My 97 300D will not start. - no fuel.

[red5jedi]

I’ve been reading here for some great information on how the fuel injection works on this 606.912 engine but I still can’t get it going. It turns over with no problems. With the attached diagram of the fuel system I’ll list out the things I have tested.
Note: I have been running a 10 gallon WVO, 5 gallon diesel, 1 gallon RUG blend for 15k miles. Before the car didn’t start it was running great with no problems- the day temps were in the 50’s. Car has 118K miles, Albuq, NM.

1. Disconnected line 4 from lift pump – pumping fuel, seams good.
2. Disconnected line 8 for the return line – flowing.
3. Disconnected the hard lines at the injectors – No fuel.
4. Installed a fuel pressure gauge between fuel filter and shut off valve – No pressure but has fuel flow.
5. Moved gauge in-between lift pump and filter – No pressure but has flow.
6. Closed off the return line and now get 15psi on gauge.
7. Checked over pressure return valve and thought it was bad – replaced with a new one and still no change.
8. Removed all injector pipes on IP and removed the spring and other parts (names???) and they looked ok. Reinstalled and no change.
9. Removed fuel line 1 (supply from heater) and line 8 (return) and put them into a fuel bottle – this was to check if the screen in the take is clogged. No change….
10. Replaced filter – wanted to see why the return line was connected to the filter mount. The filter mount has a small hole in it that allows fuel to return back to the tank before filtration.
11. Again checked for fuel pressure between filter and shut off valve and don’t get any pressure until I crimp the fuel return line..
Any suggestions on what and how to test something I’ve missed? How is the IP controlled? I see that big black line that goes into the back of the IP then travels over so some round module that has wires connected to it. How does that work?

[KarTek]

The fuel actually enters the pump via a fitting molded into the back of the SOV where it mates with the injection pump. Have you pulled the SOV and checked for fuel output there?

Also, listen for a "tok" sound from the SOV when you switch the key on while the hood is up.

The IP is controlled by a PCM signal from the computer. The 5 wires in the black bundle are the 2 for the rack positioner and 3 for the rack position sensor.

[red5jedi]

Originally Posted by KarTek

The fuel actually enters the pump via a fitting molded into the back of the SOV where it mates with the injection pump. Have you pulled the SOV and checked for fuel output there?

Also, listen for a "tok" sound from the SOV when you switch the key on while the hood is up.

The IP is controlled by a PCM signal from the computer. The 5 wires in the black bundle are the 2 for the rack positioner and 3 for the rack position sensor.

Finally got back to working on the MB.

The car does make the "tok" sound - always wondered what that sound was. I pulled off the SOV and fuel does flow out of it through the port that connects to the IP- I can see the fuel moving from the IP to the return when I interduce air when checking things.

I installed a electric pump infront of the heater thinking this would help a weak lift pump. With my pressure gauge still hooked up between the filter and the SOV I still don't measure any pressure but I do see fuel flow. If I crimp off the return line to the fuel tank I get 20psi but still no fuel out of the IP to the injectors.... I was thinking my screen was cloged in the fuel tank but if I restrect the return flow and get the pressure that the IP needs (>10psi right?), why don't I have the fuel comming out of the IP to the injectors????

How do I check if the little pistons in the IP are moving? How does this IP work and control fuel to the injectors? Could it be something electronic - not telling the IP to flow fuel to the injectors?

[KarTek]

Red,

Strange it's not doing anything. If you take the side cover off the pump, you 'll be able to see the fuel rack. If you take your finger and hold it all the way forward and have an assistant crank the engine, you should see fuel coming out of the delivery valve holders or at the injectors if you loosen the fittings.

Something else to vrify is that the rack cycles back and forth when you switch the key on. The ECU controls fuel by moving the rack in response to your input on the pedal.

[red5jedi]

Originally Posted by KarTek

Red,

Strange it's not doing anything. If you take the side cover off the pump, you 'll be able to see the fuel rack. If you take your finger and hold it all the way forward and have an assistant crank the engine, you should see fuel coming out of the delivery valve holders or at the injectors if you loosen the fittings.

Something else to vrify is that the rack cycles back and forth when you switch the key on. The ECU controls fuel by moving the rack in response to your input on the pedal.

So the fuel rack moves starting in the back (firewall side) then to the front and back to the back when the key is turned on. When I have the wife crank the engine over and pump the accelerator the fuel rack doesn't move. Should it move due to the pumping of the accelerator? Using a mirror I can see the fuel pistons moving up and down. Does this sound like the ECU is not telling the IP to give fuel? I'm assuming that this is what happens when you turn off the engine when it is running.

