Fuel delivery problem (not HPFP)

[jsondergaard]

Hey all,

I’ve recently bought a Mondeo mark 4 for a steal, but it’s not driveable at the moment. I started diagnosing when I got it, and it was a crank, no start type of deal. No errors saved, but the previous owner told me it had a code for low fuel pressure before.

After some research, I decided to change the fuel filter, but when I went to prime the system, jack-all happened. I’m able to create a strong vacuum on the return line, but I’m only getting a couple of millilitres per second.

The lead me to test the fuel regulator valve, but it’s operation seems normal. It closes when it gets current.

I’ve tried opening the valve just before the HPFP, which lets me suck the air I introduced out. So I’m thinking that the blockage is before the valve, between the fuel supply connection and the valve.

So my question is; how do I remove the fuel connection on the pump to blow the line clean?

Any ideas are also appreciated, I’m itching to take it for a spin.

Cheers!

[jsondergaard]

Alright; an update. I’ve managed to take the fuel line to the HPFP off and blow it through, doesn’t seem to be blocked. However, I still can’t bleed the car? I’m able to get a lite per minute if I prime through the fuel feed line, but when I do on the return line, nothing. 

I’m stumped, since the regulator seems to be working.. What else could block it? All input appreciated!

[nicam49]

Hi, 1stly,  are you aware that not all code readers can read Ford codes? Your safest bet is to buy one from Tunnelrat electronics and use it with Forscan software. I take it you have  a diesel? You've not included any engine  details in your posts. Have you primed the filter? You must only fill the filter via the IN spout. Have you got a diesel primer pump, one of those rubber bulb things? Best to get one before you start, but beware of a Laser one' cos they don't appear to be diesel proof and the one way valves soon fail. 

[jsondergaard]

Sorry, forgot to mention it’s a 2.0 TDCi from 2008. I’m using a strong vacuum pump rated for priming diesels, and I’m using ForScan with a ELM327 cable.

Since my last reply, I've also tried blowing through the return line, which wasn't blocked either. I then tried taking the feed line from the HPFP off, but it still holds the vacuum. So must be the pump itself, I suppose?

The system is primed all the way from filter to the fuel inlet pipe in front of the HPFP

[nicam49]

OK. To give you longer battery life while you're cranking, find the fuse that feeds the glowplugs, should be a large 60 amp one, and remove it. Then you'll get more amps to the starter motor. Also, don't crank for longer than 30 secs at a time as the starter motors are notoriously delicate! 

[jsondergaard]

Problem is that I’m not sure how comfortable I am with cranking with a dry pump.. but I’ve tried a couple of times anyhow, and zilch happens.

 

I can see that the fuel that’s in the clear lines doesn’t move when cranking, and forscan only reports 420 kPa rail pressure. Before the filter change, I got 23.000-34.000 kPa in the rail when cranking.

 I’ll keep the glow plug fuse thing in mind, thanks!

[nicam49]

Well you can't really tell if the fuel moves unless there are bubbles🤔

The pump wouldn't  be dry if you've primed the pipe to it and also the filter, I'm thinking. If you were getting 23,000 kpa 230bar before changing the filter, then that was a good enough pressure for the ecu to start firing the injectors! (provided that there's enough engine revs... (min 200rpm?)Have you tried refitting the old filter.... check that the drain screw on the bottom of the filter is tight as well. If you've got a code reader, then if you disconnect the electrical connector to the IMV (or FMV) also to all the injectors then monitor the frp whilst cranking, a good pump will give 1000bar minimum, tho' even giving out 800bar I know will start an engine. 

 

[jsondergaard]

There is an air bubble right before the pump, between the pump and the bleed valve. I’ve considered putting the old filter back, but I have no trouble sucking fuel from it, if I create a vacuum on the feed pipe, which leads me to believe it’s fine. Same part number on the old one  anyway.. The drain plug is tight as well

The starter gives 311 RPM, so I think it’s fine as well. What’s the IMV/FMV an abbreviation for?

[nicam49]

Hi, inlet metering valve/ fuel metering valve, on the back of the fuel pump

Oh, I'm guessing you referred to it as the fuel regulator valve. You got a multimeter you can use to check if you've got any sort of resistance reading from the unplugged plug to chassis. If you've a break in the wiring the IMV might stay shut! (I've recalled that I think the mk4  IMV works opposite way to the mk3, on which I'm basing my advice on) and that hpfp pressure test I told you about might not work with IMV disconnected. Hoping  that Tom on the forum can clarify that.... 🤔 

[jsondergaard]

Alright, I’ve just tried cranking with the FMV and the injectors electrical connections off, and the FRP is at 430, just like it is when I’m not cranking. RPM was at 319 now.

 Don’t know what to make of it

[nicam49]

If you loosen a feed pipe on an injector, and crank, are you getting any diesel coming out? (cover the connection with a cloth in case it spurts out) 

[jsondergaard]

Yeah, I am, my rag was soaked after cranking with the feed tube off.

I think the system is primed, sounded like it was going to start for half a second when I cranked it, but after that half a second, all I got was starter whine

[nicam49]

Wooh! Have you got a magnetic compass? You can use them to check if the injectors are triggering, tho' if you've only got low fuel rail pressure then they won't be. Still, give it a go... I'll try to post up the YouTube vid I saw it on. In the meantime I did a Google search and found this:

When the fuel filter is changed apparently there is a small bleed screw to allow air to be removed from the fuel system. The fuel pipe adjacent to the screw had an almost invisible split in it: enough to suck air in under pressure, 

[jsondergaard]

Unfortunately I haven’t got one. Got a pretty good multimeter though, will that work?

 

 Couldn’t imagine it being a problem with the lines, would be a gaping hole for the pump not to create any rail pressure at all, right?

