THIS PROBLEM HAS BEEN SOLVED, THIS IS MY STORY. SORRY THE TITLE DID NOT EXPLAIN AS MUCH.
My friend brought me a recently purchased 1996 Taurus with 160,000 miles on it to give it a major tune-up. Upon first inspection, I found the coolant expansion tank to be bone dry, the transmission fluid level to be extremely low, both front rotors and pads were beyond their service date (along with the rear drums and shoes), but the PCM
was not throwing any diagnostic trouble codes (DTC’s). My ears were hearing a different story though – the engine was not starting within the first few cranks.
First stop, battery. I tested it under load and found the cold cranking amps to be sufficient (680). Next I suspected the coil, plug wires, or spark plugs. I already had bought some new spark plugs to install, and it was nice they were already gapped to 0.044”. Perfect. As I changed the plugs I noted each plug and found them all to be normally worn (no build-up, corrosion, or wetness).
The plug wires all tested within the specified resistance (about 20,000 ohms) but due to the high mileage I replaced them. The coil pack was originals, and my friend decided to go with a new one as well. Next, I inspected every sensor and cleaning. Each sensor passed the test, except for the camshaft synchronizer sensor. I was not getting any resistance from the sensor, so I removed the sensor from the top of the camshaft synchronizer. It was slightly difficult as the wire harness was sitting right on top. I decided to remove the lower intake manifold so that I could clean and test the fuel injectors afterwards. The camshaft synchronizer sensor came off easily. I looked at the bottom and the sensor was destroyed, I mean it was totally broken off and non-existent The camshaft synchronizer was even worse. The metal tab that should spin around was bent over itself, which explains why the camshaft synchronizer sensor was totally destroyed. A quick run to NAPA and I had a new camshaft synchronizer and sensor ready to install (don’t forget the camshaft synch tool!!).
I felt lucky, but I had to clean and test all of the fuel injectors and reinstall the lower intake manifold before I could test the engine (obvious, I know…). Each injector received a thorough cleaning and I verified that each injector had a normal spray pattern. I re-installed the injectors and fuel rail, and then the lower intake manifold. I was feeling lucky, but Murphy lives in my house. The excessive cranking did not go away.
Ok, no problem. I didn’t finish inspecting the fuel delivery system yet anyways. Man, where is my fuel pressure gauge? I hooked up the gauge to the Schrader valve on the fuel rail (of course, I depressurized the fuel system first). Here’s where it all gets so very crazy. After positioning the gauge so that I could see it from the passenger cabin, I turned the key to ON but did not start the engine. I heard the fuel pump energize, and then the CCRM’s(Constant Control Relay Module) fuel relay click again. The 1 second of priming should have brought the pressure up near 40psi, but I had 0psi. Nothing, nada, a big fat goose egg. I did it again a few times and the pressure made it to 20 psi
, but not for long. After only a couple of seconds, the pressure decreased to 0psi. I know what you are thinking, fuel pump check valve. That was my first thought, but first I had a couple of other things to test to make sure.
I started with the fuel pressure regulator (FPR
). Upon removal of the vacuum hose attached to the top of the FPR
, the pressure in the fuel rail jumped about 10 psi
. The vacuum hose was also dry, so I gave the FPR
This car is a 1996 Taurus, so the it sports a return-type fuel system. Next I wanted to pinch the return line to verify the fuel was indeed going back through the fuel supply line. The fuel line is very hard to pinch however due to the hardened rubber to handle pressure.
What to do? Well, I thought if the fuel was going through the return line, the FPR
would be to blame. Since that tested ok, I had one last easy fix that might make things better – the fuel filter. Ten minutes later, I found the excessive cranking still present.
Ok then, it HAS to be the fuel pump check valve…why else would fuel return through the supply line? My friend decided to go ahead with the fuel pump replacement. I dropped the gas tank, which was easy since after I began removing one of the straps, the other strap snapped in half. Oh how I love cars in Michigan. The tank was even supported by a floor jack, what a coincidence. My friend is lucky that did not happen on the road.
Next, I removed all the filler and vent tubes, and the vapor tube. I lowered the tank to the ground and disconnected the supply and return line, and the electrical connector. I had not tested the pump since I had heard it every time I turned the key to ON (but that does not always mean fuel is being pumped, as was my case). I slid the tank out from under the car, and gave it a thorough cleaning (all hoses were plugged).
Next, I removed the retaining ring on top of the fuel pump assembly and pulled the entire unit out of the tank. There was not much fuel in the tank at this point. I removed all five 5mm bolts on the fuel tank assembly and then removed the pump. Next, I installed the new pump and new strainer for the pump as well as the assembly. Ok, good to go. I got everything back together quickly and I was ready to test it out. Keeping in mind the fuel pressure might not build up at first due to air in the lines, and I turned the key to ON about 5 times. Still, no pressure. ARGH!!! What the FRACK!!!
I read about guys getting bad fuel pumps right out of the box, but this one was brand new and I heard it energize (I know, it still might not be pumping fuel). What could it be? CCRM
(fuel pump relay is in the CCRM
for this model year)????? Bad ground??? What in the world is going on? I COULD get the car to start after cranking the engine for about 5 seconds, but fuel pressure would not hold upon engine shut-off.
I tinkered around the engine compartment for about an hour checking grounds, the CCRM
, and the PCM
. All were secure, and the fuel pump relay was receiving power. With nothing else to do at the moment, I decided to drop the gas tank and inspect the fuel pump assembly and each hose/connection again.
I took the fuel pump assembly out of the tank again, and put it up on my workbench. You know those ribbed hoses that go from the assembly cap to the fuel pump assembly? Well, the supply hose had a very small hole in it. Just as big as a thumb tacks pin. Could this really be it? I had it with testing, so I ran to AutoZone and bought a new Airtex Fuel Pump Assembly for $154. It comes with a fuel pump, and the electrical wire harness that connects to the CCRM’s wire and the fuel tank pressure sensor. I had it installed in no time, and was ready for another test. VOILA!!! The fuel rail displayed a pressure reading that held, and after turning the key to ON about 5 times….the pressure held at 40psi!!!!
I want to say, if you have the money - buying the Airtex fuel assembly may make a fuel pump replacement less time consuming. It comes with the strainer for the tank (already installed) and another installed on the assembly. If anything (DON’T FORGET TO INSPECT THOSE RIBBED HOSES!!!!).
Check out the pictures: It was a mind blower for me.