Hunting Diesel

Submitted: Sunday, Jun 04, 2006 at 01:28
ThreadID: 34589 Views:1766 Replies:7 FollowUps:7
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I am hoping for some feedback on a problem with my Maverick 4.2 Diesel.(non turbo)

At around 50 to 60 Kph in 4th gear it surges along or hunts as another descriptive.

Over 60 Kph and it drives along good.

I just had a new seal on the injector pump replaced as it was leaking and I thought this might have solved the problem.... but it didn't.

I use a fuel additive/conditioner for the low sulphur diesel on market at my usual servo and the injector fix it man says this is good as it will save seals etc in the pump. Have tried using another brand fuel for a few fills....same same

Timing was a thought and the diesel mechanic man says this checks out ok as well and couldn't give a reason for the surging / hunting.....mmm no luck here.

This leaves it to hopefully someone on this site who may please have an answer or had similar on any diesel that may lead to a possible remedy.

Thanks
Vinnie

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Reply By: markcas - Sunday, Jun 04, 2006 at 08:13

Sunday, Jun 04, 2006 at 08:13
Vinnie

Have you changed your fuel filter and air filter?
Checked the pickup in fuel tank (sometimes has a plastic filter that can suck in ).
Have you fitted a clear hose from filter to injector pump to see if it sucking air in from some where.If all has been done go and see a diesel pump specialist.

Best of luck Mark
AnswerID: 176597

Follow Up By: Maddmav - Sunday, Jun 04, 2006 at 10:37

Sunday, Jun 04, 2006 at 10:37
Thanks for this Mark

I will check and see about the hoses & tank pick-up

I did the CAV & Main filter at last service 1400k ago and it was same before & after this.

Vinnie
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FollowupID: 432689

Reply By: Geoff (Newcastle, NSW) - Sunday, Jun 04, 2006 at 09:00

Sunday, Jun 04, 2006 at 09:00
Apart from the usual suspects of changing fuel filters my only experience with diesels hunting is as below.

Don't suppose you've changed to a different sized or branded tyre lately have you?
Reason I ask is I had a couple of 2H engined Landcruisers that would run fine on the stock 750x16's but hunt as you describe on a set of 15" Sunraysia's with Goodyear Wranglers.
Fit the Wranglers, they'd hunt. Go back to the 750x16's or another brand of 15" tyre and all good.
Only thing I could put it down to was the Wranglers changed the gearing just enough to confuse the governor.

Geoff.
Geoff,
Landcruiser HDJ78,
Grey hair is hereditary, you get it from children. Baldness is caused by watching the Wallabies.

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AnswerID: 176602

Follow Up By: Maddmav - Sunday, Jun 04, 2006 at 10:53

Sunday, Jun 04, 2006 at 10:53
Thanks Geoff

I'm from Newy too!

I have 33 x 12.5 x 15's running and they are on all the time.

Thanks for the info

Vinnie
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FollowupID: 432692

Follow Up By: Geoff (Newcastle, NSW) - Sunday, Jun 04, 2006 at 11:34

Sunday, Jun 04, 2006 at 11:34
Vinnie,
Whereabouts in Newcastle?
I'm in Shorty.
Keep an eye out for a 2006 RV Troopy with ExploreOz sticker on the right rear window and a Kaymar rear bar and single wheel carrier.

Geoff.
Geoff,
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Grey hair is hereditary, you get it from children. Baldness is caused by watching the Wallabies.

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FollowupID: 432697

Follow Up By: Maddmav - Monday, Jun 05, 2006 at 08:00

Monday, Jun 05, 2006 at 08:00
Geoff

Toronto area

Sliver Maverick - Eastlakes on the windscreen - UHF 15

Vinnie
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FollowupID: 432799

Reply By: Bob Y. - Qld - Sunday, Jun 04, 2006 at 09:33

Sunday, Jun 04, 2006 at 09:33
Vinnie,

Had an 80 series turbo, bought 2nd hand, that would hunt around 100 clicks. Real pain in the bum, as this where we do most of our driving.

