kurtoli2

Hey guys. I've read a lot about this issue but still unable to overcome. There's a lot of recommendations to post a thread here and I understand this is the best place for possible solutions, so I really appreciate whatever suggestions come about. There are no bad ideas, so suggest whatever you think, even if it seems trivial.


This is the current situation.


I did a full rebuild of my 13b motor, as well as the ancillary components like distributor and fuel injection system.


The motor cranks fine. First attempt got a lot of flooding, so I installed shut off valves in both fuel supply lines so I could spend some time building compression before letting fuel back in. I did all of the usual processes like removing the plugs, adding some Ansoil 2 stroke oil to the chambers, and I have a number of brand new spark plugs to circulate through the process in case of any fouling.

Here's the thing: when I test for spark at the plugs, it's weak at best, or non-existent. I doubt that anything I'm doing is having any effect until I can assure there's a good healthy spark in the chambers.

On a number of occasions I've turned the crank to the pulley marks and made sure I have good distributor angle for leading and trailing timing and then re-attempted to start. When that didn't yield anything is when I noticed the non-existent spark.


- The coils seem fine. 12 to 13+V coming from each. Tested ohms at their terminals and was in range. Same at both wires on top of the new distributor cap (new rotor installed too)

- Have good clean grounds on the bell housing, the shock tower, and the ECU.

- Pulled the igniters and tested using the most common method I've seen on these sites, they're fine. 12-13V are being delivered to them as well.

- I can't detect any shorts in the wiring, and when I did the rebuild I made sure to go through the engine bay and clean up all the wiring there, provided new wrapping where needed, etc.


I've pulled plugs and tested by making sure the plug body is ground to the engine and looked for spark, but I've only seen a weak spark once and from only one of the 4 terminals on the plug. Otherwise there is no spark that I can see at all. Unfortunately I did accidentally check that they're getting voltage because I was still holding one when my son prematurely cranked the engine and I got zapped. But in visual observation I don't see any spark, so it's gotta be very weak at best. I should also mention that I've pulled each coil wire and also looked for them to arc when put near a ground, and though there's voltage, there's not enough to deliver a spark across the gap.


The engine can crank for a long time, but there's not even a hint of ignition, so I think if I can overcome whatever is going on and get a nice strong spark I'll be in business and be able to wrap up this rebuild. It's my first rotary rebuild by the way, and I used new housings with my original irons. It seems to have good compression when tested, and spins up nice and smooth.


Any help is totally appreciated.

KansasCityREPU

iTrader: (9)

Just for the heck of it, try pull starting with another car and popping the clutch in second gear. If it does start you'll need to be quick to push the clutch back in while playing with the gas/brake pedals.

kurtoli2

Thanks Kansas. I've seen that suggested before but isn't there a problem that there's no spark during normal cranking? I realize a push start in 2nd might get the motor spinning faster, but sheesh. I live in a populated area and pushing/pulling a car around the neighborhood is pretty tough to navigate. I'd also like to be hovering over the engine bay when it finally ignites. I wish there were a dymo or something that would turn the wheels/engine while remaining stationary, and reduce the stress on the starter too. Anyway, I may have to consider it at some point. Thanks again

diabolical1

iTrader: (3)

Welcome to the board.

How old/strong is the battery? Those tests that you posted results for, were they while cranking?
Have you tried anything to boost the combustion process? (Starting fluid, acetone, etc.)

kurtoli2

Actually, Diabolical, those results are from ignition On, not during cranking. I suppose there could be a significant drop-off of current during cranking. Even though the battery is pretty new and in good shape, I'm also keeping the car jumped from my running Dodge Caravan so I can continue consistent cranking without drain to the battery. But, I will see if there's a drop off at any of those test spots while cranking the starter.
I swear, you'd think I'd at least hear the engine attempt to ignite.. a pop..a slight change in exhaust indicating some firing....but no.. just turns and no indicator of the engine about to fire up.
I have tried using starting fluid, once. No change or slight indication of firing. I really believe a good strong spark would ignite the fuel enough to give a sign I'm headed in the right direction, and why I think there's something I'm overlooking that's preventing a strong spark at the plugs. I had to do a sanity check and pulled a plug on my Caravan and observed it while cranking - a spark so strong it makes a snap noise as it fires. Not the RX-7 though. nope...sigh
Thanks for the continued suggestions. All are welcome

