Piper Comanche PA-24 Service Manual page 651

PIPER COMANCHE SERVICE MANUAL
TABLE VIO-OI. PUMP PRESSURES (FUEL INJECTION)
En,in_ 1~
• .o.·N
lo-nO-A
At inlet to eD&me driven pump.
Electric pump on (14 voltS)
+35 psi
(max:)
<-40 psi
(max.)
Electric pum p
off
·2 psi
(min.)
-4
psi
(min.)
At inlet to injector
Electric pump off 14 psi to 45 psi 18 psi to 40 psi
(Operatinl ranp)
U
pili miD. for idle
&-32. En,in. Prim_, Syst.", (C.,bu,.tor Induction).
The eDline primer system consists ,:,' band
operated primer pump, supply IiJ1es ODd primer jets. Fuel for the primiDI system is taken iram the
main fuel lin at the fuel strainer on early models or the fuel line between the fuel strainer aDd
electric fuel pump on later models. Fuel is directed thraup the pump. supply lines and OD to tbe
jets located
at
the induction port of all cylinders, e:lcept the left rear. MaUlteDance to the system
is WlnecesSary. except at ealiDe overballl or when irrelUlu start.ing is eacOW1tered, caused by
one a more jets beinl plulled aDd/or the primer pump is dirty or leaking.
&-33. P,; ... Pump.
a. To check the flow of the pump, disconnect the supply liDe within the engine compartment
where the line divides to go to the left ..,d ript cylinders. Operate the pump, sufficient fuel
should flow to supply all jets and is determined only
by
the amount of pressure exerted on the
pump knob. When operatinl the knob, cbeck for
Ie ak",e around the pis ton.
b. The pump should be removed from the
aircraft for servicing. This is accomplished
by
discannectinl the supply liDes at the pump.
~oosing
the lock .... ut from beh.lnd the panel.
turning off the face nut, Withdrawing the piston
from the pump body and removing the pump
from the panel.
c. Further disassemble the pump and clean
with solvent to remove built up foreign de-
posits. Ascert3!n that the two check balls are
fr~e
to operate a..,'!i seat properly. Replace the
piston "0" rings and lubricate with motor oil
before inserting into pump body. If excess
pump wear is indicated, replace.
d, To check the pump operation before re-
installing, assemble, immerse in gasoline and
pum p several times to ascertain Fl'0per oper-
ation.
FUEL SYSTEM
2J15
3 4
2 13
1. ,"'E,I( '&4-4-
Z. '.U.4-
Sil'~'NG
5
12 11
:I • •
'''''''101'''
""E'","
6. ""4-ING S."'NG
5
7
8
10
!. STO~
.' 1 01
11. *,.'",E"
",
~].
9
FIGURE 8-18. PRIMER PUMP
(CARBURETOR INDUCTION SYSTEM)