Vehicle:
2007 Saturn Vue AWD 3.5L V6

Symptoms:
Normally the vehicle starts with about 3 seconds of cranking. Occasionally it cranks much longer without starting. Very rarely after a long crank it will try and start, run rough, or at low rpm, and then either stall or come up to idle. I normally stop cranking if it doesn’t start after a few seconds, then try again. I have found that if I cycle the key several times, “priming” the engine with the fuel pump, then it will start immediately upon cranking. Once running the engine runs smoothly and as expected. Never any fluctuation of power or RPM. This problem has existed for many years occurring intermittently and without ever getting much worse, I’ve just been bad about getting around to troubleshooting it.

Troubleshooting:
Suspecting a fuel pressure issue I connected a fuel pressure gauge to the Schrader valve testing port in the engine compartment. Turning the key to “ON” the pressure raises immediately to 55 psi, then after 1-2 seconds it drops very quickly (less than 1 second) to about 20 psi and continues falling to about 10 psi where it holds steady. With the engine running the pressure stays steady at 55 psi. When the engine is stopped the pressure drops rapidly as stated above.

Thoughts and questions:
From reviewing the GM Saturn manual online it seems that there is a second test to perform with the fuel pressure gauge. However it is not clear to me what exactly they are asking me to do. I think it wants me to connect closer to the fuel pump assembly and confirm the loss of pressure there? If pressure is still lost then the recommended action is to replace the fuel pump assembly. If the pressure does not drop then it states to look for a leaky injector. Can anyone offer any clarification on this second pressure test? Any advice on checking for a leaky fuel injector? As a side note, the fuel injection system was cleaned at a shop about 5 years ago, I believe they had all the injectors out at the time.

 

Please copy the text that asks you to perform the additional test and paste it here so that we can try to understand what you're being asked to do.

 

Sure, this is from the GM online service manual, found here. The specific area I am using is the Fuel System Diagnostics for my 2007 Saturn. First step was a diagnostic systems check, which I believe is just checking for codes. No codes. Second step is to check fuel pump operation, it can be heard running when key is turned on. (I don't have a scanner that can command it on.). Third step is to check fuel pressure and fourth step to see if pressure holds, which is what I described in my post. Pressure is ok, but does not hold. If pressure does not hold it goes to step 6, which is pasted below:

1. Turn OFF the ignition.
2. Relieve the fuel pressure. Refer to Fuel Pressure Relief .
3. Remove the fuel pressure gage from the fuel pressure test connection.
4. Disconnect the chassis fuel hose from the engine compartment fuel pipe.
5. Connect the fuel feed hose to the inlet side of SA9127E-7Fuel Pressure/Flow Adapter using the J 43937 3/8 inch Male Fuel Pressure Adapter Line.
6. Connect the return hose from the SA9127E-7 to the outlet side of SA9127E-7 .
7. Place the other end of the return hose into the fuel filler pipe.
8. Connect the fuel pressure gage to the SA9127E-7 .
9. Close the valve on the SA9127E-7 .
10. Turn ON the ignition, with the engine OFF.
11. Command the fuel pump relay ON for a minimum of 10 seconds with a scan tool.
12. Record the fuel pressure.
13. Command the fuel pump relay OFF.
14. Monitor the fuel pressure gage for 5 minutes.

Does the fuel pressure decrease by more than the specified value?

This is the part where I am guessing it wants me to check if the pressure is holding closer to the actual pump? If the pressure does not hold the recommendation is to replace the fuel pump assembly, if it holds then it recommends looking for and replacing a leaking fuel injector.

Thanks for having a look everyone!
Orin

 

You have a leaky injector.

 

Thanks for the input! Can you give me any further thoughts about how you reached that diagnosis?

From my reading of the service manual it seems like I can pull the injectors with the fuel rails attached, run the fuel pump, and physically look for a leaking injector, does that seem about right?

Thanks again,
Orin

 

The pressure should hold and to lose it that fast it's either a leaky injector or bad pump. You changed the pump so injector is left.

 

Ah, I haven't changed the pump actually. Sorry if I didn't make that clear. I am trying to decide which of the two problems I most likely have, a bad pump or a leaking injector.

 

My mistake. You need a pump. Injector don't drop that fast unless it's several that are leaking and if that were the case it would be setting trim codes.

 

Yeah, that was my initial thought as well, that there would be other signs/problems if it was an injector leak. Too bad in a way because it seems the injectors would be a lot easier to deal with! I'll try and follow up when I eventually get around to actually tackling this project.

Thanks again for giving it some thought.

 

I had this same problem with my 2006 Vue back about 4 years ago. Its the fuel pump, no doubt! There's a check valve there at the fuel pump that should hold pressure once the pump shuts off. My rail pressure wasn't dropping nearly as fast as you reported and our Vue would typically take two or three attempts to get it started after it sat for 15min or more. I used the CARTER P76263M from Rock Auto and its run flawless since the install. BTW, about a year later my friend was having a very similar issue with his F150. He had replaced a number of parts and was about to replace the injectors and I told him it sounded just like my no start issue with our VUE a year earlier. He finally dropped the tank and replaced the fuel pump and its been starting with no problems ever since.