 But it bothers me there’s no pressure, since there was (according to the sensor) before I changed the filter. Do you think I could have ruined a valve or something with the vacuum when priming? It was quite strong

[nicam49]

Found it! Wasn't youtube but something else.. you may as well see it:

If you have a small magnetic compass stick it next to an injector when you turn it over - that will tell you if the injector is getting a firing signal from the ECU and activating the solenoid - like this (better with a less damped compass!)

https://vimeo.com/369537989

[nicam49]

Re testing injectors to see if they're firing:  one connector of an injector will be at +12v and the other side will fluctuate while being fired, but it's too quick for the meter to respond, so you might see a change of 0.5 volts maybe. 

[nicam49]

Re your idea about 'ruining' a valve....  that's def worth pursuing 'cos you've always got to ask yourself "what's changed" and if you were getting 230bar + before changing the filter, and you've put the old filter back, could it either be this bleed valve or something in the area... Good thinking. 

[jsondergaard]

Alright, I tried to take a closer look at the pump etc. and I’ve removed it for inspection, and everything looks fine. No skipped teeth on the belt, timing was ok and the cam driving the pump wasn’t broken and didn’t budge, and springs in the pump were still springy. This leaves me even more stumped, and I can’t think of what to look at next..

[nicam49]

Time to search the Internet then. Can I suggest you raise a thread on the talkford.com.forum as you've had no other suggestions on this one. I'm not really familiar with the mk4 tdci myself, only the mk3, which uses a Delphi system so is a bit  different to the mk4. Good luck 🤞 

[Kevin#95]

You say the hpfp is not the problem. If it is faulty it can allow bleed back into the low pressure line. You could insert a one way valve into the low pressure line to stop air getting into the line. 

Can you take the injectors out and fire them onto a piece of paper to check the spray pattern?

If the injectors are not firing the hpfp might be the problem.

 

[nicam49]

Hi, you were getting good frp BEFORE you changed the filter and now you're not. How about checking if the  O sealing rings on the pipe connectors are intact or have somehow been dislodged or damaged. 

You seen this? 

Reading some of the comments it's NOT a one-off! 

[jsondergaard]

Hi nicam, yeah I've seen it, and in my last message, that was what I meant when I said the camshaft driving the HPFP was ok. It wasn't cracked and there wasn't any play in it.

I somehow got some air out of the system, which made the pump produce fuel pressure again. No luck on it starting, though. Didn't even sound like it was catching on.

I've attached scan data from cranking. And I've ordered equipment for doing an injector leak-off test, and a compression test. Other than that, I don't have many ideas as what to do, other than it might be the crankshaft sensor, causing the injectors not to open. But that should leave a DTC, right? I'm open for ideas, though!

[jsondergaard]

I've tested the cam and crank sensor today, which seemed fine. A summary of what I've done:

• Fuel feed line filter>pump, not blocked.
• Fuel return line pump>filter, not blocked.
• Fuel filter is primed and is not blocked. New was installed.
• Timing ok, no skipped teeth on belt, belt ok.
• HPFP springs are ok.
• Cam lobe driving the pump is ok, not cracked or any play.
• Injectors are getting fuel.
• Fuel rail has pressure according to ForScan.
• Cam and crank sensor ok, measured with multimeter but seemed fine.

Other than waiting for the compression and leak-off test sets, I don't know what to do. 😅

[jsondergaard]

Alright, I received my leak off test kit today. I’ve just tried it on, and I can’t fault the volume going back to the tank, and all are similar in volume. I’ve tried replacing the fuel pressure regulator and the fuel metering valve, because the rail is still having trouble reaching a good pressure range, but to no avail. Still doesn’t start even if it reaches a good pressure range in the rail.

Can the pump internals be broken enough to not be able to produce pressure reliably even though the springs in the pump are ok?

I’ve tried going though Fords diagnosing list:
- low fuel in the tank: it’s ¾ full, and it is diesel
- fuel filter element blocked: it isn’t (it is brand new), and I’m able to prime the system no problem. No air as well.
- fuel lines damaged or blocked: all lines are clear, no visible air or fuel leaks
- air ingress into the fuel lines: there isn’t any air up until the pump, and I’ve tried cracking the lines to the injectors to clear any air in the rail
- glow plugs: one glow plug has no resistance, the rest have >1 ohm. Shouldn’t affect it that much?
- incorrect valve timing: no skipped teeth on belt, timing ok.
- low cylinder compression: I’m beginning to believe so. Doesn’t sound like there’s much when cranking. Still waiting on the test kit.
- crankshaft position sensor: wiring ok, gives a signal but can’t be sure it’s right since I didn’t use an oscilloscope.
- camshaft position sensor: same as above
- pcm: probably my best bet if it has compression
- frp sensor: it’s readings are true 
- fuel pump fuel pressure regulator: tried changing today, no change as mentioned.
- fuel pump: might be. Springs are ok though.
- fuel injectors: might be? Doesn’t seem to leak excessively though.

Any help is greatly appreciated!
 

[nicam49]

OK,  try and find the fuse for the glowplugs and remove it. That way you'll get more cranking amps to the starter motor, and the battery won't run down so quickly. You don't need the glowplugs to start it. But you do need a minimum rpm before the ecu permits the engine to start. (200ish rpm)     You need to know if the glowplugs are being triggered. You've already found you have fuel on the rail. I bought a set of noid lamps which you plug into the injector socket, and they flash dimly.... they look like normal flashlight bulbs in a holder! I was a bit disappointed how low-tech they are. Did you buy a multimeter? They were on offer at Aldi a few weeks ago for a tenner...... what about a code reader...have you tried monitoring live data, frp and rpm whilst cranking?