[spark3542]

Please verify that the car was running fine, then the next day it wouldn't start...and absolutely nothing was done to it in between? What I'm getting at is it could be as simple as the fuel prefilter being changed and no O-ring installed on the new filter...or the car security system lost power and therefore does not recognize the key, and will let it crank but not fire. I've experienced both of those.

[red5jedi]

Originally Posted by spark3542

Please verify that the car was running fine, then the next day it wouldn't start...and absolutely nothing was done to it in between? What I'm getting at is it could be as simple as the fuel prefilter being changed and no O-ring installed on the new filter...or the car security system lost power and therefore does not recognize the key, and will let it crank but not fire. I've experienced both of those.

The car was running fine three-four hours before it wouldn't start and I didn't do anything to the car at all. I changed out the car radio a couple of months back. How do you check or turn off the security system?

[KarTek]

As far as I know, the rack moves back and forth once when the key is switched on. I'm not sure it would respond to the pedal if the engine is not running.

All the way back towards the firewall is off/no fuel and all the way forward is full fuel.

This sounds maybe like the K40 relay (possibly?). Do the red and green lights on the mirror flash at any time when you're trying to start the car?

[GREASY_BEAST]

If your IP turns out to be junk I'd like to speak with you about purchasing the electronic governor.

[red5jedi]

Originally Posted by KarTek

As far as I know, the rack moves back and forth once when the key is switched on. I'm not sure it would respond to the pedal if the engine is not running.

All the way back towards the firewall is off/no fuel and all the way forward is full fuel.

This sounds maybe like the K40 relay (possibly?). Do the red and green lights on the mirror flash at any time when you're trying to start the car?

No lights flashing. What is the K40 relay?

If I manually move the fuel rack forward when cranking I get fuel shooting out of the IP so I can assume the fuel supply is fine and need to troubleshoot the ECU or other control stuff.. How do I do that? Since it moves forward and back when you turn the key to start I would tend to think the IP is good. Is there any engine safety protections that would make the ECU shut off the fuel. I was getting a low oil light (oil level was fine) coming on. I think it was because the rubber cover to the oil sensor was falling apart and full of oil/fuel.

Thanks so much for the help

[KarTek]

The K40 relay is a large circuited pod under the ECU cover. It has a couple fuses on it as well as a small relay and some wires.

It's about 4" by 1.5".

It controls a variety of vehicle functions and can make the engine not run.

[red5jedi]

Originally Posted by KarTek

The K40 relay is a large circuited pod under the ECU cover. It has a couple fuses on it as well as a small relay and some wires.

It's about 4" by 1.5".

It controls a variety of vehicle functions and can make the engine not run.

I’ve done some reading on the k40 relay and looks like that could be the problem, but I’m thinking it might be the Crank position sensor. I have a 99 powerstroke and they have their problems with the CPS and I remember one way to tell if it is dead is when your cranking the engine over you don’t see any RPM movement. Well the MB doesn’t move at all when cranking. And if the K40 is bad I wouldn’t think the fuel rack would move forward and back on key on so there is some control from the ECU, right? Am I correct that the RPM feedback is coming from the CPS like the powerstroke? I did take out the K40 and touched up the solder and had no change. I might change out the K40 either way.

[KarTek]

Have you done the CPS on the truck? Ford has been bugging the crap out of me to bring it in for service but of course, I already changed mine... In the middle of the street... In the rain... At work... It was years ago too and I have since lost the receipt.

Any way, back on topic, the MB system is MUCH less sophisticated than the HEUI. All the ECU does is control the boost, EGR and rack position. But you are right that it gets it's RPM info from the CPS. I would think though, that if you held the rack forward a little while cranking, that it would at least cough a little.

Although, if you've had the injection lines off, it'll take a while to purge the air before it'll start.

[red5jedi]

I still have the injector lines off and if I hold the fuel rack forward I do get fuel shooting out -good thing I had my safety glasses on. So I think I'll change out the CPS and go from there. It will be a couple of days before I get to it (work a 12hr shift).

I change out the CPS on my truck before Ford did a recall so I have the old one as a spar. I hear some people have problems with the new ones also, so I’ll just keep what works.

Nice unimog. Do you take it rock crawling?

Thanks for your time.

[KarTek]

I rock crawled the 'mog one time... Crushed the fuel tank climbing over a 30" boulder in the dark. Never again...