tii running on 3 cylinders - UPDATE x2

[Ensign]

I have been trying to sort out low idle, hesitation and lack of power of my ‘’72 tii, that seemed to coincide with the installation of a new, 5-series fuel pump.  However, today I discovered that the engine is getting zero contribution from cylinder #2, at least at idle.  The ignition is Pertronix by the way.

When I pulled the wire from plug #2 to see if it effected the idle, I tested for spark from the wire and it was strong. I put another wire on it anyway and got the same result, the engine was running on 3 cylinders. I pulled the plug and it was dry. I assumed since the plug was dry that it was a fuel delivery issue and not spark. I further assumed that I may have a bad fuel injector. I added some Sea Foam to the fuel tank and went for an extended drive and it seemed that I was running on 3 cylinders at all rpms and that did not change.

So before I start tearing things apart to get at the fuel injector to replace it, I am wondering if anyone has other ideas regarding my diagnosis and/or other things to check before replacing the injector. Thanks in advance for your input.

Edited 19 hours ago by Ensign
revise title

[tzei]

Is KF trying to suply fuel to cyl 2?

[Ensign]

19 minutes ago, tzei said:

Is KF trying to suply fuel to cyl 2?

I haven't checked. I will.

[dlacey]

Get the Blue Book from the technical article section and go through the fault finding guide... If there's no fuel delivered then your issue is most likely a leaky check valve...might just be some debris in the valve.

[stephers]

Could be a suction valve, a delivery valve or the injector      Take off one of injector lines at the pump, turn the ign on so the pump is working, pack a few rags around the pump.   Look for a small hole at the outside edge of the pump head right where the delivery valve is, Now loosen that valve ( I use a deep 12 mm socket and extension )  see if fuel is coming out at that bleed hole ( watch , it really comes out )

If you have  fuel, tighten up the delivery valve until it stops the fuel from coming out the hole     Do each line like this, if you have a good stream from each one, the suction valves are probably OK    Put the lines back on  Next step is to pull one injector and hook it up to one of the lines ( doesn't matter which one )    and see if fuel is pulsing out of the injector while cranking it over     Disconnect the leads to both the cold start and the ign dist while doing this, they are both not needed right now.     If you have one bad injector, I would send them in and have Robbie re do them ( Paul W's nephew )     If no fuel from the bleeders, you can then try swapping around suction valves but read the trouble shooting manual first

 

Thanks, Rick 

[Ensign]

Thanks to all of the responders for leading me down the right path.

Using the fuel injection system manual as my guide, with the engine running, I slightly loosened the fuel line fitting on the delivery valve for cylinder #2. Some fuel leaked out and, according to the manual, this indicates a defective delivery valve or injector. I swapped out the delivery valve with a known good one and that made no difference, indicating a defective injector.  I have an extra injector that has been cleaned and flow-tested by Wes Ingram, so replacing the injector will be my next step.

Thanks again,

Tony

[SydneyTii]

8 hours ago, Ensign said:

loosened the fuel line fitting on the delivery valve for cylinder #2. Some fuel leaked out and, according to the manual, this indicates a defective delivery valve or injector.

If fuel leaks out and the engine note does not change (as yours wouldn’t if there’s a fault) as I understand it, then that means the suction valve and delivery valve are ok and the issue is further down the fuel route as in the injector.  Seeing as you have got this far it certainly looks like your injector is acting up. 
Please let us know what you find.

[Ensign]

Update: In my last entry I explained that the diagnostics I performed, according to the BMW injection manual, indicated that the pump, delivery valve and suction valve were okay leaving only the injector as the reason cylinder #2 was not firing. So a “new” injector was installed and nothing changed, still nothing from cylinder #2. Since I already tried a new delivery valve with no success, I swapped suction valves with cylinders 2 & 3 and now cylinder #2 was firing and #3 was not. (so much for my diagnostics…) It was a bad suction valve from the get-go.

I removed the bad suction valve and soaked it in injection cleaner for 24 hours and that made no difference. In the meantime, I contacted Wes Ingram for suggestions and he came back with this:

“Have him go to Harbor Freight and buy Evaporust.   Have him soak it for 24 hours then wash it and soak just to rinse it out with either paint thinner or preferably lacquer thinner then give it a try.  Also have him make sure that he has the sealing washer under the one-way valve.”

So the suction valve is currently soaking in Evaporust. I’ll report back with the results.

I have another Kugelfischer pump on a rebuilt engine sitting in my basement, so I stole a suction valve from that pump (something I did not want to do) and the engine runs like a top!

[tzei]

I know this is far off but does #2 inlet valve open?

[Ensign]

15 minutes ago, tzei said:

I know this is far off but does #2 inlet valve open?

Yes, with the bad suction valve replaced with a good one, the engine runs fine.

 

At this point, I'm just trying to see if I can resurrect the bad suction valve by soaking it in Evaporust.

[Ensign]

Just to close this out...

Soaking the suction valve in Evaporust did not work. This is not to say that it wouldn't work on another valve,

I just think corrosion was not the problem with this particular valve.

[Einspritz]

Ultrasonic cleaner?

[bergie33]

1 hour ago, Einspritz said:

Ultrasonic cleaner?

With Evaporust

[Einspritz]

Put the part in a baggie with the solvent, then in a HOT water ultrasonic cleaner.

Try 3x @ 20 min, so as not to overheat the cleaner.....