Very High fuel consumption

Toyota tercel 1999, automatic 4 doors ,Car consumes too much fuel, had a code p0125 the culprit was O2 sensor not the thermostat nor the coolant sensor, thought it will fix problem but still chugging fuel, changed spark plugs, still the same, no engine code came after changing sensor, car runs fine no hesitation, idles fine, its doing about 16L per 100KM!!! It's bugling my mind , it can't be tires pressure because I check it all the time, no fuel leaks, no air flow leak, the consumption amount is just ridiculous for the average mpg of this kind of car!! What's the culprit for the
Experienced mechanics share their insights in answering this question :
A P0125 code says that the engine is not reaching sufficient temperature to go into "closed loop" operation. Closed loop operation is essential for fuel economy and low emissions. Basically it’s saying that your engine is not warming up. Replacing the thermostat was a good move, but you should try to measure the coolant temperature to see if it agrees with what you would read on the scanner. It could be that the coolant temp sensor is in error of the sensor ground is not solid. If you want help with this, contact Your Mechanic. They can send a technician to your home or office to check out your gas mileage issue and tell you what can be done about it.

How to Identify and Fix Common car Problems ?

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If you`re wondering why your car is using fuel so quickly there are several causes to consider. Low tyre pressure, dirty air filters, overloading, and poor driving habits are just a few of the many reasons why your car`s fuel economy can suffer.
This bad habit is threefold – driving too fast, accelerating too quickly, and stopping too suddenly. All three of these actions lead to high fuel consumption. Where possible, you should accelerate slowly and drive with the speed of traffic.
Based on data from 14 vehicles, 1,092 fuel-ups and 336,648 miles of driving, the 1999 Toyota Tercel gets a combined Avg MPG of 37.32 with a 0.54 MPG margin of error.
Aside from mechanical issues, other factors can affect gas mileage. Miskelley says bad alignment, improperly inflated tires, poor tread and driving habits can make a difference in how far a gallon of gas goes. “Poorly maintained tires can cause your car to pull harder and do extra work to get going,” says Miskelley.
When an engine misfires, it leads to poor engine performance, which in turn also affects the car`s fuel economy. Thus, bad spark plugs can decrease engine efficiency and force it to consume more fuel, thus increasing the car`s fuel consumption.
Lower Fuel Efficiency

Because your fuel pump is pushing too much fuel into the engine you`ll burn more gas than normal. This means more trips to the gas station to feed your car, truck, or SUV. If you track how much mileage you get between fills and notice a drop, it could be your pump.

Too much fuel in the air/fuel mixture can make your vehicle surge, sputter, or even stall. For example, if the carburetor is set way too rich, it will push enough gas through to the combustion chamber and flood the engine. Your engine power might lag if the engine is being flooded while you`re driving, as well.
Mileage: Easily 35 mpg on the highway in the tested two-doorTercel DX. Fuel capacity is 11.9 gallons.
Bad oxygen sensors and air filters can reduce gas mileage by as much as 20%! It`s a must to help keep oxygen sensors with a proper mix of air and fuel so they can perform optimally. Dirty air filters, clogged with sand and debris, simply need to be replaced so that the engine can perform at its peak.
Slow Down and Drive Conservatively

For light-duty vehicles, for example, every 5 mph you drive over 50 mph is like paying $0.30 more per gallon of gas (based on the price of gas at $4.32 per gallon). Reducing your speed by 5 to 10 mph can improve fuel economy by 7%–14%.

Try to drive at or just below the speed limit to reduce fuel consumption. Also, if you`re on the motorway, don`t feel the need drive at 70mph; 60mph will get you where you`re headed to as well, with the important benefit of helping you save more petrol and diesel.
Generally speaking, yes. Cruise control can help you become more fuel-efficient and can help you save an average of 7-14% on gas thanks to its ability to maintain a continuous speed. In comparison, the constant change in acceleration and deceleration of the driver placing their foot over the pedals can eat more gas.
The estimated fuel consumption of an idling engine is 0.6 litres / hr per litre of engine displacement. This means that an idling 3.5 litre engine consumes more than 2 litres of gas per hour. Letting your engine idle 30 minutes a day for two winter months burns a full tank of gas without ever moving a kilometre!
Does Turning Off the AC Save Gas? If you turn off your AC and roll your windows down on Burlington highways, it actually uses up more gas than if you kept your AC on. This is because the drag that is produced by rolled-down windows forces your engine to work harder to get you where you`re going!
A car consumes more fuel in lower gears when accelerating. If the engine`s not pulling, shift down instead of pressing the throttle. Shifting up at 2,000 rpm (1,500 rpm for diesel) gives the best mix of speed and economy.
Fuel consumption is most commonly quoted as litres per 100 kilometres condensed to read as “l/100km”. A more traditional way of measuring it is kilometres per litre expressed in “km/l”.
All Tercels featured a 5E-FE 1.5 16v twin cam (DOHC) engine, rated at 100 hp (70 kW) at 6,400 rpm and 95 lb⋅ft (129 N⋅m) of torque at 3,200 rpm.
Using 98 might give 3 per cent reduction over 95, again assuming the computer adjusts the engine parameters. But fueling an engine with 95 or 98 won`t necessarily open the door to earth shattering performance or extreme levels of fuel economy if the engine is not specifically designed to run on it.
However, as a rule of thumb, a small city hatchback should be able to achieve an average fuel consumption of around six to seven litres per 100km, a mid-sized SUV will be closer to eight or nine litres per 100km and a full-sized family SUV will use closer to 10 litres per 100km in the real world.
These days, 23 MPG or higher in combined EPA fuel economy is considered good gas mileage for your vehicle.
What is the MPG for a 1996 Toyota Tercel? The 1996 Toyota Tercel gets 29 mpg in the city and 36 mpg on the highway.
A bad fuel injector or dirty/old fuel filter can drastically affect the flow of fuel into the engine. A fuel system problem is one of the most common causes of poor gas mileage. The more you run your A/C, the lower gas mileage you will get.
Air conditioning uses fuel

