Cougar

The fuel tank pressure sensor is on the right side of the fuel tank and the pressure control solenoid valve is on the left side of the tank. The atmospheric pressure sensor is about in the middle of the right side fender area. As for the purge control solenoid valve, the electrical connection to it is having a problem. My data shows that a yellow/red wire ties to it and should have 12 volts on it. That wire is spliced in from the yellow wire tieing to the idle air control solenoid valve. The return side of the purge valve ties to pin A2 of the ECU on a red/green wire. Check the voltage getting to the solenoid and if you have full voltage there then the problem is on the return side of the circuit if the solenoid itself is ok. To see if the solenoid coil is ok remove it and check the resistance across the contacts. You should see something around 40 ohms possibly. That is a guess.

To see if voltage is getting to the pump motor place the black meter probe to a good chassis ground point and the red probe on the wire connection to the pump and with the pump reconnected. If you have 12 volts on the wire then the ground to the pump motor is either open or the switching action in the ECU for the ground isn't working.

You're welcome for the help and glad to hear you got the problem straightened out. The Cat was laying low on this one but was ready to pounce if needed.

I suggest you check the crank sensor signals and see if they are ok when the trouble happens. If that is ok then I would look into trying to find a spare ECU and see if replacing that helps. I assume the wiring to the ignition module has been checked for a problem already.

Ok, the Cat is on the hunt here. Hopefully you have a voltmeter to check voltages with. If you don't I suggest you get one as it will really help you find the area of trouble. Since the starter works well this means the battery is in good shape. There is a seperate path for the power to tie into the accessories than the starter lead and it appears you may either have a bad connection on the main power lead to the fuse panel under the hood or there is a problem in the ignition switch area. Using the voltmeter to check for voltage drops in the wiring will show you if you are on the correct path in finding the trouble. Make sure the small red wire leading from the battery to the power panel is making good connection to the battery. If that is ok then check the voltages in the power panel and see if they are close to the battery voltages while things are on. If the voltage is low then there is a problem in the wiring to the battery. It would also be good to clean the chassis ground connections to the battery since the trouble could be there also.

It sounds like the relays are being forced on somehow. I assume that if the relay isn't plugged in the circuit the fan doesn't work. Indicating the power to the fan is going through the relay.

To check the pump motor operation just connect it to directly to the battery or a 12 volt DC power source that can handle around 8 amps of current. The differences in the voltage you saw may be due to the way the circuit is designed and the way you measured it. If you measured the voltage with the reference probe of the meter tied to ground then there is a connection problem at the connector. If you measured the voltage across the pump then the ground for the pump may be controlled by the ECU and if the pump wasn't running there would be no voltage drop across the motor, it would all be across the open ground connection.

Using a hair dryer is a good fast way to dry things out.

The power to the pump only happens for a few seconds when you turn the ignition to ON and the engine isn't running. The safety system shuts the power off to the pump if it doesn't see ignition pulses occuring. By running power directly from the battery or a 12 volt power source you can test the pump motor.

You need to check the wiring between the ECU and the O2 sensor for a problem. One common problem for this kind of thing is the wiring can touch the exhaust system and damage the wiring. Bad connection at a connector is another source of trouble.

The blue/yel wire you saw 11 volts on briefly sounds like the wire running to the pump and is operating normally. Since it sounds like power is getting to the pump you have two possibilities for trouble. Either the pump motor is bad or the ground side for the pump isn't working. The ground side of the pump circuit may run through the ECU and is controlled by it if that is so. You could try to power the pump by directly applying power to the pump and see if that works. If it does then you may need to replace the ECU if the ground is controlled by it.

It appears you have a problem in the wiring alright. I assume you are checking for any ties to ground on the wires also.

It kind of sounds to me that there is a problem with the sensor in the tank rather than the in the wiring but it may be there is a shorting problem with the wiring external to the tank. That could cause the kind of trouble you are seeing. I kind of doubt the Techron is going to help out in this case but it might, if you want to try it first.

Good work on tracking down the trouble and glad we could assist you in the hunt for the trouble. Thanks for the feedback on it.

I was wondering about that. Fuses rarely blow for no reason. I think I may know where the trouble is. The fuse SBF-2 ties to the Main Relay along with the fuel pump relay and like you said, some other points also. The Main Relay turns on with the ignition switch as does the fuel pump relay. The main relay then connects power to the ECU a.....nd the O2 sensors. My bet is the wiring to one of the sensors is up against the exhaust and shorting to ground. If you pull the Main Relay and the short clears I think you will find that is the case.

I'm not sure if the ground connection to the fuel pump is tied to ground or if it has a controlled ground connection. At any rate, 4 volts across the pump isn't good. You need to have 12 volts across the pump leads. Try checking the voltage to the pump with the meter common lead tied to chassis ground. If you see 12 volts then the ground to the pump is controlled.

I agree OB99W. Looking at pulses of the CAM sensor with a scope would be a very good thing.

You're welcome for the help and thank you for the feedback. A lot of folks get fooled by the fuses thinking they look ok at first glance.

Welcome, and hope you like it here. I agree with the above advice. Fuse SBF-2 is what you need to check and ECU's are one of the last things on the list to replace since they are very reliable but can and do go bad on occasion. Your nagging feeling of checking fuses is a good one along with suspecting relay problems. Looking for bad fuses is the first thing to do when a problem like this happens in my opinion. By proper testing before replacing parts you can avoid needless parts replacement and wasted time an money.

Spray some starter fluid into the intake and see well the engine starts then. If it fires right up you have a fuel delivery problem.

I would guess the plugs were not tightened enough when they were worked on last. As for the O2 sensor they can degrade over time and that will not cause a code to be set.

I think either coil will work for you. I am not aware of any difference at least.

Hopefully by replacing the the ignition amp it will correct the problem. As you have found out, the stock coils are the best to stay with along with OEM plugwires and NGK plugs.

Thanks for the update Howard and glad you got it fixed. It seems kind of strange these problems weren't caught earlier.

It is seldom I suspect the ECU of causing any kind of trouble in these kind of problems but after the testing you have done and the intermittent times the trouble appears I am now thinking it may be time to look at it. OB99W brought this up earlier also.