We have a 1980 Mazda Familiar 1300 (did they make them that long ago?) which has been going very well for years. Recently it has been stalling at under 1500rpm. The car goes fine above that speed, but if I lift the throttle slowly it dies immediately it reduces to 1500rpm.
I have stripped and cleaned the carburettor, and all jets were clean and not blocked. The petrol level can be seen in a clear window in the side of the carb, and it reaches half way up the window, so there is petrol. (Is that height correct?) I have replaced the petrol filter and put in new spark plugs and cleaned all the electrics. There is a spark at all plugs. I've sprayed carburettor cleaner around all the gaskets and there appears to be no air being sucked in past them. I have tried advancing or retarding the ignition.
Then the problem got worse and it would stall at under 1700rpm. Now the engine scarcely starts at all and we've ended up towing it home.
There are way too many rubber hoses around that do unknown things, and there's a couple of wires connected to the carburettor that have an unknown purpose. It makes no difference whether these are connected or not.
Does anyone have any ideas what to do next? The car's needed urgently for someone to go to work with.
I'd suspect maybe the idle fuel jet in the carb isn't working, and you're only getting enough fuel when the throttle is open and the main jets are putting out..
Yes that was my first suspicion, although I've cleaned all the jets.
There are about 7 jets from memory and I'm not sure which one is the idle jet. I'll try to look at a workshop manual if I can find one, which will probably take me all day without a car.
Gee that sounds like a challenge. I have now obtained a workshop manual for the car and it tells me that the wires connected to the Hitachi carburettor are for the fuel cut-off solenoid valve. Testing that shows a bad connection at the connecting plug. That will do for a start, although it doesn't explain the original problem where the engine ran only above 1500rpm.
The level doesn't drop. I am mystified why the manual doesn't show the correct height of fuel in the window (which is really easy to see) but instead specifies the distance (11mm) from the top of the float to the joint at the top of the carb.
In the original problem the engine cut out the instant the revs dropped below 1500rpm, but ran perfectly well above that speed.
In my car's case, when the problem started happening after I was attending to an unrelated problem, I found it was caused by a blown fuse. I don't know why, but it fixed the problem instantly. As in your case, the car would immediately stall when the accelerator was released. Check all fuses.
Sounds like you've got the same carb as on the '82 626, which wouldn't be much of a surprise, since they hung pretty much the same carb on everything from the Ford Courier (actually a Mazda in everything but nameplate) to the 626 between '79 and '83 - in the case of the 626, the courier engine was COMPLETELY interchangable. At any rate, the "frame" around the "window" into the carb has two horizontal "nicks" in it at either end, an imaginary line between them denotes the proper fuel level in the float bowl. That level is so close to "halfway up the window" that *I* can't tell the difference by eyeballing when the engine is running, although in the factory manual for this beast, it's claimed that it isn't actually half of the window being covered. For an "eyeball measurement", on an engine that's probably vibrating at least somewhat, in an awkward position, "halfway up the window" is close enough. We're not talking about needing to measure to an accuracy of .0001mm here... You just need to be "in the ballpark".
The fuel-cut valve that you mentioned elsewhere is a likely target. Check the bleed solenoid (the other wire) while you've got the meter handy. And look at the sending unit/wiring that controls each of them.
Other places to look: Distributor: Is it bolted down solidly? If not, make it so! Mine had the lockdown bolt back out a little more than half a turn, and that was enough to allow the distributor body to turn with increases/decreases in RPMs, which threw the timing clean out the window, and almost got me killed one night - "tromp on it" meant "hesitate, lug down, try really hard to die, now Sllllllllllllooooooooowly spin up to something that resembles proper speed" - And there I was, stopped dead in the middle of the lane after backing out of a driveway, only to see the lights of a semi rounding the corner about 100 yards behind me at high speed. I got it to the side of the road that time... SOMEHOW. Needed a new pair of undies afterwards, but...
Plugs/wires: New plugs is good, but I didn't see any mention of new WIRES. Skanky old wires (This car was a 300 dollar beater-mobile that had problems when I got it, and I was gradually fixing each one as it was discovered/became critical) were *SOMETIMES* (when vibration moved them into position) arcing to the exhaust manifold, causing misses and rough idling. New wires didn't clear the problem completely, until I got stopped on the side of the raod one day and figured out that I'd gotten the BOOT on two plugs seated well, but apparently hadn't gotten the CLIP inside the boot to click into place properly. Once I had good solid contact with the plugs, the problem was resolved. That one became obvious when both plug wires vibrated off their plugs - hard to miss the symptoms of a
4-cylinder engine only running on #1 and #4!
