My 03 has left me stranded again. Yesterday on my way to work I was cruising about 70 mph when it suddenly lost power and ran rough. It was acting like it was out of gas, but it would idle, a little rough and low(around 550 rpm) according to scangauge. Also, no codes and it would still drive but only like 1mph. When I went back to mess with it last night, it wouldn't even start, cranks up but immediately dies. I've read it could be a coil pack, MAF sensor, or fuel pump. How do I trouble shoot these problems, also if anyone has done those repairs let me know how you found out that's what it was. Thanks guys!

 

So, how mechanical are you?
So you are saying you have no CEL on or codes?
One possible fault, that normally won't throw a code is a bad crank sensor which can shut of your fuel or spark.

 

Wow such a low mileage truck to be giving you all these problems:-( well you you would like to believe that once cooled down the bad crank sensor would then allow you to start for a short period, but they all act just a little bit different. To me I would have to agree with mike on The crank sensor check for fuel check for spark & so on and don't just sit there and crank away you will just cause more problems.

 

Spark easy to test for with spare plug attached to a wire you pull off, lay on manifold. As stated, the CKP sensor can fail in several ways, and in one way it "resets" when engine cooled off or water poured on sensor. It is a coil of wire around a point that rides at a very sensitive space in a slotted disc that turns with the engine. It does not contact the disc, but a signal is generated as the disc flys by just a few cat whiskers away. Attached pages from Bosch manual. If you replace this under $100 sensor, plug it in and let it hang, not a lot of room to work. Every nut and spacer must go back on exactly like in came off or truck won't start. The CKP sensor has to send a signal that the engine is turning at 80 rpm or better during cranking or fuel supply is switched off by one of the brain modules.

As for fuel pressure, you should hear the fuel pump run for a second or two when you turn on the key before cranking. The fuel pressure regulator and the fuel filter are part of the pump assembly inside the fuel tank. There is a pressure test port valve from the fuel rail on the driver side rear of engine, sorta under the top of the intake and hard to get at. All the fuel injectors get battery volts from fuse F1 under the hood, and the ECU grounds each one individually to squirt. Melted wire, skinned wire; these things happen, but usually result also in codes.




Pix of sensor (bent tip or covered with metal fuzz is also bad), disc it mates to, and pages about the CKP sensor.

 

Silly question: does the Discovery 1 4.0 have the same sensor?

 

Pretty much, if it does not have a distributor. The sensor is triggered by teeth that fly by on a stamped metal reluctor disc. Sometimes teeth are savaged by bad starter, etc., get bent, break off, certainly when one rams a screw driver in there to rotate the engine.... On the D2 they have a drilled reluctor disc. In both cases there are 60 points that create a pulse, minus one skipped spot, that serves as the index to the ECU.

 

Well I'd like to think I'm fairly mechanical, I've done some pretty good work so far on this thing (timing cover, water pump, oil pan, brakes etc.) I have no new codes, I still have P1450, but it has been with me for about 4 months, with no resolution. I will test for spark and fuel pressure this weekend. When I've previously posted about my P1450 problems, I got some responses hinting at a nearly completely clogged fuel pump/filter, or a problem with that, but other posters thought that something like that would not be the problem because if it was clogged/failing that bad then it wouldn't run. It was running great, now it's down. I'm thinking a fuel pump assembly may be a good start? Would a bad fuel pump (or one that's on it's way out) set a code related to the evap system, p1450 is "leakage detection module failure"?

 

P1450 is an evap code, for evap test pump current very low, like 2 milliamps, during the rough leak test. If you clear it, it is one of those codes that will come back after 4 drive cycles if not corrected. Normal current above 15 milliamps, and below 40 milliamps. So it thinks you have a big leak in the evap system.

Speaking of amps, fuse 10 under the hood controls only the fuel pump. Might be cracked, corroded, etc. You can meter in series for amps there and my D1 pump draws about 5 amps when running, a D2 may be a little different. But if no significant current being drawn, pump is not running right - perhaps dues to wiring issues like corroded terminals at the tank or the ground cable from the pump. The ground for the pump is not where you might expect it (near the tank) - it is under the hood at Connector C0810, easy to reach and be sure it is clean and tight. Pix attached.

 

So do you think a new pump assembly may fix my p1450?

 

Have you tested the fuel pump? Have you test for fuel pressure if so what are the numbers? Have you eliminated all other tests that Buzz has layed out for you?