bottomline89 Posted February 3, 2012 Share Posted February 3, 2012 I've got an 89. 4.0 When i try to start it, it fires up and revs to ~1500 then falls on its face. i put in a new fuel pump, new fuel filter and new fuel pressure regulator valve, i unplugged the tps and it didn't make a difference, same thing with the iac valve, i got it to run for a little bit today and i couldn't hear any vacuum leaks but once it was up to temp it wanted to idle at about 1200. .. HELP Link to comment Share on other sites More sharing options...
bottomline89 Posted February 3, 2012 Author Share Posted February 3, 2012 Ballast resistor? Link to comment Share on other sites More sharing options...
txjeeptx Posted February 3, 2012 Share Posted February 3, 2012 I'm pretty sure the "ballast resistor" on the renix injection is for the fuel pump. Its the one located at the front of the inner fender in front of the air filter box. It isn't part of the ignition system, as I recall. If unplugged while the engine is running, the engine dies because the fuel pump gets cut off. If it isn't connected, or has an internal break, it won't allow the engine to start(no fuel, since the pump wouldn't run). I read your buildup thread to get more info on what you've done recently - you replaced the head gasket most recently. It could have taken a while to get the fuel system primed up. Now you're probably up against some sort of sensor problem. You said there was no change when you unplug the TPS and IAC. I'd clean the IAC, if it hasn't been cleaned already. It could be sticking open, causing high idle. You said you didn't hear any vacuum leaks, but are you sure there's vacuum getting to the MAP sensor? Could be a plugged line. As for the TPS, if its not adjusted properly, the renix system throws a fit. Tryin to help. Hope the bearings in the engine didn't suffer from the coolant in the oil. Link to comment Share on other sites More sharing options...
bottomline89 Posted February 3, 2012 Author Share Posted February 3, 2012 Thanks. Ill try bypassing it after school. Ive got a half a tank on the new head gasket so i know its primed Link to comment Share on other sites More sharing options...
txjeeptx Posted February 4, 2012 Share Posted February 4, 2012 Don't bypass it for long, of you do. Its only bypassed when cranking the engine, similar to what would be done for an ignition system ballast resistor. I forget what the purpose is for the ballast resistor to the fuel pump . . prevent it from running full-tilt all the time and prematurely wearing out, perhaps? Also, you didn't forget to plug in the coolant temperature sensor, did you? Its the one that goes in the block below the exhaust manifold and in front of the engine mount, behind the power steering pump. Without it plugged in, the EFI thinks its really cold outside, and opens up the IAC and dumps in the fuel. Helpful reading about renix sensors: http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm Link to comment Share on other sites More sharing options...
cruiser54 Posted February 4, 2012 Share Posted February 4, 2012 The fuel pump ballast resistor's sole purpose is to give 12 volts to the fuel pump on starting and then lower the voltage to the fuel pump after the engine is running so it's quieter. That resistor can be bypassed with no ill effects except that the pump might be too noisy for some folks. OP, do you have a voltmeter? I would check the TPS adjustment. It's a real possibility that it has failed. Have you ever cleaned your throttle body and IAC? Link to comment Share on other sites More sharing options...
maddzz1 Posted February 4, 2012 Share Posted February 4, 2012 If it's having these problems when you start the engine and it is still cold then it shouldn't be caused by a bad sensor. Until the engine reaches normal operating temp it runs in a closed loop mode from a preset set of parameters. Once the engine reaches normal operating temp it switches to an open loop mode and starts getting signals from the sensors. I would start by cleaning the throttle body and the IAC really good. Link to comment Share on other sites More sharing options...
bottomline89 Posted February 4, 2012 Author Share Posted February 4, 2012 My throttle body is clean and i have a fairly new iac sensor in. Could it be the ignition control module? Link to comment Share on other sites More sharing options...
cruiser54 Posted February 5, 2012 Share Posted February 5, 2012 If it's having these problems when you start the engine and it is still cold then it shouldn't be caused by a bad sensor. Until the engine reaches normal operating temp it runs in a closed loop mode from a preset set of parameters. Once the engine reaches normal operating temp it switches to an open loop mode and starts getting signals from the sensors. I would start by cleaning the throttle body and the IAC really good. Actually it's open loop when it's running off preset parameters. A Renix will go into closed loop before operating temperature is reached, but only if the oxygen sensor is working. A bad CTS, IAT, or MAP sensor come into play when cold. The vacuum line from the throttle body to the MAP, if cracked, unplugged, clogged, or melted can cause a super-rich condition resulting in a no-start. Link to comment Share on other sites More sharing options...
maddzz1 Posted February 5, 2012 Share Posted February 5, 2012 If it's having these problems when you start the engine and it is still cold then it shouldn't be caused by a bad sensor. Until the engine reaches normal operating temp it runs in a closed loop mode from a preset set of parameters. Once the engine reaches normal operating temp it switches to an open loop mode and starts getting signals from the sensors. I would start by cleaning the throttle body and the IAC really good. Actually it's open loop when it's running off preset parameters. A Renix will go into closed loop before operating temperature is reached, but only if the oxygen sensor is working. A bad CTS, IAT, or MAP sensor come into play when cold. The vacuum line from the throttle body to the MAP, if cracked, unplugged, clogged, or melted can cause a super-rich condition resulting in a no-start. I always get that backwards. I would try pulling the vacuum line on the EGR valve and plug it with a screw (the vacuum line) then start it. See if it makes a difference. Link to comment Share on other sites More sharing options...
bottomline89 Posted February 5, 2012 Author Share Posted February 5, 2012 And its this while the engine is hot or cold, under load or idling. And i just put a new coil in ill try that egr valve thing but i doubt it works. Its a new egr valve too Link to comment Share on other sites More sharing options...
bottomline89 Posted February 6, 2012 Author Share Posted February 6, 2012 ok. next thing i'm gonna try is completely cleaning my fuel system. i'm gonna drop the tank and clean it then put a new filter in Link to comment Share on other sites More sharing options...
txjeeptx Posted February 10, 2012 Share Posted February 10, 2012 You git it to run? Hope its working fer ya. Link to comment Share on other sites More sharing options...
bottomline89 Posted February 12, 2012 Author Share Posted February 12, 2012 Got her running. Loose electrical connection. Thanks for the help guys Link to comment Share on other sites More sharing options...
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