intermittent power loss

[scoota]

5 weeks ago I was cruising past the Gold Coast Wally Worlds at 100km/h in my '97 300tdi when the defender lost power and shuddered. After pulling over and switching off I was able to restart and drive as normal. The problem happened a few more times on the motorway but quickly returned to normal driving after the power loss.
I've had very few instances since then until it began happening more frequently last week in all the other forward gears and at lower speeds. On 2 occasions in 5 weeks the engine hasn't turned over with the first turn of the key.
A mechanic drove it today and the problem happened for him frequently, especially above 100k/h and then power would resume at around 70k/h. It did also happen when he was climbing up the gears.
He hotwired the fuel pump solenoid and the car ran fine. He's stumped.
I believe fuel filter is ok and I drained the fuel sedimentor a little this arvo.
Has anyone had this problem? and my obvious next question is: what's going on?
Cheers in advance, Scoota

[Aguy]

I have a Ford Transit van ( I know, different engine) that kind of had the same problem. It would lose power on full or almost full throttle. Every time I backed off or slow down, it would come back to life. In the end, it was the twin batteries that were failing. I replaced both batteries and all was good again.
This probably will not be your problem but you never know!
Hope you find the problem soon.

[scoota]

Thanks Aguy,

That is a possibility though my main and aux batteries are only 2 years old.
I have a Redarc battery isolator and have heard it clicking quite a bit lately so maybe it's not functioning properly. Any idea how that leads to the power loss I'm experiencing?
Scoota

[Blknight.aus]

sounds little like an electrical problem to the solenoid but it might be an intermittant blockage or suction leak on the supply side between the tank an the IP.

[Aguy]

Like Blknight.aus has said, it could be a problem with the wiring. if the problem goes away when hot wiring the solenoid then maybe measure the voltage before and after the "hot wiring". If you get less voltage then you might have bad connections or faulty gear. even cuts in the wiring.
Maybe wait and see if you have anyone give you better ideas! :D

[scoota]

Thanks Dave,
I assume the tank you're talking about is the main fuel tank.
Can you tell me what the IP is? Excuse my ignorance.
Cheers, Scoota

[Blknight.aus]

the injector pump.


any leak or intermittant blockage between themain fuel tank and the inecjector pump will give similar symptoms to the ones you have but will usually be acompanied by a rattling noise.

most likely its going o be the wiring to the IP and if you have the original security system spider in under the dash dont discount it being the issue

[jboot51]

IP is the injector pump.


Problem could also be the lift pump has failed as you are loosing power (starving for fuel)
If you can smell diesel when you lift the bonnet, then it is probably the lift pump.........or IP or split fuel line.


But then again, the mechanic has had his head under there and probably would have noticed.

[jboot51]

Electrically it could be the main earth wire from the battery to the gearbox.
Would possibly explain the redarc playing games, not always starting and the fuel stop solenoid wouldn't work too well with a high resistance return path to the battery.

[scoota]

Cheers jboot,
Will have to check that earth. I think I remember having problems with that a few years back but can't remember what issues it caused then.

[DazzaTD5]

The most common faults on a 300tdi is...

Feeling under powered:
Failing/failed lift pump, mounted on side of engine.

Engine stopping:
That wire and or plug connected to the fuel solenoid (on the back of the injector pump).

Hard starting or rough idle:
Leaking seal between fuel filter and housing.

Thats about all that will stop a 300tdi, such a great simple engine.

Regards
Daz

[nedflanders]

Some of the UK 300tdi's had fly by wire throttles just before the TD5 was introduced, not sure about Australia though. If it has throttle pedal sensor is it OK.
Also might be worth getting a clear bit of pipe and fitting it in-line to your fuel return line and seeing how much air is in the fuel line with the car running, could be drawing in air somewhere.

[SSmith]

No fly by wire 300tdi in Australia



He hotwired the fuel pump solenoid and the car ran fine.

What did he do to hotwire the solenoid?
Do it again to be sure, if it drives fine again then start tracing the system back.

The black plug would by my first suspect, they fatigue and get loose.

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[scoota]

Not sure exactly what he did there but he showed me a length of wire with an alligator clip. He said, "It ran like a rocket and didn't play up when hotwired." He then reconnected original set up and told me to return the car next week when they're going to replace the radiator filler because it was leaking a little. Not being a land rover mechanic he wondered if the defender had an auto cut out (Murphy switch) if it sensed overheating or any loss of coolant. Since he did this on Monday I've hardly had any issues - some very minor brief loss of power. From reading previous posts I'm wondering if the problem had been the connection to the pump and him changing between hotwiring made a better connection? I'm still not confident the problem's gone for good.
Cheers

[SSmith]

From reading previous posts I'm wondering if the problem had been the connection to the pump and him changing between hotwiring made a better connection? I'm still not confident the problem's gone for good.
Cheers

Thats what i was thinking.
Start at the pump and trace back the electrical system, prime suspect is the plug that connects to the pump, they fatigue and get loose (giving an intermittent connection and starving it for fuel) but it could be elsewhere (earth as in earlier posts)

Reach in and give the plug a wiggle, if it is loose id start there, look for corrosion & you can bend the internals with a small screwdriver to make it tight again as a temporary fix.

P.s. nothing fancy like an auto cutout in a 300tdi defender electrical system

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