2004 GT - No Start . . . THEFT Light on

[wmburns]

I'm going to assume that you never hear the fuel pump run.

There's a reason why the fuel pump is designed to prime at every key on. This also make the key on prime test the "gold standard" test of the fuel pump system.

A bad FRPS will not "cause" the fuel pump to not prime at initial key on. So your FRPS might be bad but it's not the reason WHY the fuel pump doesn't prime.

 

[Jon S]

I'm going to assume that you never hear the fuel pump run.

There's a reason why the fuel pump is designed to prime at every key on. This also make the key on prime test the "gold standard" test of the fuel pump system.

A bad FRPS will not "cause" the fuel pump to not prime at initial key on. So your FRPS might be bad but it's not the reason WHY the fuel pump doesn't prime.

Thanks for your reply.

 

[Jon S]

UPDATE !!!

Unplugged Fuel Rail Pressure Senson connector last night. Reconnected it this AM and squirted starter fluid in. It has been running for 10 minutes. Looping a bit on idle. Check engine light was on and shows Fuel Rail Sensor Malfunction. Just ordered a new Motorcraft one.

Hope that fixes my problem.

 

[Jon S]

UPDATE !!!

Unplugged Fuel Rail Pressure Senson connector last night. Reconnected it this AM and squirted starter fluid in. It has been running for 10 minutes. Looping a bit on idle. Check engine light was on and shows Fuel Rail Sensor Malfunction. Just ordered a new Motorcraft one.

Hope that fixes my problem.

Got the new Motorcraft Fuel Rail Pressure Sensor. Going to replace it tomorrow and will report results.

 

[Jon S]

Got the new Motorcraft Fuel Rail Pressure Sensor. Going to replace it tomorrow and will report results.

Installed a new fuel line pressure sensor and the car started. It ran for about three minutes coughed once kept running and stalled after about five minutes Would not restart until I added starting fluid. Getting very frustrated

UPDATE: Now getting "too rich" error messages. Cleared them and reved engine to 2000 RPM. Codes gone. Letting it idle for a while.

Shut it off, it will not restart without a starter fluid squirt.

I am convinced it is not the fuel pump but rather some sensor telling to shut the fuel pump off at initial start. It makes no sense that starter fluid will initialize the engine and something (sensor) turns the fuel pump on to keep it running for 10 minutes plus. If it was a mechanical pump I could understand but with electric pump it makes no sense at all.

Anyone else experienced a similar problem or better yet find a solution to it?

 

[General karthief]

Did you check codes after the last no start condition?

 

[Jon S]

Did you check codes after the last no start condition?

There were none. Said no codes found. PASS

 

[General karthief]

I'm not up on the 04 stuff but seems to me you need to see if the fuel pump is priming when the key is first turned on.

 

[Jon S]

I'm not up on the 04 stuff but seems to me you need to see if the fuel pump is priming when the key is first turned on.

Fuel pump is NOT priming when key is turned on.

 

[General karthief]

I just went back through this thread, you need to do that too, some of the suggested tests it seems were not done. Maybe it's time for you to buy a repair manual.

 

[Jon S]

I just went back through this thread, you need to do that too, some of the suggested tests it seems were not done. Maybe it's time for you to buy a repair manual.

Am I correct in assuming the START circuit is different from the RUN circuit as the fuel pump does keep the engine running once primed with starting fluid, but the fuel pump is not priming for the initial or repeated starts?

 

[General karthief]

I would say thats a fair assessment, but I'm not a stangnet certified tech, you were told about a diagnostic procedure by a tech, now like I said, go back and read through the thread

 

[wmburns]

Am I correct in assuming the START circuit is different from the RUN circuit as the fuel pump does keep the engine running once primed with starting fluid, but the fuel pump is not priming for the initial or berepeated starts?

If your theory is there's a problem with the start/run circuit THEN this can be ruled in/out by testing fuse F2.34, F2.2, and F2.8 for key on power. Next test for power as the key is turned from run to start. The power in each fuse should remain on and constant.

Just wondering. Have your MEASURED the the fuel pressure. It would be handy to know what the fuel pressure is before prime, after prime and during cranking.

