Tim one minute you're the Devil, next minute you're playing Angel on me. White One MPG's would be nice, for sure. What'd you say you were getting with that Del Horto?

Now the bad news. Turns out the low fuel level condition was caused by some technician (probably me) who forgot to plug the fuel pump back in after looking for places to hot wire it for the test during the thunder storm yesterday afternoon (which you don't need to do anyway, see below).

So I plugged it in and viola!: Gas

Put a Listerine bottle under the delivery hose and turned the key for 15 seconds.

0.3 liters in 15 seconds, probably could have hosed it 12 feet if I tried. Front and back float levels looking just like they should, fuel half way up the windows. That pump is looking pretty good.

Back to looking for vacuum leaks.

 

Here's some videos. HELP!

http://www.youtube.com/watch?v=RI7Cxk8JqlE

http://www.youtube.com/watch?v=1lymqo_77WU

http://www.youtube.com/watch?v=4t-Zn02_CH8

Any inclues would be greatly appreciated and awarded with beer and women.

 

Are the leading and trailing plugs connected properly? Just a stab in the dark, but with a promise of beer and women I am willing to offer any advice possible.

 

Ray if you have a few different carbs then I'd put another one on. If you still have the problem then you know its not a carb problem. If it goes away then something went wrong with the rebuilt.

 

Ray, it looks to me like your choke butterfly is closed when the engine is running. what did the plugs look like when you pulled them? compression sounds good! do you still have the acv? when the acv went bad in my 88 TII, it prevented the turbo form making full boost and made the throttle response sluggish and the engine struggled to idle.

 

Mike I have a spare carb but I still need to put it together, it's soaking in carb cleaner right now. It's worth a try, I want to have that second one on the shelf for a backup, so when I get it done I can swap it in, probably in the next day or two.

Still, I'm beginning to think this has nothing to do with the carb and it never did. At this point I'm wondering if something is wrong with the intake manifold.

Dave the ACV has been removed and block off plates have been installed, the regular Mazdatrix ones. They look alright but maybe one of them or some other seal in the manifold is bad.

In the video the choke butterfly is closed because the engine was still cold and the choke was engaged. You can see the choke butterfly open a bit when the accelerator is pressed, as it's supposed to. If I bring the engine to running temp the choke opens normally but the stall problem is just as bad.

After work today I plan to remove the carb and have a closer look at both the carb and intake manifold.

After that, if I can't find it, on to the rat's nest!

Again thanks for the suggestions guys.

 

OK, I took out the carb and inspected the intake manifold, unfortunately every thing looks fine down there.

I'll double check the Nikki tomorrow, with some daylight. But I'm sure it's fine.

Help me out guys, I'm running out of ideas.

 

take off the ACV cover plate and reseal it, i doubt its a problem, but its easy.

i'd also put the carb on and run it with no vacuum lines hooked up, ie bypass the vacuum rack.

 

Agreed. I was just about to post this, so I'll post it now. Completely block/disable the rat's nest during troubleshooting.

 

A problem in the rat's nest is something I've worried about, that would be hard to find - the diagnostic section for the nest goes on for thirty pages in the FSM - I figure about 8 hours work with skills and tools I don't have.

I will disable it and see if that helps, thanks J9 and Jeff!

 

Heres a radical idea. Get rid of the rats nest

Good luck chasing this one down. Keep us posted.

 

Too radical for me Tim, I need the improved fuel efficiency and driveability that all those rat's give the Nikki. I tried removing the nest a couple of summers ago, after several months of poor gas mileage and lousy throttle response I put it back in with instant improvement.

Still, the nest has to be working properly to provide these advantages. Right now the big question is whether it's something in the nest that's causing the current low end stumble problem. I like Jeff and J9's suggestion of just taking the nest out of the system (temporarily, of course) to see if that corrects the problem.

I might even use my second carb to build a modified stripped Nikki (with no irreversible JB weld) that I can plug in to trouble shoot like Mike was suggesting. Then once this is all straightened out I can do some serious trials on the stripped Nikki vs the Ratty Nikki to see which really does work best for mileage and driveability.

 

bypassing the rats nest = eliminating variables. the chances of it actually being the problem are small. more likely to be intake/acv gaskets

 

I suggest not looking at the rats nest as one single item - - because it's not, it's part or all of a half-dozen different, mostly-independent systems.

The chance of the entire thing being bad (unless it's ground point has failed, first thing to check)are zero, so it's better troubleshooting practice to isolate each of the systems the nest is part of, and bypass each one individually, then test. If no change, put it back, and move to the next one.

Less chance of introducing multiple variables while trying to eliminate one, in my book.

 

Good point DD, problem is that by uninstalling, rebuilding, reinstalling and uninstalling the carb, I've already introduced enough variables to make this an infinite equation.

