my 1986 mercedes 560 sec isn't getting any fuel to cylinder #4. What is the most likely problem?

20

Asked by Aug 06, 2013 at 08:35 PM about the 1986 Mercedes-Benz 560-Class 560SEC Coupe

Question type: Maintenance & Repair

19 Answers

is this a jetronic -K?

3 out of 3 people think this is helpful.
20

How would I know if it was a jetronic-k?

1 out of 1 people think this is helpful.

well it's a mostly mechanical fuel injection system....everyone used them, Volvo, Porsche, Fiat, Volkswagen...mercedes?, Nissan....26 parts of excellence~ think perhaps 1988 was the last year that Porsche used them to know that it is specifically the number 4 cylinder and specifically the fuel injector would have me takin' that one apart to find the blockage~

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http://en.wikipedia.org/wiki/Jetronic

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jeez....looks like you DO have a K-jetronic....and that was just a wild burro guess~

quite a few of my former cars had the jetronic...VW Quantum, Datsun 810, Fiat 850, Nissan Altima Volvo 240~ I should be able to speak with some authority on them, but haven't had trouble with ANY of them....had an 5 cylinder Audi with a bad thermo-time switch, but my involvement WITH them has been minimal~

1 out of 1 people think this is helpful.
20

Here's a pic of the engine. OK, I will look at the line leading to that injector, and the injector itself for blockage or problems. Thanks!

1 out of 1 people think this is helpful.
22,575

I agree with Roy, I think there might be a blockage in the injector.

2 out of 2 people think this is helpful.
18,485

who says no fuel, a misfire can be no compression. if no fuel it would be the injector tip clogged or faulty injector!

2 out of 2 people think this is helpful.

OY, that's definately a jetronic~~!

1 out of 1 people think this is helpful.

the way these things work is the "fuel distributor" pressurizes each injector, which has a release that will let go when the pressure gets to be sufficient to "spray" the fuel in~....jeez, change the fuel filter~

1 out of 1 people think this is helpful.

Good point 7Jimmy7, this may NOT have come through the fuel...I'd be takin' that bad boy apart on my workbench and spraying it with some volatiles that would probably get you high if there wasn't proper ventilation~

1 out of 1 people think this is helpful.

Gasoline is pumped from the fuel tank to a large control valve called a fuel distributor, which separates the single fuel supply pipe from the tank into smaller pipes, one for each injector. The fuel distributor is mounted atop a control vane through which all intake air must pass, and the system works by varying fuel volume supplied to the injectors based on the angle of the air vane, which in turn is determined by the volume flowrate of air past the vane, and by the control pressure. The control pressure is regulated with a mechanical device called the control pressure regulator (CPR) or the warm-up regulator (WUR). Depending on the model, the CPR may be used to compensate for altitude, full load, and/or a cold engine. On cars equipped with an oxygen sensor, the fuel mixture is adjusted by a device called the frequency valve. The injectors are simple spring-loaded check valves with nozzles; once fuel system pressure becomes high enough to overcome the counterspring, the injectors begin spraying.

1 out of 1 people think this is helpful.

doesn't get any easier than that....no it doesn't~

here's some parts if you want to play tinkertoy~

2 out of 2 people think this is helpful.
18,485

simplest system ever produced, and reliable too, replaced by low cost plastic components with a high margin of profit , hmmmmm!

2 out of 2 people think this is helpful.
18,485

simple ,the higher the the pressure the higher the needle tip lifts ,the more fuel passes the faster it goes, the more air intake passing the disc raising the pressure! sounds like a viscous cycle, it is till you close the throttle and starve the beast

2 out of 2 people think this is helpful.

I don't know about "starve", but limit to idle speed, yeah---It about sums it up~

1 out of 1 people think this is helpful.

kinda cool that these CAN be serviced in the first place~

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