Note, the fuel system should maintain fuel pressure between starts. If not, there's a leak somewhere in the system. The usual leak locations are:

• fuel pump check valve.
• leaking flexible line between the fuel pump and the gas tank hat.
• the fuel rail pressure sensor (FRPS)
• one or more fuel injectors. Note the leak could be from the injector not closing fully and the leak would never be seen.

If a fuel injector problem is suspected I have had good luck with InjectorRX.com. Once cleaned and flow tested the injectors are as good as new.

Regarding the fuel pressure test the 2004 model year doesn't have an easy way to measure fuel pressure. If this were my car I would use an ODB2 scanner to data log the fuel pressure.

While you have the data logging ODB2 scanner out, it would help to know the MAF flow as well. What would be interesting to know is if the MAF flow is reasonable for the particular operating condition at the time. In addition this needs to be compared to LTFT values while the motor is running.

 

[Jon S]

If your theory is there's a problem with the start/run circuit THEN this can be ruled in/out by testing fuse F2.34, F2.2, and F2.8 for key on power. Next test for power as the key is turned from run to start. The power in each fuse should remain on and constant.

Just wondering. Have your MEASURED the the fuel pressure. It would be handy to know what the fuel pressure is before prime, after prime and during cranking.

Note, the fuel system should maintain fuel pressure between starts. If not, there's a leak somewhere in the system. The usual leak locations are:

• fuel pump check valve.
• leaking flexible line between the fuel pump and the gas tank hat.
• the fuel rail pressure sensor (FRPS)
• one or more fuel injectors. Note the leak could be from the injector not closing fully and the leak would never be seen.

If a fuel injector problem is suspected I have had good luck with InjectorRX.com. Once cleaned and flow tested the injectors are as good as new.

Regarding the fuel pressure test the 2004 model year doesn't have an easy way to measure fuel pressure. If this were my car I would use an ODB2 scanner to data log the fuel pressure.

While you have the data logging ODB2 scanner out, it would help to know the MAF flow as well. What would be interesting to know is if the MAF flow is reasonable for the particular operating condition at the time. In addition this needs to be compared to LTFT values while the motor is running.

The fuses were checked and all have power. I cannot check the fuel pressure at start but am convinced it is zero as the pump does not prime and it takes starter fluid to start the engine. Once started by starter fluid it continues to run indicating that the crankshaft position sensor is working properly and communicating with the computer.

MAF connected or disconnected made no difference.

I believe the problem is not the fuel pump but rather the fact the fuel pump is not being primed for three seconds prior to starting The fuel pump will run once the engine is started with starting fluid which means that my crankshaft position sensor is telling the fuel pump to run The real question is why is the fuel pump not being turned on for three seconds when my ignition key is turned to start.

Again, this problem developed after I changed my battery and I had to fix the PATS System the THEFT light now goes out after 3 seconds of ignition on and engine does start and run with starting fluid initial spray so I "think" PATS is a non issue.

 

[General karthief]

Do you still have power to those three fuses while cranking?
you need to know if you have fuel when cranking, it will determine the next step.

 

[Jon S]

Do you still have power to those three fuses while cranking?
you need to know if you have fuel when cranking, it will determine the next step.

Will check and report back. Thanks

 

[wmburns]

The fuses were checked and all have power.

Just to be sure that you are testing for power WHILE the ignition switch is being turned from "run" to "crank"? I could see a case that IF there's a problem in the ignition switch such that as the key is turned to crank the power drops from the "run" circuit. This might "confuse" the PCM

I could also see a case that IF the fuel pressure is dropping to zero after the prime that might be causing your symptom. IE there's no fuel pressure to carry the motor between the time of the first motor "hit" and when the PCM detects that the motor is actually running.

I have had direct experience with a similar fuel pressure problem. Working on a F150 it was running bad with misfires and fuel smell during initial start up. Using the ODB2 scanner we monitored fuel pressure. Found the fuel pressure shot up to 40 PSI during the key on prime but the instant we heard the fuel pump stop the pressure dropped back to zero.

We found a Ford TSB talking about stuck open injectors that matched our symptoms. Sure enough when we pulled the fuel rail one of the injectors was pissing raw fuel. A trip to InjectorRX.com and the truck was back on the road.