An air-conditioning (a/c) system can increase fuel consumption by up to 20% because of the extra load on the engine. The actual load depends on the vehicle`s interior size, the outdoor temperature and other conditions.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I have a 1981 e-350 with dual fuel tanks the p.o. added a third tank and 3 electric fuel pumps along with sepparate gauges and swi
ANSWER : The switch you are referring to is vended with the required electrical and fuel schematic (I just looked in the box) that answers your installation question. If you want an advance view, here is a link as well. Yes, you need a return line and just refer to the aforementioned link. If you are retrofitting back to OEM, I strongly encourage you to buy the original Factory Service Manual (FSM). There are lots of details attending this system and obviously it is difficult to recount it all here. The FSM will make your life much easier and you can then make sure your installation is perfect. Alternatively, YourMechanic can dispatch a certified mechanic and perform the whole retrofit and check out if you desire. Just request and schedule a generic service such as fuel pump service and the mechanic will come to your location and estimate the parts and labor required. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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Fuel pressure
ANSWER : Hello,
You may want to try checking the fuel pump relay. The relay wires should have ground on two wires, power on one wire and switched power on another wire. To activate the fuel pump your ECU actually connects one of the ground wires to complete the circuit and send power to the fuel pump. If the wires all have power running through them, then it is likely you have a faulty relay. The wire coming from the fuel pump is the other ground wire. I would recommend having an expert from YourMechanic come to your location to diagnose your wiring as this can be very difficult and time consuming without the proper wiring diagram.

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How long and what is the process to replace a fuel pressure sensor?
ANSWER : A professional mechanic would require roughly 5 hours. (If just the regulator is replaced that takes about 1 hour). Some parts, as noted below, cannot be re-used, you need a precision inch pound torque wrench, FSM instructions (and TSB updates if applicable; procedure was changed in 2007 for instance) and the system has to be bled when done.

Below is partial list of steps, copied and pasted directly from the service manual:

1. Disconnect battery and put protective material in front of the charge air cooler (CAC) or damage to the CAC may occur.

2. Remove air cleaner assembly.

3. Disconnect the oil drain tube from the crankcase vent oil separator.

4. Loosen the air cleaner outlet tube clamp and detach the air cleaner outlet tube from the turbocharger.

5. Remove the bolts, the crankcase vent oil separator and the air cleaner outlet pipe as an assembly.

6. Remove and discard the crankcase vent oil separator press-in-place gasket. (To re-install, tighten to 13 Nm (115 lb-in).

7. Disconnect the PCM electrical connector (BE SURE BATTERY IS DISCONNECTED FIRST!) and retainer. Disconnect the in-line electrical connector and position the engine wiring harness on the engine.

8. Remove the pushnuts and the glow plug module heat shield.

9. Disconnect the high-pressure fuel injection pump electrical connector and detach the retainer from the glow plug module bracket. Disconnect the glow plug module and the exhaust gas recirculation temperature (EGRT) sensor electrical connectors, detach the wiring retainer and position the wiring harnesses aside.

10. Remove the nut and position the ground strap aside. To install, tighten to 13 Nm (115 lb-in).

11. Remove the engine wiring harness bolt. To install, tighten to 13 Nm (115 lb-in).

12. Remove the heater supply tube nut. To install, tighten to 13 Nm (115 lb-in).

13. Remove the bolts and the glow plug module bracket. To install, tighten to 13 Nm (115 lb-in).

14. Remove the nut and position the transmission fluid indicator tube aside. To install, tighten to 8 Nm (71 lb-in).

Warning: Do NOT disconnect the glow plug electrical connector before dislodging the seal from the valve cover or the wiring harness may be damaged.

