Engine hunting

Submitted: Wednesday, Nov 02, 2016 at 14:03
ThreadID: 133706 Views:3664 Replies:11 FollowUps:5
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Hi everybody, I have a 2001 troopy that hunts a bit in 3rd or 4th if your revs are low and you don,t accelerate evenly, if you put your foot down or gently speed up it stops.it only last a few seconds and then is smooth.It is an ex police vehicle 180,000 km and has done it since I brought it at 100,000 could the cops have adjusted the fuel pump? thanks
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Reply By: Life Member TourBoy, Bundaberg - Wednesday, Nov 02, 2016 at 14:42

Wednesday, Nov 02, 2016 at 14:42
Hi is it a 1HZ or 1HDT-FT
Cheers,
Dave
2010 Isuzu FTS800 Expedition camper
2015 Fortuner
Had 72 cruisers in my time

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AnswerID: 605633

Follow Up By: Wayne B16 - Thursday, Nov 03, 2016 at 12:36

Thursday, Nov 03, 2016 at 12:36
1HZ and in great condition apart from that , it is slightly annoying more than anything .
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Reply By: get outmore - Wednesday, Nov 02, 2016 at 15:54

Wednesday, Nov 02, 2016 at 15:54
change the fuel filters
AnswerID: 605634

Reply By: Member - mark D18 - Wednesday, Nov 02, 2016 at 16:15

Wednesday, Nov 02, 2016 at 16:15
Wayne

My troopie does the same thing and it has for over for well over a hundred thousand km (now 270,000km ), nothing wrong with it , its just a small irritation to a generally reliable vehicle .
AnswerID: 605635

Follow Up By: Life Member TourBoy, Bundaberg - Wednesday, Nov 02, 2016 at 17:15

Wednesday, Nov 02, 2016 at 17:15
The 1HZ in my coaster did it as well. I was told that it is wear in the pump and not to worry too much about it until the fuel usage became a problem or it became more pronounced at higher revs.
Cheers,
Dave
2010 Isuzu FTS800 Expedition camper
2015 Fortuner
Had 72 cruisers in my time

Lifetime Member
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Reply By: Member - Roachie - Wednesday, Nov 02, 2016 at 17:28

Wednesday, Nov 02, 2016 at 17:28
Fitting an electric lift pump will probably overcome it if it is in fact a slightly worn injector pump. I have one of these on my Chev:

https://www.youtube.com/watch?v=x4LCbGsujdU

Roachie
AnswerID: 605636

Reply By: Allan B (Member, SunCoast) - Wednesday, Nov 02, 2016 at 17:52

Wednesday, Nov 02, 2016 at 17:52
.
My Troopy does the same. If you are cruising at low speed and let the revs get too low it happens. Just a sensitive throttle.
Disappears as soon as you give it a bit of throttle or change down a gear.
Cheers
Allan

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AnswerID: 605637

Reply By: pop2jocem - Wednesday, Nov 02, 2016 at 20:44

Wednesday, Nov 02, 2016 at 20:44
Wayne,

First of all it's highly unlikely it's previous owner could have done any adjustment to cause it to hunt.
Most probably general wear in the governing mechanism of the pump. Are there any external fuel leaks? Grab the control arm where it goes into the pump and see if there is any appreciable wear in the fuel pump body.
Having said that, the fuel filters and fuel quality would have to have been a bit suss in it's previous life to have enough wear in the pump to have such a problem at that milage.
Probably a good idea to get a dedicated fuel injection shop to have a quick look.

Cheers
Pop
AnswerID: 605639

Follow Up By: Wayne B16 - Thursday, Nov 03, 2016 at 12:32

Thursday, Nov 03, 2016 at 12:32
Thanks Pop, there are no leaks so i will check what you suggested Thanks
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FollowupID: 875397

Reply By: Paul and Mel - Wednesday, Nov 02, 2016 at 21:39

Wednesday, Nov 02, 2016 at 21:39
Standard feature of a 1HZ.
AnswerID: 605641

Reply By: Wayne B16 - Thursday, Nov 03, 2016 at 12:44

Thursday, Nov 03, 2016 at 12:44
Thanks everyone I guess it,s normal, I service and change filters often so I will just live with it. I appreciate all the advice Wayne
AnswerID: 605645

Reply By: Wayne B16 - Thursday, Nov 03, 2016 at 12:49

Thursday, Nov 03, 2016 at 12:49
The reason I asked about the fuel pump being altered is my car gets up and goes on the flat out of curiosity once it reached 159km GPS and speedo.
AnswerID: 605646

Follow Up By: get outmore - Thursday, Nov 03, 2016 at 15:21

Thursday, Nov 03, 2016 at 15:21
hmm Im assuming your talking a 1HZ on the flat? ..... even so with a bit of a downhill and a tail wind that would be very much on the upper end of what they could achieve so fair enough question
however lik I posted earlier deffo change the fuel filters.
my 2001 1hz troopy suffered badly from blocked filters and contaminated fuel upon purchase
most noticeaball was the exact symptoms you describe which went away after changing filters and returned as the contaminated fuel blocked filter again.
(ive since flushed tanks etc which fixed issue)
dont forget your troopy has 2 filters with the cartridge style one being most commonly the blocked one being 1st inline
also the filter does not have to be obviosly blocked visually to get the symptoms you describe
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FollowupID: 875400

Follow Up By: Allan B (Member, SunCoast) - Thursday, Nov 03, 2016 at 16:13

Thursday, Nov 03, 2016 at 16:13
.
I would have thought that blocked filters would result in loss of power at high speeds and loads. What Wayne described was hunting "if your revs are low" which is also what I experience and have also done so in other cars if you get the revs too low for the gear you are in.

I suspect that a contributing factor is the foot moving slightly on the throttle pedal as the vehicle surges.

Whatever, it is simply overcome by either giving it a bit more on the pedal or shifting to a lower gear.
Cheers
Allan

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FollowupID: 875401

Reply By: RMD - Thursday, Nov 03, 2016 at 21:01

Thursday, Nov 03, 2016 at 21:01
A 12HT does the same at low speeds.
It is hard for the governor of the fuel to be exactly precise. A slight power ON at low speed will slightly wind the axles. Once it has happened the speed is detected as above the set position so the governor shuts the throttle slightly. then it happens again and again in a certain situation. In lower gears there is not the load on the engine because of the gearing and so it won't do it then.
AnswerID: 605651

Reply By: Corncob - Wednesday, Dec 07, 2016 at 22:08

Wednesday, Dec 07, 2016 at 22:08
If it has a egr on the manifold either remove it or put a small ball in the rubber hose going to it,it is caused by the egr opening and closing at a rapid rate at about 1800 rpm,the egr is controlled by a switch on top of the throttle lever on the inj pump which gets out of adjustment
AnswerID: 606487

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