replaced intake gasket . . now no fuel pressure
#21
Join Date: Jul 2009
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I preach and teach KISS
Anyway, I'm assuming you've verified the following:
- NO voltage to the FUEL PUMP FUSE?
- NO voltage to the FUEL PUMP RELAY at PIN 86?
Moving onto your next question:
The only other wire I see on the back goes to the dizzy, perhaps that is where the can sensor is on these engines?
Now, the question is:
Do you have POWER to the COIL?
The answer to that will help determine if a failsafe event has occurred or not. Start there and report back.
CM
#23
I do have both control and controlled circuit voltage at the relays. I do not have coil power.
Squirrels, I did not disconnect the cam and crank sensor when I did the job and the wires are not pinched. They are unbothered. I tested relays, switching them around, they are in the right places.
Squirrels, I did not disconnect the cam and crank sensor when I did the job and the wires are not pinched. They are unbothered. I tested relays, switching them around, they are in the right places.
#24
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In the event of unsafe condition, low fuel pressure, no reference signal and, many other triggers, the PCM is programmed to cut all power TO the entire EFI system via the AUTOMATIC SHUTDOWN RELAY (ASD) found in the PDC.
This as you may or may not already know includes:
- The ignition system
- Fuel system
- Sensor system
The other FUEL PUMP relay test that we DID NOT perform was to have you test for voltage at PIN 87A
This PIN is the SUPPLY TO the FUEL PUMP MODULE. Measure the voltage at this point by doing the following:
Wrap a short piece of wire around PIN 87A. NOTE: Make sure it does not come into contact with ground.
Insert the FUEL PUMP relay back into the PDC.
Turn the KEY <ON>
Note voltage on PIN 87A of FUEL PUMP RELAY
Voltage should be ~12 volts
Do that and get back to me.
CM
Last edited by cmckenna; 08-12-2010 at 06:26 PM.
#25
I do not know your numbers of the terminals, but I do know all the info from that fuel system relay. The control side, is hot when the key is on and it is hot in and out, both terminals. When the key is off, it is dead. Normal. The controlled side though . I have the hot terminal, hot at all times. But when I check the other terminal ( there are only 4 that work on this relay ) it is not hot, even when the key is on. To me, that seems like a bad relay, but I have changed relays.
#26
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I do not know your numbers of the terminals, but I do know all the info from that fuel system relay. The control side, is hot when the key is on and it is hot in and out, both terminals. When the key is off, it is dead. Normal. The controlled side though . I have the hot terminal, hot at all times. But when I check the other terminal ( there are only 4 that work on this relay ) it is not hot, even when the key is on. To me, that seems like a bad relay, but I have changed relays.
When the PCM energizes the ASD and FUEL PUMP relays, terminal 87 connects to terminal 30. This is the <ON> position. Terminal 87 supplies voltage to the rest of the circuit.
Both RELAYS are tied into the same supply that feeds PIN 86 which connects to PIN 85 which is connected to the PCM FUEL PUMP RELAY CONTROL. This energizes the coil via switched GND.
FUSE No 8 is a 20A fuse found at the PDC and, is the SOURCE of power TO the FUEL PUMP relay PIN 30. This is the one that is live at all time. Once energized, it (FUEL PUMP RELAY) supplies the FUEL PUMP MODULE VIA PIN 87A down to the wiring harness out of the PDC, down the firewall, into another connector, into another wiring harness and terminates at the FUEL PUMP connector.
The controlled side though. I have the hot terminal, hot at all times. But when I check the other terminal ( there are only 4 that work on this relay ) it is not hot, even when the key is on. To me, that seems like a bad relay, but I have changed relays.
NOTE It should also be noted that the SUPPLY for the PCM is off the FUEL PUMP fuse. I forgot about this. If the FUEL PUMP fuse is NOT working, guess what, NO power is sent to the PCM. That would explain the NO BUS condition as well.
