Hey guys, new to the slant 6 and new to the forum. Thanks for the add.

Anyways, I just bought a beautiful 1983 Dodge D150 with the slant 6. Runs and drives great. I love it. At the suggestion of my buddies i took off the factory “smog” pump. It was very simple to do. Only one big hose running off the pump into the exhaust. After I removed it I started it, drove it around and parked it. It sat for 2 days and now it won’t start. Won’t even fire. Did I inevertantly screw something up? Does the air being pumped into the exhaust create a vacuum or pressure that’s required for the truck to start? I’m at a lost.

I am certain that the air pump has nothing to do with your problem. It is just coincidental. You should start with the basics and troubleshoot things.

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-MattMan
LEANED & MEAN

The air pump itself has nothing to do with the engine starting/running.
But you may have inadvertently knocked a wire or vacuum hose off while in the
process of removing the air pump.

Is your 83 D150 still running the factory lean burn system?
Can you confirm that there is ‘spark’ while the engine is turning over with the starter?

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

I doubled check all my vacuum lines and wires and all seems well. I’m not familiar with the lean burn system. What is that?

Lean Burn was an 80’s attempt to reduce engine emissions by using a system that relied upon engine vacuum and engine temperature in conjunction with a very early ECM. Check the distributor on the engine, if from the Lean Burn era, it will not have a vacuum or mechanical advance. Also if your ‘83 is like mine, there will be a black rectangular box mounted inside the engine compartment up inside the driver side fender, that box is the Lean Burn ECM.
Today, the problem with the Lean Burn system is, they were not completely reliable when new, good certified replacement Lean Burn parts/ECM’s are not available. And there are better ignition options available today. Many, me included go with a HEI ignition. Do a search here at .org and you will find HEI information. This link goes to one of the HEI articles
viewtopic.php?f=28&t=15779

But before all of that, you need to confirm and maybe fix why your truck is not starting. Do you have a timing light? Can you confirm there is spark when the engine is being cranked over?
Also confirm that there is fuel getting to the carb.

The early 80’s D series truck have a couple of fusible links in the engine compartment wiring harness, The harness runs across the top of the driver side inner fender IIRC. Those fusible links effect power to the + terminal on the coil. If no spark, check with a voltmeter to see if there is voltage at the coil when the engine is being cranked. If no voltage at the positive coil terminal with the key in the crank position I would suspect the fusible links. You can do a quick test, if there is no voltage as described in the preceding sentence. Run a jumper wire from the battery positive to the positive terminal on the coil then crank the motor, you should have spark and it should start. Running a jumper is not a long term fix, if that gets the motor to start, you then need to address the fusible links.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

Good to know. Thank you so much for the help guys. And you were right. Fuseable link was bad. Replaced it and it fired right up. And as far as the lean burn system, the distributor does has a vacuum advance. On a hunch I contacted the previous owner and he said he removed the lean burn.

Well, it's always possible to screw something up when you remove or disable what you don't understand, but for some reason people keep doing exactly that. Glad you figured out your immediate issue... a missing air pump wouldn't cause the no-start condition, but could certainly affect other things and you might want to at least know what they are. An inquisitive mind is good. Questions you can ask your buddy include: why did it need to be removed? Was something not working well? What were you trying to accomplish?

But for this particular topic, be forewarned that your buddy will likely give you the same answer as thousands of other folks who also don't quite know, but they've heard it through the grapevine for longer than they've been alive so it must be true. (Spoiler alert: for this particular mod, you gain almost zero horsepower and you end up causing all sorts of problems, but hot rodders refuse to understand that because 'it runs fine'. And perhaps because conspiracies are intrinsically enticing? Not sure.)

You're on the right track. There are many, many resources to learn exactly what everything under the hood does. Devour whatever you have time to... many opinions exist, but I must say I've found a higher signal/noise ratio on this forum than elsewhere -- there are many very smart people here. Pay particular attention to posts like this one, wherein Slant Six Dan has recommended three books. The Stockel & Stockel textbook is an absolute gem for gaining a basic understanding. How much better off I would have been if I'd known about it when I was a teenager, instead of relying on slightly older teenagers to pass along a mixture of good info and old wives tales.

When I started, I knew probably less than you do now. But as you try things, you gain a huge jump on competence and confidence. And as you read, you accelerate that learning a hundredfold. Eventually, there's not much you haven't done, and if you live long enough you end up helping to teach the newcomers. Welcome!

