Checked the "Car Won't Start" Sticky - Nada

Norm K · 03-06-2013, 04:20 PM

Started my car (`80 930) this afternoon so I could adjust the AFRs a bit. They were in the 10s at cold idle and would move to mid 13s at warm idle. Cruise was high 13s & dropped to 10s at WOT. Figured I'd start by moving the cold idle up a bit and hoped to see mid 14s at idle.

Put the 3mm allen in place but pushed down a farther than intended and the car died. Pushed it down again, to remind myself of the "feel" of how much force I needed to depress it just enough to catch, but no so far as to kill it. When I pushed down this second time I heard a sucking sound (from the flapper, I presume). When I went to start the engine to resume the adjustment ... no joy. The engine turns over strong and there's spark present but there's not even a hint of the engine firing.

I'm going to go do what maybe I should've done before I started typing this, and see if the flapper is stuck.

What else should I be looking at?

mark houghton · 03-06-2013, 04:39 PM

Hmmm.....that's weird (I know that helps a lot!). Was the engine running when you pushed it down the second time, or was the sucking just the sound of the flapper moving down (as though you went too far again).

Forcing the metering plate arm down that small amount should not cause starting problems later. All it does is make an overly rich condition, which you already discovered in the first go-round when the engine died.

Might be the micro switch that connects the motion of the arm to activate the fuel pumps, though I don't think I've heard of anyone experiencing that switch failure. Pull the blue electrical plug from the back of the fuel head to force the pumps to run with the ignition turned to 'on'. You should hear them running...then, crank her over and see if she starts. If the pumps don't run with pulling the plug, then we've got other stuff to look at.

mooney265 · mooney265's Garage

I wonder if somehow you've jammed the adjustment screw in the down position. Therefore causing fuel to constantly flow into the cylinder heads?

Just make sure the adjustment screw is nice and "springy" - - maybe 3/4" movement freely...

Norm K · 03-06-2013, 04:56 PM

Well, you can belay my last.

Earlier, when I went to pull the allen out of the adjustment screw it got hung up a little. Apparently, in my efforts to (gently) work it free, I somehow depressed and turned the screw and created a pig-rich condition. Moved it back toward lean a bit at a time, turning the engine over after each movement and eventually it fired up.

Let it warm up and set it so the AFRs are fluctuating between 14.3 and 14.6. The War Department's car has the 930 blocked in and I was to lazy to move it (she'd want me to put it back, after all) so I haven't taken the 930 out to check cruise and WOT readings, but I'm sure feeling better (if a bit sheepish, after admitting my silly error here) than I was an hour ago.

mark houghton · 03-06-2013, 06:45 PM

Well now, that was easy. Glad that's all it was. Live and learn....and learn some more. It never stops.

jsveb · jsveb's Garage

Have you set your idle at mid 14s?

I believe that is a bit too lean. Shouldn't it be more like 13.5?

Glad you got it solved.

Richard930 · Richard930's Garage

Quote:

Originally Posted by nkowi

Started my car (`80 930) this afternoon so I could adjust the AFRs a bit. They were in the 10s at cold idle and would move to mid 13s at warm idle. Cruise was high 13s & dropped to 10s at WOT. Figured I'd start by moving the cold idle up a bit and hoped to see mid 14s at idle.

Put the 3mm allen in place but pushed down a farther than intended and the car died. Pushed it down again, to remind myself of the "feel" of how much force I needed to depress it just enough to catch, but no so far as to kill it. When I pushed down this second time I heard a sucking sound (from the flapper, I presume). When I went to start the engine to resume the adjustment ... no joy. The engine turns over strong and there's spark present but there's not even a hint of the engine firing.

I'm going to go do what maybe I should've done before I started typing this, and see if the flapper is stuck.

What else should I be looking at?

Curious as to why you think you needed to adjust it in the first place? Consensus seems to be 13.5 is a good point for idle, and unless you have an adjustable WUR you're stuck with whatever the WUR then gives you for cold start, WOT/full boost, and cruise.

mooney265 · mooney265's Garage

+1 on this...

Quote:

Originally Posted by jsveb

Have you set your idle at mid 14s?

I believe that is a bit too lean. Shouldn't it be more like 13.5?

Glad you got it solved.

Norm K · 03-07-2013, 12:24 PM

I had it a 13.5 and it seemed to idle and run well there. Couldn't keep it out of the 10s on boost though so I was hoping that leaning it out a bit at idle would help. I have a newly built Leask WUR but have left it alone for the time being because so many folks here say that he typically gets it spot-on (provided him my upgrades, elevation etc before he built it) right out of the box. Frankly, I'd rather have left it at 13.5 warm idle and (as I recall) mid-high 14s at cruise but I was concerned about the overly rich condition at WOT.

Looks like I might have to make some WUR adjustments after all?

mark houghton · 01:17 PM

Adjusting the idle mixture via the screw will have a large impact on idle AFR's and only a slight impact on the cruise AFR's, and virtually no impact on the boost AFR's. So I would leave your idle at 13.5'ish and do any other fine tuning with the WUR adjustments.

Do you also have the boost enrichment delay solenoid that Brian sells with his adjustable WUR's? That little unit is rpm activated and will not allow the boost enrichment portion of the WUR to activate (it won't receive a boost signal) until the solenoid opens at your set rpm. Especially usefull for turbos that have earlier boost thresholds, so you're not dumping extra fuel in there sooner than the engine can consume it.

Norm K · 03-07-2013, 02:16 PM

Quote:

Originally Posted by mark houghton

Do you also have the boost enrichment delay solenoid that Brian sells with his adjustable WUR's? That little unit is rpm activated and will not allow the boost enrichment portion of the WUR to activate (it won't receive a boost signal) until the solenoid opens at your set rpm. Especially usefull for turbos that have earlier boost thresholds, so you're not dumping extra fuel in there sooner than the engine can consume it.

I don't have it. Brian actually recommended against getting the solenoid for my level of build. Not that there was any negative (other than cost) in having one, he just figured I wouldn't need it.