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Tii good cold start, terrible warm running - PROBLEM SOLVED!


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Hoping for some guidance here...

My car was running great for months and then a few weeks ago it started running rough when warm, and got progressively worse.

FYI, I am running a 123ignition distributor that works great.  Running Shell V-Power 100 Octane with a bit of lead additive.  I typically get about 25mpg, and I know from the initial setup by the rebuilder that it likes to run a bit rich.

The KF was tested as good, but not rebuilt.  The injectors all tested OK, one being slightly lower than the others, but all within tolerance.

Air filters are clean.

 

It starts great, idles and runs well after the first one minute of warmup running (always misses a bit when cold and engine braking down the hill from the apartment, but then chipper from the bottom onwards), runs well for about 7-10 minutes, and then when fully warm it just gets flakey until I can hardly keep it running.

 

The idle drops and it starts knocking, and starts to stall unless I give it gas.  When running warm it's missing on cylinders, backfiring, popping, surging, but dropping power under load.

Last weekend I started at the fuel tank and checked the mesh in the sending unit - A-OK, and tank is nice'n clean:

IMG_0853.thumb.JPG.47e70d044b9dceb4de644d74b6703d67.JPG

 

I jacked up the back end and was having a delightful time (NOT) getting at the fuel pump assembly to check the conical filter.  Thank goodness I went back and read Orusty2's note that it's accessible without removing the pump!  Turns out the conical screen is missing.

I went ahead and replaced the canister filter at the radiator.  Gas came out clean.

I removed the KF banjo bolt at the input and found the filter was packed with so much grit it was hard to get out.

IMG_0868.thumb.JPG.5e5662781445a5b92fecee6b8574b167.JPG

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There was this delicate little clip holding the screen in place... I had my finger on top of it and had hardly touched it with a jeweler's screwdriver and presto! that thing was gone!  Looked all over, never saw it again. Crap!

I had a piece of thin, springy steel that I've been kicking around in a toolbox for just such occasions.  I bent a piece of it and clicked it into place in the banjo bolt:

IMG_0871.thumb.JPG.66f72a0377f46b11e8c0d39d069c5eaf.JPG

 

I buttoned everything up, powered up the pump, checked all points where I worked for leaks.  The pump sounds smoother, like it's not straining anymore.  

I fired ol' Willem Tell up, and he ran like a champ! I took him for a nice hour-long romp along the lake.  I still have some hesitation, but I believe I'm running lean, so that's a test I panned for another day with my new Innovate LM-2 AFR meter!

 

Last week when I was checking and replacing filters, I also pulled the plugs to have a look; they seem OK.  No.2 is a tad dark, but nothing unusual:, so I think my AFR mixture couldn't be too far off:

 

 

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That was last week... Clearly seems like a fuel flow issue, so I read all of the threads and thought I'd gotten to the bottom of it but...after what I thought was a successful trouble-shooting, the problem returned, only worse.  

 

I went back and re-read Mike MacCartney's Restoration guide on the Tii fuel system; he noted that an improperly operating return regulator valve could cause behavior such as I was experiencing: runs OK for 7-10 minutes, then flakes out.  Stop, let it cool off and it runs OK for 7-10 minutes...

 

Today I pulled the return fuel line and ran the fuel pump for 30 seconds - it shot a robust stream and filled a liter of gas in 30 seconds, so it's not looking like the pump (unless someone has experience with them failing consistently after a few minutes running?).

I pulled the KF banjo bolt again and verified the filter was still clean.

This time I had time to pull the return regulator valve - it felt a bit sticky, so I soaked everything in solvent.  It still felt like it hung a bit at the beginning of travel, so I CAREFULLY removed the clip and used a cotton swab to clean gunk from the walls of the valve cylinder until the swabs came out clean.  Put it back together and it felt better, but didn't feel perfect, but what to do?  I put a small dab of Vaseline in it and it felt like it moved freely (I know that will only last for a second once gas flows).

 

Willem seemed OK, so I went for a drive to try out my new Innovate LM-2 to check the AFR (no down pipe bung yet, using the exhaust mount, as I want to test my MBZ as well).  Ran fine for... wait for it... 7-10 minutes, and then got seriously flakey.

Still, I had it warmed up, so I threw on the LM-2 and looked at the AFR.  It was low at 11.7 at 1000 RPM, but went up to 14.X at 2000, and then considerably higher 20++ at higher RPMS.  I tried adjusting the mixture slightly in the tuna can at idle, but didn't really make an improvement.  High AFR value much greater than 14.7 means what, super lean?  Means something that should be changing to add gas and maintain AFR is not changing?

