PUMP.

TM 55-4920-378-14&P

Maintenance

3-6. PUMP.

There should be no problem with the electrical system nor the hoses, therefore, the remaining part of the maintenance and

overhaul should be confined to inspection. If you are not getting the total amount of vacuum or pressure that is needed to

give you maximum readings on both vacuum and pressure, find out whether the pump itself is at fault. Connect the pump

prior to entering the sump on the vacuum and pressure line to the altimeter or fuel pressure instrument to check the

correct vacuum or pressure. 29" of vacuum is necessary for the vacuum side, and a minimum of 25 pounds of pressure for

the pressure side. If the pump is capable of this operation, then you have a leak some place else in the system. If the pump is

incapable of this operation the pump should be replaced. However, this should not occur for a minimum of a year to two

years.

3-2