Now, one would ask themselves, why would power be absent on PIN 87A and, that may be due to:
- FAULT in the relay so, to CHECK that, we run another test and that is:
FUEL PUMP RELAY TEST: OPERATIONAL
-remove the relay from the PDC
-Jump the coil side wires to FUEL PUMP RELAY PIN 86 and PIN 85
-KEY <ON>
-Measure OHM reading across PIN 30 and PIN 87A
-Should meet OEM SPEC: 75 OHMs ±5 OHM
NOTE: After 3 seconds, the PCM will CUT power to the ASD and FUEL PUMP RELAYS. FYI on that. So, you've got only 3 seconds to obtain your measurement. After that, the KEY <OFF> will have to be performed and repeated to energize the relays.
In looking over this thread again, based on what I'm reading (NO POWER TO COIL or FUEL PUMP) I'm inclined to make an assessment that this is relating to an AUTOMATIC SHUT DOWN event that, we do NOT know the initiating factor for.
But, let's walk the path of the intake change.
a. we know that none of the master sensors (CKPS, CPS) were removed or touched so, we can almost rule that out - at least, for now anyway.
b. we know that the intake had to come off which means, that all sensor wires at the throttle body were removed. Those are:
- MAP
- IAC motor
- IAT
- ECT
- ECT GROUND- there's one little stud that is on the left hand side of the upper radiator hose. Make sure that is connected. For, another master sensor is actually that tiny little ECT (Engine Coolant Temperature) sensor and, it's ground. Without that ground connected, it will not work. For the PCM NEEDS the ECT input voltage to switch between OPEN and CLOSED loop mode at the PCM.
-Generator was removed. Check for SHORT, disconnected wire at rear of the generator. There's two smaller wires at the rear and one large HOT output that connects to the PDC HOT terminal. It's BLK/WHT That goes to isolated terminal in the rear of the Gen.
-There's a GND that terminates on top of the GEN mounting bracket that was removed.
- In the rear, there's the Solenoid Purge Valve that may or may not have been removed / disconnected. Make sure that connector is plugged in and that the valve is facing UP and connected with two VAC lines for IN / OUT.
I may have missed something but, you get the idea. Start walking the path and go from there. Meanwhile, I'll be around to see the results of the FUEL PUMP RELAY OHM TEST. IN fact, check the ASD relay in the same exact manner while you're at it.
CM
Last edited by cmckenna; 08-13-2010 at 11:01 AM.
#27
EUREKA !! it runs. When I was checking the wire harnesses on the left rear, I finally noticed that the most rearward intake bolt head had just barely captured the small two wire harness. The head just had bitten the edge of the wire and of course caused a direct short. Thank you so much for the aid and things to look for. The cab over design makes it tricky back in there and I'm an agile guy. Hope this helps others as well. Again, THANK YOU. . . . and of course it did end up being a K I S S item
Last edited by PetesPonies; 08-12-2010 at 07:56 PM.
#28
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SUMMARY
INCIDENT: A no start condition existed after the removal and installation of the intake manifold.
ROOT CAUSE: Pinched sensor wires under the intake bolt.
AFFECT This caused a DEAD SHORT in the 5-volt sensor supply thus, initiating the execution of the automatic shutdown command at the PCM thus, cutting all power to the EFI system. Failsafe mechanism was initiated.
SYMPTOMS:
- NO CLUSTER
- NO POWER TO COIL
- NO POWER TO PUMP
- NO POWER TO SENSORS
SOLUTION:
Repair the DEAD SHORT under the intake manifold bolt and / or repair wire as necessary
RESULT
Vehicle runs and all systems are back on-line.
CM
INCIDENT: A no start condition existed after the removal and installation of the intake manifold.
ROOT CAUSE: Pinched sensor wires under the intake bolt.
AFFECT This caused a DEAD SHORT in the 5-volt sensor supply thus, initiating the execution of the automatic shutdown command at the PCM thus, cutting all power to the EFI system. Failsafe mechanism was initiated.
SYMPTOMS:
- NO CLUSTER
- NO POWER TO COIL
- NO POWER TO PUMP
- NO POWER TO SENSORS
SOLUTION:
Repair the DEAD SHORT under the intake manifold bolt and / or repair wire as necessary
RESULT
Vehicle runs and all systems are back on-line.
CM
Last edited by cmckenna; 08-12-2010 at 08:34 PM.