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rusty ecu cause no start/ stall?

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Old 07-21-15, 12:41 AM
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rusty ecu cause no start/ stall?

Hello everyone! I have tried rebuilding my Nikki carb and adjusting timing, but I can't seem to keep my 83 gsl running. I have removed all emissions except the evap canister. I can't find any vacuum leaks. I do not know if the emission control unit has anything to do with keeping the engine running. I do know I opened my ecu and found it is rusty on the inside and on its circuit board. Also the circuit board of the instrument cluster had some surface rust on it, but I scraped most of that off. The dash warning lights acts different than other rx7s I've owned, in that when I crank the engine, the red brake light on the dash turns off, then turns on again when the key is in the on position. Anyone have similar issues..?
Old 07-21-15, 10:12 AM
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If you clean the boards, just use an electronic cleaning solvent. Don't use anything to scape things off. It could make it worse.
Old 07-21-15, 03:16 PM
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Today I'm going to try resoldering my ecu and instrument cluster. I'm hoping this may help.
Old 07-21-15, 03:18 PM
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I'll try posting this in the classifieds too, but if anyone has a known good ecu for a 83 gsl with manual trans, I'd like to buy that as a back up.
Old 07-25-15, 10:30 PM
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Bought a better soldering iron, got it cleaned up best I can, installed the ecu, and I do have spark, but the crazy thing still won't idle
Old 07-26-15, 09:46 PM
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will it idle with the choke on? sounds like you may still have a vacuum leak somewhere
Old 07-26-15, 11:57 PM
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It still won't idle, not for long. I got it to run at 2k rpm for a minute today with the choke on halfway, I hit the throttle lightly, it stumbled and died, and hasn't run since. The trailing plugs were soaked with fuel, the leading smelled like fuel. I cranked it without the spark plugs in and with the fuel pump fuse out to clear out the motor. The floats seem perfect, sight glass shows halfway all the time. I noticed when clearing out the motor, the puffing sounds from the spark plug holes sounded much less forceful. Flooding makes apex seals get sticky, right?
Old 07-27-15, 12:02 AM
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I've ripped all emissions off my car, except the evap canister. I dont think i have anything left to cause a vacuum leak big enough to prevent the car from running. When the car was running, it would stall almost every time I came to a stop. Could a leaking brake booster be a vacuum leak?
Old 07-27-15, 12:07 PM
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yes because my booster just went out saturday night and when i come up to a stop light hitting the brakes kills the motor.

remove the hose that connects to your brake booster and turn it around. The vacuum check valve will keep the motor from being able to draw a vacuum on the booster and if it idles then you have found your problem because that is what I had to do to mine.

If you decide to drive it like that to pick up parts WARNING it requires double the force to stop on the brake pedal
Old 07-27-15, 05:30 PM
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ECU = Engine Control Unit, not 'Emissions'; there's a lot more going on with your ECU than just emissions testing, and if yours was soaked/corroded, giving it the once-over with a soldering iron isn't going to fix it.

Best bet is to find a replacement ECU from a similar vehicle - actually any non-SE 12a FB will do - and then start troubleshooting from there. This should at least get you to a solid footing before you start changing a bunch of things trying to track down a no-start. Good luck,
Old 07-27-15, 10:04 PM
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We hear about this time of issue from time to time on here. Someone has a starting/running issue and they decide to remove all the emissions thinking this will solve the problem. What ends up happening is that it introduces more issues, or the original issues is never resolved.

It's always recommend to resolve the original problem before taking the emissions apart.
Old 07-28-15, 12:52 AM
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Anyone have a good ecu for sale..?
Old 08-02-15, 11:06 AM
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Check the First Gen Classifieds section for part outs and post a WTB ad in there for the ECU you're looking for.

Idling on a carburetor-fueled car isn't controlled by the ECU, so it's most likely a vacuum/emissions system leak or a faulty solenoid.
Old 08-03-15, 10:40 PM
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I might do that. So its back to doing its random running amazing for a minute then abruptly cutting out. It seems to be fuel related, the float bowls don't have even levels in the carb windows after the stall and the levels look too low to let the car idle. If I have stripped my Nikki, would it require rejecting? Still have shutter valve, but locked it in place with wire and blocked it off, still have vacuum box for secondaries, have distributors vacuum advances hooked up to second from the left nipple on the carb base plate. Also noticed #2 water temp switch was bone dry when I pulled it out to test it. No coolant came out, but the radiator is full, and the temp gauge never got above 1/3. What the hell is going on here?
Old 08-08-15, 07:12 PM
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I plugged the line from the brake booster to the intake, no change, so I can cross off the booster as a leak.
Old 08-08-15, 08:17 PM
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Son of a *****... I ran some fresh gas through it, unplugged the float bowl vent solenoid, and put the mixture screw two and a half turns out and kept screwing in the throttle screw, and after lengthy cranking, the damn thing fired up and stayed idling, at 1100, but steady and awesome sounding. Didn't use the choke, just pumped the gas and held the pedal to keep it running til it warmed up. Neighbors came around looking for a sportbike again
Old 08-08-15, 08:22 PM
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Stock temp gauge shows roughly 20% when warmed up, but no2 temp switch in the lower left of the radiator still comes out dry, with no coolant coming out. It's time to have my radiator rebuilt and to get a dual pulley for the alternator
Old 08-08-15, 09:35 PM
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Originally Posted by rx7inoregon
Stock temp gauge shows roughly 20% when warmed up, but no2 temp switch in the lower left of the radiator still comes out dry, with no coolant coming out. It's time to have my radiator rebuilt and to get a dual pulley for the alternator
I believe that lower temp sensor area is sealed, meaning the sensor does not actually see coolant.
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