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Ashyukun
09-10-2011, 10:34 AM
This last week, the weather here went from very hot and moderately humid to cooler and near-constant rain for several days. When I took 16655 out Tuesday morning after it had sat out for the evening in the rain, I had the same problems that I'd encountered driving it through the torrential rain in the mountains coming back from the East coast a few months back- past a certain point in the throttle/RPM range it would fight going any faster really hard, bucking a fair bit in the process. After fiddling with things a bit, I was able to get to my first destination (getting donuts) and after I started it back up after that stop, it behaved properly.

Through looking things over and process of elimination coupled with the fact that it hasn't wanted to shut down cleanly a few times since the weather got cooler and wetter, I've settled on thinking that the linkages on the carb are sticking/not moving properly, leading to the engine not getting enough/getting too much air/fuel. Looking at my carb, it's not wholly surprising that it might have some issues- my car tends to sit outside most of the time and not protected in a garage, and it's really not been off the car or had anything more major than adjusting the feed screws to change the idle done in the year and a half or so since I installed it.

I figure it's due for some cleaning up and lubricating- but as this is the first carb I've had to work with I could use some pointers/suggestions on exactly what I should be doing.... Thanks!

content22207
09-10-2011, 10:54 AM
I suspect your problem is electrical, especially since it only happens in the rain -- most likely ignition.

Your Motorcraft 2100 uses nothing but air flow alone to not only meter fuel, but also switch between idle and throttle circuits:
5030 5027 5032 5033 5026 5031 5028 5029

You've only got two rods: one connects the choke plate to the choke mechanism, and the other activates the accelerator pump. A choke plate not opening will cause a warm engine to bog down at fuller throttle -- simply take the top off your air cleaner and look at it: if it's open, your choke plate is operating normally. A problem with the accelerator pump will cause momentary hesitation or stumble when the throttle plates are first opened, until fuel catches up to the increased air flow, but that only lasts for an instant.

If you've turned the screw that presses against the throttle linkage too far, your throttle plates will still be open when the engine is shut off, advancing ignition (the edge of the driver side throttle plate is the on/off switch for ported vacuum) and causing fuel to be drafted through the venturis rather than the idle circuit. The combined effect is indeed a hard shutoff.

Bill Robertson
#5939

Two more short little rods:
1) Connects the choke pulloff diaphragm to the choke mechanism. If your choke plate is cracking open, it's fine.
2) Fat one that connects the choke mechanism to the fast idle cam. If you've got fast idle, it's fine.

Bill Robertson
#5939

Ron
09-10-2011, 12:49 PM
I agree with Bill on the moisture probably causing an ignition problem. Since it is intermittent, you might also check your fuel filter(s). If it is about to clog up, the vehicle can start and run fine until you put a good load on the engine. (The fuel in the bowl can get too low causing the engine to bogg and use less fuel, as it slows, the fuel can catch up resulting in a surge of power, often several times over...classic symptom. ) You can do a fairly good no tool test by winding the engine fairly tight as you go through the gears. If it boggs down, keep on the gas and see if it surges or bucks (get off the gas if it bucks since it is hard on the vehicle, of coarse). If it does either, highly suspect the filter(s) or pump strainer (~maybe float). This can be intermittent as well, but once it does it, you can usually duplicate the symptom several times over until you shut it off (...trash can settle in tank or back down the fuel line before the filter if it can't trap it).

If you still have a problem with shut off after you have insured the plates are free to close, suspect the timing being too high, especially if it has been moved recently...vacuum controls/leaks next.
I doubt the linkage would cause the engine not getting enough fuel when it comes to the symptoms you described....

The 2100 is about bomb proof once it is set up right. You shouldn't have to do anything but hit it with some carb cleaner. ...most lubricants will cause dirt to collect doing more harm than good on its linkage....

Happy carbing!

content22207
09-10-2011, 02:18 PM
Hang on -- the needle on the Suck-O-Meter is quivering. It's too soon to get a definitive reading yet, but if the needle does move in the right direction we may be able to continue using the current gauge rather than buying a bigger one.

Bill Robertson
#5939

Ron
09-10-2011, 08:13 PM
After this post, you might as well get two because yours is about worn out and about to explode again...maybe you can get a quantity discount? :fu:

content22207
09-10-2011, 08:16 PM
Didn't you see? The "Bill Sucks" thread disappeared -- prima facie evidence that I don't suck.

Bill Robertson
#5939

Ron
09-10-2011, 10:43 PM
:bootyshake: . . . :dork: You did it again!...I don't know which to respond with:

1. "Do I really have to say it?"
2. "So, now you just blow?"
3. Further investigation has reveled the evil overlord of alternative DeLorean fuel delivery did it and is currently working on this thread.

And no, I didn't see it because I wanted nothing to do with you grabbing your ankles in a crumpled tube thread.

content22207
09-10-2011, 11:02 PM
Oh dear, does anyone know where I can buy an industrial size Suck-O-Meter? Ron just blew the back off my handyman model.