The point of the story is that we got a big "leg up" during trouble shooting because we knew what the fuel pressure was doing. Armed with the symptoms finding the TSB wrapped everything up in a neat bow.

I have helped several people with "apparent" fuel pump problems. The symptom is long crank or crank with no start. But once started the motor would continue to idle. However usually the motor would die if asked to carry a load. In a couple of cases the problem turned out be a leaking flexible hose inside the gas tank. In other cases the reported fix was a new fuel pump. I know it's possible for a fuel pump to run but due to an internal problem not be able to create pressure.

The take away from this should be that measuring fuel pressure would rule the theory in or out. Other wise trouble shooting is just down to parts changing.

 

[Jon S]

Just to be sure that you are testing for power WHILE the ignition switch is being turned from "run" to "crank"? I could see a case that IF there's a problem in the ignition switch such that as the key is turned to crank the power drops from the "run" circuit. This might "confuse" the PCM

I could also see a case that IF the fuel pressure is dropping to zero after the prime that might be causing your symptom. IE there's no fuel pressure to carry the motor between the time of the first motor "hit" and when the PCM detects that the motor is actually running.

I have had direct experience with a similar fuel pressure problem. Working on a F150 it was running bad with misfires and fuel smell during initial start up. Using the ODB2 scanner we monitored fuel pressure. Found the fuel pressure shot up to 40 PSI during the key on prime but the instant we heard the fuel pump stop the pressure dropped back to zero.

We found a Ford TSB talking about stuck open injectors that matched our symptoms. Sure enough when we pulled the fuel rail one of the injectors was pissing raw fuel. A trip to InjectorRX.com and the truck was back on the road.

The point of the story is that we got a big "leg up" during trouble shooting because we knew what the fuel pressure was doing. Armed with the symptoms finding the TSB wrapped everything up in a neat bow.

I have helped several people with "apparent" fuel pump problems. The symptom is long crank or crank with no start. But once started the motor would continue to idle. However usually the motor would die if asked to carry a load. In a couple of cases the problem turned out be a leaking flexible hose inside the gas tank. In other cases the reported fix was a new fuel pump. I know it's possible for a fuel pump to run but due to an internal problem not be able to create pressure.

The take away from this should be that measuring fuel pressure would rule the theory in or out. Other wise trouble shooting is just down to parts changing.

You have been very helpful. It was hard to check but I have power at those three fuse locations in both on and crank position.

I'm starting to think it may still be a PATS problem in that after running for 10 minutes when I shut it off it would not immediately restart. Yet the other side of me says why would the car restart with starting fluid if the PATS system was disabling it?

The more I think about it I'm sure it's something very simple that we've all over looked. And it wasn't a fact I changed the battery it was the fact my new battery ran down this winter before I recharged it with a battery tender. I have since checked the battery with a hygrometer and all cells read full charge.

 

[wmburns]

I'm starting to think it may still be a PATS problem in that after running for 10 minutes when I shut it off it would not immediately restart. Yet the other side of me says why would the car restart with starting fluid if the PATS system was disabling it?

PATS works by disabling the fuel injector pulse. For the 1996+ model year the Ford factory PATS does NOT disable the fuel pump.

So by that measure it would not be possible to defeat PATS by simply using starting fluid as the PCM would never fire the injectors. The best the starting fluid could do is run the motor until the starting fluid has been exhausted.

Regardless. You could answer your own question by noting IF the theft light goes out after the 3 second "prove out" that happens at initial key on. Do this on the restart attempts. Don't be in a hurry to crank it.

The other thing about Ford factory PATS is PATS will never disable the motor once the motor has started.

The more I think about it I'm sure it's something very simple that we've all over looked.

I'm a big believer in Occam's razor. I agree that once the problem is located there will be that "light bulb" moment where everything will fall into place.

https://en.wikipedia.org/wiki/Occam's_razor

By your own admission there was an apparent ground problem that might have been addressed. However I didn't get a strong sense of what was found and what was repaired. I also didn't get the sense that once the grounding problem was repaired that trouble shooting was restarted from the top of the decision tree looking at everything anew (since a repair was made).

