Another DTC 1221, with bonuses

[LBC28730]

1987 325is w Motronic 1.3

As seems customary, I've been chasing a 1221/1222 DTC for months.

Initially the symptoms seemed exactly like a failing fuel filter.
Chugging, loss of power, bogging down, fuel related DTCs, the last of which I was only able to determine after switching from 1.1 to 1.3 ECU.
New filter had no effect.

After going through the Bentley troubleshooting methods, I found poor fuel pressure at the rail. I took this opportunity to eliminate the lift pump and go with a single fuel pump conversion.

This worked great, for a while.
Now it's worse than ever.
Only difference is I'm ONLY getting the 1221, now.

I've got a brand new O2 sensor on the way but I'm sure that won't completely solve the problem.
Initially it seemed to be only under load but today it completely died and I was stuck on the side of the interstate.
I unhooked the O2 just for the heck of it and there was no change.

After letting it set for about 30 minutes, I was able to limp it a little ways and get off the highway.
I let it set for an hour and it pretty much started right up, and ran fine for a few minutes, then began bogging down and sputtering again.
Also, the CEL used to go away after coasting or substantially decreasing load, now it's staying on, DTC 1221.

I'm only a couple miles from home so I'm hoping that after having lunch i can get it back and test fuel pressure.

So this is where I'm at:
All Bentley troubleshooting shooting for fuel system (ETC, CPS, TPS, MAF, etc) all pass and were well within spec.
I fully expect to find poor fuel pressure when I get back, and I'm starting to wonder if that could be done some crap in my lines and/or the fuel lines are deteriorated internally but still look good, much like brake lines do.

Last time I had an issue like this I pulled the fuel pump and replaced the connection hose, again, and that worked great.
I wonder if it wasn't that at all but rather just that I moved the fuel lines around and freed something up.

I'm going to test for pressure at the fuel filter "in" connection, as well as at the injection rail and see if there's any variation.

Open to any additional insight anyone may have on this.

Cheers!

[fixedwheelnut]

I would check the fuel pump relay and DME relay for dry solder joints that can break down when hot.

Also check the DME circuit board itself, pre 88 ECU's can also suffer fromdry solder joints around the output transistors.

[LBC28730]

I would check the fuel pump relay and DME relay for dry solder joints that can break down when hot.

Also check the DME circuit board itself, pre 88 ECU's can also suffer fromdry solder joints around the output transistors.

Thanks for the ideas.
Technically I think it's a later model ECU. If I recall correctly it was a green label 1.3 out of a 1990 is, maybe?

I forgot to mention that I also smoked the engine and found no vacuum leaks.

I also went ahead and ordered a 25' roll of Gates 27340 Barricade FI hose.
I imagine these lines are original so it should be done anyway.

I'll look around, I'm sure there's information on which joints could be suspect and I'll have a good look.

I'll have to look at my records but I think I replaced the FP relay as well.

[LBC28730]

It's look like, if I'm not mistaken, that the solder joint issues are mostly with the Motronic 1.1.

I discovered that if I stay above ~3200rpm it doesn't seem to be an issue.

[LBC28730]

Today I went though the motions as if I were replacing the fuel pump, short of actually pulling it out.
I feel it made a difference, albeit temporarily, which seems to support my theory of internally deteriorated fuel lines.
I've got the roll coming next week so I plan on dropping the tank, replacing all the soft lines and making sure all the hard lines are clear.

I feel good about this being a solution. Come Wednesday we'll see!

[LBC28730]

That didn't last for long.

Today, it started running really, really bad.
Bogging down really bad and actually feeling like it was slowing when I applied throttle.

Fully stalled about 2 houses from my garage.
I let it set for probably 30 minutes, it started right up and I drove it into the garage.

Just to eliminate any potential issues, I removed what I think is some sort of surge suppressor.
It's not shown in any diagrams of my fuel system and I think I recall (from the last time I had this issue) that others had removed this with no effect. If anything i could put it back if it was worse.

Hoping this could be a source of blockage, I proceeded to head to work.
Within 6-7 miles I was right back to where I was before, trying to limp it off the highway.

Managed to get close to work and now it will ONLY start and immediately die.
I imagine when I come back to it, it will run fine for a little while...

DTC 1222, NO 1221, now....

Reading on DTC 1222, I find several people calling for TPS as a solution.

Mine tested good but it seems the test really checks WOT so, maybe?
I ordered one.
I hate throwing parts at something but if it hasn't been replaced, why not.

