Fuel problems

Includes fuel system, cooling system and exhaust.

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gazza
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Fuel problems

Post by gazza »

I need help i have a vr v6 in my fj holden. the problem is when i start the car it smells of fuel the car is running to rich when i take out the plugs they are jet black if i let it sit for about an hour it wont start it is stuffing up new plugs i have change the map sensor coolant temp sensor air intake sensor all which are brand new i am running a eroflow 72 psi external fuel pump i am using the original fuel tank is the fuel pump pressure wrong what size fuel pump do i need. i put on a adjustable fuel pressure regulator it is connected to the fuel rail and a return line from the regulator to the tank thanks gary.
ardiesse
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Re: Fuel problems

Post by ardiesse »

Don't know whether this helps, but -

My brother had a VR in the '90s, and it was a difficult hot starter. You'd have to crank it over for quite a while before it fired, and then it'd cough and blow smoke until it settled down. I finally tracked the problem down to the fuel pressure regulator: it leaked fuel past the diaphragm into the inlet manifold. Wasn't a problem when the engine was running, but if you turned the engine off, it would still leak fuel into the inlet manifold until there was no pressure in the fuel rail. I replaced the fuel pressure regulator with one from a wreckers', and all was good.

I can't remember exactly how the bits go together now, but you could disconnect the hose(?) from the fuel pressure regulator to the inlet manifold, and then turn the ignition on (but don't start the engine) so the fuel system comes up to pressure, and see whether fuel dribbles out where it shouldn't.

If you remove the spark plugs after the engine's been sitting for a while, are the ones toward the rear of the engine wet with fuel? That was what tipped me off with my brother's VR that fuel was getting into the inlet manifold. Other than the injectors, I think the only place where fuel can get into the inlet tract is past the fuel pressure regulator.

Rob
Blacky
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Re: Fuel problems

Post by Blacky »

72 PSI sounds way to high - i thought the early engines were set at around 45 PSI ?

Firekraka is the expert on these motors, no doubt he will chime in soon enough
When you're faced with an unpleasant task that you really don't want to do, sometimes you just have to dig deep down inside and somehow find the patience to wait for someone else to do it for you.


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FireKraka
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Re: Fuel problems

Post by FireKraka »

Hey Blacky an expert is "ex is an unknown quantity and a spert is a drip under pressure" :crazy: :crazy:

Gazza I think Rob is onto something there and the regulator is cheap and easy to replace.

I would also like to know if your plugs were wet as well as blackened, I would check the oxygen sensor in the exhaust (do you have one or two I'm not sure when they went to two early VN VP only had one), from my understanding the oxygen sensor controls air fuel mixture via the computer again an cheap and easy replacement, they can get blocked with carbon and cause issues, if the oxygen sensor is stuffed the computer will run in whats called open loop and run rich.

A couple of other questions, is the engine standard, are you running the Delco computer, can you hear the fuel pump run for approx. 10 seconds when you first turn the ignition on and it should also run for about the same amount when you turn it off this is because the fuel system/pump runs to prime the fuel rail before starting and when stopping so that the rail is charged for when staring again, with the engine stopped the regulator should be shut and leave the fuel rail pressurized.

Do you have an engine management light? is it flashing.

I have had some similar issues with the engine in Frank but found it mostly to be timing and seems to have been sorted when he was dyno tuned, Dyno guy also told me my oxygen sensor was not working.

Hope this is not more confusing.
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Neil
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gazza
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Re: Fuel problems

Post by gazza »

Sorry engine is stock All plugs are full of fuel the only sensor i have not changed is the O2 sensor it is running stock vr computer.thanks gary
gazza
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Re: Fuel problems

Post by gazza »

It does have a check engine light but it doesn't come on it has only one O2 sensor near the cat
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FireKraka
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Re: Fuel problems

Post by FireKraka »

Hi Gazza
Does your wiring harness have the plug that they use for the diagnostic unit if it does put a jumper wire (bridge) between A & B, if you have a manual it should show you where or if you don't I can post a photo for you.

When you bridge these two terminals 2 things should happen, 1 the thermo fan should come on and 2 the engine management light should start flashing, it should flash in a code, for instance if it flashes once and then pauses for a couple of seconds and then flashes twice (1 and then 2) this is the code 12 and it means everything is ok, 13 (1 and then 3) is the oxygen sensor, 44 is oxygen sensor lean, 45 is oxygen sensor rich.
Obviously there are a lot of others if you google you can see the list.

Neil
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gazza
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Re: Fuel problems

Post by gazza »

The loom is from V6 conversion and it does have the plug to check diagnostic codes. Gary
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FireKraka
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Re: Fuel problems

Post by FireKraka »

Hey Gary let us know what you find mate.
Neil
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gazza
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Re: Fuel problems

Post by gazza »

hey Neil it is doing what you said the fan comes on and the light gives one blink and then two blinks which means code 12 and all is good i am thinking of changing the fuel pump 72 psi it might be to much it is getting the fuel in but dosnt seem to be returning to the fuel tank quick enough. i think the fuel pump might be to much pressure. Gary
Blacky
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Re: Fuel problems

Post by Blacky »

I just googled ' VR V6 fuel pressure " and the first result told me it should be between 240 - 260 kPa , which is around 35-37.5 PSI
When you're faced with an unpleasant task that you really don't want to do, sometimes you just have to dig deep down inside and somehow find the patience to wait for someone else to do it for you.


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gazza
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Re: Fuel problems

Post by gazza »

Thanks Blacky will be changing the fuel pump . Will be looking for one with about 40-50 psi will ring around the auto stores and see what is available. Gary.
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FireKraka
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Re: Fuel problems

Post by FireKraka »

Gary I would still pull the oxygen sensor and check it :esmile: my light also told me 12 but the tuner said the oxygen sensor was stuffed, he could see it though his computer.
How many K's on the engine?
If you have a thermometer gun or whatever they call them can you check the temps of each of your cylinders and have you done a compression check recently, the reason I ask is the engine in my Ute was doing a similar thing, fouling plugs and running like shit and it would get that bad that it wouldn't start, change plugs and it would be good for a little while until they fouled again.
Franks engine was in the process of being tuned so some of the issue can be put down to timing however putting my thermometer gun over the headers showed a very large scatter between the temperatures this lead me to find some other issues and the source of the problem.
I would be interested to know if it is like this with your engine, I would assume that the cylinders that have the wet plugs will be colder than the others.
Once you have taken temps with the plugs you have maybe try putting a new set in and do temps again.
As Blacky said your fuel pressure is a little high, if you are running the Commodore fuel tank with the intank pump with a standard engine you shouldn't need to run an additional external pump, I run this setup in my FC sedan with no fuel issues, FC's engine is standard sort of :crazy:
Regards
Neil.
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gazza
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Re: Fuel problems

Post by gazza »

Hi all spoke to a mechanic today o2 sensor shouldn't be a problem to start the car he said the fuel pump is pumping to much fuel in and the fuel pressure regulator cant get the fuel back to the tank quick enough because there is to much fuel and it is staying in the rail. not sure of the ks it has done Neil also was told to put a diagnostic cable on and see if any other problems show up. thanks Gary.
Robo
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Re: Fuel problems

Post by Robo »

Some Food for thought. Make sure it is getting up to operating temp as it will stay on cold start if it is not and keep the plugs fouled

Cheers- Robo
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