If I understand the diagram correctly, when we switch from the start to the run key position, the power supply for the pump switches from one relay to the other.dtrumbo wrote:If the key is turned off and/or the engine dies, the relay de-energizes and shuts off the pump.
Sticking Double Relay
- chitwnvw
- Resident Troublemaker
- Location: Chicago.
- Status: Offline
- dtrumbo
- IAC Addict!
- Location: Mill Creek, WA
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Me thinks it's a regular spade lug with a barb that sticks out to keep it in the white plastic socket. Try a small jeweler's screwdriver to gently depress the barb and then remove the spade. Solder the new wire to the spade and re-insert it in the plastic socket.chitwnvw wrote:1. How do I permanently attach a wire to that white plug?
Bad grounds are eventually the cause of everything wrong with our vehicles. Accept it as the word of God and move on! Seriously, I suppose it might have something to do with the electro-magnetic field that energizes the relay not being able to dissipate or some such mumbo-jumbo.chitwnvw wrote:2. How did a loose ground give me these symptoms?
http://itinerant-air-cooled.com/viewtopic.php?t=3665chitwnvw wrote:3. Where's that AFM mixture adjustment guide?
Fifth post down.
That's not how I read it. When the key is turned to 'start', the voltage that goes to the starter solenoid also goes to energize the one half of the double relay that powers the fuel pump. Then when the key is released and the engine is running, the microswitch in the AFM continues to provide power to this half of the relay and the fuel pump continues to run. The other half of the relay (energized by the key in the 'on' position) provides power to the injectors, the ECU and to the microswitch in the AFM.chitwnvw wrote:If I understand the diagram correctly, when we switch from the start to the run key position, the power supply for the pump switches from one relay to the other.
- Dick
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
1970 Transporter. 2015cc, dual Weber IDF 40's
1978 Riviera Camper. Bone stock GE 2.0L F.I.
1979 Super Beetle convertible.
... as it turns out, it was the coil!
- Amskeptic
- IAC "Help Desk"
- Status: Offline
(ahh no-editor)chitwnvw wrote:If I understand the diagram correctly, when we switch from the start to the run key position, the power supply for the pump switches from one relay to the other.
(ahh yes-editor)dtrumbo wrote: That's not how I read it. When the key is turned to 'start', the voltage that goes to the starter solenoid also goes to energize the one half of the double relay that powers the fuel pump. Then when the key is released and the engine is running, the microswitch in the AFM continues to provide power to this relay and the fuel pump continues to run. .
There are two relays in a double relay, this particular relay (the fuel pump relay) is energized either by starter or AFM. The other relay inside the double relay is the main relay that energizes the rest of the junk as necessary.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
- Amskeptic
- IAC "Help Desk"
- Status: Offline
Interrupted ground paths can lead to weird "other paths to ground". These can energize circuits that are not supposed to be, or they can put voltage potential on both sides of an electrical consumer thus killing it, just like the alternator warning light goes out because both sides get 12 volts. A novice might do a voltage test on the alternator warning light, and conclude that it is supposed to light up because their test lamp sure does! The double relay has an important twist . . . there are two diodes to prevent electricity from "back feeding" when the relay coil is wired to two different sources. For example, when the engine is running and the AFM supplies electricity to the fuel pump's relay coil, that very same electricity could attempt to energize the starter solenoid. . . that would be "bad". The diode prevents electricity supplied from the AFM to back through the starter solenoid. The other diode prevents the one relay from feeding through the 85 ground path (particularly when someone forgets to secure that little brown wire to the firewall/mounting screw) up to the ignition coil via the main relay.chitwnvw wrote:Can you explain the bizarre behavior being cause by the ground? The ground that kind of sort of worked?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
- chitwnvw
- Resident Troublemaker
- Location: Chicago.
- Status: Offline