Okay, but at starting, the engine is breathing through the BAC and pretty slowly at that. I'd be surprised, based on the spring force on the door at rest, if cranking speed can develop enough vacuum or flow to push the afm. Maybe the ECU will wait a few seconds after the engine starts for the airflow to pick up before it checks the AFM for a "quit" signal. Of course, it also makes sense that an AFM that's been sitting out of the car for a while might be a little sticky at first, anyway. Manually deflecting the door is a great tip. Thanks.

FWIW, my AFM has a few little glitches in it when the door moves. It's like there are a few tiny high spots on the casting that come up from the "floor" of the AFM, and make it drag a little. I hesitate to try to knock them down with a dremel stone or anything for fear of changing the cross-sectional area exposed as the door moves. Does everyone have these little bumps in the casting of the AFM? Is there anything that should be done in terms of cleaning or lubing the AFM door, or is it best left alone?

Edit

Nevermind. I imagine that the pulsation damper is there because the manifold acts like a little high-pressure reservoir or accumulator to a small degree, plus there's pressure in the fuel lines. I forgot that we're talking about the fuel pump cutting out vs the ignition or something else. Even if there was a short hiccup from the fuel pump from the time that you let go of the key to airflow really pulling the door open, you'd have enough fuel on-hand in the rail and tubing to keep it turning for a few revs. This is great - I'm learning a lot, given that the car's not even running yet.

But a float bowl would still be a better solution to this particular problem

 

I'm not sure if this helps but I'll say it anyways.

IIRC, the shop that used to work on my car, the tech told me that the reason for the PD is that the fuel is pulsed because of the way the motor is setup so it's there to dampen it. Okay, yes, that's why it's called a PD but...eh.

And, as far as the AFM door, I noticed that when I set my idle properly I started to hear a small hiss coming from the AFM. The more I turned the idle adjust screw, the more it would hiss. So, I backed off a bit and made sure I got my proper idle. I don't ever recall hearing it hiss but then again back then my idle wasn't right. Now, anytime I'm on that side of the car, I can hear a little hiss.

 

I'd think you just weren't listening for it. Any time you're pulling vacuum around a throttle plate, AFM door, etc you'll get some pretty high-velocity air through that little exposed crack. My Dakota hisses like crazy as it's a fairly big displacement through just one throttle plate. I'd be curious to know if the hissing gets louder if you turn the idle speed up. I expect it would.

I did finally find that my supposed relay on the floor is actually the ambient pressure sensor, so that's one less question mark. I know it only goes to the ECU and it's a 4-plug connector, so that's one less plug. Unfortunately, it means that the rest of the plugs on my floor have no home, and I have no idea where they'd all go. Is there a separate emissions ECU or some other major component that goes down there?

 

Actually, it wasn't really there (probably not as loud) until I started messing with the idle adjustment. I remember because it stuck out like a sore thumb when I started rotating the idle screw to bring the idle up past 850 RPM. My idle was more along 700, 650 . When I turned it back down, the hissing went away (well, not as noticeable).

Tho, you'd be amazed what you start to notice when you work on your car, tho. *L*

 

Just for my own understanding, is the PD there because the fuel pump puts out significant pulses, or because the injectors release the pressure in significant pulses? If the damper isn't pulsating, which I understand you can feel pretty well, it might be a good indication of whether or not your injectors are doing their thing.

Don't know first-hand, but maybe worth talking about as an easy check.

 

One thing the tech told me was that to ensure it's working properly was to just place your thumb or finger on it and feel it pulse. If you don't, replace it. A lot seem to do the banjo fitting mod.

And, I believe the PD is there to even out the flow of the fuel because of the injectors. Tho, I'm not all that familiar with it as others maybe.

 

Well, I got all the fuses I need (and then some) and got the car cranking again. The tach does register the cranking revs, and I connected the atmospheric pressure sensor by the ECU. I've still got several 2, 3, and 4-pin connections down there. Is there an emissions ECU or something else that belongs there?

