I have a Nissan Sunny – what type of fuel can I use? 91 or 95 – both are available in Saudi Arabia

ANSWER : The Nissan Sunny is not considered to have a high performance, high compression engine. Saudi Aramco’s general advice with regard to 91 versus 95 octane fuel is to use 91 octane unless the vehicle specifies 95 only or if the vehicle is known as and sold as a high performance vehicle. The Sunny is comparable to the Nissan Sentra here in the states and the fuel used for the Sentra is typically rated (by U.S. authorities) as 87 octane. Nissan Global technical support, reachable by e-mail and or telephone, would have additional technical data but I believe they will advise you to use 91 octane as well.

ANSWER : If you are noticing a decrease in fuel mileage, there are a few things that you can check. The first thing I would recommend checking would be the air filter. If the air filter is dirty, this will cause the engine to use more effort during running and therefore decreases fuel economy. I would also check the level and condition of the oil. If the oil is black or low, the engine will also use more fuel due to extra effort required. Finally, I would recommend checking the tire pressures. The tire pressure going low can cause a major difference in fuel economy.

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.

ANSWER : Hi There,
Octane rating is the measure of a fuel’s ability to resist "knocking" or "pinging" during combustion, caused by the air/fuel mixture detonating prematurely in the engine. Most gasoline vehicles with factory engines (assuming no modifications) are designed to run on 87 octane, but others are designed to use higher octane fuel. Higher octane fuels are often required or recommended for engines that use a higher compression ratio and/or use supercharging or turbocharging to force more air into the engine. Increasing pressure in the cylinder allows an engine to extract more mechanical energy from a given air/fuel mixture but requires higher octane fuel to keep the mixture from pre-detonating. In these engines, high octane fuel will improve performance and fuel economy. Using a lower octane fuel than required can cause the engine to run poorly and can damage the engine and emissions control system over time. It may also void your warranty. In older vehicles, the engine can make an audible "knocking" or "pinging" sound. Many newer vehicles can adjust the spark timing to reduce knock, but engine power and fuel economy will still suffer. As always, it is best to refer to your vehicle’s specific owner’s manual which will indicate the specific octane requirement for your vehicle’s engine model.

ANSWER : Hi there:

As a United States based online mechanic service, we’re not that aware of the different climate changes in Kuwait. However, in general, when you have extreme heat, keeping your fuel consistent is very important for overall performance and engine efficiency. A change of fuel from 95 to 91 octane is a rather large jump; so you might want to seek advice from a local mechanic for your application.

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.

ANSWER : An 89 octane fuel should work fine, granted a 91 octane is recommended. With having a turbo engine you may have harmful effects using a lower grade fuel due to what they call pre-detonation. This can occur under higher loads or speeding. The damage can result in damage to your turbo or possibly your engine.

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.