- Erik

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Lots of early Valiants and Barracudas have crossed my path.
Also a handful of other toys for variety now and then.

Welcome to the board. "Remove air pump" is not in the first 3/4 of the length of the longest version of the to-do list on a newly-bought Slant-6 vehicle. Did your buddy have a reason to claim that's a good idea? Or was it just run-of-the-mill "Hurr, derp, emissions equipment sukks LOL" ignorance?

See here.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan is on target as usual. I'd like to add some context: the reason people first adopted the trick of yanking out all the electrical and vacuum spaghetti is because it really did make the car run better. That was in the early 70s. By the late 70s things ran much better, and by the 80s the engineers had figured out how to make controls that really worked. Unfortunately, millions of hot rodders never got past the initial reputation. Here we are nearly a half century later (!) and the old wives tales will never, ever die.

In that link, Dan mentioned the smog pump only a little bit. Let me add more.

By far the most common comment (from shade tree mechanics) is, "Rip out that smog pump and you'll free up horsepower." But when you ask how much you'll gain, people grow strangely quiet, or change the subject, or justify that any gain at all would make it worthwhile. After much searching, I've seen numbers in the 1-2 HP range for normal driving, and anywhere from 1-4 HP for WOT (Wide Open Throttle) racing conditions. Wish I could find an actual test. Shall we investigate the claim for viability?

The first question is whether this could be true, and the starting point is to examine exactly what does this pump accomplish. It sucks in a very small amount of incoming ambient air and pushes it through pipes/tubes to inject it into the exhaust stream. It will either put it into the manifold right near the exhaust valves, or further downstream into the catalytic converter, or it can switch between those locations depending on what mode it's in and what kind of car you're thinking of. The average test, to see if it's working, is to disconnect the output and see if you can feel little puffs of air on your hand. Any amount is acceptable, and in my experience it certainly doesn't puff very much. Since there's very little air flow (CFM) and no appreciable pressure (PSI), that pump is basically doing not much more than freewheeling, so it makes sense that there can't be much parasitic drag. In contrast, think of the water pump or the oil pump -- they're doing actual work with considerable volume and pressure, respectively. For some reason, people actually do measure those, and you'll see numbers in the range of 10-15 HP required for each. Funny, very few people try removing either of those "to free up horsepower." You'll see an electric water pump in some drag strip cars, but not much of anywhere else because they aren't really reliable enough for 100k+ mile street use.

The next question is whether it's worth it. The simple cost/benefit analysis is useful -- and you don't even need to be a scientist or economist to understand the concept: remember that a bargain is not defined by how much (or little) you pay. A bargain is defined by what you get for what you pay. (Yes, use that line when negotiating a salary increase and watch their reactions; it's priceless.)

So, what benefit do you get for "spending" 1-2 HP with an air pump? The answers are nothing short of miraculous: thanks to the catalytic converter, the air that comes out of the tailpipe is cleaner by at least an order of magnitude (10x), sometimes two (100x). There are new cars that are running so clean you could almost breathe it directly (not that I'd recommend it.) Older technology exhaust can't even begin to compete. The two main reasons the pump exists are to help break down excess hydrocarbons (HC) and to help the cat have a long life. If you feed the cat all those HC that the lack of pump exacerbates, it will at the very least be poisoned easily, and likely overheat. Either way, an expensive (and needless) repair bill. Ever drive behind someone else's stinky old car? Do you really want to be "that guy" (or gal)? I don't. The stinky old car syndrome is the exact problem that (sadly) influences public perception of our hobby.

Whenever we are tempted to think one car doesn't matter, it helps to remember that no single drop of rain believes it's responsible for the entire flood. We all like to breathe, last I checked... the old folks remember what air was like in the 60s, especially in places like the LA basin. (I could pass along eye-opening stories if wanted.) The young folks are apparently tuned in better to the idea that we're messing up our planet. I wish I could write something that would get even one single additional person to care. Any ideas? (I mean positive ideas. Cynicism I've got plenty of.)

Just from a standpoint of expanding knowledge, the computer-controlled systems are considerably more precise than the first attempts. This thread contains a pretty good (and short) description of the mid- to late-80s (and early 90s) Ford EEC-IV system, then some troubleshooting steps which won't be relevant to any slant six car, and then some chemistry equations which (at least for me) were yet another key to unlock the door. I found it amazing to understand what it does, and to see a continuous stream of "clean as a whistle" smog test results all the years I drove a 5.0 Mustang, which is not exactly a car most people buy for its emissions controls. But hot dog, they really work. And that car ran like a chicken with the Colonel after it. Why would I need one more HP, at such a tremendous long term cost?

