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-   -   Fresh rebuild won't start (https://www.rx7club.com/new-member-rx-7-technical-256/fresh-rebuild-wont-start-1099179/)

Coinshark 04-19-16 07:47 AM

Fresh rebuild won't start
 
Question for all of you smarter guys than me ( which is everyone). I recently rebuilt my engine, timed according to everyone's posts, got it to fire for about 30 sec last night, couldn't get it started again after. Any ideas?

I tried moving the timing a tooth back and forward which seemed to make it worse (sounding). I've seen were some say rotaries are notorious for having low compression after a fresh rebuild until everything seats.

Let me know your thoughts :dunno:

satch 04-19-16 08:07 AM

You could place oil in the housings via the spark plug holes (a tablespoon should do) to help build compression. And did the engine die after 30 seconds or did you turn the engine off? If you turned it off then you should try letting the engine run longer.

Coinshark 04-19-16 08:16 AM


Originally Posted by satch (Post 12053630)
You could place oil in the housings via the spark plug holes (a tablespoon should do) to help build compression. And did the engine die after 30 seconds or did you turn the engine off? If you turned it off then you should try letting the engine run longer.

It just died. I tried to keep it going but, it didn't stay running.

FührerTüner 04-19-16 08:33 AM

Check compression. if its not terrible, pull start it.

Rx7ADK 04-19-16 09:03 AM

before changing your timing and risk detonation or something serious I would just check the simply stuff first (triple check ground connections, main fuses, main vacuum lines, fuel pressure and fuel cleanliness, spark, compression, deflood) You can check all that in less than an hour without tearing off UIM and stuff. All this will eliminate most your questioning.

FührerTüner 04-19-16 09:34 AM

Yeah wait, i didnt notice you said youre moving teeth. you need to set your base timing first. Turn it over and check with a timing light and get ur marks close.

Coinshark 04-19-16 10:02 AM


Originally Posted by Fuhnortoner (Post 12053672)
Yeah wait, i didnt notice you said youre moving teeth. you need to set your base timing first. Turn it over and check with a timing light and get ur marks close.

Well, I had my base timing set and one person suggested moving it a tooth. I did that yesterday and it didn't help. It actually made it sound worse and didn't want to grab while starting. So I moved it back to where it was. A friend of mine has a timing light though so, I'll check it when I can get him over and I can verify spark.

I'll pull my plugs tonight and check them, perhaps they are dirty or something.

FührerTüner 04-19-16 10:47 AM

You should just start over.

Do this:

Startup
Ensure the throttle reads smoothly from 0-100% in its full
range of movement.
Power up the fuel pumps and check entire fuel system for leaks before attempting
to start the engine.
Once verified that all sensors are correctly operating and fuel system is functional,
attempt to start the engine. If engine does not start check:
1. Ignition Timing
2. Correct Fuel Pressure
3. Spark Plugs are not fouled or wet
4. Engine Compression
5. Ignition is wired in correct firing order
6. Ignition is firing on intake stroke not exhaust stroke
Once engine is running, ensure fuel pressure remains correct under all conditions and
that battery is charging.

Coinshark 04-19-16 10:52 AM


Originally Posted by Fuhnortoner (Post 12053706)
You should just start over.

Do this:

Startup
Ensure the throttle reads smoothly from 0-100% in its full
range of movement.
Power up the fuel pumps and check entire fuel system for leaks before attempting
to start the engine.
Once verified that all sensors are correctly operating and fuel system is functional,
attempt to start the engine. If engine does not start check:
1. Ignition Timing
2. Correct Fuel Pressure
3. Spark Plugs are not fouled or wet
4. Engine Compression
5. Ignition is wired in correct firing order
6. Ignition is firing on intake stroke not exhaust stroke
Once engine is running, ensure fuel pressure remains correct under all conditions and
that battery is charging.

Thank you, will do. Guess It's time to buy a fuel pressure gauge. :doh:

Coinshark 04-22-16 08:18 AM

So, I think after over 6 months of being down for the rebuild the gasoline in my tank went bad. I checked timing, fuel pressure, plugs, ignition wiring. I ran out of time last night to do my compression test though.

FührerTüner 04-22-16 08:20 AM


Originally Posted by Coinshark (Post 12054999)
So, I think after over 6 months of being doing for the rebuild the gasoline in my tank went bad.

Its possible but i doubt it.