I tuned the dizzy advance +/- to see if it would stabilize, but it seemed the best of the worst is right where I had it, 15 degrees at 1000RPM.  My current advance curve (gold color):

image.png.d529c57f58aba8122f1e9fc27d1278e1.png

So where does that leave me? 

All fuel lines are new, and I just re-checked everything (except following the steel lines from end-to-end).  The filter is new, the banjo filter is clean, and I cleaned the return regulator (but still a ?).

The return regulator is flakey?  If it was, would I get such a strong return flow back to the tank?

My warmup valve is not operating properly?

 

The "hat" doesn't appear to be far above the lever, but the lever does appear to be meeting its stop:

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Air getting into the fuel line somewhere?  I checked all of the fittings, and I cannot find a drop of fuel outside of the system.

Air getting into the plenum?  I just followed Zinz's advice about using a penetrating oil to maintain the aluminum engine parts; I wiped and inspected the whole top end. Can't find any gaps. As the engine stumbles on idle I did hear a distinct faint "wheeee"  sound coming from the exhaust side of the engine. That could be what my fuel pump sounds like from outside the car...

Could I have hopped a tooth on the KF pulley?  But again, the car runs well until it fully warmed up.

 

Just heading out of town for the week, so any ideas I can test next weekend would be appreciated!

 

Tom

 

1972 BMW Inka 2002Tii  ?

1974 BMW Turkis 3.0 CSi ?

1972 MBZ Weiss 280SE 4.5 

2006 BMW Cobalt 530i (38,700 m original)

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Mmmm sounds very very similar to the problem I had a few years ago.

My car was running lean.

I did the same went through everything.

New 5 series fuel pump.

Checked and cleaned everything.

KF return valve was crap and not functioning properly, I replaced it, it has to hold 2 bar (i think pressure in the KF pump)

After all of that including readjusting the tuna can for idle etc it still popped and banged on deceleration coming into roundabouts and corners.

So I read Mikes book again and then...... Yes the Verboten screw, I marked its starting point, and very carefully adjusted it, in small increments, I went for a drive, pulled the plugs checked them, rinsed and repeated until it ran well. It now runs really well, marvelous piece of kit the KF.

Mine had never been perfect but it is great now. This is before I bought an innovate, but to be honest I remember having this same chat with Mike many many years ago.

The trick is don't do anything too radical, just small incremental changes, my engine is far from new so I thought there may be a bit of give and take in AFR settings if I even had a meter/gauge at the time anyway, so I just thought take it easy see how it goes.

The car will tell you whats going on..

The only thing that intrigues me is that it did run well, so has something gone faulty?

Have a look at what else can make it run lean past the warm up cycle.

Report back let us know what happens.

 

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Tom,

Check the hose running from the warm up regulator to the intake air accumulator for cracks.  Would let in additional air after WUR was closed.  Was an issue on mine about 25 years ago.  Very hard to see.

Good luck,

Glen

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  (AFTER it's running stable)Thanks Both, some things to think about.  Glen, that "wheee"  sound has me thinking I've got a leak somewhere.  Sydney now that I've got an AFR meter I am more confident to take on the "verboten screw" (AFTER it's running stable!).

Edited by Swiss 2002Tii

1972 BMW Inka 2002Tii  ?

1974 BMW Turkis 3.0 CSi ?

1972 MBZ Weiss 280SE 4.5 

2006 BMW Cobalt 530i (38,700 m original)

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You are not alone. 

 

Good work on the fuel system.  I don't think that's your issue.  Although the crud didn't help.

 

Your plugs are too fouled.  They should be a light coffee color. Improper air/fuel mixture is my first guess.  

 

Rule out the cold start injector.  Pinch the hose and disconnect the power.

 

It sounds very much to me that your warm up regulator is still engaged after warm up.  Letting in too much unneeded air.

 

From the warm up regulator pictures you sent it looks like the piston is not rising the full 10mm.  It must rise completely to cut off the auxiliary air that is ONLY required for warm up.WUR_FunctionDiagram.thumb.jpg.4ca713c8195713617a43f3c7bdfcb50d.jpg

 

 

To confirm this pinch the air hose behind the WUR when the engine is at warm idle.  I use super-long pliers.

