Surging Defender

[strazzman]

recently, (since the weather has cooled down) the engine has started surging, It only does it at a certain rev range. Most obvious doing 57-59 km in forth gear on a flat stretch of road whilst maintaining a constant speed. When the engine and pump have warmed up the surge is noticably less, but still there. Looking through 59 pages of previous threads not much has been written about surging diesels. one clue could be a chafed fuel line allowing air into the fuel line. In the mornings the motor takes a few seconds of cranking to start, once started takes a few more seconds to settle into a smooth rythem. Other than that the motor is fine. Should I be concerned about the surge?. What could be cousing this to occur?. Vechicle is a 1995 Defender with 55000k on the clock.

[DEFENDERZOOK]

<span style="color:darkred">it hasnt even been run in yet.......

have you checked the pump timing?</span>

[LRHybrid100]

The starting problem sounds the same as the one Langy had - turned out to be a split fuel hose.

As Langy found, if there is a hole in the fuel line then once switched off all the fuel in the lines will run back into the tank - hence the reason why it takes a couple of turns before firing up.

This would also effect the running lean - that’s if a diesel can do this? and possibly giving the symptoms given

HTH

LRH

[LRHybrid100]

oh and have to agree, motor should run like a dream with such low Kms!!!

LRH

[sclarke]

Let me confuse all of you......

My Fender Surges at 100kmh
It starts 1st pop, suged since i've had it but comes good at 110kmh....

So as for air in the line my case i would doubt it....

OK hear is the next thing i noticed....
When it surges the lights dim.....
I had a similar problem some years ago in a Volvo. Turned out to be the Alternator getting an internal load (short) and pulling the engine down... and the electrics.

I'll change my Alternator and see if mine improves.....

I thought orig that the pump was not Fat enough... ie not enough fuel but as it clears after 110kmh it cant be that.
I cant pick mine surging at any other gear. so it is rev related, but i cant get it to do it in 4th...

I'll play and let you know of my outcome...

[UncleHo]

What's the posibility of a waxed-up filter :?: That problem usually does not present itself until it starts to get cool :idea: we found that that a Wynns diesel conditioner works well in older diesels style_emoticons/<#EMO_DIR#>/smile.gif But I would definataly check that chaffed line.

[MickG]

I have recently had a problem with the engine surging on my Manual S2 Disco. Had a remapped ECU fitted a few months ago and all was fine but recently the revs contiinue slightly when changinbg gear - like you have left your foot on the accelerator accidentally and then take it off. It only seems to do this in 2nd or 3rd gear. On 2 occasions it has also surged when in low range which gives you the fright of your life and nearly sent me over the edge on the first occasion. Have had he ECU checked and all is showing no faults so no idea.
Anyway, that's my story soI'll keep watching this thread to see if any solutions arise.

Cheers, Mick

[disconut]

Mine has a slightly different surge problem. When coming down the range in 3rd gear at 60 k/hour no throttle or brakes, all is good. When it slows down to 50 / 55 klms on a flatter section, and touch the throttle lightly to hold 60 k/hr, it surges. Has been doing this since new. It has not been checked out to date. Does any one else get this on light throttle application during big downhill runs?
Trev.

[one_iota]

The surging on a Tdi and Td5 could be different. As I understand it the Td5 has electrics designed to avoid excessive surging. I've not experienced or recognised this phenomenon with my Tdi.

[disconut]

My TD5 powered DII ES Auto did not do this down the same hill. It used to run in 2nd with the air con on as an aid to braking and hold 60 klm/hr.
Might just be a manual thing?
Trev.

[DEFENDERZOOK]

<span style="color:blue">sounds like the idle speed controller or stepper motor having a bit of a hissy fit....</span>

[Gilligan]

Strazzman,
Before you start spending money change your fuel filter, I've seen it happen a fair bit with diesel engines this time of year, [farm machinery and 4WD's] out here in the bush.When the filter is cold and waxy your fuel pump will hunt for fuel if demand excedes supply before filter warms up.
It happend last year to a Nissan Hugger I work with,[Quote] she's a bit doughy these cold mornin's like me!
Nissan stopped 200m from his house one morning ,we pulled the filter off it was full of jelly waxy snot and you probably have guest bye now he didn't have a spare filter at home.
all the best,
James.

[DEFENDERZOOK]

<span style="color:blue">this may be more than just one problem....

alternator is a strong possibilty.....
pump timing.........i doubt it though......

fuel pressure regulator or even leaky injectors......
faulty fuel pump....


it is very difficult to diagnose a faulty alternator that only faulters intermittently......the best way to test this is by replacing with a known good unit.....
you will not believe the problems a faulty alternator will give....all it takes is one sticking brush and it confuses all the computers....
but works perfect for the auto electrician.....</span>



<span style="color:green">whatever the problem is....it sounds like it has something to do with the pump...are there any visible leaks at the pump?
could it have a faulty diaphragm?</span>

[blackapache]

Let me confuse all of you......

My Fender Surges at 100kmh
It starts 1st pop, suged since i've had it but comes good at 110kmh....

So as for air in the line my case i would doubt it....

OK hear is the next thing i noticed....
When it surges the lights dim.....
I had a similar problem some years ago in a Volvo. Turned out to be the Alternator getting an internal load (short) and pulling the engine down... and the electrics.

I'll change my Alternator and see if mine improves.....

I thought orig that the pump was not Fat enough... ie not enough fuel but as it clears after 110kmh it cant be that.
I cant pick mine surging at any other gear. so it is rev related, but i cant get it to do it in 4th...

I'll play and let you know of my outcome...

mate mine does the same, same symptoms - ever since I've had it i've mucked around with everything else wastegates, relays, fuel pumps, fuel pressure regulators, mafs, maps, ECU's, harnesses you name it. I'd be VERY interested to know what you came out with??:D