I checked timing, fuel pressure, plugs, ignition wiring. I ran out of time last night to do my compression test though.
Yeah you need to check compression. Even a ghetto check will work. Compression tester 20 bucks at oreilly

Coinshark 04-22-16 08:22 AM


Originally Posted by Fuhnortoner (Post 12055001)
Its possible but i doubt it.



Yeah you need to check compression. Even a ghetto check will work. Compression tester 20 bucks at oreilly

It really wanted to start last night but, it just never fired. :( I has a compression tester already. We just ran out of time.

Rx7ADK 04-22-16 08:36 AM

Check your fuel pressure yet? Pull injectors and look at them.

FührerTüner 04-22-16 08:54 AM

Actually, after reading through this again, your engine may be flooded. Have you pulled your plugs and inspected them? Wet?

Coinshark 04-22-16 09:03 AM


Originally Posted by Fuhnortoner (Post 12055019)
Actually, after reading through this again, your engine may be flooded. Have you pulled your plugs and inspected them? Wet?

I checked that last night also. Forgot to post. They were wet so, I deflooded.

warpig 04-22-16 09:25 AM

I have A second gen and when mine floods i pull the fuel pump fuse and the injection fuse crank it for a little then plug them back it and it should start.

Coinshark 04-22-16 09:26 AM


Originally Posted by warpig (Post 12055038)
I have A second gen and when mine floods i pull the fuel pump fuse and the injection fuse crank it for a little then plug them back it and it should start.

That's how I deflood as well

lduley 04-22-16 10:54 AM

Fresh rebuilds can be a biatch to get running, deflood it again, pull the plugs and put oil in the chambers, hook up a battery charger with a boost start option and try it, if that doesn't do it, pull start it

Aaron Cake 04-24-16 10:00 AM

Stop farting around with timing. It has little effect on startup as long as the CAS is on the right tooth.

By this time the engine is very flooded.

Push start it with another vehicle. Don't waste further time and frustration. Get it up to about 20 MPH then carefully let the clutch out in 1st gear. As long as the engine is capable of running (ie. fuel, spark), it will run.

Hold the RPMs up around 2500 to burn off all the crap.

Rx7ADK 04-24-16 12:45 PM

Just for my own learning sake, is the point of pull starting it all for the purposes of "forcing" rotational motion because the starter is too weak to turn a flooded rotary?

lduley 04-24-16 01:30 PM

Its not that the starter is to weak, its that the starter can only spin up to so many RPMs, and you have alot of things going against you

One being its a fresh rebuild, compression is going to be pathetically low until you get it running and give the seal time to seat

Two being its flooded, when an engine is flooded, it lowers the compression even more, so now you have even LOWER compression

The thing with pull/push starting it is when you release the clutch, the movement of the car will spin the engine over faster than the starter ever can, which the faster a engine spins, the more compression it will build (to a point)

Before you push/pull start it, do as i said and put some oil in the plug holes, it will help bring the compression up to fire it

Rx7ADK 04-24-16 01:31 PM

Thanks for clearing that up. Makes sense.

Coinshark 04-25-16 09:55 AM


Originally Posted by Aaron Cake (Post 12055806)
Stop farting around with timing. It has little effect on startup as long as the CAS is on the right tooth.

By this time the engine is very flooded.

Push start it with another vehicle. Don't waste further time and frustration. Get it up to about 20 MPH then carefully let the clutch out in 1st gear. As long as the engine is capable of running (ie. fuel, spark), it will run.

Hold the RPMs up around 2500 to burn off all the crap.

Lol Aaron, I ended up pull starting it saturday. Got it to run. Timing was weird. Really advanced but it was smooth around 1k rpms. It didn't like to be much lower than that. Then I pulled 4 codes. 2 were the MOP (which is deleted) So I think I'm going to get the rtek chip since I premixed already. 1 was the air flow meter and the other was a intake air thermosensor which I assume is just backwards since theres only 2 prongs. Also, after I shut it off it was very hard to restart it. Maybe because of the coded problems?

Thanks for all the suggestions everyone! Sorry for being a rotary nub :lol:

satch 04-25-16 11:57 AM

The MOP should not be deleted, but hooked up or if not then you risk damage to the ECU

Coinshark 04-25-16 12:26 PM


Originally Posted by satch (Post 12056243)
The MOP should not be deleted, but hooked up or if not then you risk damage to the ECU

It's still plugged in as per what everything I read about it was telling me to do. It's capped but still plugged in for now.


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