15. Using an appropriate tool, dislodge the glow plug wiring harness seals from the valve cover.

16. Disconnect the glow plug electrical connectors by pulling on the glow plug wiring harness tee above the seal. Remove the glow plug wiring harness.

17. Remove the nut and position the crankcase ventilation drain tube aside.

18. Disconnect the wiring harness retainer from the valve cover stud.

19. Disconnect the wiring harness retainer from the generator bracket.

20. Disconnect the A/C pressure switch electrical connector. Position the harness aside.

Warning: Do not bend or flex the heater supply tube or damage to the tube may occur.

21. Remove the stud bolts, bolts and the valve cover. Remove and discard the valve cover gasket. To install, tighten to 9 Nm (80 lb-in).

Warning: Contact with exposed fuel injector wiring, if energized, may result in electric shock.

Use care when working on or around energized fuel injector wiring. Fuel injector wiring supplies HIGH VOLTAGE to operate the fuel injectors of course, you disconnected the battery though.

22. Disconnect the fuel rail pressure (FRP) sensor electrical connector.

Warning: Fuel injection equipment is manufactured to VERY precise tolerances and fine clearances (think space shuttle). To prevent fuel system damage, it is essential that absolute cleanliness is observed when working with these components. Always install fuel system caps on any open orifices or tubes.

23. Remove the FRP sensor. To install, tighten the FRP sensor in 2 stages.

Stage 1: Tighten to 7 Nm (62 lb-in).
Stage 2: Tighten an additional 40 degrees.

24. Bleed the high-pressure fuel system.

If you feel like this job may be too overwhelming or run into any issues, consider YourMechanic to get it done. One of our mobile technicians can come to your home and replace the fuel pressure sensor at your own convenience.

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Just replaced my fuel pump but its not getting any power tested fuel pump relay and fuel fuse both good tested the wires all good.
ANSWER : You need to look at the theft light on dash to make sure it comes on and goes off when you turn the key to the on position. If light comes on and stays on then your theft system is causing the fuel pump to not be engaged. I recommend you check the theft system and then scan the computer for theft system codes. You may need to reprogram the keys to work or you have an bad sensor for the ignition key in the steering column.

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Replaced fuel pump. Car won’t start. 2002 Infinity I35
ANSWER : Hi there – the metal component you describe is a fuel check valve on the fuel return line. Its function is to maintain a small amount of pressure in the fuel system so that starting does not require the fuel pump to run very long before the engine will start. Having replaced the fuel pump and fuel filter, I would check fuel pressure while the car is running. This is to check the fuel pump relay for burned contacts that won’t support full electrical current to the pump, and for proper fuel pressure – a malfunctioning fuel pressure regulator could also restrict power and higher speeds if pressure is too low. I would recommend an inspection of the fuel system by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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Installed new delphi fuel pump and fram fuel filter. still no pressure on fuel rail valve and wont start. 2003 Chevrolet Tahoe
ANSWER : Hi there – I suspect you have weak power getting to the fuel pump. I would first check the voltage coming out of the fuel pump relay. If the contacts in the relay are burned, you will not get reliable current flow to the pump. Check the fuel pump ground as well (voltage drop across the ground, not just continuity). I recommend a fuel system inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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I have a truck that won’t run and is not getting gas to the engine. Fuel pump is running, have a new filter and new fuel pressure
ANSWER : Hi There,
It sounds like you may have a clogged fuel injector or potentially a faulty injector that is fried internally. I would suggest testing them if you have access to a multi meter. Disconnect the injector from the electrical connector and set your multi meter to Ohms mode and measure the resistance of the injector. After testing all injectors, compare the resistance. They should be the same or very close. If they are not, they will likely need to be replaced.

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1996 F150 4.9 5 speed. Frt. Fuel pump quit working. Put fuel in rear tank and it sucked the fuel to the frt tank.
ANSWER : The two tanks are designed to work together and so BOTH pumps must be functioning and, as well, the related fuel system supply code, the Code P0232 that has set has to be resolved. P0232 means that the fuel pump relay is stuck on, keeping power supplied to the fuel pump even after the ignition has been turned off although another possibility is the fuel pump secondary power circuit has a short to battery voltage. The factory service manual (FSM) specifies a very lengthy diagnostic (because you have separate tanks). If you do not have the FSM, your best bet is to request a fuel pump diagnostic – dual tanks and let a certified mechanic get to the bottom of this. With regard to the other code, P0704, that code will set if the clutch switch is defective, there is worn clutch pedal lever or clutch lever bushing, shorted or open wiring and/or connectors in the clutch switch circuit, a blown fuse or burnt fusible link and/or, rarely, a faulty PCM or programming error. If you request the pump diagnostic the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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