2000 2.8D Running/Fuel issue...

Submitted: Friday, Sep 06, 2013 at 22:36
ThreadID: 104211 Views:6619 Replies:3 FollowUps:1
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Long time lurker, first time poster!

Vehicle: 2000 Holden Rodeo, 2.8D, 330,000 km, Manual

My rodeo has recently developed the following issue:

Car will start and idle fine, will appear to drive fine through 1st and 2nd gears.

In 3rd gear around 2500rpm, engine will begin to 'hesitate' and appear to starve for fuel, happens also in 4th and 5th.

If i stop, and pump the primer, the issue will go away for maybe the next 5 km's or so (car will drive fine) but returns every time. I've replaced the fuel filter and am still having the same issue.

Is this a known issue/any helpful advice or things to check over the weekend, before taking it to a diesel specialist.

Very grateful for any insights,

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Reply By: Ron N - Saturday, Sep 07, 2013 at 00:08

Saturday, Sep 07, 2013 at 00:08
Pezza - O.K., let me see if I've got this right. The 2.8D Isuzu engine is the 4JB1 model with mechanical fuel injection (no electronics), right? That eliminates any electronic glitches or a need to reach for the OBD (On-Board-Diagnostics) reading tool.

It would pay to check the following before going to a diesel specialist.

(1.) Check that the fuel priming pump isn't leaking. If this pump develops a leak, it will allow fuel in the filter and lines to return to the tank when standing, and admit air to the fuel.
Upon startup, and upon the initial couple of minutes running, the engine will run normally, then the air in the lines will find its way to the pump and injectors and make it hesitate and appear to be suffering fuel starvation (which it is, it's getting, say 80% diesel and 20% air).

(2.) Check for pinholes in any steel portion of the fuel line between tank and filter. Steel fuel lines are notorious for developing pinholes from rust, particularly where dirt sits against the fuel line. The dirt holds moisture and corrodes the line and pinholes develop.
The diesel might leak out a little, but be hardly visible. What happens is the fuel transfer pump commences to suck fuel from the tank, but it sucks in air from the pinhole/s.
The air goes to the pump and injectors and you have a similar result as (1.) above.

(3.) Check for a blocked suction screen in the fuel tank. Fuel tanks have a nasty habit of gathering crap - rust, dirt, water, textile and fabric trash from rags. All this comes from 13 yrs of use, and hundreds and hundreds of fuel tank refills from dirt and water-containing, drums, jerry cans - and gasp - dare I even mention it - underground fuel tanks! (yes, service station tanks!)
The screen is usually a fine mesh screen that fits over the end of the suction pipe in the tank. It can become clogged with a combination of all the above, that creates a rusty, clogging mess. A clogged suction screen will produce the same result as a clogged fuel filter.

(4.) If it's a steel tank (can't recall if the Rodeo has a plastic or steel tank), check for pinholes in the top of the fuel tank. Holes in the top of the tank will admit dirt, dust and water to the tank, and cause fuel line and filter blockage, as above.

You can do a pretty simple test for pinholes by removing the fuel cap, grabbing your air compressor hose with a blow gun attached, wrap a rag around the blow gun nozzle, and insert it in the filler pipe.
Operate the blow gun to pressurise the tank with some air, while you hold the rag and blow gun tightly in the filler neck. You don't need much pressure - 3-5psi or 20-35Kpa. Don't overdo the pressure. Get a helper, and tell them to listen for air hissing out, or fuel weeping out.

I hope this gives you some ideas on where to start.

Cheers - Ron.
AnswerID: 517760

Reply By: The Bantam - Sunday, Sep 08, 2013 at 09:28

Sunday, Sep 08, 2013 at 09:28
The other one that is a beauty, is

Blocked fuel tank vent.

various vehicle have fuel tank vents in all sorts of interesting places and they generally have a poppet valve in the line.

during expansion air flows out of the vent, during contraction or as the tank empties air flows via the poppet valve into the tank.

Problem is diesel is oily and that air carries with it a small amount of fuel.....a bit of oil, a bit of dust and over time the breather fills with a pretty hard composite of dust and oil.

If you travel in red dirt a lot you'd swear someone bunged up the end of ya filler with stag sealant.

If you have a diesel pump that is strong on the suction it'll suck the sides of ya tank in, before it starts to stave for fuel.

Stop for a while the pressure equalises and the vehicle will run fine for a while.

The solution is to relocate the end of the breather to a better location and fit a filter to the end.

AnswerID: 517799

Follow Up By: Ron N - Sunday, Sep 08, 2013 at 10:27

Sunday, Sep 08, 2013 at 10:27
Bantam - Yes, a good point that I forgot to mention - the blocked tank vent. Not in the least uncommon in dusty conditions.

One can pick it up by stopping when the fuel starvation problem appears, shutting the engine down, making sure all is quiet - then removing the cap and listening for the big "sigh" as the tank sucks in air, to equalise the vacuum.
FollowupID: 797519

Reply By: pezza08 - Tuesday, Sep 10, 2013 at 10:09

Tuesday, Sep 10, 2013 at 10:09
Thanks for all of the great help and insights.

After doing the basic checks, as suggested - thanks so much, I replaced the fuel lines in the engine bay to track down the air leak. This showed up that air was leaking in from the water seperator/primer unit. To test and prove this theory I bypassed the primer unit, i.e. straight from fuel tank to fuel filter, and after an extensive test drive concluded that this indeed was the problem.

I've ordered a replacement part from isuzu (OEM 8970818143 - for anyone future reference), should arrive and I'll install it tonight.

Thanks again for replys!

Happy 4wding.
AnswerID: 517911

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