I've also got the sheetmetal cover for the false floor over the ECU, but have a plastic cover about the same size, too. Any idea where a big sheet of plastic the size of the ECU belongs on the car?

Edit - I'm looking at page 50-17 in the FSM, and it details all the hardware on the floor. I have the main relays connected, but have two more round relays on a common bracket available to me and I have a white and black connector near the main relays. They look like they go together, but I don't see what they do.

The FSM calls out a vacuum pressure sensor, but I have a black sensor on the floor that doesn't contain a vacuum line. Does a vacuum line need to run there, and my atmospheric sensor is actually somewhere else?

Does anything go in the O2 sensor check plug? What about the fail check connector? It seems reasonable that these two connectors might not connect to anything.

I've seen a circuit opening relay recently, and can see that it belongs on the floor. There's also a control unit down there, but I don't know what it's for or what it looks like. Is that the black lump on the floor? That little thing has me totally confused.

 

Let's see if this helps some:

ECU area:


relays:


vacuum sensor (behind sub-zero tank):

 

The PD simply dampens out the fuel pressure pulse caused by the injectors openong/closing. The main control box under the passenger's feet is the ecu, Emissions Control Unit, They became Engine Contol Units in 86 with the phase ot of the dizzy and introduction of the CAS. There are 2 pressure senders/sensors, one in the engine bay, one on the passenger side under the dash. The vacuum pressure sender in the engine bay sends it's reading via wires to the ecu, the atmospheric sensor under the dash does also.

If the plastic cover doesn't fit the ecu, then it covers one of the other boxes either under the seat or hidden under the bins. Check connectors are generaly left open, all green plugs are for testing and left open, except the O2 plug under the intake.

 

Excellent. See above pics. There are several connectors that have no match there. I see that ithe circuit opening relay is left out on my pic. It is hiding behind that connector. It is a small black box (looks like a relay) with a yellow part for the connector.

Not sure offhand. Do you have a pic of what it looks like?

Check the pic above. See if that helps.

The vac sensor is that little sensor behind the sub-zero reservoir.

These are for testing only. No connection to them.

Circuit opening relay, atmospheric pressure sensor, ECU, and relief solenoid control unit all go in the same area. See above pics.

 

Hey Addict, that's exactly what I needed. I've now got the floorboard straightened out with the ECU, pressure sensor, etc.

1.) It looks like the relief solenoid control unit is the black module with N304 on it - is that right?

2.) By elmination, does that make the circuit opening relay the little black lump at the very bottom of your footwell pic, almost out of view?

By the way, the FSM shows the black box immediately left of the ECU - the atmospheric pressure sensor - and calls it the "Vacuum Pressure Sensor" though it's just vented to atmosphere in your pics and on the unit I've got. I was about to run a vacuum line to it through the firewall because of the crappy component name in the FSM. Anyway....

In the second pic, I have the top-right relay sitting on my bench, so I know where it goes now. I also have the two round main relays mounted to the fender rather than that hanger for all the relays, so it's been throwing all my wire positions off.

3.) Is the relay behind your two main relays scribed on the top with the name of it? I want to say it's the check relay, if memory serves.

4.) Finally, what is hiding behind the unmarked nippondenso relay in the top-right corner?

You also helped me mount the cold-start, as the PO mounted the vacuum switch further inboard along the firewall and used a threaded hole for the cold-start.

Now that I know where everything goes, I can figure out which plug goes to all these things. There's enough other nonsense in this thread that it might not be to an archive standard, but I'd love to put it all together into one clean thread to document this stuff. Thanks so much for the help.

BTW, does the circuit opening relay basically just replace a traditional fuel pump relay, in that it'll open the circuit and cut power if the AFM is shut? It looks like it's powered in the RUN position and cranking, and interrupted if the AFM isn't open or you're cranking. I'm still not getting fuel yet although the relay's in place, but I don't expect it to work correctly until I get the rest of the relays in place - I'm not ready to cuss the fuel pump just yet.