Bill Robertson
#5939

Farrar
09-12-2011, 12:34 PM
3½" gauge face (http://www.amazon.com/Equus-3620-Vacuum-Gauge/dp/B000EW0KPY).

Farrar

Canon20DFan
09-12-2011, 02:30 PM
Switch to K-Jet and your carb problems go away!

sean
09-12-2011, 02:42 PM
Switch to K-Jet and your carb problems go away!
Wilson for the win!

stevedmc
09-12-2011, 02:44 PM
Switch to K-Jet and your carb problems go away!

What are you talking about? That little Motorcraft 2100 is way more reliable than K-Jet and possibly more reliable than EFI.

sean
09-12-2011, 02:58 PM
While this is a carb thread, the bickering can be taken here if you really need to continue the "mine is better" exchanges:
http://dmctalk.org/showthread.php?95-Ask-Bill-about-carbing-a-DeLorean-and-other-K-Jet-Carb-tangets

Ashyukun
09-17-2011, 11:17 AM
Sorry for the long lead in getting back to this thread, but it's been a nice enough week that I've been able to bike instead of drive much of it, and I've also been very occupied otherwise.

However, last night on my way to practice (have to drive, can't safely carry all my gear on my bike...) I think I found what the problem actually is. I had largely discounted it being an electrical problem just on how it felt- the way it felt and sounded, it seemed far more likely that the problem was that the engine wasn't breathing properly than something electrical. I had assumed the issue was on the much more complex (comparatively) 'front-end' of the system with the carb- but when the engine started behaving even worse than before on the drive to practice last night and I pulled over and took a look at the engine to try and figure it out, I found that the back half of the catalytic converter was glowing red hot.

So, it seems far more likely that the cat is clogging intermittently and causing the engine to not be able to 'exhale' properly. The annoying thing with this is that I HAVE everything necessary to fix this (read: Hervey's headers/muffler setup)- it's just that I've been completely unable to find a shop or person with the equipment to do exhaust work that will do the work- either because most shops won't touch if if you're removing a system with a cat in it and putting back one without or because the 'smaller' places are scared of damaging something on the car and won't touch it.

content22207
09-17-2011, 02:59 PM
John Marconi is still running a single converter with his conversion. Of course he is HEI as well, which arguably gives him more complete combustion than stock ignition.

Bill Robertson
#5939


I've been completely unable to find a shop or person with the equipment to do exhaust work that will do the work- either because most shops won't touch if if you're removing a system with a cat in it and putting back one without or because the 'smaller' places are scared of damaging something on the car and won't touch it.

Buy a couple of $20 converters off eBay and have a shop install them in lieu of the mufflers. If anyone asks, tell them you are going to modify the muffler at home to fit the new system. Converters are about as quiet as mufflers, so the drive home won't be unpleasant at all.

Bill Robertson
#5939

Ashyukun
09-27-2011, 11:50 AM
*sigh* Well, I'm kind of back to square one on this.

I had the car at a shop taking a look at the exhaust and whether they'd be willing to take a crack at it (no- they're scared of breaking the manifold studs), and through his looking at it said that he was pretty certain that the the problem wasn't a clogged cat- meaning that the issue was on the other end of the system with the carb.

I'm not wholly convinced that there isn't something weird with the ignition/electrical system- but I did take a closer look at the carb to check something I had noticed before and set up to see if it continued- and there is fuel coating the shaft that the throttle plates are on outside of the body of the carb, and down onto the linkages that attach to it (lower part of the throttle linkage, lower part of the choke linkages). I'm 99.9% certain that's not normal. It's not leaking from the fuel line connection, and appears to be coming from the shaft itself.

I'm not wholly certain there isn't also something of an issue with the electrical side of things- there's an odd issue with the washer fluid pump/switch and the wiper switch that I need to resolve, but I don't see how it would be causing ignition problems- but these problems first manifested both times when I had the wipers running in the rain, and I need to resolve them anyway, so...

Farrar
09-27-2011, 04:30 PM
I have a different fuel leak -- I will take pictures and post them here in case anyone has any ideas.

Farrar

Ashyukun
09-27-2011, 11:13 PM
OK, got some pictures this evening. They're not the best, but will at least let me point out where I'm seeing the fuel. Don't bother noting, "Hey, it looks like your bowl cover is loose!", I know, I was checking that everything was working properly with the float (and pulling the gasket so I can get a new one).

The RHS, where the fuel was most noticeable, is annotated- the other side it was difficult to get a good shot of the other side of the throttle plate linkage...
5556

sean
09-28-2011, 07:49 AM
How old is this carb setup and was it new when you installed? There seems to be a lot of surface rust on the fasteners and brackets.

Ashyukun
09-28-2011, 09:23 AM
How old is this carb setup and was it new when you installed? There seems to be a lot of surface rust on the fasteners and brackets.
The carb is, I believe, a reman. Bill ran it for a little while on his car after the manifold was first finished to tune it since mine was the first of the newer dual-plane manifolds. I got it about 15 months or so ago (a month or so before DCS). My car has lived outside much of the time though, since my RX-7 has much of that time been immobile and in the garage.