Help: Rough idle, then stall, already tried a few things but no improvement

jwrrc · Sep 17, 2021

My 200TDI was running fine a week or so ago. It sat for a week, then it started OK, but lost all power under load, pedal went dead, then it stalled.
Since then, I have:
1) Replaced the intercooler and top hose. The hose was collapsing when revved, and the culprit seems to have been the intercooler (disconnected bottom hose and the top still collapsed, even with a new hose on).
2) Opened the bleed screw, to find it was cross threaded in and stripped the thread, so replaced the fuel filter housing.
3) solved a small fuel leak between the tank and lift pump, but there is still a leak further back, next to the tank.

The engine now idles OK for about a minute, then tries to stall or does stall. The exhaust is a little smokey (black) when you rev it hard, but I think that's normal for a 200TDI, right?

I've taken a video of the idle. This is with no input from peddles etc. Any advice or thoughts welcome!

My current theory is that the leak back by the tank is sucking air in when the lifter creates a vacuum, and those air bubbles are what's causing the issues.

jwrrc · Sep 17, 2021

Here's the video

lynall · Sep 17, 2021

What car? and is it the original engine for the car or a retrofit?
Start from the beginning, intercooler hoses should not collapse ever as they are never really under negative pressure, try again with the air filter to turbo pipe removed.
Same with the fuel supply, start from the tank and check every bit until you get to the injector pump, dont skimp or say to yourself it looks okay, confirm it is actually okay.

If its disco the steel fuel pipes rot out on top of the fuel tank sender unit.

jwrrc · Sep 17, 2021

Thanks Lynall, appreciate your comment.

It's a Range Rover Classic, started life as a 3.5 V8 EFI, and was engine swapped before my ownership. The 200TDI is from a later Range Rover (number starts 14L so not a disco engine).

The fuel hose at the back, where it bends to run along the chassis, is definitely degraded and has leaked, thus my thinking that it's probably air being pulled into the system there.

My question really is, is there another obvious cause I've not considered. Possibly the lift pump, fuel injector pump or the injectors are all possibilities but seem to me to be less likely to be causing the variable nature of the current problem.

lynall · Sep 17, 2021

Tbh it could be anything, but you have to start with what you know is wrong and go from there.
The bosch ve pump self bleeds so for it to cut out it must be a pretty bad air leak.
Even if the lift pump packs up totally the engine will still run, as the bosch pump has its own internal fuel pump, but it will lack power at higher rpms.

steve2286w · Sep 17, 2021

jwrrc said:
My 200TDI was running fine a week or so ago. It sat for a week, then it started OK, but lost all power under load, pedal went dead, then it stalled.
Since then, I have:
1) Replaced the intercooler and top hose. The hose was collapsing when revved, and the culprit seems to have been the intercooler (disconnected bottom hose and the top still collapsed, even with a new hose on).
2) Opened the bleed screw, to find it was cross threaded in and stripped the thread, so replaced the fuel filter housing.
3) solved a small fuel leak between the tank and lift pump, but there is still a leak further back, next to the tank.

The engine now idles OK for about a minute, then tries to stall or does stall. The exhaust is a little smokey (black) when you rev it hard, but I think that's normal for a 200TDI, right?

I've taken a video of the idle. This is with no input from peddles etc. Any advice or thoughts welcome!

My current theory is that the leak back by the tank is sucking air in when the lifter creates a vacuum, and those air bubbles are what's causing the issues.

i would agree with that , to be fair the rough idle sounds just like mine and normal apart from an intermittant squeaky sound , a 8mm bore clear pvc tube useful for looking for confirming air leaks

jwrrc · Sep 17, 2021

steve2286w said:
i would agree with that , to be fair the rough idle sounds just like mine and normal apart from an intermittant squeaky sound , a 8mm bore clear pvc tube useful for looking for confirming air leaks

Thanks, it sounds fine for a minute or so, then dips and wants to stall. The pedal does nothing at that point too, so I think it's starved of fuel. New hose from tank to lift pump is the next plan!

The squeaky sound is the altenator belt that's next on the list of jobs once it runs right again

jwrrc · Sep 17, 2021

lynall said:
Tbh it could be anything, but you have to start with what you know is wrong and go from there.
The bosch ve pump self bleeds so for it to cut out it must be a pretty bad air leak.
Even if the lift pump packs up totally the engine will still run, as the bosch pump has its own internal fuel pump, but it will lack power at higher rpms.

Thanks again, going to start with the tank to lift pump hose and see where I am. Really appreciate your input.

lynall · Sep 17, 2021

jwrrc said:
Thanks again, going to start with the tank to lift pump hose and see where I am. Really appreciate your input.

Has the RR still got the sedimentor fitted over the rear axle same as the disco 200?
If so bypass it.

Kev12 · Sep 17, 2021

+1 on sedimentor. On mine I had to replace this part https://www.brit-car.co.uk/product...._vin_ga464553_and_1992_1994_from_vin_ga399973
as the pipes had rusted through right where it comes out the top of the tank. You need the right size olives to re-use the compression fittings (I got a pack the right size from screwfix).
The other issue will be as yours was a v8 it could have a different version of pickup in there. Boot floor out or drop the tank....there's not much in it but personally I would take the boot floor out as the crossmembers that support it would probably need a coat of paint and/or rust treatment

jwrrc · Sep 17, 2021

lynall said:
Has the RR still got the sedimentor fitted over the rear axle same as the disco 200?
If so bypass it.

Good point, tbh, I don't know, so I'll get the floor up and have a poke around. Thanks very much!

jwrrc · Sep 17, 2021

Kev12 said:
+1 on sedimentor. On mine I had to replace this part https://www.brit-car.co.uk/product...._vin_ga464553_and_1992_1994_from_vin_ga399973
as the pipes had rusted through right where it comes out the top of the tank. You need the right size olives to re-use the compression fittings (I got a pack the right size from screwfix).
The other issue will be as yours was a v8 it could have a different version of pickup in there. Boot floor out or drop the tank....there's not much in it but personally I would take the boot floor out as the crossmembers that support it would probably need a coat of paint and/or rust treatment

Thanks, Kev, that's useful info too.
Boot floor out is the preferred for just that reason. I'll be interested to see how much was swapped when the previous owner engine swapped it, I suspect that while everything up front was done, things were a bit more lackluster at the tank end.

jwrrc · Oct 1, 2021

Just to close this thread out:
- New diesel tank fitted
- New fuel lines throughout
- Bled the fuel system

Running spot on now, and boosting better than I've had during my ownership.

Thanks again for input!

Help: Rough idle, then stall, already tried a few things but no improvement

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