Have you checked the level of the radiator yet?

When it is cold of course.

If its low, Houston we have a problem.

Lumens,

Good idea, Thank you.

The radiator has not been checked recently. I saw one of the guys do it when working on her but can't remember exactly when, within the last month I think. I will do that when she cools down (I just went to the mailbox) and will report back if she DID need coolant. I'm writing a lot, and will not fill the pages if she did not need any. Hope that is ok.

Jai

 Zed Head, I agree with all of the possibilities except the f. pump. Can't figure out why a bad pump would cause black plugs.

 Jai, Possible success? We won't know until you try again several times. It may be just a normal glitch in the EFI cold to warm-up process. Do you remember it happening in the past? I really don't know squat about EFI,  I remember RossiZ mentioning a similar symptom with his EFI. When he switched to SUs, the temporary rough running, when cold, went away. 

 How long has the tach been bad? Was it dead before the problems started & does it ever show any life?

Edited November 2, 20159 yr by Mark Maras

Zed Head, I agree with all of the possibilities except the f. pump. Can't figure out why a bad pump would cause black plugs.

 Jai, Possible success? We won't know until you try again several times. It may be just a normal glitch in the EFI cold to warm-up process. Do you remember it happening in the past? I really don't know squat about EFI,  I remember RossiZ mentioning a similar symptom with his EFI. When he switched to SUs, the temporary rough running, when cold, went away. 

 How long has the tach been bad? Was it dead before the problems started & does it ever show any life?

Mark,

I know the fuel pump was suspect long ago. But do not know the status of it now.

Yes, first success with the rough running. I know more needed to make sure.

She arrived here in March, drove fantastically until mid June when all this stall, missing, rough running began.

The tach never worked when she arrived, nothing not even a twinge.

Thank you,

Jai

Try running it without the gas cap, maybe its clogged.

As far as the black spark plugs go, it could be just the cold start injector

not shutting off all the way or even shutting at all.

 Zed Head, I agree with all of the possibilities except the f. pump. Can't figure out why a bad pump would cause black plugs.

 Jai

 

 How long has the tach been bad? Was it dead before the problems started & does it ever show any life?

These engines will actually run really well with a rich mixture.  So the new tune and clean that was done might still give a great running motor, but still give dirty plugs.  (Edit - meant to say that a bad pump and rich running may not be related.) Plus, mailbox trips tend to not warm the engine up completely.  Not a criticism, just a reality.  Anyway, it turns out the plugs are still from when it was running poorly.

 

I've kind of ignored the odd details and focused on the engine dying.  That's the biggy.  You can ramble around the country-side with a lean condition causing poor throttle response, or a rich condition causing watery eyes from the gassy smell, but engine dying tops them both.  As many of us know, these engines will run very poorly for a long time, without dying.  Engine dying and not restarting is unusual.

 

Too bad about the tachometer.  It's a good diagnostic tool, but they do go bad.  I have a 78 tach in my 76. My 76 tachometer started hanging up when it got warm.

 

I think that you're right about the EFI glitch causing the short-term stumbling while warming up.  The AAR keeps RPM up for a short time when cold and if it closes a bit early there won't be enough air for the engine's temperature for it to run well.  I wouldn't worry about it now, as part of the big problem.  If it's consistent, you can just live with it while trying to figure out the dying issue.

Edited November 3, 20159 yr by Zed Head

Had a little spare time today and I made it over to Jai's to have a quick look/see as to the current issue.  I also brought along a new set of plugs. Here is list of what happend.

 

1)Visually examined the head and saw no visible cracks, leaks or obvious problems , Did not do a compression test, I did not have the time or the equipment.

 

2) Checked the radiator and it had plenty of coolant, again, no visible problems.

plenty of oil also.

 

3) Removed the old plugs and made a proper, albeit iphone photo to judge by. 

