After having a diesel leak I have had my 2.8jtd motorhome back to the diesel specialists Sewells of Leeds on lots of occasions.

When the van is going up a hill at full speed about 65 to 70 (its 4.5ton) and you lift off the accelerator over the top , the engine light comes on and it goes into limp home mode.

If I pull over turn the key off and try to re-start it will only crank, but if I leave it a minute or 2 it will re-start fine with no warning lights.

They have changed the seals and cleaned the pump valve twice.The fault code reads low common rail pressure. Does anyone have an idea here?

Do a leakback test on the injectors when they are warm.

They have now changed the Valve in the pump and the issue is still there, any other suggestions?

Still reckon if you check the leakback on those injectors when its cranking without starting that you'll find one leaking.

paddyponchero said:

Still reckon if you check the leakback on those injectors when its cranking without starting that you'll find one leaking.

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Would that not cause problems at other times also? The fault only happens shortly after the van has been doing over 60 under load ? The van only has 15000miles on it.

It could be the rail pressure sensor too but it costs nothing to check the injectors.
The reason I suggest the injectors is that the tolerances are infinitesimally small in common rail injectors the heat produced under load would expand the injector partsand could lead to leaking.

paddyponchero said:

It could be the rail pressure sensor too but it costs nothing to check the injectors.
The reason I suggest the injectors is that the tolerances are infinitesimally small in common rail injectors the heat produced under load would expand the injector partsand could lead to leaking.

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Would the leakback test show anything when the vehicle is stationary? As the fault only shows under load.

Jezport said:

Would the leakback test show anything when the vehicle is stationary? As the fault only shows under load.

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The fault does show when its stationary

Jezport said:

If I pull over turn the key off and try to re-start it will only crank"

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Its at that time I'd be checking, you'll obviously have to have the covers off already.you don't need fancy tubes and bottles if an injector is leaking badly enough to stop it starting it'll be obvious just pull the clip and pop off the return pipe.

Not being a mechanic that is a bit beyond me, however it is something I will mention when I take the van in.

So would one injector leaking cause the van to show low common rail pressure? And would it stop it starting for a short time after I stop the engine? I get no smoking.

The ecu won't fire the injectors until the rail pressure reaches a certain number of bar 200 or 300 can't remember. So if when hot one of your injectors is leaking slighty more and your only making say 199bar you'll have no start. When the injector cools a little and you make 200bar engine starts. Once started it will keep running because tickover is probably at least twice rpm of cranking so it can maintain pressure despite leaky injectors.

That sounds right, my van is going in on Friday and being looked at Monday. I will print off what you have posted and let you know what they find

Can a leak back test be done while the van is being driven?

OK, had it tested,and its showing quite a high leakback from 2 of the injectors and above average but not bad from the other 2.

So I have to get 2 injectors done, and at 15000 miles it seems strange. My main doubt is that there is also an issue on the pump, as the fault only appeared after the pump seals were done.

Sounds like fuel contamination started the problem, injectors and pump are supposed to be overhauled in clean room conditions hardly anyone can do it properly. In case your wondering this is what a proper rebuild shop looks like.

2 new injectors are in and they took it on a test drive. Injectors are now not leaking back however the fault still is present, he even ran it with a new pressure sensor as he had one in stock. He is trying a new pump tomorrow and hopefully this will be an end to the issue.

This all started after the pump was repaired after a leak. So I have to ask. Was the leak from a pressure fault on the pump? and did the original repairers get dirt into the injectors?

The Bosch agent I have the van with is going to examine the parts to see if he finds any evidence.

I just want the van sorted so we can enjoy using it, as it is our only means of holidays.

OK well the pump is also faulty. the original garage thought it a good idea to put silicone sealant around the 3rd piston cut off solenoid.

So it looks likely that some had migrated into the pump and injectors, as the fault with pressure only started after they had tried to fix the leak.

Any opinions ?