QuestionQUESTION: I have a 1994 Plymouth Voyager Se with a 3.3L Engine. I have recently done a full body and mechanical restoration of the car, (new engine, currently only 5,000 Km on the engine), new ECM, fuel pump, coil pack, ignition wires, plugs, filters, radiator etc.) The car has been running beautifully, up until the onset of winter. As soon as the temperature dropped below freezing, the car has been nearly impossible to start. The problem is due to lack of spark, there is no voltage into the coil pack. Fuel pressure at the rail is fine. At first I usually ended up running the battery dry trying to start it, (although sometimes it would start before it did). Then recently I discovered a way to eventually get it started before the battery was exhausted, that I will describe below.
Let me state that when the key is turned to the run position, the fuel pump can be heard to run for a second, as is normal, (and again, fuel pressure is 60 psi at the rail). I had a similar problem in early summer shortly after the engine was replaced, (although only when the engine was cold, if it was warm, then it would start). I believe that the shop replaced the crank sensor to cure the problem.
If I turn the starter just for a faction of a second,wait a few seconds, and then repeat the process over and over again, (sometimes it takes 50-60 attempts), I would eventually hear the fuel pump run for a second after the starter had stopped). Once that has happened, the car will always start the next time the key is turned.
Do you think that it is the crank sensor that has failed again, or maybe the ASD relay or even the ECM? I don't want to start throwing parts at the problem, (and again the ECM and the crank sensor were recently replaced). What is the best way to determine the point of failure without having to replace parts.
Best Regards,
Steve
ANSWER: Hi Steve,
The fuel pump relay and the ASD relay (which powers the spark coil among others) are both 'closed' by the same signal from the ecm. If you see a connection between the no starting and the fuel pump 'after-running' it has to mean that either the crank or cam sensor is not working so the ecm is not getting the go ahead to close the two relays, or the fuse that powers both relays (fuse 16 under the dash, 10 amp) has a crack that opens/closes spontaneously. You could check for fault codes using the ignition switch to see if it is a sensor:
"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light, which remains 'on', to see it begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat to assure an accurate set of counts. Group the counts in pairs to form the 2-digit fault codes. 55 is always the last code, it means 'end of readout'. Then either write back or go to www.allpar.com/fix/codes.html for a code list. An 11 code is for the crank, the 54 is a code for the cam sensor.
Let me know what you learn.
Roland
---------- FOLLOW-UP ----------
QUESTION: Hi Roland,
Sorry, I forgot to mention that no computer fault codes are being sent, (although I suppose it could still be sensors if it was on its way out). What if it was the ASD relay that was flakey? Could that not result in intermittent voltage to the coil?
ANSWER: Hi Steve,
I assume though that you got a 55 fault code, correct?
Sure, if you have fuel pump function while you are cranking but not power on the dark green/orange wire at the coil, then I would suspect the ASD. But you appear to have tied the two together which implicates the sensors or the ecm. Why not check wire at the coil (which relies on the ASD) and at pin 22 of the fuel pump relay (the front pin of the socket, sneak a fine wire in and then reinsert the relay) and see if both are or aren't showing 12v while you are cranking it. If one isn't then presumably that relay is bad. If both aren't showing voltage, then I would check the sensors by measuring the voltage between the black/light blue and the tan/yellow (cam) and the violent/gray and black/light blue wires (crank) while you turn the engine over by hand with the ignition in the 'run' position. You should see the voltage oscillate between 5 and 0.3V several times per revolution of the crank. Turn the crank with a socket and handle on the crank pulley bolt. That would tell you if the sensors are working or not.
Roland
---------- FOLLOW-UP ----------
QUESTION: Hi Roland,
Yes your assumption is correct, the normal 12/55 codes are present.
I am not sure which relay is the ASD. I know that it is in the relay compartment on the drivers side under the hood, but my Haynes manual does not identify these. Can you tell me which one it is?
AnswerHi Steve,
The power distribution center in the '95 manual I am working from, which I believe is the same as in your '94, is rectangular with a small lobe in the front left corner. The relays on the in-board side are from front to back: ASD, rad fan lo, fuel pump, and rad fan gnd.
On the out-board side: rad fan hi, a/c clutch, b/up lamp, etax, starter. The pin I described for the fuel pump relay output is the front-most in the socket. If the output wire is not accessible then I suggested that you thread a fine insulated wire into the socket and out from underneath the relay when you plug it back in if that is possible. Another way to read the fuel pump relay output is to find a four-pin square black disconnect that supplies the oxygen sensor on the left side of the engine where the dark green/black wire is indeed the same wire that is the output of the fuel pump relay.
Roland
