IP won't produce adequate pressure

[lbitto]

Howdy,

Some background. I left my car in a lot for 2 weeks. I think it was losing prime, but I after resealing the injection pump I found out I had a bad 109 relay. Replaced that.

The injection pump is leaktight as I tested it with a mityvac. I may need to remove the check valve at the sender unit, and am waiting on a part to seal the thermostatic tee on the filter... in the mean time i decided to isolate just the injection pump and tried the bottle method and just feed the IP diesel that way.

The ongoing issue i have is that I can't seem to get the hard lines to bleed. Or, at least I get two lines to squirt fuel but it's almost like there's not enough pressure to get them to bleed. Also, some fuel would be pulled from the bottle, then quickly back with alot of air bubbles, almost like the pump couldn't pull the fuel. I tried adjusting injection quantity by hammering the head to the right; it stopped pulling and pushing the diesel from the bottle and the flow seemed to be steady. No change in trying to bleed the hard lines. Two seem to bleed, not necessarily the same two each time. That's with all the injector fittings cracked, or one by one.

I double checked the timing belt. Cam, crank and fuel pump pulleys are where they should be. I was extra careful to assemble the IP so that it wasn't 180 off, so im 98% sure that's not the issue. The case pressure relief valve is intact and everything is pushed in flush. I did lose one of the rubber grommets for the valve cover and am waiting for a new one. I highly doubt that affects anything related to fueling, but figured id include.

I've been racking my brain trying to go through every possible issue. I really don't want to buy a new injection pump

Thoughts?


UPDATE:

I was able to resolve this issue. I chalked it up to a sticking fuel shut-off solenoid. Jumping a wire straight from the battery to the solenoid seemed to help it open so that I could start it. I replaced the normal wire and tried starting, and it fired right up. It also could have been some loose grounds, which I resecured.

Hope this helps the next person who has this issue.

 

[KLXD]

You took the pump off the engine to change the seals or no? I ask since you felt you needed to check the timing.

If you did it in place are you sure you didn't drop the shim that's between the cam plate and the distributor shaft? To do so would greatly decrease the stroke of the pump decreasing the amount of fuel it can inject.

 

[lbitto]

Yes, I took it off to reseal it. I know of the shim. I was pretty careful that it went back in and everything lined up, spun the thing and shook it to see if anything rattled around. Nothing seemed out of place. I am checking my shut-off solenoid because i suspect it might be weak and isn't staying open. That's really the last thing I can think of before I tear the thing down to see if I made a mistake while assembling.

I appreciate the response!

 

[lbitto]

Update:

As I mentioned, I thought the fuel shut-off solenoid might be the culprit. Click on, 10 seconds, click off. I tried wiring it straight to the battery and it clicked right open. Ok, so it works. With it connected to the battery i was able to bleed all lines very quickly, then it started right up. An electrical issue downstream of the solenoid... interesting

 

[ninedee_golf_tdi]

I've found a few fuel shut off valves that although clicked, were faulty. So sez vcds.

 

[KLXD]

Normal for it to not stay open when the engine isn't running BUT should open again when you start cranking the engine. If you have to jump power to it to keep it running you have an electrical issue but I think you said that.

For future reference, you can take the plunger out and the engine will start and stop fine. The ECU sets the IQ to zero to shut the engine down. The cutoff valve is left from the old mechanical pump days when it was the only C/O.

 

[MunchiMk3]

How do I check for a faulty shut off valve? I think I'm having the same problem but don't quite know how to diagnose this. Backstory: I changed all the seals on the IP yesterday after months of dealing with long crank starts and now I'm getting near no pressure coming out the lines when trying to bleed after the reseal job. Here's a video I took just now of the situation. Thanks in advance to anyone reading this.

 

[lbitto]

How do I check for a faulty shut off valve? I think I'm having the same problem but don't quite know how to diagnose this. Backstory: I changed all the seals on the IP yesterday after months of dealing with long crank starts and now I'm getting near no pressure coming out the lines when trying to bleed after the reseal job. Here's a video I took just now of the situation. Thanks in advance to anyone reading this.

I realized I didn't mention the resolution to my initial issues. Hopefully it helps resolve some of your issues because looking at your video, it looks exactly like what was happening to me. Injector lines seemed to be bled, but no start. Do air bubbles seem to pulse through your fuel lines after each revolution? That would hint at a sticky shutoff solenoid.

I would try jumping a wire straight from the battery to the solenoid. You should hear a solid click. Try cranking it over and see if it starts. This is what I did and it started immediately. Funny enough, I took the wire off and put the regular wiring back on the solenoid and it started fine like that. I don't know if it was a tad worn out and 24v straight to it had some sort of affect. (It could have been the fact that I had messed with the brackets where all the grounds are, and some were kinda loose 🫣 so maybe check your grounds, too). That would at least isolate the issue a bit more. If you verify the solenoid is strong and clicks open and it still doesn't start, I'd imagine you might have some other issue like air getting into your fuel lines.

Hope this helps.

