin your catalytic converter also.

Best Regards,
Jim

Whereas a misfire would cause the engine to 'shake', this should not normally be transmitted to the frame/body to make the car shake. However, even a properly running engine will cause some sort of shaking of the car if a motor mount has collapsed. Look for signs of recent leakage around them, and use the 13 mm bolt-head test to check.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

Check your engine mount for worn?

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95 R129
04 Infiniti G35.5 BS
10 X204

I assume this happens in neutral.

Our 1994 Grand Marquis (207k miles) would shudder and vibrate quite noticeably, especially with increasing throttle at low speed with the torque converter locked into direct drive.

My daughter and I changed the old plugs (100+k miles on them) which improved the vibration, but did not eliminate it. We then changed the plug wires (207k miles on them) and finally, the vibration is gone. Smooth as silk.

That was my experience. Of course, it could also be the motor mounts.

I believe that a 'weak' cylinder will introduce enough disturbance into the normally smooth engine so that it becomes noticeable, even with good motor mounts.

My bet is still the problem is ignition related, but I am not betting the farm...

I hope we find out.


Best Regards,
Jim

I don't know about the Marquis, but MB uses fluid-filled mounts that essentially lose all effectiveness once dry. Quite a different effect from the slow hardening of old rubber, and it could happen rather quickly.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7