Sudden increase of fuel consumption

[freewheel]

Anyone could help me with this??

My kzn130 Surf is consuming over 40% more fuel, 6 km (3.7m) each litre, instead of 10 -11 km

-The problem occurred after I had replaced the engine thermostat; on February the temperature was raising to red line within minutes because the water not circulating, I noticed it soon because the air remain cold (even if the temperature was high) so I stopped the engine.

So far the mechanics could not fault any part because of the following:

performance are very good - unchanged, no black or white smoke, oil ok, starts perfectly, no high vibrations; this may exclude injector issues and head gasket problem, fuel pump does its job, there are no leakages in the engine area, I also tried milllers diesel ecomax additive with no success
there are no engine lights when the engine is on, ECU should not report any fault

-the only cause I can see is that on the denso fuel pump 1 of the 2 resistors (gray and brown) - http://www.hiluxsurf.co.uk/showthread.php?t=72099 -
who regulate the timing and fuel quantity is faulty, I learned one of the 2 does not send any fault signal to the ECU (so I was told no engine warning therefore no fault code 32. **fault code 5 for the 2.4TD)

I also learned that
The t resistor corrects fuel injection timing. The higher the resistance, the more advanced the timing.#
The o resistor corrects fuel quantity. The higher the resistance , the larger the fuel injection quantity.#
If true, to "tune" I would increase the resistance of the t resistor (advance timing) and decrease the resistance of the o resistor (reduce fuel)#
at the moment I do not know which is which


**Perhaps someone can advise what else I can check / where the issue? Or

**in addition I have a switch to increase the timing in cold weather (on the 3.0TD ssrv) could also increase the fuel quantity and is faulty?

**Anyone knows where to get the original resistors?

[Albannach]

Is the engine oil level OK?

[TonyN]

In my experiance ECU will normally throw a Check light if the resistors don't match expected resistance. You might have to pull the codes to check though.

Why would they design a the whole EDC system and leave one resistor out? It may just be internet waffle, I've never heard of it before.

I wouldn't mess with them if they are ok though, replacements are available easily from Toyota if you just want to change it anyway and see.

Otherwise get the injectors checked, if the truck runs quietly with out much 'diesel' engine noise there is a good chance the injectors arn't working 100% and atomising the fuel properly.

Check the coolant temp sensor too, if the ECU thinks the engine is still cold it'll be running richer, and you won't get lockup or O/D on the gearbox either with will increase fuel useage.

[BUSHWHACKER]

Very amusing thread title for someone called Freewheel.

[freewheel]

In my experiance ECU will normally throw a Check light if the resistors don't match expected resistance. You might have to pull the codes to check though.

Why would they design a the whole EDC system and leave one resistor out? It may just be internet waffle, I've never heard of it before.

I wouldn't mess with them if they are ok though, replacements are available easily from Toyota if you just want to change it anyway and see.

Otherwise get the injectors checked, if the truck runs quietly with out much 'diesel' engine noise there is a good chance the injectors arn't working 100% and atomising the fuel properly.

Check the coolant temp sensor too, if the ECU thinks the engine is still cold it'll be running richer, and you won't get lockup or O/D on the gearbox either with will increase fuel useage.

Hi TonyN, thanks a lot for your hints!

I am not an expert but I refer to what the mechanic say, also someone recycling toyotas connected to an MOT centre .. they may test anyway tho

1 - I have no check light when the engine is on, according to them I would not get a fault code.
But the fuel goes this is why i think the info of some post may be true:

http://toyotasurf.asn.au/forum/viewtopic.php?t=29886

IMPORTANT INFORMATION. The "wisdom" on this site is that diagnostic code 5 reports an error if the Pump Timing Correction Resistor and / or the Pump Fuel Delivery Correction Resistor is faulty. I do not believe this to be true. When testing, at one time I had the Timing resistor unplugged and the variable resistor not connected. The Check Light DID NOT come on. The truck just ran but with timing retarded to buggary - maybe even as far retarded as Top Dead Centre. I believe Code 32 (*correction, 5 for 2.4TD) is invoked ONLY for the Fuel Resistor.

