QuestionQUESTION: Hi,
We have a 1992 Fifth Avenue with the 3.8L. It was running but then quit, with symptoms that made me think the fuel pump had failed. Upon further looking I found that when the key is turned ON, the fuel pump does not come on, nor does the Check Engine light. Sometimes it does come on, and when it does you can hear the pump running and the Check Engine light comes on. I cannot get it to behave consistently. I also cannot read trouble codes from it because the light is not coming on. Please help!!! Thanks----Andy
ANSWER: Hi Andy,
It may be that a fuse has a crack in its internal wire that is opening and closing spontaneously or when called into service, or it might be the ignition switch is flakey in one of the sections. If you have a voltmeter or a 12v test light that would be of help.
The fact that the check engine light is also flakey leads me to suspect the output of the ignition switch which powers the single board engine controller is the problem. Start in the power distribution center in the engine compartment and look for a 40 amp fused labelled for the ignition system. That fuse powers a section of the ignition system which in turn powers fuses 6,7,8 and many other components including the autoshutdown relay's activation coil which has to close that relay to provide power to the fuel pump. So verify that you do have power on any of those three fuses under the dash (6-8) when you have the key in the run and the start positions.
Also in the power box check the 30 amp fuel pump/trans fuse for a possible crack in its internal wire as that is the source of current through the closed autoshutdown relay to the fuel pump.
So between those two fuses in the powerbox and the ignition switch I think we will find the source of your no start.
Thanks for the rating and nomination, Andy.
Roland
---------- FOLLOW-UP ----------
QUESTION: Roland,
Thank you so much for your prompt reply! I have done the indicated fuse swapping under the hood with no effect, as well as swaps of the fuel pump and auto shutoff relays. Tomorrow I will get those voltages at the fuse box, which is currently laying on the floor. By the way, as I was making my way through this process, I accessed and removed the anti-theft/RKE computer/radio box. I found it to be unplugged at the main connector, and upon initiating and reprogramming the system I discovered why. Every time the battery is disconnected, the RKE loses its memory, the fob won't work, and the four way flashers come on and wont turn off until either the fob is reprogrammed and cycled, or the main connector unplugged, which is how I found it. Don't know if this relates to the starting problem, but wondering if I can fix this? Also, the RKE system does not cycle the locks when the program connector is grounded, nor does it cycle the locks to indicate the completion of the programming activity.
I know this is getting rather wordy, but there is one more thing. There is a vacuum manifold connected to a valve on the passenger fenderwell under the hood. It has two wires, a larger and a smaller. This smaller one (It's red with a stripe) has another piece of wire spliced into it, and this wire has been run to one of the wires that goes to the a/c compressor clutch. What gives here, to me it smells like a dead output in the computer or something.
Again, thanks Roland, I really appreciate your expertise in chasing down these gremlins-----Andy
ANSWER: Hi Andy,
I would prefer to handle one issue at a time, unless they are related. One thing I should warn you about is that you should not have disconnected the anti-theft module UNLESS the engine was running because evidentally in the design of the anti-theft system the engineers wanted to circumvent theft of the vehicle via the removal of the anti-theft module. So the manual warns to not disconnect its plug if the engine is not running. If you did that I will try to find what the remedy is now for the situation. Usually though when the anti-theft has been alarmed or unplugged the symptom which ensues is that the engine will start but then die in a few seconds until you have successfully disarmed the system. Has that 'die after a few seconds' behavior occurred since you removed the anti-theft/rke computer/radio box OR is the issue that it won't even catch and run?
Roland
---------- FOLLOW-UP ----------
QUESTION: Hi Again,
No, when I gained access to the anti theft box the main connector was already disconnected from it. It was coming on briefly at times (the fuel pump and check engine lights) but usually the light would go out and the pump stop before i could start the engine. I have been able to get it to run for a few seconds at a time, but now it's not even doing that, and that could have been related to the fob programming, because what little response I had from the fuel pump and the engine computer seemed to go away completely after I did that. I didn't mean to ask anything unrelated, for all I know any or all of the issues could be related to each other. And yes, I did unplug that main connector on the RKE after I had plugged it in and I did it without the engine running. Thanks again for your time and attention, it sure would be nice to have it running again, it runs so good when it's running------Andy
AnswerHi Andy,
Let us make sure we are on the same page. The theft security module has a 21-page connector and that is the one that should not be unplugged unless the engine is running. The keyless entry module has 2 8-pin plugs, and if you have a lamp outage module that has 14 pins. All are mounted on the same bracket. So which one(s) were unplugged when you gained access and did you plug which back in?
The pump is supposed to run for about 1 second when you turn the key to run. That is normal. It is supposed to start running again when you move the key to start and continue to do so as long as you are cranking it over. Then it will cut off after you return the key to run position unless the engine is running. The key fob and its module have nothing to do with the engine running or not.
As some point in the past everything worked, correct? What is the history after that?
The check engine light will come on when you first turn the key to run which is to show you that it works. It goes out soon after that, just like the fuel pump does and it doesn't come on again until the engine controller gets a fault code or the engine dies while running.
So keep all that in mind why you are trying various things.
You can temporarily by-pass the ASD relay by jumping from the rear pin to the front pin of its socket. That will turn on the fuel pump. But don't leave it that way because of safety issues related to driving the car with the ASD by-passed and of course the battery will run down. This temporary by-pass will energize the fuel pump and the injectors and the spark coil and test whether the engine no start is related to those items or not.
Please rate my answers, which you can do for each answer if you choose as well as to 'nominate;.
Thanks,
Roland
Roland