Pinch1.jpg.2bb02818101832a33eb1bf6448ec62c8.jpg

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 If the engine speed drops that means you have (reduced) air getting into the plenum from the WUR.  NO air should come from the WUR after warm up.  GlenKarr, above, mentioned a crack in the hose.  I've never been that lucky.  Maybe you will be. :)

 

I've had some success dismantling and cleaning regulators so they work again.

5b03b6dc736d0_WUR3_HeightsandTemps.thumb.jpg.32415d8cf86a1bf16d43ac643ef1e050.jpg

 

 

 

Edited by PaulTWinterton
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73 Inka Tii #2762958

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If the air hose running from the WUR to the bottom of the plenum splits then you get very inconsistent behaviour... Cold start normally ok, but warm running is poor... Also the standard Tii tuning at idle methods create extremely rich mixture at wider throttle openings...

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'59 Morris Minor, '67 Triumph TR4A, '68 Silver Shadow, '72 2002tii, '73 Jaguar E-Type,

'73 2002tii w/Alpina mods , '74 2002turbo, '85 Alfa Spider, '03 Lotus Elise

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Thanks All, sounds like a plan for next weekend.

 

Paul, can the the WUR be separated from the KF without dismounting the KFish, breaking open fuel system?

I’ve got the KF manual, so I’ll be studying up for the weekend.

Tom

1972 BMW Inka 2002Tii  ?

1974 BMW Turkis 3.0 CSi ?

1972 MBZ Weiss 280SE 4.5 

2006 BMW Cobalt 530i (38,700 m original)

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Technically yes, but you will have to disconnect all the linkages, air and water lines, which means you have to drain the coolant system.

 

And probably the dip stick and associated brackets.

 

I haven't looked at one for days, so don't know if you can get to the bolts holding it on the back of the pump.

 

Paul did this not long ago.

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6 hours ago, Swiss 2002Tii said:

Paul, can the the WUR be separated from the KF without dismounting the KFish, breaking open fuel system?

 

Yes, 3 bolts into the KFish and 1 bolt/nut to a support bracket to the block.  Throttle linkage needs to be lifted out of the pivot point on the WUR.  Loosening the clamp on the intermediate shaft and lifting cam up from inside tuna can will free up the linkage to move it out of position. DO NOT LOSE THE PLASTIC CUP OR RUBBER DUST COVER ON THE BOTTOM OF THE THROTTLE LINKAGE. 

 

 A good time to measure your linkage lengths.  I like to remove the 1st and 2nd runner to get easy access to that area.  That entails removing the check valve on the back of the KFish FIRST.   No biggee, (14mm open-end wrench) but be prepared for a small amount of fuel discharge.

 

I've had success with pinching hoses so as not to lose much coolant.  I hate draining coolant if I don't have to.  Just wrap tape or cloth on whatever Visegrips you use on the hoses.  Caveat: the original water hose into the WUR was wire-reinforced.  Do not clamp it.  It will be instantly destroyed.  If it's a newer hose it will be all rubber.

 

 

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73 Inka Tii #2762958

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Isn't the WUR separate from the pump?  I've been thinking about this - changing my pump and leaving the WUR connected to the cooling system...  I've been thinking about just unbolting the WUR from the pump and leaving it in place...  The WUR just moves the enrichment lever (verobten screw), no?  Based on coolant temperature?

 

But I've also had too much too drink sitting at a bar on Key West, so I might not be the best person to speak on this subject...

 

Ahh, you're trying to go the other way.  I believe people have run the KFish without the WUR altogether, simply removing it from the system...  Might be a good test...

Edited by irdave
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Dave.

'76, totally stock. Completely.

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I used a home made smoker to confirm that the WUR was operating correctly by warming up engine, turning the car off,  pumping smoke in the throttle body and looking for smoke at the top of WUR. Nothing came out warm, but as the engine cooled down and the hat started dropping, smoke started to come out, as you would expect/hope.

 

Found an air leak was coming from a cracked intake runner. 

 

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'72 2002tii 'Liesl'

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On ‎5‎/‎22‎/‎2018 at 10:40 AM, 2002Scoob said:

Man! Hope ya get this figured out, seems like you're in good hands. I get my 02 running swell, and you trade places with me. hah. May we someday meet on equally well-running playing field!

Ha!  Let's plan on it as soon as I can drive longer than... 7 minutes!

1972 BMW Inka 2002Tii  ?

1974 BMW Turkis 3.0 CSi ?

1972 MBZ Weiss 280SE 4.5 

2006 BMW Cobalt 530i (38,700 m original)

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