Engine problem

[Philturner100]

We have a Mercedes Sprinter 313 on a 52 plate, we use it on aregular basis and often stop and start. The engine starts fine when cold. However when it has been running for a while it struggles to restart.

Any advice on how to solve this problem, Thank you.

[rolandrat]

you don't mention what mileage it's done or whether it has an up to date service record. There could be numerous reasons for the problem you have mentioned. Normally Merc's are very good starters.

[euroserv]

Hello Phil,

 

You need to get your glow plugs checked first.

 

I know that sounds a bit odd, but the Merc engine runs the glow plugs after starting as part of an emissions clean-up protocol. We have seen several vans with this problem (or very similar).

 

Because the van did not need the glow plugs much if at all to start up, the ECU runs them after start and notices a problem. For some strange reason it does not tell you about it, by putting a warning light on perhaps, but stores the fault for a bit, and does not allow it to start again.

 

A 'bit' seems to vary from an hour to a day, and then it mysteriosly disappears, allowning the engine to start as normal.

 

It is reasonably cheap to get the glow plugs checked, and I bet you will have at least one that is doing nothing.

 

I could be wrong, of course but this is an excellent place to start from anyway.

 

Nick

[rolandrat]

Nick, are glow plugs on common rail engines?

[gordonaldson]

Ok, yes Euroserv has got the injectors right about them staying on after starting as in "Assist in controlling emissions" as Merc says.

Infact i've got info here saying that these Merc engines will usually start happily from cold even if the glow plugs are inoperative. Is this a clue.

Right two answers here regarding Merc common rail engines.

One is difficulty in starting can be caused by "Excessive Fuel Leak-Off from Injectors". Reluctant to start occasionally followed by getting worse.

If you've a code reader it will read "rail pressure plausibility errors" or "fuel pressure deviation.

In other words the excessive fuel leak off at one or more of the injectors causes a pressure imbalance or delay.

Sorry but leak off test kit here required where all the leak of pipes are removed and the test rig pipes fitted to show fuel flowing through this see-thru plastic unit. Mmm, something could be made up here.

Two is an easier remedy, hopefully you've got it. Air ingress to one of the connection points within the plastic fuel pipe pipework. Here in the hot engine room plastic becomes brittle and cracks.

So I think you can start checking the incoming plastic fuel pipes from the tank to the pressure pump. In this instance I'm not sure if you've got a low pressure pump before the main pump.

Air added to the fuel doesn't work so stop it.

Hope this helps.

Gordy...

[euroserv]

Err, not quite.

 

Excessive leak-off will prevent starting initially, or make it difficult, but subsequent re-starting should be easier. Never known one do it the other way round. Also a cracked or otherwise compromised fuel pipe would cause problems all of the time, not just on 'warm' starting.

 

Get the glow plugs checked first.

 

Nick

[weldted]

how old is the fuel filter, it is worth changing first as one of the cheaper options. if it is partly blocked it can have strange effects on how the engine performs, If you change it you can then rule it out before spending money on fault finding?

[Mel B]

Not sure it this is applicable to diesel engines, but when we had a Bond Minicar (petrol) engine, it used to occasionally suffer from fuel evaporation when it got warm. :-S