surging under load

[Geoff]

I just got my 1999 diesel disco back from getting a new auto and it is surging really bad under load, making it hard to even reach 100kmh and a little bit hairy when overtaking. I don't think it has anything to do with the new auto as it was doing this before the auto got changed over, just not as severely and I did run out of fuel a while ago. I have replaced the fuel filter last night but no change.


do the fuel lines need to be bleed when changing fuel filters or when it runs out of fuel?


any ideas on what it could be and how to go about fixing it would be great.


Cheers, Geoff

[Toppa]

Overboost?

[Toppa]

Yes fuel filter needs to be purged. I do this by turning the ign on, then pumping the accelerator 5-6times until the engine warning light appears on the dash. It will then run the fuel pump for a few minutes which should be all you need to to get rid of any air.

Alternatively just turn the ign on and the fuel pump will run for a minute, turn off and repeat 5-6 times.

[sierrafery]

There could be some common issues for that symptom but without plugging in a tester is quite a quess game, some simple checks you can do is to check if the wastegate is not stuck, unplug the MAF and test drive it so, replace the air filter if it's old, if it still has EGR see if it's not clogged with muck... though some live data readings with tester would be the short way to the answer... maybe even some fault codes are stored.

[Graeme]

Don't forget about the wastegate modulator which often fails allowing uncontrolled boost which will result in fuel being cut.

[Outback 1]

if you need a hand Geoff I have a modulator here to try on it plus most other components

[discorevy]

Maf or boost controller ?
To diagnose disconnect maf or bypass boost controller ,one at a time

[scarry]

The MAF was the culprit on mine,did it mainly with throttle fully open.
It will cause the auto to kick back,then change up, continually.

[Geoff]

hi all, thanks for the replies.


I started it up after changing the fuel filter and ran out of juice in the lines so I sat there turning it on and off until I got fuel into the filter and lines again. the air filter is new but I can try unplugging the MAF.


I would not have any idea how to check the other things so I may have to take you up on your offer ken, I'm busy Friday rattling a tin with the CFA but any other time you would be available, let me know and I can shoot (limp) over.

[3doug6]

I had similar symptoms when my fuel pump was on the way out. I kept checking everything else until it died completely. Is there a way to test the fuel pump to rule it out?

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