Steve Adleman

where are the instructions for rat's nest removal? the links in the FAQ's are no longer working, and I haven't been able to find anything using the search function. in fact it's difficult to find ANYTHING using the search. not sure what I'm doing wrong

diabolical1

iTrader: (3)

here's one: https://www.rx7club.com/1st-generati...4-rx7-1139690/

there's a link to a pdf file in it.

Steve Adleman

thanks, looks like I maybe shouldn't do it yet,until i get the car running right. I'm just trying to simplify the vacuum system so I can figure out why it won't run after the choke opens. checked compression today and all the chambers were more or less equal which was good to see, all hoses seem to be in good shape, but the vacuum system is complex enough that it's not apparent where the problem is, or if I'm even looking in the right direction. what's next replace all the hoses?, I have a vacuum gauge and checked all the diaphragms and they hold vacuum, I'll try spraying with starting fluid next. could it be a problem further back in the carb?

mazdaverx713b

iTrader: (91)

If you are having issues with the car running properly, eliminating the rats nest will not help matters. In fact, I feel its much easier to diagnose issues with the rats nest in place. The engines seem to run great with the rats nest as it was what Mazda intended be in place for multiple reasons. Cold start timing advance and throttle up operation when load is placed on the engine with the a.c. switched on to name two good ones. There is no need to simplify the vacuum system as it helps control cold start timing, deceleration control, helps eliminate backfiring under closed throttle conditions. The solenoids and vacuum lines work together with the ecu to help the engine to run well and to be more fuel efficient. It will net you zero power gains and can cause frustration if it does not run well after the removal. Some people love it and have had great luck with it. I did it once and was not happy with the results so I reinstalled everything and the engine was easier to start, ran smoother on deceleration, and fuel mileage went back to normal.

The first thing I would do is replace all of the vacuum lines if you feel a leak may be present. This should be done as preventative maintenance anyways. When was the carb rebuilt last? If never and depending on the year, the carb could be 41 years old and likely in dire need for a rebuild. How are the plugs, wires, cap, and rotor? Do the coils pass a resistance check? Have you looked at the fuel filter to ensure its not clogged? Are you picking up sediment from the tank?

These are the things to look at first.

Steve Adleman

carb just rebuilt, new fuel pump/filter. carb is getting fuel. wires, cap, rotor, plugs are 2 years old but have 0 miles on them .motor starts, but won't run as soon the choke releases. the reason I was going to delete the rats nest is because the A/C and anti afterburn solenoids have broken ports, so
I would need to replace them., but have sealed them for now. . are the rats nest/afterburn solenoids essentially all the same? or do they have different electrical properties? it's a bone stock 79 sa, so the rats nest only has 2 solenoids.+anti afterburn on carb. do I need to replace them with solenoids that match the color? or are they interchangeable? haven't checked the coils, but it fires good cold, so I would think that's not a problem, compression seemed ok. just wish I had an expert available here in western illinois (small town) like I did in ChampaignUrbana..

KansasCityREPU

iTrader: (9)

If it runs while the choke is out, that tells me that either the car has low compression, big vacuum leak, or the idle circuit needs adjusting.

ry starting the car with the choke out and then place your foot on the gas pedal to maintain the RPMs while pushing the choke in. Does it still run?

Steve Adleman

thanks, I'll try this today

Steve Adleman

it does run keeping the revs up with the gas, it seemed to run smoother when i sprayed starting fluid at the drivers side of the carb, so I guess I should be looking for leaks again there,even though I pulled each hose which seemed tight, inspected them, and used a vacuum gauge to confirm they were air tight. it's. easy enough to replace all the hoses, but I'm wondering if it might be the carb gasket or something else

KansasCityREPU

iTrader: (9)

Might want to do a compression test now.

Steve Adleman

did one yesterday w my new $30 harbor freight compression tester, read about 75 on all chambers

79 12a 22000 miles on original motor, but wasn't maintained too well, then sat for the last ten years

mazdaverx713b

iTrader: (91)

You'll want to do a compression test with a proper rotary compression tester. You can get one at www.rotarycompressiontester.com. Steve is a great guy to work with. Best tool I've bought in years!

You may want to check the carb spacer. It has a gasket thats built into the spacer and should not be removed and replaced. I've seen people attempt to remove them and they end up ruining the spacer plate. Can you confirm yours has not been altered??

Where is the fuel level sitting at in the bowls? You should be able to see it in the front sight glass. Should be half way up or a little more.

