QuestionQUESTION: I got a 91 Mercedes 420 SEL, crank no start. vehicle seems to hesitate under load/acceleration.I got spark at spark plug wires, previous owner replaced the plugs with Denso plug. I can here the fuel pump buzzing when key on. Did check pressure at the fuel distributor,by removing fuel line going into it, lot of pressure when crank, no fuel pressure gauge was used.Please help
ANSWER: are you getting fuel to the injectors pull one of them and see if you are getting a spray pattern to your injectors if not it could be your ovp protector is fried your crank sensor is fried or you have bad compression or too much air going to your airflow sensor check for all tubes going into your air intake system after you pull your injectors
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QUESTION: what is a ovp protector? I've checked my crank sensor(on the transmisson, it is ok, got spark to the spark plugs#all 8 cylinder)I disconnect the crank sensor and re-check, no spark at the plugs.I know for sure is not the crank sensor on the transmission.
I removed one injector and check for spray pattern while cranking-no gas at all, if I manually depress the air flow plate downwards, then the injector start to spray fuel.Please what you think is wrong this?
Note-No intake leak at all, compression above spec-no problem.
Answeroverload valve protector it is a silverbox on passenger side it will have a relay 10amp fuse on it
check the fuse. Otherwise try jumping your fuel pressure relay it will be by the ovp it is a black box jump with a wire terminals 87 and 20 or 30 (it is the one behind 87 towards firewall)
jump it and you will hear a buzzing then try to start car. if not try gas down the airflow sensor and try to start car. It should start. I would be skeptical about your Fuel pressure regulator first and replace that or adjust your airflow sensor plate. First thing I would do is take off air flow sensor and check for cracks on the boot that connects it to the throttle body they crack between the seams it is fairly easy then clean your throttle body also you need to just take off your air cleaner and need a 10 mm and a screwdriver and it should pop out.