2 - The engine is not more quiet, exactly the same also the noise

3 - I was told if the injector do not atomize properly may be more white smoke and you could feel some performance changes, is not the case
(I though was possible the temperature may have caused the injectors not to atomize well, also used additives)


Anyway I will check further and update
also with Toyota
***I will look into the water temperature sensor

[Albannach]

1 - I have no check light when the engine is on, according to them I would not get a fault code.

They are talking nonsense, if there is something wriong with the resistors, you will get a fault code; check them, just to be sure.

2 - The engine is not more quiet, exactly the same also the noise

Exactly the same as what?

3 - I was told if the injector do not atomize properly may be more white smoke and you could feel some performance changes, is not the case

Also nonsense. Unburnt fuel will produce black smoke.

Have you checked the oil level?

[freewheel]

Update: Thanks all for taking the time to read this, at the moment my local toyota in salford (which was very friendly and helpful) could not sell the resistors but referred me to
http://www.dieseljones.co.uk some of them are also extremely helpful and phoned denso the jap make of toyota pumps.
For reference the resistors
7020012 – 0.619
7427018 - 0732
**those values are taken from the 2.4 TD denso pump, not sure if the resistors have different value on the 3.0 TD

where only in stock in Amsterdam for £50 delivered

Toyota could not properly test the surf ECU (like most branches) to see if I get any fault codes
they did see that the sensor temperature (cooling) can be ordered but is probably not faulty, often in this case when you start engine idle go higher few seconds
**after checking they only stock the intake sensor T89424-12010

Albannach:
appreciated your hints, but at the moment I can mainly rely on other people tests
http://toyotasurf.asn.au/forum/viewtopic.php?t=29886#
-for some sensors, also toyota just admitted ECU may not give a fault code in very rare occasions

-engine quiet as before (when the fuel consumption was normal)
-mechanic who also build racing cars say unburned fuel may produce also white smoke ** anyway there is no smoke (white or black)

I hope to update soon

[BUSHWHACKER]

Unburnt diesel fuel can produce white-ish smoke from the exhaust.
Overfuelling or not enough intake air to fuel ratio (blocked filter) causes the black smoke.

[Albannach]

The OP says +40% consumption, that would smoke. A lot.

[freewheel]

Unburnt diesel fuel can produce white-ish smoke from the exhaust.
Overfuelling or not enough intake air to fuel ratio (blocked filter) causes the black smoke.

Yes, thanks again, all is ok with filters oil etc. ..more suggestions? no smoke signs
will try to test the ECU soon tho

[TonyN]

They may be right about the other resistor, I just havn't come across it, dosn't mean its not true, but have always replaced both resistors when getting the 32 code just so its done.

(code 5 is a 2.4 code..)

You often don't get a fault light when its running, you have to get the codes by bridging the connections with the ignition on and see what its stored.

Forget about Toyota for help, just use them for parts. If they can't even use a paper clip to get your fault codes then you know its not going to work there..

As Andy mentioned, 40% extra fuel is a nearly double the fuel usage, I can't see how it isn't smoking, whatever colour! Or you're driving twice as fast.

[freewheel]

They may be right about the other resistor, I just havn't come across it, dosn't mean its not true, but have always replaced both resistors when getting the 32 code just so its done.

(code 5 is a 2.4 code..)

You often don't get a fault light when its running, you have to get the codes by bridging the connections with the ignition on and see what its stored.

Forget about Toyota for help, just use them for parts. If they can't even use a paper clip to get your fault codes then you know its not going to work there..

As Andy mentioned, 40% extra fuel is a nearly double the fuel usage, I can't see how it isn't smoking, whatever colour! Or you're driving twice as fast.

I am driving twice as slow as consequence !!!
but ty!

[meooo]

someones syphoning the fuel out the tank?

How are you coming to the conclusion that you're using so much more fuel?

We get lots of folk say this, "I only get x miles from £10 fuel, before last week I got more" forgetting fuel prices have gone up and the amount you get is less.

To test the fuel consumption you need to FILL THE TANK, drive 100 miles, return to the SAME pump and re-fill. This shows how much fuel you've used over that distance and you can get an accurate idea of fuel consumption.

[BUSHWHACKER]

I am driving twice as slow as consequence !!!
but ty!

Pardon? Speak up!

[freewheel]

Pardon? Speak up!

Sure