Fuel leak and rough idle

[musicars]

This is my first attempt at a post. We have a ’97 Contour with the 2.5 V6 and automatic transmission. The car has just over 80,000 miles on it. I love driving this car but it has been driving me nuts. It has never gotten over 18mpg since purchasing it last fall and I have been constantly working on it. The first couple of months it had a different code every couple of weeks. It has been code free for a few months now but has the following problem that I’m guessing is related to a leaking fuel pressure regulator or injector:
It starts and runs fine when cold. If you start it up immediately after turning it off when warm it runs fine. If you start it up between 5 minutes and a couple of hours (depending on outside temp) of shutting it down it shakes, the idle may cycle up and down, and there is a rattle sound that appears to be coming from the fuel pump. That usually clears up within a few minutes. Driving harder or bringing up the idle seems to clean it out and it is fine until the next time. There is also the smell of gas sometimes. It has gotten worse with the hot summer weather and has now added what sounds like the “moosing” sound accompanied by even more severe idle fluctuations.
I checked fuel pressure a month ago and it charged to 41 pounds when the ignition is turned on (car not running) then drops a few pounds and stabilizes. It will then drop about 1 pound per minute and be at zero in about 30 to 35 minutes.
The rough starts are similar to other vehicles I’ve had with leaking injector units or pressure regulators. Does anybody know how I can diagnosis this problem?

 

[Tony2005]

Welcome . At a minimum, take it to Advance or Autozone and get a free "reading" of the codes. Then post the exact codes here. A better diagnosis would be to get a "live scan or freeze frame" readout which will tell more parameters of the engine (about $100 at a dealership or independent dealer). Then post all the parameters here. You could buy a $200 (Actron 9180 or 9175) scanner which will also do this.

If you have the moose problem, fix that first and see if it helps. A 10 year old car would probably need a new Idle Air Control Valve too.

Moose info and what it sounds like here.
http://www.contour.org/ubbthreads/s...er=1148660&page=&view=&sb=5&o=&fpart=all&vc=1

IAC valve.
http://www.contour.org/FAQ/FAQ.php?s=probs&displayid=7

 

[Rogerm60]

It starts and runs fine when cold. If you start it up immediately after turning it off when warm it runs fine. If you start it up between 5 minutes and a couple of hours (depending on outside temp) of shutting it down it shakes, the idle may cycle up and down

This is a classic ECT problem. The Engine Coolant Temperature sensor will read the engine as being almost cold soon after shutdown and will not match the actual engine temperature unless it is up to temp, or completely cooled off. When the ECT reads too cold the engine runs rich. Test or replace the ECT, it sticks out of the coolant outlet toward the firewall and has two wires.

 

[Tony2005]

Picture of ECTsensor.
http://www.contour.org/ubbthreads/s...d=allposts&Main=983239&Search=true#Post983852

 

[musicars]

Thanks for the replies! I’ll check into those things you recommend. Here is some additional info. First, the CEL has not been set. I do have an Innova 1003c scanner. I hooked it up anyway to check and see if it were possible to have a pending code without setting the CEL. There were still no codes. Would there still be any info a scanner could supply? Secondly, the “moosing” didn’t start until I had already had the start up problems a couple of months and it does not seem to follow the normal “moosing” rules like when the A/C is on and other things. Could it still be related? Thirdly, if this were an ECT problem wouldn’t I have the start up problems anytime I started the motor warm and not have that “grace period” of a few of minutes after shutting it down and wouldn’t a code set? That’s why I thought I had fuel slowly leaking into the intake system or cylinders. How else do I explain the fuel smell and pump noise?

Thanks again, Joel

 

[Rogerm60]

Would there still be any info a scanner could supply?

Not that scanner. A better one would allow you to read the ECT output.

Thirdly, if this were an ECT problem wouldn’t I have the start up problems anytime I started the motor warm and not have that “grace period” of a few of minutes after shutting it down and wouldn’t a code set?

No, the sensors commonly fail by underreporting the temperature only as the actual temperature starts to fall. This causes "cold start" fuel enrichment until the engine actually cools off. No CEL will occur if the condition clears up before the reported temperature gets back up to 180F.

Leaking fuel injectors will leak any time the engine is shut down. You can easily check for this by connecting a fuel pressure gage and seeing if the pressure drops with the key off.


The ECT is also quite cheap and not too hard to install.

 

[musicars]

I mentioned in the first post that when I checked fuel pressure I found it would drop about a pound a minute and be at zero within 30 to 35 minutes. Isn't that drop excessive?

I'll try to look at the ECT this weekend. I appreciated that picture showing the location I was given earlier. It will save a lot of time. Thanks to both of you for your help!

 

[Rogerm60]

I mentioned in the first post that when I checked fuel pressure I found it would drop about a pound a minute and be at zero within 30 to 35 minutes. Isn't that drop excessive?

Seems a bit slow to cause the problem but you could be right. Slow drops are often the valve in the fuel pump or FPR leakage. If fuel is leaking into a cylinder you can pull the plugs and visually find out which one it is. Then pull the fuel rail and take it to be cleaned. This would be a good opportunity to replace intake gaskets and clean the manifolds.