IMO the other outstanding question is "what is the fuel pressure"? Perhaps more importantly. Is the PCM getting an accurate fuel pressure as the FRPS could be ok but there be a problem in the wiring (didn't you have a DTC for a FRPS circuit malfunction?)

At the risk of hurting feelings, if you had an ODB2 scanner this might have made very short work of this problem. For the cost of parts already installed (without a fix) a budget priced scanner could have been acquired. Fixing modern PCM driven cars is a data driven undertaking. But trouble shooting is a "process". Sometimes it's necessary to come up with a theory and then either rule it in or out with test results or other methods.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

Note an ODB2 reader and scanner are not the same thing. A reader will only access DTC codes. Where as a scanner can access operational real time PID's.

The added benefit of having an ODB2 scanner is that it can answer other questions such as what is the MAF value seen at the PCM? In some of your earlier posts you were asking questions about which sensor could be turning off the fuel pump after the motor is stated. The closest I can think of is the MAF. For example IF the MAF were way under reporting the air flow then the fuel injector pulse width would be too small (too little fuel).

Other sensors that "might" play a role in this is the cam sensor. We know the CKP sensor is working or it would never start. But maybe the PCM using to cam sensor to determine IF the motor is running. However I personally don't have a lot of faith in that theory because I know that a bad cam sensor will not prevent a 4.6 V8 from starting. Note a bad cam sensor will prevent a V6 from starting.

If looking for an out of the box suggestion. Since there have been grounding problems on this car, test and CONFIRM there's a solid ground at the MAF. Test the ability of the ground to carry current all the way back to battery negative. Recommend using a test light that will apply some load to the circuit.

Another "out of the box" suggestions might be two problems. Say for example a leak in the fuel system such that it's not holding pressure AND an electrical problem to the FRPS.

 

[Jon S]

PATS works by disabling the fuel injector pulse. For the 1996+ model year the Ford factory PATS does NOT disable the fuel pump.

PATS works by disabling the fuel injector pulse. For the 1996+ model year the Ford factory PATS does NOT disable the fuel pump.

So by that measure it would not be possible to defeat PATS by simply using starting fluid as the PCM would never fire the injectors. The best the starting fluid could do is run the motor until the starting fluid has been exhausted.

Regardless. You could answer your own question by noting IF the theft light goes out after the 3 second "prove out" that happens at initial key on. Do this on the restart attempts. Don't be in a hurry to crank it.

The other thing about Ford factory PATS is PATS will never disable the motor once the motor has started.


I'm a big believer in Occam's razor. I agree that once the problem is located there will be that "light bulb" moment where everything will fall into place.

https://en.wikipedia.org/wiki/Occam's_razor

By your own admission there was an apparent ground problem that might have been addressed. However I didn't get a strong sense of what was found and what was repaired. I also didn't get the sense that once the grounding problem was repaired that trouble shooting was restarted from the top of the decision tree looking at everything anew (since a repair was made).

IMO the other outstanding question is "what is the fuel pressure"? Perhaps more importantly. Is the PCM getting an accurate fuel pressure as the FRPS could be ok but there be a problem in the wiring (didn't you have a DTC for a FRPS circuit malfunction?)

At the risk of hurting feelings, if you had an ODB2 scanner this might have made very short work of this problem. For the cost of parts already installed (without a fix) a budget priced scanner could have been acquired. Fixing modern PCM driven cars is a data driven undertaking. But trouble shooting is a "process". Sometimes it's necessary to come up with a theory and then either rule it in or out with test results or other methods.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

Note an ODB2 reader and scanner are not the same thing. A reader will only access DTC codes. Where as a scanner can access operational real time PID's.

The added benefit of having an ODB2 scanner is that it can answer other questions such as what is the MAF value seen at the PCM? In some of your earlier posts you were asking questions about which sensor could be turning off the fuel pump after the motor is stated. The closest I can think of is the MAF. For example IF the MAF were way under reporting the air flow then the fuel injector pulse width would be too small (too little fuel).

