wipers trouble

gianjeep · Post by **gianjeep** » Fri Jan 08, 2010 1:12 am

hello jeep people i've a question for you
when i go full trottle the vacum wipers stop,when i release the accelerator they run ok....
is that a mystic jeep
tanks a lot gianjeep

maeserik · Post by **maeserik** » Fri Jan 08, 2010 2:34 am

bad connected, before instead after vacuumpump
or bad vacuumpump.

explanation :
directly at the intakemanifold is always full vacuum on idle with closed trottle, nearly no vacuum with open trottle
Erik

Post by **wesk** » Fri Jan 08, 2010 11:45 am

As Erik explained it is not correct behavior.

The wipers rely on manifold vacuum which is strong at low RPM and week at high RPM. To overcome this problem the fuel pump has a vacuum boost pump with it. The manifold vacuum is piped to the fuel/vac pump and then piped to a "T" fitting near the firewall where the hose from the vacuum wipers connects to it.

If you have your system plumbed correctly and the boosted manifold vacuum at the wiper selector valve is at least 10" Mercury at 200 RPM and at least 12" Mercury at 1500 RPM then all is well in the vacuum supply and the wipers require rebuilding. If this is the case in your situation then try spraying a small amount of very light lubricating oil in the inlet to your wiper motors. If their operation improves they need rebuilding.