Thoroughscrub

New battery, fuel filter, fuel, starter motor.

The engine with turn, but not start without starting fluid, but it REFUSES to idle without revving it over 4k.
It dies within 2-3 seconds of starting unless you give it gas right away. Holding the clutch doesn't change anything either.

Does this sound like a compression issue? I'd rather not spend the $30 on a compression tester, as I've sunken as much into the car as I spent on the car in a matter of 20 days.
If it is my apex seals, would it be a better idea to have the engine strait up replaced, and if so, what all would I need to stick a 13b in there to bump up the power a bit?
Looking to sink less than $400 more into this car...

It's probably worth mentioning that none of the vacuum hoses are hooked up. I can't find a good diagram and the manuals I have really don't make sense to me.

DarrenTRS

iTrader: (1)

None of the hoses are hooked up but are the vacuum barbs plugged? vacuum leaks depending on where they are present very different symptoms, make sure to check that first and at the very least cap ALL of them.

Also take the leading spark plugs out, disconnect fuel and spark fuses/fusable links, have a helper hold down the throttle and turn the engine over, hold your hand over the leading holes and listen for 6 equal sounding puffs, if you only hear 1 good puff on say the front rotor but hear 2 weak or dead ones, it's likely an apex seal, if you hear 2 good puffs and a weak one, it's likely a side seal. a compression tester is ideal but this should give you a very rough idea of whats going on.

LizardFC

iTrader: (1)

Without the vacuum hoses hooked up, the car isn't going to run well or at all. So I wouldn't worry about compression just yet. Read through the FAQ if you haven't done so already. Here's one link on there that might help you:

https://www.rx7club.com/forum/showth...hreadid=118577

Kentetsu

See if you have spark on the leading plugs.

Also, check the level of fuel in the float bowls (small windows on carb, front and back).

Post back with answers to those two things, and it will greatly reduce the number possible causes...



.

Thoroughscrub

[QUOTE=DarrenTRS;10672504]None of the hoses are hooked up but are the vacuum barbs plugged? vacuum leaks depending on where they are present very different symptoms, make sure to check that first and at the very least cap ALL of them.

I forgot to mention, I just bought and installed brand new plugs that were $7 a piece.

It's better to plug up every vacuum hose??
I'd've thought the opposite completely! Thank you for that bit.
A mechanic at work today told me to poor a bit of diesel fuel into the engine via the spark plugs. He said that it could re-expand the seals which may have dried out while sitting (before I purchased it). Is this a plausible solution as well?

Kentetsu

No! Just a regular oil change, no special tricks like diesel in the chambers. If you do have to add something because it flooded, then use either oil, 2 cycle oil, or Seafoam.

Thoroughscrub

Kentstsu, are you suggesting getting an oil change might help it start? (It does need one)

I plugged all the vacuum tubes and I already put at most an ounce of diesel in where the spark plugs go. I sprayed some starting fluid in the carb and it fired up and idled on its own for a solid 15-20 seconds. Longer than ever before. There was huge cloud of exhaust and it died.
Now today I returned the battery and got a replacement as it wouldn't turn over at all. Turns great now, but it won't start. The motor turn and turns and turns, puts and spits but trying for 20-30 minutes I only got it started once and died (possibly because the fuel pump was off) after about 10 seconds revving it at 4-5k rpm - wouldn't start again.
Is it flooded? How can I get it started if it is? Would something like starting fluid in the gas tank make a difference? Or is that something Seafoam is good for?

74RX4

iTrader: (10)

What Darren meant was you need to plug all the nipples where the vacuum hoses are supposed to be hooked up. Any nipple left unplugged on the carb or intake manifold will create a vacuum leak. Symptoms could be exactly what you are describing. Why are all the lines disconnected?

Thoroughscrub

I don't know why so much has been disconnected. My friend said whoever had it before him messed with a lot of things, not knowing what they were doing. So, your guess as is good as mine as to why someone would unplug things from an engine.
I'll go through and plug anything that looks like it should have a hose connected to it. I'll be back with an answer.

One question though. I don't understand the concept of a vacuum leak. Do things require compression, or negative pressure? And what are they?


I can't thank you guys enough for all the answers and support you're giving me! I'd've given up long ago it it weren't for this place!

rotordogg

iTrader: (4)

The engine runs by allowing a specific amount of air/fuel into the intake and then ignited by the spark. The air enters through the top of the carb and as it passes through the carb, fuel is added to it. The continuous draw of air into the engine creates a vaccuum inside the intake manifold.

The engine management devices take advantage of this Vacuum for various things. For example, increasing spark advance on the distributor. As the load on the engine increases so does the vacuum inside the manifold. With some smart hose routing, the vacuum signal can pull on a lever inside the dizzy and advance the timing.

If any of these hoses is disconnected (or if the manifold gasket is leaking) it creates a vacuum leak. A vacuum leak means air is being sucked into the intake AFTER the carb has already created a proper air/fuel mix. The result is too much air and not enough fuel. The car will run lean and idle high, or not at all. Most small vaccuum leaks can be overcome at higher RPM's because the amount of air/fuel being drawn into the engine is much greater than the small amound of extra air introduced via the vacuum leak. So you can drive it, just not idle. And performance will suffer at any rpm because of the unmetered air in the system.