Other sensors that "might" play a role in this is the cam sensor. We know the CKP sensor is working or it would never start. But maybe the PCM using to cam sensor to determine IF the motor is running. However I personally don't have a lot of faith in that theory because I know that a bad cam sensor will not prevent a 4.6 V8 from starting. Note a bad cam sensor will prevent a V6 from starting.

If looking for an out of the box suggestion. Since there have been grounding problems on this car, test and CONFIRM there's a solid ground at the MAF. Test the ability of the ground to carry current all the way back to battery negative. Recommend using a test light that will apply some load to the circuit.

So by that measure it would not be possible to defeat PATS by simply using starting fluid as the PCM would never fire the injectors. The best the starting fluid could do i s run the motor until the starting fluid has been exhausted.

Regardless. You could answer your own question by noting IF the theft light goes out after the 3 second "prove out" that happens at initial key on. Do this on the restart attempts. Don't be in a hurry to crank it.

The other thing about Ford factory PATS is PATS will never disable the motor once the motor has started.


I'm a big believer in Occam's razor. I agree that once the problem is located there will be that "light bulb" moment where everything will fall into place.

https://en.wikipedia.org/wiki/Occam's_razor

By your own admission there was an apparent ground problem that might have been addressed. However I didn't get a strong sense of what was found and what was repaired. I also didn't get the sense that once the grounding problem was repaired that trouble shooting was restarted from the top of the decision tree looking at everything anew (since a repair was made).

IMO the other outstanding question is "what is the fuel pressure"? Perhaps more importantly. Is the PCM getting an accurate fuel pressure as the FRPS could be ok but there be a problem in the wiring (didn't you have a DTC for a FRPS circuit malfunction?)

At the risk of hurting feelings, if you had an ODB2 scanner this might have made very short work of this problem. For the cost of parts already installed (without a fix) a budget priced scanner could have been acquired. Fixing modern PCM driven cars is a data driven undertaking. But trouble shooting is a "process". Sometimes it's necessary to come up with a theory and then either rule it in or out with test results or other methods.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

Note an ODB2 reader and scanner are not the same thing. A reader will only access DTC codes. Where as a scanner can access operational real time PID's.

The added benefit of having an ODB2 scanner is that it can answer other questions such as what is the MAF value seen at the PCM? In some of your earlier posts you were asking questions about which sensor could be turning off the fuel pump after the motor is stated. The closest I can think of is the MAF. For example IF the MAF were way under reporting the air flow then the fuel injector pulse width would be too small (too little fuel).

Other sensors that "might" play a role in this is the cam sensor. We know the CKP sensor is working or it would never start. But maybe the PCM using to cam sensor to determine IF the motor is running. However I personally don't have a lot of faith in that theory because I know that a bad cam sensor will not prevent a 4.6 V8 from starting. Note a bad cam sensor will prevent a V6 from starting.

If looking for an out of the box suggestion. Since there have been grounding problems on this car, test and CONFIRM there's a solid ground at the MAF. Test the ability of the ground to carry current all the way back to battery negative. Recommend using a test light that will apply some load to the circuit.[/QUOTE

Thanks for your detailed reply Let me try to address the issues one at a time. In reference to my scanner I bought this specifically for my newer computer controlled cars and those my son's own. Most of my cars are carbureted Classics dating back to 1958 so this computerized scanner was bought for high-level diagnostics at best. All of our cars are maintained in pristine condition and the scanner has always been plugged in to say no codes found and "passed". I've never had any major problems with any of my cars and I do rebuild carburetors and I am very automobile savvy in reference to changing points plugs condensers etc.

I'm not sure I had a ground problem but I did find a video that showed that Ford used a primer paint under the ground points on their cars including a Mustang so I did clean it down to bare metal and coated areas with dielectric grease to assure I had a good ground.

I am glad to hear the 1999+ PATS does not disable the fuel pump. One less thing to worry about. And it appears the injectors are working as designed.

I am 72 and have been working on cars since age 15. Not as agile as I used to be especially crawling under the dashboard to the fuse box. LOL

You have been a great help and once I get this resolved I will make sure we finish this thread with a solution so others with similar problems can refer to this in the future.

I have someone coming to my house Saturday with detailed analytical equipment to see if he can ascertain what the problem is. Will keep you posted.

BTW, this is how I keep my engine: