1994 rx7 5 speed. cranks, no start, no spark, new battery. gets air and fuel.
07-17-19, 12:42 PM
#1
zoom zoom tree boom
Thread Starter
1994 rx7 5 speed. cranks, no start, no spark, new battery. gets air and fuel.
so car was wrecked, back in 2017, before i owned it...purchased wrecked. but it started up and drove. idled strong.
grabbed parts over the last 2 years for repair. new spark plugs 2 months ago. new battery...so no CEL codes. on that note, the CEL light does not come on during gauge precheck, 1 click key turn. all other lights work fine.
so after waiting for a long time, the car went on at my buddy's shop's frame rack. at that point (4 months ago), she would turn over, and idle, a bit rough. gas is 2 years old now. (took forever for the shop to pull the frame). looked for the tank drain that is supposed to be there, could not find it on mine to save my life.
car frame is pulled pretty straight, welded a new front support on, and i drive her off rack. she stalls out. now, she cranks, won't turn over. i, nor are the guys i know, rotary experienced at all. i replaced the PTU, didn't help. the ecu has been moved (by some previous sloppy ex-owner of the car) and has a couple wires patched in to that harness that run right to engine sensors (will have to figure out which ones). should i focus on that?
also, all those grounds that bolt to the front support. should i do those differently from stock?
Last edited by #600; 07-17-19 at 12:48 PM.
07-17-19, 12:49 PM
#2
RX-7 Bad Ass
iTrader: (55)
What is a PTU?
With so much time and various changes you'll have to go through a lot of steps to troubleshoot. If the gas stinks, drain the tank (there's a 14mm plug on the bottom) and put in fresh gas.
Engine may be flooded from body shops starting/moving/shutting off.
You'll need to go system by system - are you getting fuel? Spark? ECU has power and is working?
The grounds on the front support - why would you need to do them differently? Just hook them up like stock.
Dale
With so much time and various changes you'll have to go through a lot of steps to troubleshoot. If the gas stinks, drain the tank (there's a 14mm plug on the bottom) and put in fresh gas.
Engine may be flooded from body shops starting/moving/shutting off.
You'll need to go system by system - are you getting fuel? Spark? ECU has power and is working?
The grounds on the front support - why would you need to do them differently? Just hook them up like stock.
Dale
07-17-19, 01:28 PM
#3
zoom zoom tree boom
Thread Starter
ptu, wrong term i'm sure. the igniter bolted driver's side near the fender/firewall.
engine not flooded. i did the procedure to unflood it as described on this site.
fuel, yes. spark, no. ecu has power. no one touched it since the last 5 months, when the car was running well.
the slide on grounds are just a crappy design. i thought people redid those as a maintenance item.
engine not flooded. i did the procedure to unflood it as described on this site.
fuel, yes. spark, no. ecu has power. no one touched it since the last 5 months, when the car was running well.
the slide on grounds are just a crappy design. i thought people redid those as a maintenance item.
07-17-19, 03:35 PM
#4
RX-7 Bad Ass
iTrader: (55)
The igniters pretty much never fail. The no spark is where to start troubleshooting. Is it a stock ECU?
Dale
Dale
08-11-19, 06:56 PM
#5
zoom zoom tree boom
Thread Starter
updated to say thank you to Dale. 
well, update and progress. i unplugged and reseated the ECU harness. the car turned over and idled. this was last wednesday.
i got the car to idle pretty well. i also pulled out the old gas and put in fresh. it was idling, and then, there was an audible click from the passenger footwell area, and the engine turned off. would not crank again.
i idled for about a minute and a 1/2....and yes, it's a stock ECU. although, it is not mounted, so could have been replaced by some previous owner.
what would make a click over there, and kill engine power? i'm going to unplug and reseat the ECU plugs again.
i've covered everything in the engine bay. the passenger side footwell is the problem location for me. any input will be awesome. thanks...
well, update and progress. i unplugged and reseated the ECU harness. the car turned over and idled. this was last wednesday.
i got the car to idle pretty well. i also pulled out the old gas and put in fresh. it was idling, and then, there was an audible click from the passenger footwell area, and the engine turned off. would not crank again.
i idled for about a minute and a 1/2....and yes, it's a stock ECU. although, it is not mounted, so could have been replaced by some previous owner.
what would make a click over there, and kill engine power? i'm going to unplug and reseat the ECU plugs again.
i've covered everything in the engine bay. the passenger side footwell is the problem location for me. any input will be awesome. thanks...
Last edited by #600; 08-11-19 at 07:03 PM.
08-11-19, 10:13 PM
#6
I'm having trouble thinking of any relays or other things that might click and are mounted near the passenger footwell on a USDM left-hand-drive car. If you're working with a JDM right-hand-drive car, that's something you should mention. Check for blown fuses in the engine bay and cabin fuse boxes. There is a ring terminal or spade terminal near where the ECU mounts, it should be grounded to the chassis.
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08-12-19, 08:04 PM
#8
zoom zoom tree boom
Thread Starter
I'm having trouble thinking of any relays or other things that might click and are mounted near the passenger footwell on a USDM left-hand-drive car. If you're working with a JDM right-hand-drive car, that's something you should mention. Check for blown fuses in the engine bay and cabin fuse boxes. There is a ring terminal or spade terminal near where the ECU mounts, it should be grounded to the chassis.
there is only one plug- in relay (or looks like a relay) i even located in the passenger footwell area. i unplugged it completely, and the car still runs/idles without it, so it's not the issue. i will plug it back in, going forward.
it could be some alarm for all i know. or a fault in the ECU. it appears to have been changed at some point in it's lifetime. it's hard to get under the dash with where the car is parked now. but at least i did something that caused it to turn over and idle (unplugged ECU, checked harness, replugged it all back together), since it left the rack. and it did run better with fresh gas. will have to change the fuel filter again, obviously...but want to clear some more excess out of the tank first.
all fuses in the engine bay are good. tested them all twice out of circuit.
that ground wire is tightened to the floor/metal near the ECU with a few ground wires attached to it.i have not checked any internal/interior fuse panels...actually not sure where they are, but that's a google search.
i'll snap a picture of the sloppy ECU and harness area.cranks normally. never had an issue with cranking.
Last edited by #600; 08-12-19 at 08:13 PM.
08-13-19, 08:54 AM
#9
Your posts are a little confusing to diagnose. You say in post #5 that the engine doesn't crank, but in #8 you say it not only cranks and never had an issue with cranking
So, does it crank or not? What symptoms are you experiencing now?
Check the basics and go from there. Fuel, Compression, and Spark (at the right time), where fuel means you have a good fuel pressure and spray at the injectors. If the gas has been sitting for some time, you need to clean out the tank (not just add new gas) and replace the fuel filter. The injectors should also be sent out for servicing.
An old school test for fuel problems is spraying some starter fluid in the TB. If it starts (or kicks over) but then stalls after the starting fluid burns off, you have a fuel problem
If it doesn't crank, it's an electrical problem (or frozen motor)
Check the basics and go from there. Fuel, Compression, and Spark (at the right time), where fuel means you have a good fuel pressure and spray at the injectors. If the gas has been sitting for some time, you need to clean out the tank (not just add new gas) and replace the fuel filter. The injectors should also be sent out for servicing.
An old school test for fuel problems is spraying some starter fluid in the TB. If it starts (or kicks over) but then stalls after the starting fluid burns off, you have a fuel problem
If it doesn't crank, it's an electrical problem (or frozen motor)
Last edited by TomU; 08-13-19 at 08:56 AM.
08-13-19, 06:48 PM
#10
zoom zoom tree boom
Thread Starter
whoops, that's on me. i edited that post to thank Dale, and no idea how i slipped "would not crank again". should have read "will not turn over again"
i was wondering where that came from. thank you.
to follow the car's history...before me, it hit a tree.
so, i started out with a car that ran, idled, drove...
went on a rack at a buddy's body shop to get pulled. took a while to get it on the rack.
drove on the rack.
rack work done. drove off the rack. car died. and that's what i've been chasing down since.
it was no spark. went thru everything on earth, and by unplugging and replugging in the ECU, the car started up. so i found my issue, or at least, one of them.
car runs, idles, and drives...but something is turning off spark, and i suspect the ECU or a relay close by.
today's results...she cranked over, started up, idled for about 10 seconds, then she turned off (no click from the passenger footwell today, at least none heard). i pulled the battery to charge her up (it's new, just weak from sitting), and have some pictures coming for a couple of relays i'd like to get ID'd near the ECU location.
i'm at a point where i can get the rx7 to start and run. it might turn over tomorrow, or just crank. if it does, i reseat the ECU plugs, and she'll fire right up. might be a coincident. but it's a reliable one thus far.
i will be getting the injectors checked. technically, the whole car. just want to cover basics on my end before it goes to the shop.
fuel filter is new, but will be changed again. fuel in the tank was "good", just 2ish years old. so removed, and fresh fuel put in. new correct plugs in the right locations. i've been following site tips for 2 years now. much appreciation.
i was wondering where that came from. thank you.
to follow the car's history...before me, it hit a tree.
so, i started out with a car that ran, idled, drove...
went on a rack at a buddy's body shop to get pulled. took a while to get it on the rack.
drove on the rack.
rack work done. drove off the rack. car died. and that's what i've been chasing down since.
it was no spark. went thru everything on earth, and by unplugging and replugging in the ECU, the car started up. so i found my issue, or at least, one of them.
car runs, idles, and drives...but something is turning off spark, and i suspect the ECU or a relay close by.
today's results...she cranked over, started up, idled for about 10 seconds, then she turned off (no click from the passenger footwell today, at least none heard). i pulled the battery to charge her up (it's new, just weak from sitting), and have some pictures coming for a couple of relays i'd like to get ID'd near the ECU location.
i'm at a point where i can get the rx7 to start and run. it might turn over tomorrow, or just crank. if it does, i reseat the ECU plugs, and she'll fire right up. might be a coincident. but it's a reliable one thus far.
i will be getting the injectors checked. technically, the whole car. just want to cover basics on my end before it goes to the shop.
fuel filter is new, but will be changed again. fuel in the tank was "good", just 2ish years old. so removed, and fresh fuel put in. new correct plugs in the right locations. i've been following site tips for 2 years now.
much appreciation.
Last edited by #600; 08-13-19 at 07:01 PM.
08-14-19, 01:13 AM
#11
The cabin fuses are near the clutch / dead pedal /firewall area on the LHD cars. I think all the cabin fuses are under a single cover.
When the engine stops running after 10 seconds, does the it shut off quickly like turning the key off, or does it sort of sputter and stall? Sputtering and slowly stalling might happen if the fuel pump turned off and fuel pressure bled off. Engine immediately shutting off could be from killing power to the injectors or coils, or losing the CAS signals. The stock ECU would never shut down the engine as a fault response, all the possible faults just result in a lower rev limit. It's unsafe to kill the engine on purpose because the brake booster and power steering stop working.
When the engine stops running after 10 seconds, does the it shut off quickly like turning the key off, or does it sort of sputter and stall? Sputtering and slowly stalling might happen if the fuel pump turned off and fuel pressure bled off. Engine immediately shutting off could be from killing power to the injectors or coils, or losing the CAS signals. The stock ECU would never shut down the engine as a fault response, all the possible faults just result in a lower rev limit. It's unsafe to kill the engine on purpose because the brake booster and power steering stop working.
08-14-19, 06:09 AM
#12
Ban Peak
iTrader: (49)
The cabin fuses are near the clutch / dead pedal /firewall area on the LHD cars. I think all the cabin fuses are under a single cover.
When the engine stops running after 10 seconds, does the it shut off quickly like turning the key off, or does it sort of sputter and stall? Sputtering and slowly stalling might happen if the fuel pump turned off and fuel pressure bled off. Engine immediately shutting off could be from killing power to the injectors or coils, or losing the CAS signals. The stock ECU would never shut down the engine as a fault response, all the possible faults just result in a lower rev limit. It's unsafe to kill the engine on purpose because the brake booster and power steering stop working.
When the engine stops running after 10 seconds, does the it shut off quickly like turning the key off, or does it sort of sputter and stall? Sputtering and slowly stalling might happen if the fuel pump turned off and fuel pressure bled off. Engine immediately shutting off could be from killing power to the injectors or coils, or losing the CAS signals. The stock ECU would never shut down the engine as a fault response, all the possible faults just result in a lower rev limit. It's unsafe to kill the engine on purpose because the brake booster and power steering stop working.
Post a picture of the ECU area, if the problem is spark it's usually due to a baked harness, hack wiring, or a loss of a coil ground. On top of that, was any wiring damaged in the crash?
08-14-19, 08:59 AM
#13
zoom zoom tree boom
Thread Starter
The cabin fuses are near the clutch / dead pedal /firewall area on the LHD cars. I think all the cabin fuses are under a single cover.
When the engine stops running after 10 seconds, does the it shut off quickly like turning the key off, or does it sort of sputter and stall? Sputtering and slowly stalling might happen if the fuel pump turned off and fuel pressure bled off. Engine immediately shutting off could be from killing power to the injectors or coils, or losing the CAS signals. The stock ECU would never shut down the engine as a fault response, all the possible faults just result in a lower rev limit. It's unsafe to kill the engine on purpose because the brake booster and power steering stop working.
When the engine stops running after 10 seconds, does the it shut off quickly like turning the key off, or does it sort of sputter and stall? Sputtering and slowly stalling might happen if the fuel pump turned off and fuel pressure bled off. Engine immediately shutting off could be from killing power to the injectors or coils, or losing the CAS signals. The stock ECU would never shut down the engine as a fault response, all the possible faults just result in a lower rev limit. It's unsafe to kill the engine on purpose because the brake booster and power steering stop working.
,,,it sounds like its only running on the prime or flooding and then not starting. When cars sit they go to hell, install a fuel pressure gauge and watch it- your pump may be dying or the fuel pump relay and or resistor could be failing.
Post a picture of the ECU area, if the problem is spark it's usually due to a baked harness, hack wiring, or a loss of a coil ground. On top of that, was any wiring damaged in the crash?
Post a picture of the ECU area, if the problem is spark it's usually due to a baked harness, hack wiring, or a loss of a coil ground. On top of that, was any wiring damaged in the crash?
also, can someone ID the relay? circled in red. above the ECU's stock mounting location, passenger side footwell. not an issue, just like to know what it's purpose is.
i was able to ID everything else in that area, thanks to this group...
Last edited by #600; 08-14-19 at 09:08 AM.
09-20-20, 09:14 AM
#14
zoom zoom tree boom
Thread Starter
to close this out, it seems the main issue was the ECU harness connection. after i had removed the harness from the ECU and cleaned the pins, car's been reliable to start since then, finally got her home, rode around for @35 minutes yesterday. now just to buy the 350 pieces to finish it up.
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