74RX4

iTrader: (10)

A couple of clear pictures of the vacuum hoses and the left and right sides of the carb might help us help.

Thoroughscrub

Rotordogg, that makes a lot of sense now! Thank you!
There are several very small holes here and there that don't look like a hose could or would connect to them. I'm not sure of they need to be plugged or not.

Here are some pictures though, best I could do with the light outside getting dim.

http://img803.imageshack.us/img803/9535/img5204z.jpg
http://img821.imageshack.us/img821/4104/img5203k.jpg
http://img580.imageshack.us/img580/4319/img5207od.jpg

Here are the mystery holes as well.
http://img137.imageshack.us/img137/1214/mysteryhole.jpg
http://img815.imageshack.us/img815/8...steryhole2.jpg

Kentetsu

(cough cough) still waiting...

Right now you are looking at everything. If you check the two items above, it will tell you whether your issue is related to the ignition, or the fuel system. Right now you're just shooting in the dark hoping to hit something...

rotordogg

iTrader: (4)

Kentetsu is right, double check those two things really quick and let us know. However, those pictures show a cluster f*ck of a hack job on the hoses. I would be surprised if there wasn't a few vacuum leaks.

Thoroughscrub

My bad! The float is right in the middle of the front window, when I checked the back one it was dark, but I'll go out now and check.

ztfdrake61

Your mystery holes are the pivot points for internals on the carburetor, they don't need to be plugged

Kentetsu

Check the level of fuel in the bowls, not the height of the float...

Thoroughscrub

They're all very blurry.. but here's the best of what I could get of the rear float.

http://img232.imageshack.us/img232/7690/float3.jpg
http://img857.imageshack.us/img857/5549/float2.jpg
http://img695.imageshack.us/img695/2005/floatk.jpg

Thoroughscrub

Do I just pull the whole plug and keep it hooked up to the distributor? Would it be a problem with the distributor if there was no spark? Because the plugs are brand new.

rotordogg

iTrader: (4)

Unplug all of the spark plugs so the engine doesn't try to start. Pull the fuse to the fuel pump so fuel doesn't keep spraying into the engine. Remove a spark plug (doesn't matter which one) and connect it to a plug wire. Lay it down on the engine so that the threads are touching metal. It needs a ground to create a spark. Have someone crank the engine for a couple seconds. You will immediately see it spark if everything is working. Do this for all 4 plug wires. Make a note of any wires that do not spark, or that seem to have very weak spark.

Ignitors or coils will cause no/weak spark.

Safety Note: the open plug hole will allow gas vapor to spray into the engine bay. Keep the plug away from the open plug hole and don't smoke. Don't overcrank either. It only takes a couple rotations of the engine to be sure of spark.

Thoroughscrub

So say one plug doesn't spark. Would I just need another spark plug?

rotordogg

iTrader: (4)

If only one plug wire does not have spark (and you used the same plug on the other wires) then you know it isn't the plug. If it is just one plug, then the only possiblity I can think of is the distributor cap or plug wire.

The coil creates power for two plugs. ie. the leading coil will supply voltage to both the leading plugs. The ignitor triggers the spark to both plugs. So if only one plug isn't firing, the only thing between the plug and the voltage is the contact point inside the distributor cap and the plug wire itself.

Thoroughscrub

I... Don't quite understand.
I've had some serious trouble getting anyone to help me in person. Much less someone that knows anything about rotaries... I'm tempted to just take it to a shop... problem is I can't drive it...
Those pictures of the rear float are as good as I'm going to be able to get.

I got it started after spraying about 6-7 seconds worth of starting fluid. I ran it for 7-8 minutes, revving between 3k and 5k, and tapping it up to 8k like two times. When it gets below 3k I can feel it start to die.. If it hits 2k it flat out dies - clutch or no clutch. This is leading me back to believing that it's is mainly an issue with my vacuum tubes. I'll take it to a shop to get them all hooked up correctly though, and probably use new hoses... I'm just tired of doing things so blinded.
The front float bowl is fine but it looks like the rear might not be so hot, although it's really difficult to tell.

http://img857.imageshack.us/img857/5549/float2.jpg

http://img695.imageshack.us/img695/2005/floatk.jpg

I found a used motor/tranny/carb or CL for $200.
Sounds like a good deal, springing for that if it'd fix my problem would be a no brainer for me at this point. But If I'm stuck with the same problems I'd shoot my 7 with a hundred giant guns.

Thoroughscrub

Still need answers and help!

LizardFC

iTrader: (1)

Until you have all the vacuum lines hooked up correctly and all possible leaks blocked off, it's going to be nearly impossible to diagnose any other problems. I wouldn't go buying another motor because an install is going to be far more technical than just hooking up what's missing from this one. This is a good opportunity to learn "what goes where/what does what" on the 12a. Think of it as school

Also, don't let it rev so high when the motor is cold if you can help it. It's not good for the engine.