I read that, if TPS was disconnected and it's faulty, the car should run fine.
Can anyone confirm this?
I'm going to try it as soon as I have a moment to step away


I'm still leaning towards some sort of progressive blockage bc of how it gets better after sitting but I'm open to any possibility right now.

I don't think it's related but maybe worth mentioning:

I just noticed that sometimes when I shut the ignition off, the tach indicator goes up a bit and the MPG gauge goes down.....it may have always done that and I just noticed, idk.

[LBC28730]

As anticipated, after sitting for about 7hrs, I was able to drive home (~15 miles) with no issue until the very end where I could feel it starting to hiccup, CEL flashed, DTC 1222.

Disconnected TPS and idle went up. Reconnected and idle returned to normal.

One of the only fuel related tests I haven't run yet is a delivery (volume) test so I am going to do one and see what I find.

[fixedwheelnut]

As anticipated, after sitting for about 7hrs, I was able to drive home (~15 miles) with no issue until the very end where I could feel it starting to hiccup, CEL flashed, DTC 1222.

Disconnected TPS and idle went up. Reconnected and idle returned to normal.

One of the only fuel related tests I haven't run yet is a delivery (volume) test so I am going to do one and see what I find.

When it packs up again, undo the fuel filler cap and see if you hear a rush of air get sucked in, I have seen fuel tank breathers blocked or incorrect caps causing a vacuum lock in the fuel tank, some even implode a bit

[LBC28730]

As anticipated, after sitting for about 7hrs, I was able to drive home (~15 miles) with no issue until the very end where I could feel it starting to hiccup, CEL flashed, DTC 1222.

Disconnected TPS and idle went up. Reconnected and idle returned to normal.

One of the only fuel related tests I haven't run yet is a delivery (volume) test so I am going to do one and see what I find.

When it packs up again, undo the fuel filler cap and see if you hear a rush of air get sucked in, I have seen fuel tank breathers blocked or incorrect caps causing a vacuum lock in the fuel tank, some even implode a bit

I'll try that. Thanks for the suggestion.

[LBC28730]

No pressure in the tank when poor driving condition is present.

Today it started straight away so I am absolutely positive it isn't temperature related.

Found something strange:
I am getting 12v at Fuel Pump Relay terminal 30 but when I jump with 87 the fuel pump does not run. As per Bentely procedures, jumper 30>87 with ignition off should put 12v at the lift pump (my only pump, now, since doing the single pump conversion, trying to address this issue, before). Same with ignition off or on.
I put a pressure gauge just before the injector rail and it started fine. So for some reason, the pump is only running when the engine is running/starting.

Due to this I can't really test the pump itself other than by using an external power supply.
I DID test this pump externally before installing and it was perfect.

I tried switching back to the Motronic 1.1 DME with no change, so I replaced with the 1.3. The whole reason I went with the 1.3 is to have the stored DTC codes, as 1.1 does not offer this.

Installed fuel pressure gauge just before the rail and started the engine.

Started out at about 31psi (just over 2bar) and very quickly began to fall. At about 8psi the engine stalled.

Started again to test the Fuel Pressure Regulator as per Bentley by clamping the hose to see if pressure increased.
Pressure started out better, about 35psi, but did not increase by clamping on the regulator return hose.

To me this says there MUST be something blocking the feed line.

I was planning on dropping the tank and getting all the hoses on Wednesday when my roll of hose comes.
For now I am going to replace what I can easily get to like the section coming off the fuel pump itself.
Maybe I will get lucky!

[LBC28730]

Dropped the tank, replaced the lines, put everything back in place.

Figured out the relays had been installed in the wrong positions and the fuel pump relay was actually nearest the windscreen.

Unfortunately, now, I am getting even less fuel pressure (21psi) so I guess I am going to pull the pump, again.

All this trouble, assuming the new pump is good. This is already the second pump as I had the first replaced wtih warranty after IT failed...

[fixedwheelnut]

Have you inspected inside the tank? make sure there is no rust or water that can contaminate the pump and clog up the flow.

I can't remember if you have already changed the filter? note one of the fuel pipes is a specific 'U' shape, I have seen people use a length of normal pipe that 'kinks' and causes a blockage, see hoses 13 & 9 on the link below, the shorter one has now superseded to the same number as the longer one and you just cut it down to length.

https://www.realoem.com/bmw/enUS/showpa ... Id=16_0303

[LBC28730]

Have you inspected inside the tank? make sure there is no rust or water that can contaminate the pump and clog up the flow.

