2004 Suburban cranks but won't turn over
February 27th, 2018, 5:53 PM
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2004 Suburban cranks but won't turn over
I have a 2004 Suburban Z71 that will not start after having the battery disconnected for a couple days. I know most of you are thinking it's the security system, but I have tried the 30 minute relearn procedure 3 times with no luck. Also, I believe when this happens and it's the security system, the engine will turn over and run for a few seconds before dying. This is not the case. The fuel pump does not prime when the key is switched to on or when cranked. I have also swapped the relays and checked the fuses. If I take a paper clip and jump from the lower left socket to the upper right socket where the relay is, the fuel pump kicks in, but stays running no matter what. I am able to start and drive it with the paper clip in.
The paper clip does get rather hot when I do this, so I am thinking maybe the fuel pump is drawing too much power and causing some safety mechanism to switch? I had the battery disconnected while checking under the under hood fuse box for shorts, since I have been experiencing a small parasitic drain also. Aftermarket components in the vehicle include the braking and towing system, 3 amplifiers totaling 3000 watts, and auto-start. Most of the drain turns out to be coming from the auto start and a small amount from my amplifiers even with the ignition off. I used a 200 amp relay to switch the amplifiers on with the ignition. To do this, I tapped in to an ignition wire under the steering column. The parasitic drain is now down to 60 milliamps, which is manageable enough for my new red top battery and 165 amp alternator with big 3 upgrade.
Anyway, I got a little off-topic there. Main thing right now is to get this no-start condition in order. Does anybody have any suggestions? I am about out of ideas here...I'll probably take the fuse box back out and check the connections under there, but since inserting a jumper works, I don't think I'm going to find the solution under there. My local mechanic says the oil pressure sensor has nothing to do with the fuel pump on Chevys and that it's only Fords that have that, but I think he may be mistaken. Diagrams online show that the sensor is involved in the fuel pump circuit. After getting the Suburban started, if I pull the jumper from the relay socket, the engine sputters and dies within a few seconds. Isn't it supposed to stay running without the relay in if the oil pressure is high enough? I believe the sensor is wired in parallel with the relay.
The paper clip does get rather hot when I do this, so I am thinking maybe the fuel pump is drawing too much power and causing some safety mechanism to switch? I had the battery disconnected while checking under the under hood fuse box for shorts, since I have been experiencing a small parasitic drain also. Aftermarket components in the vehicle include the braking and towing system, 3 amplifiers totaling 3000 watts, and auto-start. Most of the drain turns out to be coming from the auto start and a small amount from my amplifiers even with the ignition off. I used a 200 amp relay to switch the amplifiers on with the ignition. To do this, I tapped in to an ignition wire under the steering column. The parasitic drain is now down to 60 milliamps, which is manageable enough for my new red top battery and 165 amp alternator with big 3 upgrade.
Anyway, I got a little off-topic there. Main thing right now is to get this no-start condition in order. Does anybody have any suggestions? I am about out of ideas here...I'll probably take the fuse box back out and check the connections under there, but since inserting a jumper works, I don't think I'm going to find the solution under there. My local mechanic says the oil pressure sensor has nothing to do with the fuel pump on Chevys and that it's only Fords that have that, but I think he may be mistaken. Diagrams online show that the sensor is involved in the fuel pump circuit. After getting the Suburban started, if I pull the jumper from the relay socket, the engine sputters and dies within a few seconds. Isn't it supposed to stay running without the relay in if the oil pressure is high enough? I believe the sensor is wired in parallel with the relay.