kurtoli2

I'm going to test something when I get home, an idea that I had from reading your post; What if all is well in the ignition system UNTIL I engage the starter? Is the ignition system effectively cut off as soon as I start cranking? It's a 5sp manual, so no neutral safety switch to be concerned with. i.e. doesn't have to be in Park in order to get ignition. But I'm wondering if something is being completely cut off while cranking. That would lend itself to the idea of push starting as suggested earlier. I'll update this thread if (or, if not) I find something changes in the ignition system when the starter is engaged.

diabolical1

iTrader: (3)

The starter does suck a lot of juice. However, since you said the battery is fairly new, it's probably not your main issue.
Well, you can add a few things to your checklist, some of them will probably be redundant, but being thorough never hurts.

1. make sure the starter terminals are clean and tight
2. make sure the engine ground (at the starter bolt) is clean and tight
3. double, triple and quadruple check the plug wires for correct position
4. double, triple and quadruple check the distributor TDC position - if you can rustle up an extra pair of hands, then once you install the distributor, have the other person crank the engine while you turn the distributor and see which side starts to give you some action
5. de-flood chambers, add a little oil to them, then clean and dry the plugs

kurtoli2

The starter terminals: The negative battery cable is grounded to the top of the bell housing right below the clutch hydraulic and not the starter's mounting screw. It was always that way so I never changed it, though I see it posted often that it should be mounted to the starter mount point. But, the starter is mounted to the bell, and so on..so probably not an issue?
Plug wires: Yeah, had a few rotaries in my lifetime, rx4 wagon, 2 rx7's, I know about the T&L wires, 1st and 2nd rotor, and so on. Those are good.
Distributor: With distributor out, hand turned the motor until the Leading mark on the pulley lined up with the indicator pin. Aligned the indicators on the distributor shaft and gear, then carefully mounted the distributor, aware that the gear is going to turn from where I started as it lowers in to place. Made sure to account for that by keeping it slightly out of alignment so that once it was lowered in to place the cam would line up properly with the igniters.
On piston engines I know you start with aligning the indicators on the distributor gear and shaft and then let the motion of meshing the gears do its thing and the shaft will turn slightly from where you started. That's normal. Is it the same on the wankel? Should I have let the gears mesh and turn the shaft slightly from where I started? In any case, I think where it ended up is what counts.

One question though: I remember thinking when I was reassembling the engine (eccentric shaft, rotors, etc); how in the hell do I know that this is indeed TDC and that the notches on the pulley are accurate anymore - or something like that. I did position the rotors properly in each housing as I assembled, but I'm sure I was thinking about the eccentric shaft and how any of this could be spot-on, and how the notches on the pulley could possibly be accurate anymore. And then recently I saw someone's post to look at the flywheel under the inspection cover on the bell to make sure you're lined up right. Does that ring a bell? Not sure where I saw it now. It was some time ago that I completed the block assembly. It sat on the engine stand for months before I got around to finally installing it back in to the car but I was pretty satisfied that it came together well.

tim.

iTrader: (1)

In simple terms, for the engine to run you need fuel, compression, and spark.
It sounds like you don't have a great spark, so that is where I would focus my efforts .
You said you tested the igniters, well I would try testing them on the car, you can take them off the distributor, and leave them connected to the coils. Put a plug wire and plug directly into each of your coils and set the plug on the engine. Then you can ground the G terminal, and trigger the S terminal on and off with 12 volts. You should see a nice fat blue spark at the plug when you do this.This will tell you if you need to look at the distributer or the coils/igniter/wires/plugs area.

diabolical1

iTrader: (3)

For the distributor, I get the engine to TDC, then I line the marker (the little tang on the shaft) up with the the little divot on the gear and try to insert it so that the adjustment is as close to the center as possible. I let it mash together by itself. Sometimes it moves a little. Sometimes it moves a lot. As long as I have some adjustment, I will attempt to start the engine. The two ways I've learned to obtain true TDC are:
1. the front eccentric keyway at 9 o'clock
2. the flat side of the flywheel toward the intake/exhaust side of the engine

Check this out: Finding TDC

kurtoli2

Great idea. I'l try this tonight. Thanks!

kurtoli2

Here's an update of this thread and my not starting issue after a rebuild.
Thanks everyone for their advice so far. I used people's advice posted here to assure that my timing is correct by removing the front pulley, checking that the rotor's were in the right position and then mounted the front pulley accordingly. The distributor is also in the correct position while the Leading marks are lined up with the needle. I think I'm all good with initial timing.
The no spark issue is resolved now. I installed an Optima red top starting battery, and sure enough that was all that was needed. The battery I was using, though pretty new, was a Duralast 500CCA. That should have been enough, but given that it's a rebuild needs a good hot spark for initial starting. The Optima is 720CCA, turns the motor faster, and I clearly have spark going to all plugs.
Still can't start it though and I think I know why. My son was watching as I cranked and pointed out that there's fuel coming out of the rail while I'm cranking. It's coming from the relief valve on the end of the rail, so I dismantled the EFI system, removing the fuel rail and the injectors. There's nothing visually wrong with any of it, nice and clean from my rebuild, but here's where I have a question: With the injectors on the bench I applied a voltage to each and there's no 'clicking' sound. They don't appear to do anything. Is that all that's needed to test that they're good or not? Because if the fuel is backing up in the rail due to pressure and the relief valve is opening (I adjusted it so it won't open at all for the moment), and the injectors aren't doing anything, then even though I'm getting some fuel in to the motor, it's not being atomized and even if I have spark now it won't ignite in the chamber - like putting a lit match in to a can of gas - it just snuffs it out.
I ordered new injectors and will try that but I'm stumped as to why the old injectors both went bad in the first place. What happened during the engine rebuild? The engine was running fine right up to the rebuild, so I don't know what happened to the injectors that makes them both bad after putting back in to the rebuilt motor. I also replaced the electrical connectors by the way, as the old one's were brittle and had fallen apart when trying to remove them from the injectors.
Sound like I'm on the right track?
Thanks all!

diabolical1

iTrader: (3)

Just to be clear, you're saying fuel was leaking from the regulator, but that issue has been addressed?
Sounds like you're putting in some serious work. So, while I believe anything is possible, I'm also a bit skeptical about both injectors going dead at the same time, too. When you applied the voltage, did you try to simulate pulsing? I know people also run resistance tests on them, so maybe you could try that. Hell, I'd say try whatever tests your situation affords you to. You've already ordered new ones, so it certainly doesn't hurt anything trying stuff with the old ones.

Oh, most definitely!

diabolical1

iTrader: (3)

Hey, I don't know how much of these tools you have, but I just watched this video on fuel injectors that seems fairly thorough.

kurtoli2

Thanks you guys. I watched the video and that was really helpful. The biggest takeaway is toward the end where it show's that yes, I can test them by simply adding voltage directly from the battery and then they should at least do something. In my case, neither one does anything. No clicking sound, no spray....they're both dead. I know that doesn't seem likely to have both be bad, but hey, they invented the word coincidence for a reason I guess lol. Maybe they got damaged during cleaning, or maybe somewhere along the way while dealing with the electrical issues they got zapped....all guesses right now.

The new injectors arrive Friday and I'll test them right on the rail before mounting them. Still not clear why there was fuel coming from the damper on the end of the fuel rail when I was cranking the motor, but I've set the screw to the closed position for now, but not quite sure what the adjustment process is for that part. My guess is the damper is there to let air out if there's any in the line? Maybe it was open too much, I dunno.