I can't remember if you have already changed the filter? note one of the fuel pipes is a specific 'U' shape, I have seen people use a length of normal pipe that 'kinks' and causes a blockage, see hoses 13 & 9 on the link below, the shorter one has now superseded to the same number as the longer one and you just cut it down to length.

https://www.realoem.com/bmw/enUS/showpa ... Id=16_0303

Yes the inside of the tank looks great, like new.

Got a real good look at it today as it was completely out. That job was a bit of a hassle but more time consuming that anything.

I did change the filter very recently, and I changed it again this time just to be sure.

Mine doesn't have the "U" shaped hose anymore, since I converted to the single pump configuration.

I just took the pump assembly out and everything looks as it should. I'm going to reinstall and test pressure right at the pump.
Just in case, I have a Mustang fuel pump with a lifetime warranty, from my local supplier, on the way.

I appreciate the input. I'll update as to what I find out.

[LBC28730]

I haven't did a test run yet but, it COULD be that the hose from the pump to the carrier just wasn't tight enough.
I have had solutions before that didn't pan out so I'll see how this does the next couple days/weeks/etc

I removed the assembly and clamped down the one clamp that wasn't fully compressed. This was on the pump side and maybe I didn't get it as tight as it could be for fear of collapsing the nipple on the pump.

I'm getting 60psi before the rail.


Thanks so much for brainstorming this with me, Fixedwheelnut!

[LBC28730]

I haven't did a test run yet but, it COULD be that the hose from the pump to the carrier just wasn't tight enough.
I have had solutions before that didn't pan out so I'll see how this does the next couple days/weeks/etc

I removed the assembly and clamped down the one clamp that wasn't fully compressed. This was on the pump side and maybe I didn't get it as tight as it could be for fear of collapsing the nipple on the pump.

I'm getting 60psi before the rail.


Thanks so much for brainstorming this with me, Fixedwheelnut!

For future reference to anyone looking at 1221/1222 issues, this is NOT unique when doing the single fuel pump conversion.

Initially I had not compressed the ear clamp on the pump side fully down for fear of collapsing the pump nipple.

I fully calmped it down (I think it was a 14.3mm clamp) and now everything is absolutely fine.

[fixedwheelnut]

I haven't did a test run yet but, it COULD be that the hose from the pump to the carrier just wasn't tight enough.
I have had solutions before that didn't pan out so I'll see how this does the next couple days/weeks/etc

I removed the assembly and clamped down the one clamp that wasn't fully compressed. This was on the pump side and maybe I didn't get it as tight as it could be for fear of collapsing the nipple on the pump.

I'm getting 60psi before the rail.


Thanks so much for brainstorming this with me, Fixedwheelnut!

For future reference to anyone looking at 1221/1222 issues, this is NOT unique when doing the single fuel pump conversion.

Initially I had not compressed the ear clamp on the pump side fully down for fear of collapsing the pump nipple.

I fully calmped it down (I think it was a 14.3mm clamp) and now everything is absolutely fine.

Good to get to the bottom of it well done!

[LBC28730]

Well, turns out that wasn't the end of it.....damnit!

That worked great for a couple days and out of nowhere is back and quick.

At this point I'm thinking it must be how the pump is secured, that's allowing it to back off and release pressure.

Previously I was only securing the pump with zip ties but I recently secured with one banded ear clamp.

I no longer have the rubberized surrounding on the pump and I wonder if that actually helps in keeping the pump from backing off?

I haven't pulled the pump yet but I'm 98% sure that's what's happening.

If I install the same assembly I'm going to use 2 straps and maybe groove the body of the pump to make it impossible to back off (down) from the assembly.

[LBC28730]

In the process of all the issues I ordered this assembly.
After ordering it I thought it may just be a lift pump replacement but thought I'd try it out to have on hand, anyway.

Now that I have it, i see that's it's very different in that it feeds it what should be the return line and there's actually no provision for the return line.

This seems totally strange because I'm pretty sure even the E30 with two tank openings still have the feed/return on the same side?

Is URÖ parts trying to make a drop in single pump conversion?

I'm going to test this and see what pressure it produces, just for the hell of it.
I'm not sure how it would be very useful though, as it would bypass the fuel pressure regulator by pushing the fuel into the rail in reverse. If it would work at all..... ?

[LBC28730]

Haven't tested that pump yet but my car was not getting any fuel after work.
I removed the pump and found about a 3mm gap from the bottom of the connecting hose and the pump.
I only pushed it back up and it runs fine.

I'm using the good ear clamps so I'm just going to try to place it closer to the ridge on the pump nipple.

This should absolutely keep it from backing off and that should work.

Still curious about this other pump assembly so I'll need with that soon, too.