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Have a 2002 Mustang GT, the problem started as the car sat for about a year, with bad fuel pump, installed new pump and car ran for about a week, then pump won't come on, was shown a way to by-pass the fuel pump driver module and found it was faulty, replaced module. Car ran good for a few weeks and started to hard start and had a miss when give it more gas.. had code P0340, replaced the cam position sensor, still the same. Now to start car need to start at short cranks and after around 8 or so times car will start but had miss. I seemed to misplace the way to bypass the module, does someone out there know what color wire goes where?
Any advise would be greatly appreciated. Thanks, Aloha
Always always always have the alternator tested anytime there is a cam related DTC code first. Have the alternator tested for excessive AC ripple and correct output. Almost all auto parts stores will do the test for free.
You will not get a recommendation from me to bypass the FPDM. This will only create a new set of issues for a street car. The hard start problem is the result of some other "failure".
Have you been driving the car a lot with the P0340 DTC? If so this may have something to do with the current problems. The PCM uses the cam sensor to sense the power stoke from the exhaust stroke. When ever there is a cam related DTC, the PCM switches to "limp in" mode to keep the motor running. For a cam problem the PCM fires the fuel injectors on every stroke. This results in twice as much fuel being used. Continued operation could result in:
Oil dilution with gas
gas washing the oil from the cylinder walls with increased wear
spark plug fouling
over heating of the cats
Check the oil for gas contamination. If present change the oil.
Focus on fixing any and all DTC's outstanding.
Perform a through check for vacuum leaks. Don't cut corners here.
Try this. Cycle the key on/pause/off several times. Listen for the fuel pump to run each time. If the fuel pump does NOT run, STOP and find out why.
After a few key cycles crank the motor. Does key cycling improve starting? If so, the problem is related to fuel pressure leak down.
Disconnect the MAF. Does this improve starting?
2003 GT Convertible (sold)
2000 GT coupe (fix up project)
thanks so much for your response, in answer to some of your questions, car hasn't been on the road for about a year, only runs
in driveway, for when i got the car had a bad fuel pump, broken windshield, bald tires, now i have finnally got all the papers in order,
replaced fuel pump and car ran good for a few days (just in driveway and around the block) had a P0340 code so I replaced the
cam position sensor, then the pump wouldn't run so i got directions
on bypassing the fuel pump driver module, did it and car ran good,
got a module and once again car ran good , code came back. Ran good, now it is hard starting, seems if i start it with short bursts, after around 8 or so starts it will start, if i give it gas to fast it shuts down, leave it idle and it will run but misses at time while it idles. Code P0340 is back. to me it seems like pump doesn't always run. One of my suppects is the wiring on connector to the fuel module?
Thats why i was asking about the bypass wiring. I hear alot about the alternator, i test and i get 14.7 volts. I'm awaiting your response, thank you so much for your time and effort in this matter. Aloha, dave
The force is weak on this one. Putting a DC VOM on the alternator does NOT test for a bad diode.
Also requested the results of a specific key cycle test. Don't crank the motor between key cycles. Does the fuel pump run for a few seconds during each key cycle?
With the explanation given about what happens with a cam DTC, the possibility of gas in the oil being part of the problem hasn't been ruled out?
OBTW, on a 99+ Mustang, the fuel pump isn't supposed to run all the time. It is supposed to run for only a few seconds at initial key on and then shut off. The PCM will not restart the fuel pump until the motor has been confirmed running.
OBTW, there are several causes for the symptom of "motor will not take gas". Examples include:
disconnected fuel pressure intake vacuum reference line
low fuel pressure
poor engine vacuum perhaps from a base motor problem.
If this were my car, I would make sure there are no vacuum leaks or exhaust leaks.
It would be handy to "know" the fuel pressure. An external gauge is nice but it also helps to know what the PCM "thinks" is the fuel pressure. An ODB2 scanner is the best way to get this information.
Does holding the throttle half way open during cranking improve starting? If so, consider a bad IAC (black vented) is not allowing starting air to enter.
Does disconnecting the MAF improve starting?
Again, go back and cover the basics before digging into what's wrong. You will thank me in the end.
2003 GT Convertible (sold)
2000 GT coupe (fix up project)
Aloha, ok have done some more stuff, there is no sign of gas in the oil. Turning key on and off does not help with the starting. Start car around 10 or so times and it starts, when try to give it gas it wants to die. If give gas very slowly will come up in rpm. Misses at idle. Code P0340 keeps coming on. Today i found a code P0190 Fuel
Rail Pressure Sensor. Thanks for your time and effort in this matter.
I replaced cam senors still had problem. Then I found a mustang forum and was advised to replace alternator. Had alt chk out and reading came back that alt ok. The post I read told me that the readings might show the alt is find, but it's the problem. Drove the car for about month with the same code. My problem was that the car would not start right away and sometimes would turn off on me. Finally was driving and all my electronics shut off A/C, radio, lights, and my gauges. And the then the car few minutes later. So I knew it was the alt. Replaced it and car was running better and chk engine shut off. So just a suggestion also I did noticed alt was making a weird noise too.
It sounds like you may have several problems, but 1 problem I am sure you are having is the alternator, that may also be causing other problems. You need to confirm this and replace it if needed, this will make fixing your other problems much easier. It may even remove all your other problems.
A volt meter will not tell you if there is a problem with the diodes and I am not sure about an auto store test. When the diodes start to go out they create spurious noise that messes with sensors, especially the cam shaft position sensor. That will make it hard to start the car, I had this problem.
There is a simple test you can do to see if it is the alternator:
Using an ODB scanner clear all the engine codes
Now figure out what set of actions will make the P0340 code come back, like starting X number of times, revving the engine, what ever
Clear the code again and repeat this a few times to make sure you know what will throw the P0340 code
Next unhook the electrical connections to the alternator
Clear the check engine codes again
Now repeat the sequence of events that will throw the P0340 code (the engine is going to act weird since it does not have the alternator hooked up)
If the code does not come back it is the alternator
If the code comes back then the alternator is likely OK
Seriously if it is your alternator you need to replace it before going after other problems, the other problems may not be real. I recall there being 3 bolts for it, the hardest part is getting the belt back on.
There is also a thread for the cam shaft position sensor on this forum with lots of info.
I also had the cam sensor code coming up on my 2002 GT. Had a hard start problem\poor performance and back firing after driving car a few miles and shut off (at say a store) and come out and restart and car would back fire. I replaced MAF sensor, as well as cam sensor. After this did not fix my problem I started reading posts here on AFM. I tested my alternator with my voltage meter and it was OVER charging at 15.9 to 16.2 volts!( normal charging is 13.8 to 14.2) Our computer controlled cars are very dependant on sensors getting correct info(voltage) and if you have a elec system that is over or under charging it is going to cause all types of trouble. I would re-test charging system FIRST and if out of spec 13.8 - 14.2 I personally would replace alternator and then drive car, fresh fuel would be great as you say the car has been sitting for a long period of time. Best of luck