85 se
02-27-15, 08:24 PM
#1
85 se
Ok I just picked up my car and the guy said it ran but was low on power. It has auto light plugs in it and I think the coils are going out. Now should I try and start it after I correct the problems or take it out and rebuild it. It has 140xxx miles. It has sat 5 years. I'm on the fence hear.
02-28-15, 01:10 PM
#6
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the autolite plugs have a gap that is really big, and the stock ignition doesn't seem to be able to handle it, and then you get low power and fried coils and stuff.
weirdly, when you jump to a more powerful ignition the autolites work really well.
weirdly, when you jump to a more powerful ignition the autolites work really well.
02-28-15, 01:16 PM
#7
Yes I can rotate by hand with all the plugs in. I hooked up the c test and turned it over by hand. No battery to crank and I got around 5 psi on both rotors. With all the plugs out I can hear the air with a faint pop. And the throttle is wide open.
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02-28-15, 05:59 PM
#10
So a little up date I have 95-110 I can't read the gage that well but both the front and rear are very close. So I tried to start it. It cranks and tried to start( with a quick shot of eather) followed by a after fire that set my buddys car alarm off. But after it just cranks. Re tested after and still in the same spots on the c test. Now mazda says 100 psi min correct. Now I dont think I'm getting fuel. Is there a test port on the fuel line?
02-28-15, 11:52 PM
#11
84SE-EGI helpy-helperton
On the air cleaner side, between the MAF sensor and the airbox, you'll find a plug with 2 connections on it - if you shunt a wire across the 2 connections, it will simulate the MAF sensor reading intake air, and turn on the fuel pump anytime the key is in 'run' mode. Once you do this, turn the key on and listen at the rear driver's side wheel for the sound of the fuel pump running.
As you're new here (14 posts so when I read this), you may not know that the -SE gets the ECU signal for injector pulse timing from the coils. There's a connection on one of the coils which goes to the ECU and is a triggering signal for injectors to fire. If that's not connected, your injectors won't be moving fuel into the intake path. You can check this with a rod and a stethoscope by putting the probe on top of the injector when you're cranking it - a clicking sound is the fuel injector opening and closing, spraying fuel.
While you're checking Air/Fuel/Spark - also take the airbox lid and air filter out and run your finger down the MAF sensor intake. You should be able to move the mechanical air door in and out smoothly feeling spring pressure to close the door. This is how the ECU determines volume of incoming air, and also how it determines when to run the fuel pump and duration of injector pulse to match fuel to air ratio. A stuck MAF/AFM door will result in no fuel pump on, no fuel pressure, no intake air, and no start. In that case, the only thing you would get is spark.
Speaking of spark - an easy test is to remove a trailing plug and while holding it with an insulated glove or dry/non-greasy rag, ground it against something solid - like the driver's side strut tower bolt - and have a friend turn the engine over with the starter - you should see and hear spark plug firing, confirming that you have spark for ignition.
Don't forget to remove the AFM/Fuel Pump shunt wire when you're done troubleshooting - leaving it in there could lead to flooding issues down the road. You only want fuel pump on when air is coming in. HTH,
As you're new here (14 posts so when I read this), you may not know that the -SE gets the ECU signal for injector pulse timing from the coils. There's a connection on one of the coils which goes to the ECU and is a triggering signal for injectors to fire. If that's not connected, your injectors won't be moving fuel into the intake path. You can check this with a rod and a stethoscope by putting the probe on top of the injector when you're cranking it - a clicking sound is the fuel injector opening and closing, spraying fuel.
While you're checking Air/Fuel/Spark - also take the airbox lid and air filter out and run your finger down the MAF sensor intake. You should be able to move the mechanical air door in and out smoothly feeling spring pressure to close the door. This is how the ECU determines volume of incoming air, and also how it determines when to run the fuel pump and duration of injector pulse to match fuel to air ratio. A stuck MAF/AFM door will result in no fuel pump on, no fuel pressure, no intake air, and no start. In that case, the only thing you would get is spark.
