Demon Fuel Systems 1905 - Manual (Page 17)

17
Warm Starting
(Cont.)
2) Choke is closed when engine
is hot. 2) Find & fix cause for choke staying closed. Check power and
ground, make sure power wire has a full 12v or something
jammed or bent, check choke linkage to air cleaner clearance
3) No fuel 3) Check fuel delivery volume and pressure. Look for clogged
lines, filter, or pump. Check for kinked or swollen fuel lines.
4) No air. 4) Check for clogged air filter, especially after driving through
muddy or dusty area.
5) Too much air. 5) Look for big vacuum leak, such as broken hose, blown
gasket, bad power brake diaphragm, bad PCV valve (Rough
Idle).
Engine starts, then
dies within a few
seconds.
1) Choke is staying closed 1) Diagnose and fix choke problem.
2) Carburetor flooding. 2) Fix cause of flooding.
3) Venting system failure. 3) Check out entire fuel system venting system, including the
vent valve on the carb, the charcoal canister, all hoses & check
valves in the system, and any solenoids that trigger the vent
system to operate.
4) Step-Up Piston up in bore 4) Remove step-up piston and fix sticking issue or use a lighter
step-up spring
Engine starts, then
races for a few
seconds and then
dies.
1) Big vacuum leak somewhere. 1) Find the vacuum leak & fix it. Also look for wrong base gasket
or one that is installed wrong. If engine has been spitting back, it
may have blown out the base gasket or a gasket in the carb.
Engine starts OK,
but then gets real
rough. Lots of black
smoke.
1) Slow flooding. 1) Fix cause of flooding.
2) Step-Up Piston up in bore 2) Remove step-up piston and fix sticking issue or use a lighter
step-up spring
3) Venting system problem. 3) Check entire venting system & repair.
4) Fuel dripping from secondary
nozzles 4) Tighten secondary air door ¼ turn counterclockwise
Cold Engine
Drivability
Condition
Engine stalls when
transmission is put
into gear.
1) Fast idle RPM incorrect (too
slow) 1) Speed up the fast idle to factory specs.
2) Engine running too lean
because of vacuum leak or dirty
jet. 2) Check for vacuum leak. Flow test carb to check jetting.
Hesitation, stalling,
stumbling, dead
spot during
acceleration:
Backfiring or spit
back through carb.
1) Vacuum leak. 1) Check for vacuum leak & repair.
2) Ignition timing retarded too far. 2) Reset timing.
3) Accelerator pump nozzle has
dirt in it. 3) Clean out the nozzle tip.
4) Accelerator pump cup swollen
up from contact with bad gas or
chemicals. 4) Replace the pump cup.
5) Secondary air door opening
too quickly 5) Adjust air door
6) Vacuum hoses hooked up
wrong. 6) Connect up right. Be especially careful of the EGR & Dist.
connections
7) Distributor timing not
advancing properly (worn breaker
plate, worn shaft, pin hole in
distributor diaphragm, cracked
hose, etc.) 7) Check distributor and all related systems carefully. Replace
defective parts.
Warm Engine
Drivability
Condition Hesitation under
light throttle: dead
spot & stumble.
1) Vacuum leak somewhere, or
hose off or hooked to wrong
vacuum port. 1) Inspect hoses. Route and lead the hoses correctly. Look for
leaks caused by the wrong base gasket or if it was installed
upside down.
2) Accelerator pump problems. 2) Inspect and adjust pump stroke, pump plunger, discharge
nozzles and check valves. Inspect the accelerator pump, look
for swollen pump cup.
3) Float level set very low. 3) Set float to factory specs. Factory setting, with air horn
upside down, is 1.01”+/- .015” from the cast surface to bottom of
float.
4) Ignition timing retarded. 4) Set to factory specs. Make sure advancing correctly.
5) Idle speed set too fast &
mixture is too lean (common) 5) Richen up the idle mixture, reset the idle speed to factory
specs., then reset the mixture using the lean drop method.
6) EGR valve stuck on or coming
on too early (hose on wrong?) 6) Inspect hose routing to EGR valve & inspect valve. Replace
as necessary.