Importance of Sound Operating Practices

Although Emergency Medical Service operation by its very nature will sometimes unavoidably subject a vehicle to extremely severe demands, there are actions an operator can take to minimize the effects of these demands on the vehicle and to minimize the potential for excessive fuel pressures and possible fuel expulsion. Actions that are essential for an operator to take are to properly maintain the vehicles to keep all systems functioning properly and to avoid the excessive heat build-up associated with a poorly-tuned engine. Other important practices operators should adhere to are the following:

^ Do not overfill the fuel tanks. Stopping the fill of the tanks at the first shut-off of the automatic fill nozzle of the pump will maintain adequate vapor expansion space in the tanks. It is improper, and dangerous, to bring the fuel level into the filler neck. Remember, heated fuel both expands and produces vapor at a faster rate. The vehicle should have fuel added only while on level ground, both fore-and-aft and side-to-side. The tanks can be accidentally overfilled if the vehicle is facing downhill or slanted away from the filler neck. Remember - Stop filling at the first automatic shut-off of the pump nozzle.

^ It is helpful to use approximately two gallons of fuel out of each tank at the first operation following a fuel fill, particularly if the unit may be operated in a stationary state at an emergency site. Start with the mid-ship tank, then switch to the rear tank. Primary operation should then be on the mid-ship tank.

^ Never remove the filler cap if a hissing sound is heard from the cap or fuel is observed to be seeping around the cap. These are signs that the cap is venting due to high pressure in the tank. Removal of the cap could cause liquid fuel to be expelled. Even if cap is not hissing or fuel wetting is not observed, the cap should always be held firmly and be removed slowly.

^ Use only high quality fuel to increase the likelihood of obtaining the lowest obtainable RVP (volatility rating). Alcohol-blend fuels raise the RVP and should not be used. Owner guides generally address permissible levels of alcohol blends that are acceptable in terms of not causing chemical damage to fuel system components. However, the guides caution that if driveability problems are encountered use of alcohol blends should be discontinued. In the severe service environment that EMS service often involves, alcohol blends should be avoided. An approximation of the RVP for the fuel in use in any vehicle can be made using Rotunda Kit No. 113-00004, "Gas Check". This kit is sensitive to testing conditions. Be careful to follow the directions in the kit exactly.

^ Minimize the time spent with the engine running while the vehicle is stationary. Although high engine speed and stationary vehicle operation sometimes will be necessary in emergency service, there often are circumstances where the duration can be shortened. When the vehicle is stationary, lack of the airflow through the engine compartment and under the vehicle that occurs while the vehicle is moving, results in elevated temperatures of components underneath the vehicle. Whenever possible, limit the operation of the air conditioning while the vehicle is stationary. The load of the air conditioner on the engine produces greater heat in the engine and exhaust. Remember, higher fuel temperatures result in increased fuel vaporization, which can increase pressure in the tank to excessive levels.

^ Drive in moderation except where high speed is really necessary. Wide-open throttle accelerations increase engine and exhaust system temperatures and are seldom actually called for by the response situation. Driving that way significantly reduces life of the vehicle powertrain. Rapid accelerations also require frequent braking in traffic and increase brake wear.

^ Avoid parking the vehicle over combustible materials, especially with the engine running.

^ Do not overload the vehicle. Both gross vehicle weight rating (GVWR) and gross axle weight rating (GAWR) should never be exceeded. A label on the driver's door pillar or door rear edge face specifies intended GVWR and GAWR. Exceeding these limits can cause damage to vehicle suspension components and taxes the powertrain and brakes. Excessive loads also cause additional heat build-up due to the demands on the power system.

^ Do not overfill the transmission. Transmission fluid expands when heated. An overfilled transmission will overflow when subjected to heat. Fluid expelled from the transmission onto a hot exhaust system can result in an underhood fire.

^ Never shut the engine off while it is being operated at elevated speeds or is still on high idle. This can result in engine dieseling, which can cause engine damage and a backfire in the exhaust system.

^ Check and regap spark plugs every 6,000 miles in accordance with unique operating conditions. If your vehicle must be idled for prolonged periods, in spite of the above recommendations, spark plug maintenance should be performed even more frequently as the idling time is not reflected in accumulated mileage. For a complete listing of maintenance specifications and intervals for unique operating conditions, consult your Owner Guide or Maintenance Schedule and Record Log.

^ Visible portions of the electrical wiring should be inspected every 6 months for heat damaged insulation, especially in the engine compartment and underbody areas near the exhaust. The wiring should also be inspected for damage resulting from contact with sharp or jagged surfaces. Damaged wire should be replaced with wire with high temperature insulation and should be routed away from excessive heat and securely fastened in place.