'91 Pajero 2.5 TD Dies When Revved
Discussion
My friend has a '91 Pajero 2.5TD which has had a few issues. It started with a cracked head which was replaced with a new head. Prior to the head failing it ran absolutely fine, if pretty slow.
Now that it is all back together, it starts on the key, probably not one full revolution before it fires.
Idles absolutely fine with a clean exhaust.
When the revs are brought up, it gets to a point where it just dies with a rich smelling exhaust.
On attempting to restart, it requires bleeding at the injectors before it fires.
In order to isolate air leaks from the tank lines to filter, a seperate tank with clear hose was rigged to feed the high pressure pump
direct. No change.
In order to isolate a blockage in the return from the injectors, this was also fitted with a clear hose drain to a catch tank. Good flow of fuel and no change.
Does anyone have any better ideas?
Now that it is all back together, it starts on the key, probably not one full revolution before it fires.
Idles absolutely fine with a clean exhaust.
When the revs are brought up, it gets to a point where it just dies with a rich smelling exhaust.
On attempting to restart, it requires bleeding at the injectors before it fires.
In order to isolate air leaks from the tank lines to filter, a seperate tank with clear hose was rigged to feed the high pressure pump
direct. No change.
In order to isolate a blockage in the return from the injectors, this was also fitted with a clear hose drain to a catch tank. Good flow of fuel and no change.
Does anyone have any better ideas?
Diesel engines are really simple when they are working.
Assuming there is sufficient compression you (pretty much) just need the right amount of fuel to be in the combustion chamber at the right time for it to run.
If I was a gambling man, I would be putting my money on either the HP fuel pump or injectors, assuming it is a common rail diesel.
If these have been off during the work, just make sure everything is connected right & then try to do a test on each injector delivery.
Assuming there is sufficient compression you (pretty much) just need the right amount of fuel to be in the combustion chamber at the right time for it to run.
If I was a gambling man, I would be putting my money on either the HP fuel pump or injectors, assuming it is a common rail diesel.
If these have been off during the work, just make sure everything is connected right & then try to do a test on each injector delivery.
An injection air leak was my first thought, but you seem to have ruled that out.
I don't know how the fuel is metered on that engine, but if it is done mechanically is there a possibility that the regulator has jammed/got dirt in and is causing overfuelling? As a side effect of bleeding the fuel lines you might be relieving the excess pressure.
I don't know how the fuel is metered on that engine, but if it is done mechanically is there a possibility that the regulator has jammed/got dirt in and is causing overfuelling? As a side effect of bleeding the fuel lines you might be relieving the excess pressure.
The injection is mechanical indirect injection. It does have a load position sensor on the pump and an engine coolant temp sensor. It also has a boost fuel compensation diaphragm on the pump. I have discounted this as the engine behaves the same when the turbo is plumbed in as when the intercooler is removed and the turbo compressor is blowing to air, hence making no boost.
The pump was not disturbed when replacing the head with the fuel supply and tank returns remaining connected.
Over fuelling as engine speed increases is my theory, due to the engine smoking rich before it cuts out.
Is it possible that the injector leak off pipe is restricted and causing an over fuel when engine speed increases?
The pump was not disturbed when replacing the head with the fuel supply and tank returns remaining connected.
Over fuelling as engine speed increases is my theory, due to the engine smoking rich before it cuts out.
Is it possible that the injector leak off pipe is restricted and causing an over fuel when engine speed increases?
stevesingo said:
The injection is mechanical indirect injection.
...
Is it possible that the injector leak off pipe is restricted and causing an over fuel when engine speed increases?
I don't know how that injection system works, but if it does pressure regulation by dumping the excess fuel via a regulator like a two line petrol injection setup then regulator failure or a blockage on the return line would give excess pressure and hence overfuelling. I would have thought it would have to be massively over pressure to be too rich to run at part load though and as a side effect it would be over-sensitive to the throttle pedal input at part throttle, which you haven't mentioned as a symptom....
Is it possible that the injector leak off pipe is restricted and causing an over fuel when engine speed increases?
GreenV8S said:
An injection air leak was my first thought, but you seem to have ruled that out.
I don't know how the fuel is metered on that engine, but if it is done mechanically is there a possibility that the regulator has jammed/got dirt in and is causing overfuelling? As a side effect of bleeding the fuel lines you might be relieving the excess pressure.
FWIW overfueling makes a diesel engine produce more power and/or black smoke. It wouldn't stop it running unless the overfueling was so bad it resulted in a holed piston.I don't know how the fuel is metered on that engine, but if it is done mechanically is there a possibility that the regulator has jammed/got dirt in and is causing overfuelling? As a side effect of bleeding the fuel lines you might be relieving the excess pressure.
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