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Complete Troubleshooting Guide for Caterpillar RP7500E Portable Generators

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Table of Contents

Engine Will Not Start

Reset and try to start the engine

  • STEP # 1 – conduct a walkaround the generator to make sure that there are no loose wire connections, physical damages or leaks on the ground
  • STEP # 2 – Disconnect any electrical devices and/or extension cords from the receptacles
  • STEP # 3 – Turn ON the fuel supply line by moving the red fuel switch to the green circle marked “I” (letter i) position
  • STEP # 4 – CHOKE controls the amount of air that is mixed with fuel. This is not an all-or-nothing proposition. You can try to partially push in or pull out the choke knob to try to get your generator started. If the engine is cold, PULL OUT the choke knob so that more fuel vapor is delivered to the chamber. If your generator has been operating, your engine is warm so PUSH IN the choke knob.
  • STEP # 5 – Turn and hold the generator switch to the START position (logo that looks like a flask) for 3-4 seconds to see if you can start the generator. Please do not hold the switch in the START position for 5 seconds or longer. Doing so may damage the starter. If the engine fails to start, release the switch and wait 10 seconds before trying again.

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Check the oil level / low-oil level switch

RP7500E comes with a low oil level shutoff switch that may prevent you from starting the generator.

  • STEP # 1 – Check the engine oil level
    • The oil dipstick is found on the left side of the generator (red cap). Check the oil level by inserting the oil level dipstick into the filler neck. Do not screw on the dip stick when checking the oil level.
    • #5 indicates the low oil level and #4 indicates the full oil level.
  • STEP # 2 – Excess engine oil can damage your engine so you will need to drain some out of the engine oil reservoir.
    • You can use a 5/8″ socket wrench to remove the lug nut (#3) found on the bottom left side of the generator.
    • Do not overtighten when reinstalling the lug nut,
  • STEP # 3 – If the oil level is low, incrementally add (i.e. small amount at a time) oil to achieve the FULL level (#4)
  • STEP # 4 – RP7500E uses a splash method to lubricate the internal engine components.
    • Generator engine is NOT pressurized so you cannot use an oil pressure gauge for to troubleshoot issues related to oil pressure
    • There is no direct way to test the low oil pressure (LOP) switch other than swapping it out with a new unit

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Dirty Air Filter

  • STEP # 1 – A dirty air filter will reduce air flow into the carburetor (i.e. artificially acting as a choke) so it may prevent you from starting the engine, cause poor fuel economy or may damage the engine!
    • If the air filter seems to be clogged, you can use some dish soap and warm water to wash the filter. Just make to completely rinse out any soap reside and it is air dry (do not wring the air filter as that will cause damage) before reinstalling the air filter
    • If the air filter is ripped, degraded or otherwise in poor shape, replace it. You can get the part number down below.

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Other Steps to Try

Possible CauseSolution
Battery discharged or defectiveTry starting the engine using the recoil starter. If the generator starts, check the battery. If the battery is providing less than 12.4 volts, replace the battery
No fuelFill the fuel tank with “fresh” gas
Old or contaminated fuelVisually inDrain and refill if necessary
No fuel at the carburetorMake sure the fuel switch is in the “I” (on) position. Check the vent in the fuel cap. If vent is plugged, clean the vent
Not enough fuel to the engine(1) Make sure the needle valve is closing properly. Clean or replace as needed. (2) Inspect the fuel nozzle. Clean if needed. (3) Inspect the float. If the float is damaged or sticking, repair or replace as needed
Engine floodedWait 5 minutes. Then remove and clean the spark plug. Suction out fuel or let fuel evaporate before reinstalling spark plug.
No spark (a)Inspect the spark plug. Clean the spark plug, adjust the spark plug gap, or replace the spark plug as necessary
No spark (b)Inspect the spark plug wire. Replace if damaged. Check the resistance. If the resistance is out of tolerance, replace the wire.
No spark (c)Inspect the ignition coil. Replace if damaged. Check the resistances. If any of the resistances are out of tolerance, replace the ignition coil.
No spark (d)Inspect the gap between the ignition coil and flywheel. Adjust gap if necessary.
No spark (e)Inspect the magneto. Replace if needed.
No spark (f)Check the wiring to make sure that none of the wires are shorted to ground.
Cylinder pressure (a)Inspect the cylinder head bolts to make sure they are properly torqued to 40+- Nm. Tighten if needed
Cylinder pressure (b)Check the valve clearance and seats. Adjust or repair as needed.
Cylinder pressure (c)Inspect the cylinder head gasket. Replace if damaged.
Cylinder pressure (d)Inspect the cylinder head and cylinder block surfaces for flatness. Repair or replace if out of tolerance.
Cylinder pressure (e)Inspect the piston rings. If the piston rings are worn or broken, replace the piston rings.
If the engine still will not startContact the repair service center.

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