| Symptoms |
Test |
Indicative Results |
Diagnosis +/or Reference#
|
| Engine light comes on |
Turn gas off | Light goes out |
Injectors not physically able to close down enough (5) |
| Hook hoses together with gas off |
Light goes out | Unit is resticting too much air (1) |
| Engine surges at idle consistently |
Shut gas off, hook hoses up together |
Surging stops | Unit is restricting too much air (1) |
| Surging continues |
Check for a vacuum leak |
| Engine is hard to start or flooding occurs |
Take off 1/8" copper tubing at unit |
Gas spurts out inconsistently | Vapor locking is occuring (2) |
| Gas flow is more than a fast drip |
Adjust the valve on the tee down |
On fuel injected models only!
Gas continues after engine is turned off |
Make sure the tee is in the return line (3) |
| Run clear hose test with the PCV line connected |
Is the gas moving slower than when PCV line is disconnected |
PCV line is restricting too much air (7)
|
| Check the position of the unit |
Is the vapor out hose higher than the unit |
Raise unit so the hose is going down from unit |
| Check vapor adjustment |
Is the lever more toward the front of the unit |
Close adjustment, and start over, moving it a 1/16" at a time |
| Idles rough on carbureted vehicles |
Check for fuel filter between gas tee and carburetor |
No | Clean or replace needle valve in carburetor |
| Yes |
See: "Hard to Start" in Row 1 |
| Sludge chamber fills up with gas |
Turn engine off |
Gas drips in sludge chamber |
Tee is in high pressure line on fuel injection or the gas line has a
lot off pressure and volume on carbureted vehicles (3,4) |
| Take off 1/8" copper tubing at unit |
Gas spurts out inconsistently |
Vapor locking is occuring (2) |
| Disconnect vapor out hose at unit |
Vacuum on vapor out nipple |
Switch hoses around on the unit |
| No vacuum on hose |
Hose or intake manifold port plugged |
| Test Vacuum on PCV nipple |
no vacuum |
Faulty unit, send back for repairs |
| Pull PCV valve |
No vacuum |
Replace PCV valve |
| Gas mileage not consistent |
Take off 1/8" copper tubing at unit |
Gas spurts out inconsistently |
Vapor locking is occuring (2) |
No positive MPG results: carburetor + throttlebody or
Fluctual results |
Open vapor control lever all the way |
Engine doesn't flood |
Open the gas tee more |
| Check vapor out hose |
Is it less than 4' |
Replace with 4' hose |
| On fuel injection, increase in horsepower is noticed but not in gas mileage |
Check oxygen sensor | Replace if necessary |
| On carbureted, check tail pipe |
Is it black or does it throws black smoke when started |
Float in carburetor needs lowered |
| Positive MPG: fluxuating |
Computer or 02sensor |
Generally Dealer Item |
Mechanic's computer reading or take a chance: EFI-Thottlebody |