 

[MunchiMk3]

I realized I didn't mention the resolution to my initial issues. Hopefully it helps resolve some of your issues because looking at your video, it looks exactly like what was happening to me. Injector lines seemed to be bled, but no start. Do air bubbles seem to pulse through your fuel lines after each revolution? That would hint at a sticky shutoff solenoid.

I would try jumping a wire straight from the battery to the solenoid. You should hear a solid click. Try cranking it over and see if it starts. This is what I did and it started immediately. Funny enough, I took the wire off and put the regular wiring back on the solenoid and it started fine like that. I don't know if it was a tad worn out and 24v straight to it had some sort of affect. (It could have been the fact that I had messed with the brackets where all the grounds are, and some were kinda loose 🫣 so maybe check your grounds, too). That would at least isolate the issue a bit more. If you verify the solenoid is strong and clicks open and it still doesn't start, I'd imagine you might have some other issue like air getting into your fuel lines.

Hope this helps.

Thanks for the quick response. I do see tiny bubbles forming in the return line after each attempt. I also jumped a wire straight to the solenoid and it made clicking noises, but it wasn't the same solid CLICK it used to make; sounds much quieter than usual. As for checking the brackets/grounds, I am not quite sure what to check. I have a new solenoid on order right now though just to make sure it's not sticky.

 

[lbitto]

Thanks for the quick response. I do see tiny bubbles forming in the return line after each attempt. I also jumped a wire straight to the solenoid and it made clicking noises, but it wasn't the same solid CLICK it used to make; sounds much quieter than usual. As for checking the brackets/grounds, I am not quite sure what to check. I have a new solenoid on order right now though just to make sure it's not sticky.

You could try starting it with the wire jumped and see what happens. If I recall, it did sound a bit weaker when I jumped it, but as long as there's only one click, meaning it's being held open. As far as your grounds go, they are down near your shifter weight on the side of the engine on a metal plate. Sometimes the ring terminals get pretty cruddy down there and need a good brushing off. Or maybe they're loose, as was the case with mine.

You could also just take the plunger out of the solenoid and see if it starts like that as KLXD said in a previous comment. I've never tried that, but apparently it doesn't actually need the solenoid to shut the engine off.

 

[Abacus]

Update:

As I mentioned, I thought the fuel shut-off solenoid might be the culprit. Click on, 10 seconds, click off. I tried wiring it straight to the battery and it clicked right open. Ok, so it works. With it connected to the battery i was able to bleed all lines very quickly, then it started right up. An electrical issue downstream of the solenoid... interesting

This sounds like a classic 109 relay problem. Do the glow plugs come on for a second when you turn the key in the ignition? If not, then replace the 109 relay under the dash. The old black ones developed cracks in the solder and could flake out. I always keep a spare 109 in the door pocket or center console.

 

[lbitto]

This sounds like a classic 109 relay problem. Do the glow plugs come on for a second when you turn the key in the ignition? If not, then replace the 109 relay under the dash. The old black ones developed cracks in the solder and could flake out. I always keep a spare 109 in the door pocket or center console.

That wasn't the culprit. Initially, relay 109 was bad. I did replace it after all of this. Sorry I didn't mention it, but I resolved this. Chalking it up to bad grounds or a sticky solenoid. Either way the thing runs so I can't complain

 

[TDeanI]

I had this problem, died when running. Then no start. Couldn't bleed any fuel out of the hardlines lines. Replaced the Relay 109 with two different ones.
Jumped the fuel solenoid. Replaced the fuel Thermo T, fuel lines, fuel filter. Nothing. Never started. Never did narrow down the culprit.

Replaced the whole injection pump with a junkyard one from an ALH.

Runs great now. I think my 1z pump was just bad. It had a lot of shuddering near the end before it finally crapped out.

 

[MunchiMk3]

I finally got it firing to my liking. Most of my issues seemingly revolved around nudging the QA to the left and right until it found adequate power. I replaced the solenoid and checked the grounds, all seems well now. Thanks for the advice. Also wanted to note that I couldn't turn the car off when jumping the solenoid. I had to pull the jumper wire to get the car to shut off. I assumed the ECU would bring the IQ to zero but maybe not?

 

[Steve Addy]

I finally got it firing to my liking. Most of my issues seemingly revolved around nudging the QA to the left and right until it found adequate power. I replaced the solenoid and checked the grounds, all seems well now. Thanks for the advice. Also wanted to note that I couldn't turn the car off when jumping the solenoid. I had to pull the jumper wire to get the car to shut off. I assumed the ECU would bring the IQ to zero but maybe not?

If you installed a new seal in the top cover then no matter what you do, even if you scribe a mark, you will never get the IP back to where it was without doing hammer mods to get it running so you can use vcds to make adjustments.

It's just how it works.

Steve

 

[KLXD]

What Steve said. That's the reason there was a big blob of yellow paint on a "tamper proof" bolt on the QA. The QA position was set on a test bench at the Bosch factory.

Those who have gone before us have learned how to get around or rather replicate that calibration but it wasn't with a scratch.