#6 on the left to #1 on the right

They are just blackened and can be easily cleaned, but I replaced them anyway. Set the gap to about .38

 

4) Jai and I then warmed up the car for about 20 min.  It started up easily and idled very well, just as Tim had set it previously. No smoke.  I felt confident enough that we then took it for a little "spirited" drive, about a mile or so.  I was driving so I pushed it a little, upwards to 4k rpm. It accelerated well with no stumbles or hiccups.  

 

However, when shifting at higher rpms there would be a little backfire between shifts. No smoke though.  When decelerating in gear at her higher rpms the backfires were more pronounced, one very loud. I saw some smoke in the mirror, seemed to be grey. pulled over. The car idled fine. smoke was gone.

Drove it back to the house and ran it a little harder.  This time, intermittent smoke, not constant, with acceleration and deceleration.  It ceased by the time we made it back.

Pulled it under it's shed, still idling fine with no stumbles. Popped the hood and reved it to about 5k a couple of times. There was some smoke, lighter in color but it more like heavy exhaust from an old Z, not a cloud at all.

Visibly checked the engine and head again, nothing obvious.

 

5) Removed the new plugs to reset the gap to about .34.

I didn't have time to make a photo so I will describe them from what memory I have. Jai wrote it down as I pulled them, maybe she can correct me.

 

#6 was black. dry

#5 was a little less black, dry

#4 was blackened and wet

#3 same as 4

#2 I think was a little wet

#1 was black and I think dry 

 

6) Time was up and I had to leave.

 

It probably is running rich.  That being said. IMO, I want to think that the problems she had before are not related to this one. The car runs much better, especially after the new AFM.

I also want to think that maybe she got a bad tank of gas?  That hasn't happened to me in quite a while but I do remember the symptoms being the same. I do think the car is driveable, only locally, until she runs that tank out and/or uses the products SteveJ mentioned to help remove whatever else is in there.  

 

 

Why not .44 gap which is what it calls for? Does it depend on plug type? NGK calls for .44 gap BP6ES11/B6ES11

Edited November 4, 20159 yr by rcb280z

Gwri8

Thanks for your effort. I think you're right about the gas. Hopefully RB is going to be reliable now. Is the potentiometer add-on the best method of leaning it out a bit? Temporarily, will keeping the revs up keep it clean enough to not foul plugs? In your opinion.

Thank you Greg, for coming to replace the plugs, plus the total looking over RB to check for anything else. She says thanks too!

Your remembrance of the spark plugs was almost right. Here is what I wrote down.

#6...was black, dry.

#5...was a little less black, dry.

#4...was black, wet.

#3...was black, a little wet.

#2...was black, dry.

#1...was black, wet.

So glad to see your Mistress with her fresh green paint. Oooo, she is beautiful. Post a photo soon for all to see.

Thank you again,

Jai

She has a 76 with the lower energy ignition system.  You might be thinking of 78 and on.  Spec. for 76 is actually .031 - .035" so it was on the high end.

 

I looked back through the original thread but can't find anything about miles on the engine.  My 76 had high miles and worn valve seals and burned some oil at high RPM.  Those plugs seem pretty black and the fact the engine ran very well but you still ended up with black, wet plugs, after just a few miles with the new plugs seems to indicate some oil leakage in tot he cylinders.

 

I can't recall much at all either, about the general state of the car when received.  Maybe it's a high mile car that sat, or a low mile car that sat, or a high mile car that was a daily driver.  The first two could cause a little rust in the cylinders that might wear in to shape, the last would mean it just is the way it is.

 

Someone mentioned Italian tune-up a while ago, I think.  Maybe it just needs some good road runs to settle down.  The daily warm-ups and mail box trips though, might not be enough to keep it in good shape.  They like to run.  

Why not .44 gap which is what it calls for? Does it depend on plug type? NGK calls for .44 gap BP6ES11/B6ES11

According to the FSM and the previous plugs: The gap should be 0.7 to 0.8mm (0.028 to0.031 in)