Injector Stuck On
07-28-11, 07:42 PM
#1
Injector Stuck On
i am in the process of getting an 87 t2 that sat for 20 years back on the road. i recently replaced the fuel pump and got rid of all the emissions, rat's nest etc. i also had the injectors serviced. after the pump install, when moving the afm door, the secondary (further up on the intake manifold?) injector on the rear rotor sticks open thus filling the intake runner with fuel until the afm door is released. i checked it out and it looks like this injector is getting 12v at all times? any idea on where i should start troubleshooting? Thanks.
07-29-11, 12:27 AM
#2
The secondaries don't operate until there is enough load on the engine (manifold pressure 0 or greater) and the RPMs are 3800 or above. If you put a multimeter on any injector clip with the key 'ON', it will show 12v. You'll need a good meter like a Fluke to monitor duty cycle. Have you pressurized the fuel system with the UIM removed? I'm assuming that's how you've narrowed it down to one single secondary injector?
Also, holding the AFM door open just lets the fuel pump run without the engine idling. None of the injectors should fire if that's all you're doing.
Also, holding the AFM door open just lets the fuel pump run without the engine idling. None of the injectors should fire if that's all you're doing.
07-31-11, 08:35 PM
#3
yes, i have the uim removed at the moment. when i checked for voltage, i probed both of the terminals on the clip and got 12v on the injector that sticks. when i checked the other secondary the same way, i had no voltage. does this mean that the ecu is holding the injector open by closing the circuit? i think i am understanding this correctly, please feel free to correct me!
08-01-11, 12:24 AM
#6
Lets say having 12 volts between the two terminals is no good. You could disconnect the smallest ECU plug which houses the injector wires and check the terminals again to see if the ground source is coming from the ECU or the wire is accidentally grounding out.
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08-07-11, 12:02 PM
#8
Finally got a chance to work on her today, so I disconnected the small connector at the ecu and got no voltage between the connectors. Reconnected the ecu and have voltage between the terminals again. So am I correct to assume that the ecu is constantly grounding the injector, and I need a new ecu?
08-07-11, 02:09 PM
#10
Which injector is problematic, primary or secondary? If it's the secondary (front or rear) you could disconnect the plug at the injector and w/the small ECU plug connected backprobe the injector wire w/key to on and it should read 12 volts. Or disconnect the small ECU plug and probe the ECU itself w/key to on and see if it has 12 volts. The wire that leads into the back of the ECU plug "might" be pulled back and thus not creating a good contact w/the ECU and causing a ground signal to that particular injector. A member on another board indicated by measuring the voltage at the injector pin at the ECU and it had voltage less than .5 volts which would be low enough to similate a ground signal and his problem was the connector inside the ECU plug was loose and pulled back and not mating w/the ECU properly when the small plug was connected to the ECU.
08-12-11, 12:34 PM
#11
Ok made a discovery today! Car was "stored" outside since 91 and it looks like she took on some water in the passenger footwell. Basically the ecu and the bracketry supporting it are all corroded! Had to take the ecu apart with an impact screwdriver lol. Soo.. Looks like I need an n332 ecu and some brackets if possible.
08-21-11, 04:42 PM
#12
Ok, bought an ecu off a member on here and put it in. Went to hook up the battery and reversed the polarity. $@%%^%$&$%&*$! Take it easy on me, I feel like a total moron. So mad at myself! So anyway, the main fuse is fine, but the car will not crank or turn the fuel pump on. I went and tested the ignition switch and fuel pump relay\resistor according to the fsm and everything checks out. Did i just fry my new ecu?!?!?!
08-30-11, 09:01 PM
#14
ok lil update: ignition switch is def good. i found a ground that was not connected and now when i move the afm i can hear a relay (fuel pump relay?) but am not getting any fuel at the rail. i decided to check out the cicuit opening relay and got some interesting results. i checked it as per the fsm and i attached my results below. that top left number is .12 btw. it looks like this relay is bad? what you guys think? my apologies for the sloppy spreadsheet!
