DIESEL PROBLEM i NEED TECH HELP

[chuckaduck]

I have a renault dci 120 diesel engine in a 51 plate renault master which i want to put in the boat

It runs fine but sometimes without warning it refuses to start, I have done all the usual things ie compression fuel pressure popped the injectors etc.

The heater light though only stays on for 3 seconds and if I give it a squirt of easystart it starts, but I dont want to continue with easystart as diesels get addicted to it

My question is are the pre heaters controlled by an ecu or is it a relay ?

 

[xr3i]

Getting quite a common problem with modern diesels. What you have is a pressure drop in the fuel rail below 300psi caused by leaking injectors. Unforunately easy start will make vehicle start and run because when ignites parameters change and ECU switches injectors thus continuing to run .

The only other problem may be intermittent Cam sensor or Fuel Rail Pressure sensor .
With regard to glow plugs ,controlled by temp sensor and relay, earth switched by ECU but you will find they should continue to operate after light has gone out.

Hope this helps.Geoff

 

[omega2]

Do not use easy start!! if you suspect the glow plugs, try this -- get the air gun i.e. paint stripper electric black and decker type or the mrs's hair dryer and before even trying to start up, warm the inlet manifold and air intake if possible, then go for a start, if it works then I would be looking to change the glow plugs.

 

[VicS]

3 seconds does sound very short. It worth clipping a voltmeter onto the glow plugs and checking because you may well find that they stay energised for longer than the light stays on. That my experience with two diesel cars anyway. If that proves to be the case just wait a bit longer before starting.

If you suspect a glow plug problem then check them. Disconnect all the wiring and measure the resistance to earth of each one (or if they are two wire types across each one) They have an immeasurably low resistance if OK. Well it is a fraction of an ohm. Replace any that are burn out. They do burn out. My Peugeot requires regular replacements although the Ford before it only ever burnt out one.

Can't say if you have a separate control relay both of mine have had but then neither have/had any form of electronic ecu.

 

[tinkicker0]

When the light goes out turn the ignition off, then back on again. When the light goes out again, start up.

Peugeot and Ford indirect injection motors were notorious for doing this.

 

[Latestarter1]

Your Renault dci 120 is not really suitable for a marine conversion for several reasons;

I am not aware of a propriety marine exhaust manifold to suit the motor.

You will need an vehicle immobiliser clone for the engine to run out of the vehicle.

You will need to sort out a pop for the electronic throttle with a idle validation switch to be on the safe side.

Sorting out a transmission adaptor is not impossible I expect Lancing Marine would help, at a price. All sounds a little like a solution looking for a problem.

On the subject of engine health. Unlike indirect motors your engine is direct injection and only uses the heater plugs to reduce start up smoke, glow plugs go out very quickly after starting dependant on ambient temp.

If the engine can be induced to run with ether then you have a fuel supply issue. Test with a slave fuel supply with a sight glass and look for bubbles.

Surprised that that you say that injectors pop tested as there is no test plan for Bosch common rail injectors, unless you have the rotary pump VP 37 engine. Even then a pot test is pretty valueless. In addition compression testing particularly on direct injection diesel engines tells you very little, particularly as only a few manufacturers bother to publish the figures. If the engine is not suffering excessive blow by it is in good health.

All sounds like a bundle of work with little reward.