No fuel, any ideas?
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02-03-08, 06:10 AM
#8
HAILERS
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No. The tea leaves say when the fuel lines were routed, they were routed wrong. As in "the FPR should be the last thing in the system and should be connected to the Return line.
02-03-08, 12:53 PM
#9
wow! im really sorry guys.
The car was running before just fine, then one day i went out to start it and it didn't start and i couldn't hear the fuel pump running. So i pulled the fuel feed line ( the one coming off of the fuel filter) and no fuel came out. Next i ran a 12 volt line direct to the fuel pump and the fuel pump worked. I then tested for voltage at the fuel pump connector and got nothing. Then i checked the fuel pump relay, the resistances across the pins were all correct, i could hear it switching and i could see that it was switching by checking continuity with my multimeter. It was getting its signal to open just fine from the main relay. it just wasn't getting the main fuel pump voltage to it. I then checked the circuit opening relay and all the resistances between terminals were correct. What i did notice about it was that it is getting the main fuel pump voltage but no cranking voltage from the ecu. Also i took the relay apart to see if it was physically closing but it was not, so i closed it manually and it stayed closed as long as the ignition switch was on or cranking. I checked the voltage coming from the ecu and i was getting 1.88V with ignition on and 1.5V while starting. So I'm not sure if the relay is just bad or if both the computers i have are bad. My main question as previously asked is what does it mean when you put the jumper in the test connector by the air flow meter and the fuel pump runs with ignition on and in the starting position.
The car was running before just fine, then one day i went out to start it and it didn't start and i couldn't hear the fuel pump running. So i pulled the fuel feed line ( the one coming off of the fuel filter) and no fuel came out. Next i ran a 12 volt line direct to the fuel pump and the fuel pump worked. I then tested for voltage at the fuel pump connector and got nothing. Then i checked the fuel pump relay, the resistances across the pins were all correct, i could hear it switching and i could see that it was switching by checking continuity with my multimeter. It was getting its signal to open just fine from the main relay. it just wasn't getting the main fuel pump voltage to it. I then checked the circuit opening relay and all the resistances between terminals were correct. What i did notice about it was that it is getting the main fuel pump voltage but no cranking voltage from the ecu. Also i took the relay apart to see if it was physically closing but it was not, so i closed it manually and it stayed closed as long as the ignition switch was on or cranking. I checked the voltage coming from the ecu and i was getting 1.88V with ignition on and 1.5V while starting. So I'm not sure if the relay is just bad or if both the computers i have are bad. My main question as previously asked is what does it mean when you put the jumper in the test connector by the air flow meter and the fuel pump runs with ignition on and in the starting position.
02-03-08, 01:40 PM
#11
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The ECU has close to zip to do with the fuel pump running. All it does is output a gnd signal to the fuel pump relay/resistor assy to vary the voltage to the fuel pump from 9vdc to 12vdc. Even if this wire (green/red) is cut at the ECU, the pump will still run at full voltage. There, that's settled. ECU not a player in YOUR problem.
Nornally, the fuel pump only runs if the engine is running or the key is HELD to START. It does not run just by turning the key ON.
There are exceptions. If you jumper the fuel pump check connector and have the key to On or better, then pump runs. Or if the key is ON and you push the vane in the afm aft at least an 1/8" the pump will run.
So if you did do the last two things mentioned, and the pump did not run, then pull the plug off the Fuel Pump Relay/Resistor package. With the jumper in the fuel pump check connector, check for 12vdc on the Blue/Red wires. Both should have batt voltage if the key is on and the check connector jumpered.
No voltage? Go make sure the Engine fuse is good. It powers the Circuit Opening Relay and Main Relay. Fuse good? Pull the Circuit Opening Relay and see if there is 12vdc on the black/white wire. Key ON.
Or say you had 12vdc on the L/R wires at the fuel pump resistor/relay earlier. Then jumper the L/R to the L (blue) wire. Either L wire of the two will do. 'And either of the L/R will do. Both L/R and both L are one and the same. So, if the pump runs with those wires jumpered, then the relay might be on the wane.