08-30-11, 10:17 PM
#15
The Circuit Opening relay is what some refer to as the fuel relay and it's located next to the steering wheel column (just to the right of it and under the dash) and is Black and Yellow. Is this the relay that you hear clicking.
The pump should flow fuel if the fuel check connector were jumpered and key to on. Also, the solid Black wire in the Circuit Opening relay (not the Black/White wire), if jumpered to the Brown wire in the same relay, would also cause the relay to power up the fuel pump w/key to on. When either jumper is in place w/key to on the Blue wire in the Circuit Opening relay will have voltage which runs to the back of the cargo area where it mates w/the fuel pump pigtail.
At the fuel check connector there are two wires. The Black wire is a ground and always should have o voltage while the other wire is Brown (same one found in the Circuit Opening relay) and that wire has 12 volts w/key to on and drops to a ground voltage after the car is started and the engine rpm climbs above 500. When this occurs the open fuel switch contact in the AFM closes and the ground on the Black wire passes the ground through the contact onto the Brown wire at the AFM and onto the Circuit Opening relay. So, when the fuel check connector is jumpered it simulates the switch contact closing within the AFM (jumper at the Circuit Opening relay accomplishes the same thing basically except the Black ground wire in this relay is different then the Black wire in the fuel check connector).
The pump should flow fuel if the fuel check connector were jumpered and key to on. Also, the solid Black wire in the Circuit Opening relay (not the Black/White wire), if jumpered to the Brown wire in the same relay, would also cause the relay to power up the fuel pump w/key to on. When either jumper is in place w/key to on the Blue wire in the Circuit Opening relay will have voltage which runs to the back of the cargo area where it mates w/the fuel pump pigtail.
At the fuel check connector there are two wires. The Black wire is a ground and always should have o voltage while the other wire is Brown (same one found in the Circuit Opening relay) and that wire has 12 volts w/key to on and drops to a ground voltage after the car is started and the engine rpm climbs above 500. When this occurs the open fuel switch contact in the AFM closes and the ground on the Black wire passes the ground through the contact onto the Brown wire at the AFM and onto the Circuit Opening relay. So, when the fuel check connector is jumpered it simulates the switch contact closing within the AFM (jumper at the Circuit Opening relay accomplishes the same thing basically except the Black ground wire in this relay is different then the Black wire in the fuel check connector).
08-30-11, 10:29 PM
#16
When I move the afm or jump the fuel pump connector, i can hear something clicking on the driver's side somewhere (circuit opening relay?), but no fuel. The actual fuel pump relay is behind the passenger headlight correct? Shouldn't I hear that relay click under these conditions? I'm wondering if the no crank situation is also somehow related...
08-30-11, 10:42 PM
#17
Forgot you had a turbo S4. On an S4 Tll there is a fuel pump relay and resistor which changes the voltage to the fuel pump during different load situations etc and it's located near the AFM. The Blue/Red wire from the Circuit Opening relay runs to this other relay before running to the actual fuel pump. The relay by the AFM could be bypassed by disconnecting the plug to it and jumpering the Blue/Red wire from the Circuit Opening relay to the Blue wires in the same plug. One jumper should do here. You should check for voltage at this relay on the Blue/Red wire when the connector is jumpered and key to on. If the relay near the AFM was doing its job (when not disconnected and jumpered) then the Blue wires (two of them) at this relay would have voltage as well (connector jumpered and key to on). And this relay by the AFM relies on the Main relay to power the coil inside it and also relies on the ECU for the ground signal that goes to this coil.
09-14-11, 07:31 PM
#18
Alright, so I have 12v at the fuel pump relay/resistor connector when the afm is open. I tried jumping the "a" and "b" terminals and with the key on the fuel pump does not run. Also, when i turn the key on, i can hear/feel the circuit openeing relay click. Also, no pump activity with the test connector on the passenger strut tower jumped. So....does this mean that my fuel pump relay in the engine bay is bad?? Grrrrrr.