 

No prob. Yes, the N304 module is the relief solenoid control. The circuit opening is under that white connector towards the bottom of the pic. It is a small black module with a yellow part where the connector plugs in to. I can snap another pic if it at lunch or tonight. Yes the circuit opening relay = fuel pump relay. It is shown on pg 50-16 of the FSM. You can see if you have power to the circuit opening relay by checking voltage on the BW (black w/ white stripe) wire that is on the connector to the relay. Test with key to 'ON' position. That should have power even now. If not, check the 20A engine fuse or that harness isn't tied into the main harness (for power, tach signal, etc.).

Yes, that relay toways the back (big one) is the check relay. It it what senses if the alt is charging and turns off the idiot lights after the car starts.

I'll get you more info on that other relay later today. Let me know if you need pics of any other areas. One thing that is helpful is to take each connector that doesn't have a mate and look through section 50 of the FSM. It has pictures of every connector. First eliminate option by the size/shape of conector and then look at the wire colors. Once you track down the name for each one, label it with some masking tape. Once you know the names of them, I can help you figure out where they go.

By the time you are done with this, you'll be an SE expert.

Kent

EDIT: One more thing. Check to see if that yellow connector in the bottom pic is plugged in. If I remember correctly, it is what brings in power and tach signal to the ECU.

 

Crit,

Here is that relay that was hiding behind the nippondenso one. Let me know if you need any pics or help with what plugs where.

Kent

 

Well crap. I've learned that there's the No. 1 AC, No. 2 AC, and AC Cut relays that I'm missing under the hood. I'm 95% sure I have everything else except for an exposed rubber-coated plug near the air pump area. It has a rubber boot like the ignitor pickups.

I have the Masen relay shown above, but it's plugged into the circuit opening relay plug. It's for the AC and I'll move it, but it means that I'm short the opening relay. I'll see if I can't find a fusible link or something to jumper the fuel pump on. I want this bitch to crank now.

 

Thats the spirit! Glad to see you got it this far, getting it running should be a piece of cake. I have been following the thread for a while, and gotta say... Love it!

Stu

 

if you let me know exactly what you are missing, i can see if i have it and i do i'll send it to you at no charge.

 

Crit,

You need a pic of the circuit opening relay? I'd be happy to get a pic for you. All the AC relay stuff can wait (until summer anyway). They aren't needed to make the car run. That rubber boot connector by the airpump is not supposed to be plugged in to anything. It is for testing the fuel pump. If you put a jumper wire between the two pins in that connector, the fuel pump will run when the key is in 'ON' (car not doesn't need to be running, AFM doesn't need to be open). It is used when testing fuel pressure or checking for leaks (like after working on the injectors). You will need the circuit opening relay to perform this operation, though.

Perhaps for the time being, one of the other relays may work in that position (have to check the wiring) or just use a jumper wire in the circuit opening relay connector so that the pump will run when the key is 'ON'.

Let me know if I can help in any way.

Kent

 

Well, I did find the circuit opening relay in a plastic bag in the car, and have plugged it in. When cranking the car normally I don't ever hear the fuel pump run, but when the car's just keyed on the pump takes off the moment I touch the AFM door. I'm used to hearing the slow ticking from my Holley, but this pump is quiet. The fuel rail itself makes more noise than anything else.

Anyway, I got new plug wires put on the car, cleaned the plugs again, popped the AFM door open to start the pump, and she just won't light. I have a noid light set with an inline plug tester, and I'm getting spark to all plugs. The engine looks great inside with minimal flaking and nice springy seals, so I can only think I have an injector problem.

I can use the noid light set to test the injector wiring, except that it's impossible to get to with the manifold on. Is there a trick that would allow me to pop the connectors off the injectors with minimal fuss?

Regarding the AC, I just want to hang the condenser when I hang the radiator for the sake of not doing it all twice. I'm not worried about any of it, and I'm not sweating the relays.

