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Discussion Starter #1
Hello guys,

I have a problem, this morning my megane started but had rough idle and after a few seconds shut down. After a few times, when started I gave a lot of accelerator, and everything went fine. I could start it again no problem. Now it was just standing for a few hours, and no start again. But this time it completely doesn't start, the engine is cranking but no other sound. I loosen the injector screw and when cranking there is fuel coming. What else I could check? What else could be blocking the start?
 

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Technical Supremo, Platinum Member
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Air is getting in somewhere, pump the primer bulb and see if diesel sprays out from a split pipe. Check for air bubbles in the fuel pipe as the leak could be in the line under the car from the tank or if the pipe has come unclipped alongside the alternator pulley. Fuel won't drip out as the line is under vac from the injector pump on the top of the engine.
 

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Discussion Starter #3
So the split pipe is the pipe that goes from the fuel filter to injection pump?
 

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Technical Supremo, Platinum Member
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Could be but its the only section of pipe that you can put under pressure with the primer bulb. The leak may be in the pipe between tank and filter, check it carefuly if the pipe post filter is OK. Check the fuel filter cap as well.
 

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Technical Supremo, Platinum Member
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Think that pump is for an earlier injection system as the lift pump for the dTi is part of the Bosch main pump. Its the electric noise you hear when the ignition is switched on before starting the engine. Primer bulb should go hard after a few squeezes, if it doesn't its non return valve may be defective causing difficult starting. Does priming before starting make starting any easier?
 

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Discussion Starter #7
Yes, I hear a buzzing sound from the engine compartment when the ignition is switched on. The primer pump becomes harder than when the pipe is disconnected, but it doesn't go full hard that I couldn't press it anymore. Should it get completely hard?

It still doesn't start after priming the pump. However I didn't test to prime the pump while starting the engine.
Where is that non return valve located?
 

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Discussion Starter #9
I managed to start the car. The issue was that the low pressure fuel pump inside the high pressure pump was not buzzing on startup. And the fuel solenoid got only 8,5V.
I just don't know what I did that it started to work. I disconnected the round 7pin connector, and plugged it again. Then there was 12V on the solenoid, and the low pressure pump was working. It very strange :D

Sadly but the issue should appear again. What does power up the low pressure pump? Because when applying direct 12V from the battery to the solenoid, it only activates but the pump is not buzzing... The 7pin connector is only for sensors, and while it is disconnected the pump is working... The shut off solenoid always has 12V so it shouldn't activate the pump.

I don't see any other connectors for the low pump.
 

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Super Moderator Technical Supremo Platinum Member
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Surely the low pump is driven from the timing belt?
Buzzing will be a solenoid not quite triggering fully, quite likely from the low voltage.

Thanks for feedback.
Maybe worth unplugging and replugging other connectors in the engine bay.
If one is dirty others are likely to be.

There is also the old adage if it ain't broke don't fix it so choice is yours.:d
 

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The high pressure fuel pump on the Dti engine has a fuel-stop - mmobiler - fuel control unit. If it or it's wiring is faulty then it's operating solenoid motor is likely to buzz.
 

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Discussion Starter #12
Yeah, I won't do anything for now while it is working :D

The buzzing should be, because my dad has the same car and the buzzing is there. When there was 8,5V there wasn't any buzzing. But when 12V appeared (from nowhere:D) the buzzing went on.


Renault cars are magical :D
 

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On your dti set up runs on a rotary pump the round plug which twists to disconnect has 7 terminals 1 centre terminal marked 7 & must have a 12v feed at key on the other 6 terminals 7&4 fuel quanity adjuster 1&2 fuel quantity adjuster position sensor 6&5 fuel temp sensor.The solenoid you are referring to is the fuel injection timing solenoid Hth Regards Mickeybo
 

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Technical Supremo, Platinum Member
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I think we are all singing from the same hymn sheet. Just listened to mine, there are two sounds from the dTi pump when the ignition is switched on, one is solenoid type sound that lasts a couple of seconds and the second is a fast ticking like an in tank fuel pump that lasts about 8 seconds.
I can post a video on U tube if you are desperate!
 

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Discussion Starter #15
Yes, I hear the first click, but the fast clicking is missing. Who is making the fast clicking noise? How can I test where is the problem? One morning the car started but after a few days it is dead again :/
 

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The best place for you to start checking your megane 1.9 dti out which has a 68 terminal ecu plug & runs on a bosch msa 15.5 system. You certainly would need to check out the main engine control relay to check this at key on you can do this with ecu plug disconnected as they are input voltages to the ecu .At key onyou should have 12v's at the following ecu pin no's 23 45 68.At key off pin no 42 should have12v's. To check out inerta switch ensure you have a 12v feed at key on ecu pin no 38. Can you check & post back Hth Regartds Mickeybo
 

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Discussion Starter #18
I changed the crankshaft sensor and the problem was solved. It had 520ohms resistance instead of 700ohms. Thanks for the help guys.
 
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