09-14-11, 07:55 PM
#19
So which wire at the Resistor had voltage w/the AFM flap open? I would suppose it was the Blue/Red wire or was it the Blue wire and the Blue/Red wire? If it was the Blue/Red and not the Blue wire then this is important!
Secondly, did you jumper the Blue/Red wire to the Blue wire or not? Forget about letters and talk to me in terms of the wire colors.
You need to focus primarily on the Circuit Opening relay first. Why? Because it's first in line and thus is before the Resistor so things need to be good to go there before the Resistor wires are checked and or jumpered. As stated before, the Blue/Red wire at the relay passes voltage on to the Resistor so this wire would be the focal point when testing. At start this wire would have voltage and w/the fuel check connector jumpered and key to on it should have voltage as well. If it does not then jumper the "solid Black wire in the relay to the Brown wire in the relay plug, which is basically the same thing as the fuel check connector, but jumpered in a different place within the circuit. Try this and see what results you can get.
Secondly, did you jumper the Blue/Red wire to the Blue wire or not? Forget about letters and talk to me in terms of the wire colors.
You need to focus primarily on the Circuit Opening relay first. Why? Because it's first in line and thus is before the Resistor so things need to be good to go there before the Resistor wires are checked and or jumpered. As stated before, the Blue/Red wire at the relay passes voltage on to the Resistor so this wire would be the focal point when testing. At start this wire would have voltage and w/the fuel check connector jumpered and key to on it should have voltage as well. If it does not then jumper the "solid Black wire in the relay to the Brown wire in the relay plug, which is basically the same thing as the fuel check connector, but jumpered in a different place within the circuit. Try this and see what results you can get.
09-14-11, 08:36 PM
#21
Are you removing the plug from the Resistor before you attempt to jumper the Blue/Red wire(s) to the Blue(s)? This makes things much easier for it removes the chance of the Resistor from shorting the jumper. If you haven't removed the plug to then jumper then do so.
When you did the jumper and you got nothing what does this mean? Does it mean no voltage on the Blue wire or the pump does not run?
When you did the jumper and you got nothing what does this mean? Does it mean no voltage on the Blue wire or the pump does not run?
09-14-11, 09:09 PM
#23
It makes absolutely no sense how the jumper would not pass voltage from a wire with voltage present to a wire w/o voltage. Try the jumper again as there is no explanation other than the jumper was not placed properly in place. No explanation at all unless the Blue wire somewhere down the line is grounded out. To check for this try ohming out the Blue wire between two points with the two points being at the Resistor plug at one end and the connector at the rear of the car by the fuel pump where the front harness mates with the rear harness. Usually this connector of these two harnesses is located under/behind the carpeted rear fender/speaker panel.
09-14-11, 09:18 PM
#25
Then retry the jumper from B/R to Blue and if you get the same results then look for high resistance (via an ohm test) on the Blue wire as it runs from the Resistor plug to the rear connector to see if it is grounding out and thus causing all of your problems.
EDIT: And this is important. When you say you got nothing does this mean the pump did not run "or" the Blue wire had no voltage. If the Blue wire has voltage then forget the ohming of the Blue wire but rather go to the harness pigtail of the fuel pump and manually supply voltage to the Blue wire that powers the fuel pump to see if you can manually turn it on. If this does not work then jumper a ground wire to the Black wire in the rear pigtail which is the ground wire for the pump in addition to voltage to the Blue pump wire and if this has no effect then the pump is likely kaput!
EDIT: And this is important. When you say you got nothing does this mean the pump did not run "or" the Blue wire had no voltage. If the Blue wire has voltage then forget the ohming of the Blue wire but rather go to the harness pigtail of the fuel pump and manually supply voltage to the Blue wire that powers the fuel pump to see if you can manually turn it on. If this does not work then jumper a ground wire to the Black wire in the rear pigtail which is the ground wire for the pump in addition to voltage to the Blue pump wire and if this has no effect then the pump is likely kaput!