Speaking of spark - an easy test is to remove a trailing plug and while holding it with an insulated glove or dry/non-greasy rag, ground it against something solid - like the driver's side strut tower bolt - and have a friend turn the engine over with the starter - you should see and hear spark plug firing, confirming that you have spark for ignition.
Don't forget to remove the AFM/Fuel Pump shunt wire when you're done troubleshooting - leaving it in there could lead to flooding issues down the road. You only want fuel pump on when air is coming in. HTH,
03-01-15, 12:31 AM
#12
Yes I'm new 
but want all of the knowledge. 1st yes the maf gate moves freely heard it open and close when cranking and moved it with my fingers. 2nd do you know which wire that is from the coil to the ecu? 3rd I did check for spark before hand, so I have spark.4th I will jump the maf and listen for the pump. I ordered the repair book and spark plugs no auto parts shop within 100 miles has them.
but want all of the knowledge. 1st yes the maf gate moves freely heard it open and close when cranking and moved it with my fingers. 2nd do you know which wire that is from the coil to the ecu? 3rd I did check for spark before hand, so I have spark.4th I will jump the maf and listen for the pump. I ordered the repair book and spark plugs no auto parts shop within 100 miles has them.
03-01-15, 11:03 AM
#13
Factory service manuals can be found here:
1985 Mazda RX-7 Factory Service Manual
Foxed.ca - Mazda RX-7 Manuals
1985 Mazda RX-7 Factory Service Manual
Foxed.ca - Mazda RX-7 Manuals
03-02-15, 01:08 AM
#15
84SE-EGI helpy-helperton
^^^ Thanks, NCross - I wasn't sure, so I didn't post it before. I do remember that the Trailing Coil is the one near the FRONT of the car, with the Leading Coil located behind that when viewed from the Driver's side of the engine bay looking in. HTH,
03-03-15, 08:26 AM
#18
Factory configuration has the fuel pump external to the tank, just rear of the drivers seat under the car. Page 4B-3 for GSL-SE.
http://www.foxed.ca/rx7manual/manual...ssions_13B.pdf
http://www.foxed.ca/rx7manual/manual...ssions_13B.pdf
03-03-15, 01:43 PM
#19
My phone is dumb and won't open any of the links do to not having a sd card. Which I have in it. Ughh but thank you. I'm going to feed it direct power and see if it works although from what I have read is the relay goes bad and I can jump it. So I'll try both.
03-04-15, 01:11 AM
#21
84SE-EGI helpy-helperton
The stock pump is adequate for the stock injector setup (2 injectors, non-staged), and not much else beyond that. If you're going with a later generation staged (4 injector) setup, you'll want either the pump from that car, or a high performance fuel pump meant for turbo applications.
As it stands, the -SE fuel pumps are plenty durable and I've replaced mine once in 222k mi at about the 150k mi point. I would strongly look at the electrical connections before you just remove the pump or you may find that the new pump isn't getting power either and you wasted a bunch of time. Shorting 12v to it is a good test, though.
As it stands, the -SE fuel pumps are plenty durable and I've replaced mine once in 222k mi at about the 150k mi point. I would strongly look at the electrical connections before you just remove the pump or you may find that the new pump isn't getting power either and you wasted a bunch of time. Shorting 12v to it is a good test, though.
03-04-15, 10:10 AM
#23
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I have a spare aftermarket pump for the SE if interested, used for less than 100 miles. Turned out my original pump was working fine so i reinstalled it. By the way, you need to go through the entire fuel system. Drop your tank now and even if it is okay, at least you'll know. These tanks tend to rust out after 30 years of use. At the pump inlet from the tank, there is a small plastic in line screen. If this is clogged, your tank definitely has issues. You may opt to check that first.
03-05-15, 08:46 AM
#25
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I coated my tank and haven't had any more problems. I bought the pump on rock auto and it was correct for the car. I don't know the GPH, but I can try to find out.