@Gaz_21

I would start by reading some of the hard starting issues here >>> LINK

 

Thanks. Wondering if a split Air Intake Hose would cause hard starting/long cranking? Thanks in advance.

 

A split air pipe would not help with starting issues because it would alter the AF (air fuel) ratio.

 

Thanks. So replacing the air pipe would help with it?

 

Forgive my ignorance but if the air intake was repaired/replaced wouldn't the starting issues be better when the air/fuel mixture is correct? Thanks in anticipation.

 

Sorry do not know diesel. But, the air/fuel ratio is very important. Say a gasoline engine has a bad engine coolant temperature sensor (ECT). It is reading warmer than it actually is outside. This would cause the ECU to think the engine is warm and thus provide less fuel than needed to properly start the engine. Testing would be to try to spray some starter fluid into the intake (avoid the MAF sensor). If engine starts easy and keeps running then could be the ECT.

Diesel has a regular fuel pump in the diesel fuel tank and a high pressure fuel pump just before the fuel injectors. If failing high pressure fuel pump then could cause issues. But, as I said, I do not know diesel engines.

Oh, answering the question, yes, repairing or replacing the air intake would help as the air and fuel is monitored or controlled. If too much unmetered air is allowed in then air/fuel mixture may not have enough fuel to start engine?

 

Have you checked the fuel lines for corrosion? I recently had to replace mine as the had pitted and was letting air into the fuel system. Eventually they were leaking also, but the first signs were longer starting and knocking noises from the injectors.

 

Thank you both for your replies. Very much appreciated. I will try the air intake hose first & if no improvement will get the others checked as you have indicated.

 

Doesn't diesel engines have glow plugs?
How about diagnosing those too.
If they are not heating up enough, you won't get it going as quick.

Sorry but my diesel tech. knowledge is very imited.

Gl

 

A resistance test found the glow plugs to be ok, do you think they should be removed to visually check them? Thanks

 

A resistance test found the glow plugs to be ok, do you think they should be removed to visually check them? Thanks

If it is the glow plugs at fault, usually the tell tale sign is after hard starting the exhaust will make a large cloud of black smoke, then no smoke when running.

I thought you had tried new glow plugs?

 

It was suggested to me that as the glow plug resistance seemed fine then the glow plugs would be fine. Is that not necessarily the case? Thanks

 

@Gaz_21

I believe your problem may be the over / under fuel rail pressure relief valve, either failed or stuck in the open position and sending all the fuel rail pressure / fuel back to the tank.

Your target rail pressure should be approx. 30MPa/300bar at engine cranking and has to reach a minimum of 20MPa/200bar for the injectors to actually be allowed to operate by the ECU. You need a local mechanic capable of checking your rail pressure to check this for you.

We have seen this problem many times and it is the fuel rail over / under pressure relief valve that is causing the problem and needs a new one.

It could also be an injector problem so get a injector leak-back test done to eliminate this as being the issue.

A good service tool / scanner will tell you what your fuel rail pressure at cranking and engine running and had you done a search of the forum as I suggested you would have seen that we have had this problem many times in the past.

 

If not already asked, what circumstances does the hard starting happen? Does it happen all the time, just when hot/cold, or when sitting over night? If you stop and restart, is it hard to start again? If you first cycle the ignition, does it still start hard?

 

Harder to start in the morning. It will start better if not left too long. Also now a knocking sound (quite loud) from the off side (possibly near the pulley). Thanks