Steve Adleman

thanks, I'm not really interested in buying a $250 tool for a one-time use, I'd rather pay someone to do it, if necessary, not sure that it is. the money would be better spent on parts, etc.
Is the carb spacer attached to the tray that sits under the carb with all the vacuum ports? if so I haven't removed it, but It's difficult to see how it attaches, or to see under it because of the tray
also very hard to see where the fuel is on the sight glasses not sure if its all the way up or not at all, but it doesn't look halfway.
the car has had very little work done to it ever, the owner bought it new, drove the hell out if it for 20,000 miles then let it sit for 10 years

mazdaverx713b

iTrader: (91)

The carb spacer is the part with the vacuum ports. Theres an upper and lower gasket built into its. If the gasket is compromised, there's a good chance of a vacuum leak at that point.

As for the tool, I see your point. But it does pay for itself after two uses if you ever do decide you don't want to pay someone to compression test your engine on this car or another in the future. If you were closer, I'd run the test for you for free with my rotary compression tester. For me, owning 8 rotary powered cars, its a necessary tool.

Seeing the fuel level in the sight glass can be difficult. You may have to shake the car while looking with a light to get the fuel to move in the bowl in order to see it.

Steve Adleman

that;s exactly what I just did, shook the car and could see that the front bowl was high, just past the glass, and the back bowl was low, around the bottom of the glass. my mechanic here (who has been great with my ford and had rebuilt rotaries before) had the car for 2 1/2 months puttering around with it. he may have adjusted the floats, or bumped them when he checked the carb or I guess they could be stuck too,. when I got it back from him I could see that he'd made a few other mistakes with it so, I won't be letting him touch it again. I guess I should try tapping the carb one more time, but probably need to open it up again

I also found a used rats nest on Facebook marketplace

mazdaverx713b

iTrader: (91)

It wouldn't hurt to go through the carb in my opinion. I would just want to know its been rebuilt properly. The float level does not always need to be altered. In fact there are some guys that advise to never adjust it from its original setting. Over the years I have found them way out of spec from previous repair attempts and have adjusted them within spec with my micrometer.

Also, the rats nest itself is likely ok. You can go through and test each solenoid if you suspect one has failed.

Steve Adleman

I plan on opening it up, when I rebuilt it the floats were almost perfect, but they must have been bumped/adjusted since then. the A/c and anti afterburn solenoids both have broken ports where the hoses attach, so need to be replaced. I tried gluing them, but I think the glue blocked the opening.
just wondering if all the solenoids are electrically/functionally equivalent or if the color code means they cant be interchanged

mazdaverx713b

iTrader: (91)

I believe the solenoids are interchangeable. The color code them for assembly purposes because some on the rack are identical. Just a bonus for us 30 plus years later that the stickers are still attached. You should be able to apply source voltage and a ground to the pins on the solenoid and hear the solenoid click to verify operation.

Steve Adleman

I had another carb that I got from salvage yard on car-parts.com that I was in the middle of rebuilding anyway, so I finished that and swapped it with the original that I've been messing with for months now, it ran better as soon as I started it, but was still rough, the front float bowl was low, but eventually it filled to halfway and it's running much smoother now, it still won't idle, but I think it just needs to have the idle speed and mixture screws adjusted. I opened the orig carb and adjusted the floats and made sure everything else was right, but I'm going to leave the salvage carb on there for now and maybe test the original later on

Steve Adleman

carb adjusted and Idling smooth at about 1000 rpm, drove it around and it ran pretty good, but got weird above 4000 rpm when I tried to wind it out, but this is the best it's run so far since I've had it.

mazdaverx713b

iTrader: (91)

Glad to hear that you're making progress!! As for the 4000rpm issue, what's it currently doing or not doing?

Steve Adleman

above 4000rpm it seems to miss or "cut out" not sure how to describe it properly. I'm thinking maybe fuel starvation or a timing problem? maybe the secondary isn't opening? IDK

diabolical1

iTrader: (3)

glad to see you're making at least some headway. timing is a simple check. however, i would start with the secondaries.

Steve Adleman

I couldn't find the timing marks, the pulley is pretty crusty, I'll need to clean it up, but I just moved the distributor to the center of it's travel ( that's where my '84 always used to sit) and it ran better above 4K

Steve Adleman

the story continues in the 1st gen forum under the title: 79 SA runs good/runs bad...seems like at this point the problem is with the gas tank and pick up tube being clogged with gunk. so i'm draining/dropping/cleaning/sealing the tank this weekend

mazdaverx713b

iTrader: (91)

That's an absolute must. I fond that many running issues with these cars is attributed to a bad or dirty fuel tank. A dirty tank will cause all sorts of running issues. Very good idea tor emote the tank and have it professionally cleaned.