- Erik

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Lots of early Valiants and Barracudas have crossed my path.

Also a handful of other toys for variety now and then.

The heater blower motor would easily spin the air pump all day long without even thinking about breaking a sweat. 1hp is a giant overestimate of the amount of power required.

(Also, was this "buddy" aware that removing the air pump dooms the catalytic converter, already on the bleeding edge of meltdown because of sloppy carburetion? Or maybe Buddy recommends ripping that out, too…)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The reason I removed the smog pump on mine was that it was seized and didn't have a belt on it. So it was just in the interest of uncluttering the underhood area. But I didn't see where the OP did anything about the hoses. Did I miss it? Because mine made a horrible racket out of the back of the head when I removed mine. A pipe plug solved the problem. But if the OP is driving around with the hose connected, it's spewing exhaust out of the hose. That can't be good.

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If it was easy, everybody would be doing it.

Quite possibly, but I have not actually seen the results of anyone's test. The pump does have a tiny bit of work to do, pushing air through tubing (friction resistance) and building up enough pressure to overcome the checkvalve and exceed whatever is the exhaust backpressure. That certainly won't be much, but it's not zero. A quick test to discover the ballpark power would be as simple as bypassing the pulley with a shorter belt, attaching a motor to the pump pulley and measuring the current draw, while attempting to correlate the pump speed with engine speed, and then get several points from idle to roaring. I shall do that, just to satisfy my curiosity, but it won't be soon (because life is busy.) It would be nice to have at least one real data point.


That's the reason for the checkvalve in the system. (In some cars, there are two.)

See, this is the whole point. Messing with what you don't understand is often not good. But rather than just blindly tell people, "don't do that, you're being stupid", it helps much more to present all the facts so that a person can make up their own mind. Education is the only way anything will shift. If I resort to argumentative cynicism (yes, I re-wrote my posts several times before finally releasing them…) then what will happen? The Original Poster (OP) and anyone else who sees this will come to the conclusion that I'm just an old fart blowing smoke. Or I'm the teacher/principal/preacher/drill sergeant telling them what to do. Or (heaven forbid) part of a government conspiracy that wants to take my cars away. If you truly believe that the only reason to keep that stuff is because you're "supposed to", then we all know that when the cat's away, the mice do play.

Unfortunately, there's strength in numbers. If a buddy says it's all bad, yank it out, and then 15 other buddies agree wholeheartedly because they've heard it through the grapevine (and Internet) for more years than they've been alive, those opinions are going to hold a lot more weight than the reality that Dan and I are trying to convince people of. Do a search on Google for "remove smog pump" and you'll get nearly 800,000 results. Compared to a small handful of nutcases presenting facts here? I'm trying my darndest to not be that nutcase. The facts are indisputable, so my presentation needs to not turn people off. Otherwise, the OP is long gone; why would anyone stick around to be chastised?

I'm hopeful that if someone begins to understand that the pump "robs" virtually no extra horsepower, while helping the rest of the system perform absolute miracles, they'll understand the cost/benefit ratio. We really do want to breathe better air. All of us. And perception of the old car hobby is quite negative to those not involved, because of what we do to the air. Even if it's only a few of us.

But unless we can address the myths, and get people to actually think for themselves, there's no shift possible. What else can we say that might be even more compelling?

- Erik

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Lots of early Valiants and Barracudas have crossed my path.

Also a handful of other toys for variety now and then.

The OP, after getting the three books listed in this thread as soon as he can, could start here, which is not perfect but is pretty darn good.

But I can't help noticing the OP, who has been responsive elsewhere (voltage regulation thread, for example) is silent here. ¯\_(ツ)_/¯

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I often find that chastising is a great way to learn. I have found that often the person chastising you does it out of a desire to actually help you. After all, if they didn't care about you, why would they take the time to chastise you? One must be able to accept criticism if one ever hopes to learn and grow.

I do agree that the original oster would be very wel served to purchase the books Dan mentions and actually read them. There is a large amount of bad information (some downright dangerous) floating around the internet, under shade trees, and in car clubs regarding the emissions systems of the 70s and 80s.

This dude has a lot to learn about working on old cars, but y'all beat that horse so dead the rest of the horses are running for the hills. If I were him, I'd probably stay out of this thread, too.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing