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Thread: Hard starting
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mwpayne1
Redlining
Posts: 239
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posted August 19, 2010 09:01 AM |
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Hard starting
Hey guys, I'm having an issue with startup on my 74. Once started, its fine. If started every day, no problems. Problem is, it may sit for weeks. Everything is new, cap, plugs, coils, wires, carb rebuilt.
Today, I couldn't get it started at all...it would fire for a second, but just wouldn't catch completely. Almost like it was flooded. I pulled plugs, pulled fuel pump fuse, blew it out. reinstalled. No luck. Gas is fresh. Tried swapping ignitors, too. Gas is on plugs, so fuel is there. Ordered BR7EIX plugs today to try those. Any other ideas?
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Klaus42
Rotorhead
Posts: 1877
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posted August 19, 2010 11:52 AM |
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Intake manifold vacuum leak? Aged/brittle/cracked vac caps?
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Klaus42
Rotorhead
Posts: 1877
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posted August 19, 2010 11:54 AM |
 Edited By: Klaus42 on 19 Aug 2010 11:54 |
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How about the ignition switch itself? Known to develop an issue sometimes where it will no longer run in the normal 'on' position... even as it cranks fine, and will keep running if held barely past the 'run' position... could maybe be on its way out?
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mwpayne1
Redlining
Posts: 239
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posted August 19, 2010 12:41 PM |
Edited By: mwpayne1 on 19 Aug 2010 12:43
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Vac caps all new, good suggestion, though. Vac lines all new as well. Will recheck, could have worked loose.
Hadn't thought about the ignition switch. You're saying it could crank, sputter, not quite fire, all this could be the switch?
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Klaus42
Rotorhead
Posts: 1877
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posted August 19, 2010 06:12 PM |
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Yes -- all that and more (or less) can be the ignition switch, definitely... IF it's not something else...
The 'typical' failure I experienced was that I could crank the starter as long as the battery would hold out... and every time it wanted to run, and I let go of the key -- it died. Figured out I could find an 'in between' spot that I could carefully back the key off the start position to, to where it would run, and keep running... just shy of spinning the starter. Bad/worn out ignition switch.
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dhood
Hauling
Posts: 134
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posted August 19, 2010 07:44 PM |
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I've gotta second the ignition. In my case, if I wanted to listen to the radio while parked the key had to be in the on position. But that would turn on the ingition and fuel pump circuits. So I just backed off the key a little till I heard the fuel pump shut down, then listen to the radio. Kinda have to balance the key and spring a little to make it work. So far no running problems.
If your ignition is good but your engine is bad, then could be compression. My first project truck was very hard starting due to gunk in the apex seals. Sitting around too long and oil settling into the chamber, I think every seal spent its time at the bottom of the chamber in the sludge. Spinning the rotors while running would mostly free them up. I wouldn't have a problem if it was driven daily.
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mwpayne1
Redlining
Posts: 239
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posted August 20, 2010 05:04 AM |
Edited By: mwpayne1 on 20 Aug 2010 05:06
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As for the ignition, I found the post about that and put a meter on the + of a coil while cranking. Seems to stay at around 11V while cranking. So, I bought new plugs (BR8ES as a stopgap till my good uns arrive) and slapped those in.
Beast fired right up. Don't get it...2nd time this has happened, the 'old' plugs had maybe 300 miles on them. Compression is a thought, but I've had rotaries for years, and this one never, ever has had a warm start issue. Even now, once warm, starts easily.
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Klaus42
Rotorhead
Posts: 1877
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posted August 20, 2010 08:41 AM |
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What do your 'old' (300 mile) plugs look like?
Recommend B-12 Chemtool + a brass wire brush for cleaning.
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sparky
Redlining
Posts: 299
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posted August 20, 2010 10:01 AM |
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I have had starting issues with my last engine. Spent WAY too much time dealing with plugs, ignition, and carb. Everything was fine once engine was warm. Found i had a small water leak fouling the plugs on cold start. It would try to start and just never get there. The previous owner must have overheated the engine and never disclosed it.
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'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition
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mwpayne1
Redlining
Posts: 239
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posted August 20, 2010 10:53 AM |
Edited By: mwpayne1 on 20 Aug 2010 10:55
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Hmmm...there's a thought. As for plugs, leading rears would have a small amount of black that would all but wipe off. leading fronts even better. Trailings pretty darn clean.
That small coolant leak thing is a real possiblity, might not be able to see that on the plugs. If the new ones coming in don't make a difference I'm leaning that way. Sparky, did you end up doing a rebuild, or find another solution?
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mwpayne1
Redlining
Posts: 239
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posted August 20, 2010 11:24 AM |
Edited By: mwpayne1 on 20 Aug 2010 11:25
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Just for discussion, whats the technique you guys have for cold start anyhow? Book says pull choke out, crank till start, then push choke in till RPM is a 2k till fully warm.
Frankly, I've been giving the gas a couple of pumps first.
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sparky
Redlining
Posts: 299
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posted August 20, 2010 08:23 PM |
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Funny how i figured it out. I noticed that my inductive timing light was not flashing while attempting to start the motor. I also had voltage at the coils. If the plugs were grounding out then there would be reduced voltage through the wires.
Another thought, Connect a voltmeter on the coils plus terminal and verify voltage while cranking the engine. I also had an issue with the ignition switch turning off power to engine with the key in the start posiiton. Ended up installing toggle switch for starting.
As far as the engine fix.... found a thread on rx7 club. Ended up flushing cooling system with degreaser. Then used some acrylic copper engine block sealer you add in coolant. Perform 3 heat up and cool down cycles. Drove the truck for 2 more years. Upgraded the ignition to DLDFIS and NEVER had another starting problem.
The engine is on a stand and will be disassembled in a few months. Let me know what you find.
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition
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mwpayne1
Redlining
Posts: 239
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posted August 21, 2010 05:02 PM |
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Thanks for the tip on the block sealer, always wondered how well that would work on our engines. I did the meter check, voltage stays constant on the coil so OK there. Direct fire upgrade is something I've considered, couldn't hurt.
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sparky
Redlining
Posts: 299
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posted August 22, 2010 08:17 AM |
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I tried it as a bandaid and it worked very well. The engine is an old school 4 port that ported and rebuilt. Have mo history on the motor. Will know more when i tear it apart.
____________
'77 REPU
Stock 6-port
T-2 tranny
Weber IDA 48
Alum Flywheel
3rd gen Torsen in rear end.
DLDFIS ignition
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mwpayne1
Redlining
Posts: 239
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posted September 05, 2010 05:32 AM |
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Can you guys believe this...
The whole problem that's been going on with my hard starting and rough idle for months and months was, embarassingly, plug wires in the wrong place. However, I have a bit of an 'out', because months ago when I bought the cap I bought it from advance auto (I usually buy OEM). The cap is marked WRONG.
The other day while it was idling poorly I pulled one of the leading plug wires, noticed no spark. Was spark on trailing, swapped. Idle better. Hmmm. Did the other two.
Wa, freakin' la. SMOOOTH. Jeebus. Oh well, live and learn, huh? Cap says L1, going to T1, etc.
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