Vacuum lines: Check 'em for cracks/holes/blockages. A half-inch long crack that only leaked when "in use" was responsible for a month and a half of trying to find the reason the car couldn't meet emissions-testing standards (critical here in California). Replacing that one lousy hose was all it took to bring the car back into spec and get a passing result. The problem was *FINDING IT* to replace it. The crack was on the "under and behind" section of the hose, so wasn't visibly obvious, and required an actual "OK, let's pull THIS hose off and put in a known good length of hose - Nope, that didn't change anything. Put the old one back and let's try THIS hose..." process to pin it down.
Those Mazda engines are TOUGH - Keep 'em full of oil, and keep the radiator topped up, and they'll run practically forever. Keep 'em in adjustment (not particularly hard) and they'll run *WELL* practically forever. That's why when my white one got crashed out, I went looking for another '82 626. Sure, I could've gotten something newer, or snazzier, or whatever, but then, I wouldn't be driving a car that I
*KNOW* I can count on to start, first time, every time, no matter what. Since I drive it to put food on my table, that's an absolutely critical requirement - Car don't run, I don't make money.
No there are no marks of any kind. I've looked with a magnifying glass. But I am satisfied that the level is correct when it's half way up the circular window.
It seems to be working perfectly, and I've tried removing the part that closes the valve, to no effect.
The distributor seems OK. Remember the engine works perfectly above
1500rpm. I have tried advancing or retarding to no effect on making it go at low speed.
Yes there are skanky old wires. However if I lay the 4 spark plugs on top of the engine, I can see a spark to each of them as the engine is cranked. And the car climbs hills etc fine at above 1500rpm.
The vacuum lines look fine, but there certainly are a lot of them - around 17, all carefully labelled and in the right place. What is this thing, the space station? There is a row of 4 solenoid controlled vacuum lines that don't seem to belong to a car as early as this according to the manual.
The problem with this car is that it's worth about $300 and we've spent over $100 so far with no effect. A mechanic, with better test gear than I have, would cost more than the car is worth. But if it comes to that I'll get one. I just have this feeling that the problem is something simple, and no problem has beaten me yet after 40 years of fixing old cars.
It's my son's first car and he's learned a lot about fixing it so far, even replacing the head gasket, doing a valve grind, fixing the steering, brakes, suspension. I could buy him a new BMW out of my bank account, but I think that would be bad for him.
Circular window? Oops. Wrong carb! My info may or may not be right. But at a guess, I'd say having the bowl half full should be on target no matter what shape the window.
Ehhh... OK, I can go with that. But don't COMPLETELY write 'em off as innocent just yet.
Same sort of plumbing, including the solenoids, is on the '79-'82 626 engines. Vacuum lines EVERYWHERE. It's all about emissions. Without the catalytic converters (yes, plural - there are two of them) and the air-injection system, they're NASTY dirty little engines. With the emissions gear, even though it's complex to look at and mess with, they're tidy citizens.
One thing you can say about Mazda: They find something that works, they tend to stick with it. The vacuum-controlled emission-control system is a prime example.
I like the attitude :)
You better believe it. Much as he may talk he wants that beemer, I guarantee he's better off with "old reliable".
You've definitely got yourself a stumper going on here, guy... I'm sitting here scratching my head and wondering what it is that's causing the problem.
How does it die? Does it seem like it lacks fuel? Or like it has fuel, but just can't get it fired? If you mentioned it, I wasn't paying attention - stick or automatic? Could a dud clutch or torque converter be dragging it down?
It's a manual transmission. The original problem was that the engine would start fine but if the speed was reduced down slowly to precisely 1500rpm it would immediately die. After removing and checking all the jets in the carburettor, and cleaning the distributor and putting in new plugs, it would then die precisely below 1700rpm.
Clearly there is some speed related gadget that is getting in the way. There is a row of 4 small valves with wires and vacuum tubes on them which look rather like the "shutter valve control system" which is fitted on B3 and B5 engines "to improve combustion efficiency and decrease engine noise". This is not supposed to be present for the E engine or the Hitachi carburettor which we have.
Now it won't start at all. The plugs have fuel on them and I suspect that somehow the spark is disappearing at times. Yesterday I noted that sometimes there was a good spark and sometimes there was no spark.
I have here a Hawk engine analyzer which has no manual for it so I don't know whether it's suitable for electronic ignition, or how to connect the three wires it has.
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