Have a good week everyone.

kurtoli2

Btw, I think I might have answered my own question about that adjustment screw on the damper after some thinking about it. I bet the screw is to bleed any air out of the line after pressurizing the fuel system. I had it somewhat open when I was cranking the engine, so excess fuel was flowing out of the rail. I should probably only open it when it pressurizes so that air in the line escapes, and once I get fuel coming from it, close it again. That would explain why it has a plastic cap covering the screw, just like a bleeder screw does on brake calipers. That's my theory anyway and I'll stick to it for now.

diabolical1

iTrader: (3)

This was why I asked for clarification. So you're talking about the pulsation damper? (THIS?) If so, replace it or perform the modification to it.

kurtoli2

Yes, though the Clymer repair manual (sucks, btw...don't use Clymer) doesn't call it a pulsation damper, but that is the part. Mine looks good as far as I can tell and it's just that I had the adjustment screw turned out so it was opened enough to allow fuel to leak out. With the screw tightened I used the air compressor to check and no leaks from the rail. As I backed the screw out I got more and more air coming out, so it's probably doing it's job. Works the other way too, in that it's working as a one-way pressure relief valve - which I think is its purpose. Only other question is where the screw should be set permanently..i.e. closed completely, or just enough to relieve excess pressure in the fuel system, but not so much that it lets fuel leak out. There's also a pressure regulator on the throttle body, so I'm making sure that works too. In any case your article tells me I'll be watching that component closely.

Thanks for clarification.

kurtoli2

Update to this: Found the problem but it's unfortunately a major one: The second rotor is spewing coolant in to the exhaust, so the whole problem has been a water jacket breach. There must have been a problem with one of the water jacket seals when the engine was reassembled. The first rotor is perfect, but the second one is breached - no compression. Fortunately the engine and bay are totally clean and it only took an hour to get the engine ready to hoist out. Will put it on a stand and reassemble with new seals, and check ALL while it's on the stand before putting back in. I'm sure it's gotta be my fault during the rebuild. So I'll suffer a re-rebuild as I should. I've learned a lot since the initial rebuild anyway.
One question: I had purchased two perfect condition 79-85 13B rotor housings. Thing is, they are street ported. I didn't want street porting, but as you know those housings are hard to come by, especially in excellent condition. My originals are in decent shape but I keep looking at the street ported housings which are identical in every way to the originals, but have the street port honed out. Can I just plug the street port with freeze plugs and expect otherwise normal operation? I'd love to use them for this second build.

Thanks everyone for your help.

tim.

iTrader: (1)

Would you be able to take a picture of the port you are describing, on both housings,? It might help clarify your question a bit.

diabolical1

iTrader: (3)

Yeah, those housings (unmolested) are hard to find, and cost a pretty penny when you do.

On a separate note, the porting that you're referring to, are they the exhaust ports? If not, then that's not a street port.

kurtoli2

Sorry all. I meant, Peripheral porting. But in my case it's technically called, Semi-peripheral porting, similar to what's shown here, minus the cut out's in this picture on the housing for Bridge porting. (I'm not at home this weekend so can't take a pic of mine)
So, a simple 1" hole as seen here that would normally be used to host a modified intake system, but I'd rather just plug the hole with a freeze plug and use the housings as normal aspirated with the factory FI system. Everything about my PP housings are identical to the originals (minus the 1" hole) so I wonder if just not using the peripheral porting would cause any issues.

kurtoli2

If I put a 'physics' hat on, I imagine the plugged hole would simply be empty space; the rotor would pass it and still bring in air/fuel to the chamber normally and would have nothing to suck from the empty hole, then continue on to the compression and exhaust strokes without interruption.
That's my amateur attempt at an explanation anyway. My head hurts.

diabolical1

iTrader: (3)

Your "physics hat" scenario would theoretically be right; except, the timing of the port matters. Blocking the port will create an empty chamber like you said, but when the apex sweeps past it, you have basically opened intake and exhaust at the same time. So even with the entrance blocked off, it will give you the drawbacks of a functional peripheral port with none of the benefit.

kurtoli2

Thanks for your message. It occurred to me that the biggest issue is that even with those chambers blocked, there's more volume to fill during the intake stroke. That may cause problems that couldn't be compensated with tuning. I better just stick with the originals. The hassle of removing and reinstalling the motor just to find out is too big a risk. To use these would require a completely different intake system. I was just going for a simple, normally aspirated [and quiet] RX7. Engine is ready to pull and I'll dismantle to see what happened to let water into the second rotor housing. It isn't mixing with the oil so I bet one of the o-rings was breached when reassembling the block. That would explain all the problems. I've been trying to ignite water. duh
Thanks all. Hopefully next time I post is to show a normal running motor.