Besides, doing it logically takes some of the fun out of it. At the very least I'll get a bunch of rebuilt systems out of this.

A few years ago I stripped a Nikki (which is a whole lot easier than rebuilding one the right way) and put installed it without the rats nest. It worked fine, it just didn't have the sophisticated throttle response and fuel efficiency of a well adjusted dressed Nikki with a rat's nest.

So I think I'll take J9's back to basics approach, redo the intake manifold gaskets (just to be sure), disconnect the rat's nest, put a bunch of rubber nipples on everything and pop in the stripped Nikki.

Then if it's still messing up someone can pick up a really nice '85 GSL for cheap.

 

very true, its actually very simple. but um first you bypass the whole thing, as its easy. it'll either fix it or not. if bypassing the whole rack doesn't fix the problem then you do not have to go further.

if bypassing the rack does fix the problem, then you can take it one solenoid at a time, its super simple that way. i find you actually must do this on like t2's as the vacuum diagram isn't good enough, and on a turbo the vacuum rack isn't all vacuum

we are both looking at the same fault tree, we're just cutting it in different places =)

 

Hey folks, could something as simple as a leaky check valve on the fuel return line be causing these problems? I just discovered the one on the car is leaking a bit, it doesn't totally cut off air when you blow through it.

 

it could. try another one. it should not let any air through. fuel could be getting backed up in the carb... but then i feel that the sight glasses would show the fuel levels higher than normal but its worth a look.

 

Yeah, I agree Dave, not likely, I'm giving up on that idea too. But as you can see I'm getting desperate for ideas. I'll put the good check valve in when I put it back together, but I don't think that's the problem.

Right now I'm focused on two possibilities:

1) the Air Vent Solenoid - when I checked this a little while ago (with the carb off the car) it does not appear to be cutting off the vent line when the ignition is on. Maybe that's the problem. Thanks to Durwood at Japanese Motor Works in Athens GA for putting me on to this possibility. I have a good spare so I'll put that one on the current rebuild.

2) the primary emulsion chambers. On the last rebuild I didn't remove the boost venturies and clean out the emulsion chambers, instead I just flushed them really well. Not likely, but maybe there's some obstruction in the primary emulsion chambers or those little plastic nozzles are screwed up.

On this second rebuild I'm taking it down to raw metal and going over everything twice, taking nothing for granted.

Should know the results in a few days.

 

Sorry Ray this has been such a bugger....

 

Judging from your videos I would say that you have a monster vacuum leak somewhere after the carb. I had this happen to me when I ditched the rats nest/emissions junk, I had (somehow) missed capping a hole on the side of the intake manifold that is closest to the firewall, that just goes straight to the secondary or primary runner if memory servers.

I forget where the vacuum line goes and I can only see the side of the hose in your pictures so I'm not sure where its running or if you have it blocked off.

Anyways with this huge vacuum leak I had, mine was running exactly like yours is in your third video, it would start and rev up but then the revs would drop really slowly then around 2k it would stall out.

 

Yeah that hose likes to crack from exhaust heat. Ray, check that hose if you haven't yet. Block the nipple in the rear secondary runner (around 1/2" in diameter) as part of your rats nest troubleshooting.

 

I sure do agree about the massive vacuum leak, but I'll be damned if I can find it, event though it must be large enough to drive a VW through to cause all these problems.

Anyway, I'm taking J9's "back to basics" approach, I ripped everything out (including the intake manifold, now I need a new gasket, which arrives Monday) and I'm put it all back together by the book, checking over every detail.

Only difference is I want to keep the rat's I still have so I'm going though each one of these systems too while I'm at it, fixing what I can. You just have to do this every once in awhile if you want to keep rats.

So far I've found:

One bad check valve (fuel return line)

One bad air vent solenoid

One bad choke diaphragm

And a few small mistakes on the rebuild details (missing washers, etc) probably not enough to matter but nice to catch anyway.

I just finished the rebuild of the rebuild, I switched everything from the first rebuild onto another carb body that got a thorough cleaning the emulsion chambers, including the boost venturi's and those little plastic do hicky's (which I didn't do on the first rebuild):









Here's the finished, fully checked product:





You can see I don't have the air vent solenoid in there yet, I'll play with these after I get it installed.

In the meantime I'm rebuilding the second carb, quick while I still remember where everything goes.



So on Monday, when the intake manifold gasket gets here, I can start experimenting again with two carbs and a much better understanding of rats.

 

it works for me! if you give me a t2 i START with it like that....

guess what i did yesterday? i rerebuilt my weber... i know more about it now, and found a bunch of little things that could be better.

oh yeah on the vacuum rack (rats live in the air cleaner!) check the purge valve, ive seen a few bad ones

 

So Ray whats the word? I know your getting some stuff today. Good luck.