Got the injector pump done up, in Mt Isa, and no more hunting. Went like a rocket after that too. In fact pulled better than the 97 model 80 series we have now.

Hooroo...
Seen it all, Done it all.
Can't remember most of it.

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AnswerID: 176609

Follow Up By: Maddmav - Sunday, Jun 04, 2006 at 10:57

Sunday, Jun 04, 2006 at 10:57
Bob

After having the seal fixed the injector man checked the pump out and gave it the all clear. Though he did say for abot $800 he can put a new seal kit in it but reckons since I run additive/conditioner it would not likely need it.

It only does the hunting around 50 to 60 Kph

Thanks

Vinnie
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FollowupID: 432693

Reply By: guzzi - Sunday, Jun 04, 2006 at 10:36

Sunday, Jun 04, 2006 at 10:36
Maddmav,
A workmate has recently purchased a 4.2 td patrol and was haveing similar problems.
Being financially challenged he bauked at the "Youll have to rebuild the injector pump " $1500 + replies he got from all the diesel places he went too.
So being in the aviation trade he did a bit of troubleshooting, long story short, it seems the fuel filter houseings can develope leaks. This lets air into the fuel system, it surges and burps around, you bleed the system the symtems go away for a 100k or so and then return.
He changed his fuel filter over to a CAV style filter and houseing and the problem has not returned.
Im not saying this is YOUR particular problem, but it's worth a look.
AnswerID: 176624

Follow Up By: Maddmav - Sunday, Jun 04, 2006 at 11:04

Sunday, Jun 04, 2006 at 11:04
Thanks Guzzie

As above - I have been in touch with a GQ guru and he is gonna have a look this arvo at a few items mentioned in this post feedback.

Another idea came to light about in talking - in short - I am having new rotors and pads fitted on Monday, the front wheels shake on braking and when jacked up are tight to spin.

Guru thinks - warped discs - low speed - tight spinning = probable cause also.

He wiil check all out after I let him read all the feedback.

Thanks again to all who returned ideas they will be looked at.

Vinnie
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FollowupID: 432694

Reply By: Member - Nick (Kununurra) - Sunday, Jun 04, 2006 at 11:03

Sunday, Jun 04, 2006 at 11:03
Our Cruiser used to do this,especially bad going down hill with slight throttle application,it would surge badly.Had the transfer pressure in the pump adjusted(apparently some re-adjust them selves) and all was good.
AnswerID: 176629

Reply By: Rigor - Monday, Jun 05, 2006 at 09:38

Monday, Jun 05, 2006 at 09:38
Hi Madmav , just a thought , the previous suggestion about the transfer pump sounds good to me . As this is part of the injector pump it would be adjusted / repaired when the pump was serviced , fine , but you will still be up for the $1500 or so . May I suggest that you fit a low pressure inline electric pump (under $100 ) to assist the lift and delivery of fuel to the injector pump , I have seen this work before and is an affordable way of trouble shooting , I might add that it can be left there as an assist . Good when you run out of fuel or change filters as the system will self prime when the ignition is turned on.

Cheers dave l.
AnswerID: 176765

Follow Up By: Maddmav - Monday, Jun 05, 2006 at 13:58

Monday, Jun 05, 2006 at 13:58
Rigor

Thanks for the suggestion, will look into that as a fail safe option

I had it checked out yesterday with a GQ guru and found two hoses that were letting air to be sucked into the system. After fixing them the truck runs good, but, still a hint of the problem there -- only minor but liveable.

If/when the system needs to be ovehauled - then it will get the thorough treatment.

Vinnie
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FollowupID: 432852

Reply By: eca - Tuesday, Jun 06, 2006 at 19:32

Tuesday, Jun 06, 2006 at 19:32
Hi
if problem persists try the fuel inlet hose to the injector pump, there should be a little plastic filter that goes down into the pump. This can get blocked because it is so small. check it out.
Eca
AnswerID: 177084

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