I did finally realize that the plug hanging from the plenum was for the ACV, which is one of the few things that have been removed. I now just have the nippondenso AC relay from your pics as the only thing not plugged-in, but that's because I don't have a 4-conductor plug left in that corner of the car. Even the AC Cut relay, which is on the strut tower, is in place, so I don't thing the PO would have gutted it.

In any event, I'm now just trying to start an SE. Everything else is in place, provided it doesn't run for too long (no cooling system yet). I'm sure there's a good thread on starting an SE, so I'll do some looking.

 

there's a ground wire with a through bolt that needs to be grounded for the injectors to open. i ran into this problem a few years back when i was building my SE. i THINK the wire was either a single black wire or a set of three balck wires with one eyelit.. i ended up grounding it to the emissions rack on the left side of the engine. i know its a pretty vague description but i hope it can help you.

 

Yep. Dave is correct. It is 2 black wires near the emissions rack. They need to be bolted down to the engine for the injectors to work. Have you tried to check the voltage at each pin of the ECU and compared to the FSM? That will tell you if something may be unplugged or not getting power.

 

Hey Crit. I almost called you today too see if you got it running yet. To check if it is not getting fuel just pull the air hose off the trottle body. Open the the throttle plate. Pour a little gas down her throat. Put the hose back on. Turn it over. It should bust off. I used this method checking a second gen that I almost bought. The owner couldn't figure out why it stopped running. Did this, and it fired off for a few seconds. Let me know that it wasn't getting fuel. I know this won't tell you if it's the injectors not opening or not, but it will tell you if the other electronics are ok. I think I'm excited as much as you are about seeing that thing come back too life !

 

Sam, while I appreciate the sentiment, I think I might be a little happier to see her run than you.

Well, she's got a bit of a smoking problem on account of all the MMO, but she's alive. She'll run for about 3 seconds and then die, but I'm not worried just yet. It smoked the house up so bad with just 5 3-second sessions that I'm not forbidden to run it until I make some changes

The plan is to install the muffler, back the car up to my creek, and run some water runoff tube down to the creek so I can water-bong the thing and keep the smoke down. Once that's done, I've got to throw in the radiator, fill 'er up, and get everything tuned.

Can someone tell me if it's typical for a pickled engine to only run for a few seconds once it's started up? Is the ECU learning something, or do I just need to adjust the idle stop, mixture, and TPS?

I've gotta say, that's probably the most productive lunch break I've ever had. I don't know if the car just woke up in a better mood today or what, but she's alive.

 

Sweet. Once you get some coolant in her, tighten up the throttle linkage a bit and see if it will continue to run. Is the coolant sensor (plug on the back of the waterpump) plugged in? It needs to be, or it will flood out almost instantly. Also, are you pressing the accelerator once to the floor before starting? You need to do that to set the fast idle mode.

 

Now I don't know anything about fast idle. I guessed based on what I've overheard once from a local quack, but never understood it. Is pushing the throttle just an input to the ECU to go ahead and open the BAC for me, or is it a magnetic grip like a choke, that keeps the throttle held in?

Why do I need to tighten the throttle linkage? And yes, I got it to rev just a little once while giving it some throttle, but ceiling started to shake and bugs began dropping out of the air with all the smoke and noise. Good times. It died with a little throttle, though, and the smoke was just too heavy to go for it again.

I'm so used to being able to lightly tap the accelerator for a little AP squirt - I have to remember that it's not the case anymore.

 

The fast idle is a mechanical cam. Part of the thermowax system. It just holds the throttle plates open a bit until the engine is warm. I have mine set for about 1500rpm fast, 800rpm normal. When you press the throttle down once before starting, you set the cam into place. There is more about it in section 4b of the FSM.

As for the linkage, I was saying that by holding the throttle open a bit (by tightening the linkage), the car may keep running. Many time you have to do this after a rebuild until things seal up a bit and will idle normally. Wouldn't hurt.

Also, maybe the AFM is sticking or is bad. If the switch inside is bad, the fuel pump will turn off after starting. The car will run a bit and die. Could be something like that. You could jump that connector with the rubber boot to make sure the pump keeps running. At least to see if this may be a problem.