So try some of that stuff above. I bet the Engine fuse is kaput. Check that first.
Nornally, the fuel pump only runs if the engine is running or the key is HELD to START. It does not run just by turning the key ON.
There are exceptions. If you jumper the fuel pump check connector and have the key to On or better, then pump runs. Or if the key is ON and you push the vane in the afm aft at least an 1/8" the pump will run.
So if you did do the last two things mentioned, and the pump did not run, then pull the plug off the Fuel Pump Relay/Resistor package. With the jumper in the fuel pump check connector, check for 12vdc on the Blue/Red wires. Both should have batt voltage if the key is on and the check connector jumpered.
No voltage? Go make sure the Engine fuse is good. It powers the Circuit Opening Relay and Main Relay. Fuse good? Pull the Circuit Opening Relay and see if there is 12vdc on the black/white wire. Key ON.
Or say you had 12vdc on the L/R wires at the fuel pump resistor/relay earlier. Then jumper the L/R to the L (blue) wire. Either L wire of the two will do. 'And either of the L/R will do. Both L/R and both L are one and the same. So, if the pump runs with those wires jumpered, then the relay might be on the wane.
So try some of that stuff above. I bet the Engine fuse is kaput. Check that first.
02-03-08, 01:59 PM
#12
the wiring diagram for the fuel system shows the ecu coming into play twice and the place in question for me is at the circuit opening relay as the starting input. I will post the wiring diagram in a minute. I hope you are right and its not the ecu but you havent quite convinced me.
02-03-08, 02:38 PM
#16
at key on the the one of the black and white wires has 12 volts.
also when the test port is jumped the fuel pump tuns on at key on and start
the fuel pump relay/resistor check out fine with the exception of getting the main power for the fuel pump but the relay function is working fine.
also when the test port is jumped the fuel pump tuns on at key on and start
the fuel pump relay/resistor check out fine with the exception of getting the main power for the fuel pump but the relay function is working fine.
02-03-08, 03:06 PM
#20
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There are two ways the Circuit Opening Relay will pull in. Remember, it has two coils.
One coil will pull the contacts in if the afm vane is moved aft at least a 1/8" or so. That makes a gnd circuit to the circuit opening relay so it will pull in. The other way for this coil is if you jumper the yellow, two socket fuel pump check connector. It does exactly the same thing as the vane did above. Puts a gnd on one of the two coils in the circuit opening relay. That particular coil has 12vdc from the Engine fuse if the key is to ON.
The OTHER coil in the circuit opening relay pulls in when the key is HELD to Start. It's gnd is permanet as in always there.
Again, there is no PRIME in this system. Never has and never will be a Prime on a series four RX-7.
One coil will pull the contacts in if the afm vane is moved aft at least a 1/8" or so. That makes a gnd circuit to the circuit opening relay so it will pull in. The other way for this coil is if you jumper the yellow, two socket fuel pump check connector. It does exactly the same thing as the vane did above. Puts a gnd on one of the two coils in the circuit opening relay. That particular coil has 12vdc from the Engine fuse if the key is to ON.
The OTHER coil in the circuit opening relay pulls in when the key is HELD to Start. It's gnd is permanet as in always there.
Again, there is no PRIME in this system. Never has and never will be a Prime on a series four RX-7.
02-03-08, 03:10 PM
#22
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the wiring diagram for the fuel system shows the ecu coming into play twice and the place in question for me is at the circuit opening relay as the starting input. I will post the wiring diagram in a minute. I hope you are right and its not the ecu but you havent quite convinced me.
EDITED SOME SINCE FIRST POSTED.
Last edited by HAILERS; 02-03-08 at 03:25 PM.
02-03-08, 03:28 PM
#23
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at key on the the one of the black and white wires has 12 volts.
also when the test port is jumped the fuel pump tuns on at key on and start
the fuel pump relay/resistor check out fine with the exception of getting the main power for the fuel pump but the relay function is working fine.
also when the test port is jumped the fuel pump tuns on at key on and start
the fuel pump relay/resistor check out fine with the exception of getting the main power for the fuel pump but the relay function is working fine.