Cranks, but won't start...
05-24-10, 01:03 AM
#1
Excelsior!
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Cranks, but won't start...
Ok, here goes- A few weeks ago I was driving home from work and my FC started cutting out like as if it had a bad spark plug or wire, or was running out of gas. It wasn't cutting out too bad then it started running ok again. I was low on gas and figured that was probably the problem- that I was running out of gas. I made it home and shut the car off. A couple days later I jumped in and the car fired right up. I drove to the gas station and got gas and took off. The car drove fine for approx 3.5 miles and then started cutting out BAD. I sputtered and chugged it home and it died trying to pull into the driveway. It then started back up and pulled into the driveway still cutting out like it was before. I hopped out and smelled a burning smell so I hit the ground and looked under the car. I then saw my Bonez high flow cat glowing bright orange. Oh ****, I just melted a $250 cat. Awesome. I then figured that the screens in the cat were melted to a nice clump, clogging my exhaust causing it to cut out. Easy fix. Not so much. I jumped the gun being as I saw the cat glowing and ordered a new one from RX7.com. When it arrived I pulled my old one and compared it to the new one. They were identical. Not a single screen had melted in my cat after it was glowing. You could still see straight through it like the new one. Money well spent. I then sent the new cat back and have to figure out what the hell was happening. Since then I have checked and replaced my plugs and wires. Coils check good. It's getting spark. Checked the fuel pressure before and after the fuel filter and 30psi on both ends. Replaced the fuel pump which was initially diagnosed as bad, but ended up being good. All the fuses are good. Vac tested the fuel pressure regulator and it seemed ok. Injectors seemed ok too. WTF is the problem? This is driving me insane. I've also tested multiple sensors and relays and they are all up to spec. Help me rotary brethren so I can go to the meet on Saturday!
05-24-10, 01:40 PM
#4
^ lol.
Anyways, did you check your thermo Sensor? If that is bad it will cause it to run very rich.. A very rich fuel mixture can cause your cat to get extremely hot possibly even glowing. A bad thermo sensor will also cause it to buck like you described.
Anyways, did you check your thermo Sensor? If that is bad it will cause it to run very rich.. A very rich fuel mixture can cause your cat to get extremely hot possibly even glowing. A bad thermo sensor will also cause it to buck like you described.
05-24-10, 02:47 PM
#5
Excelsior!
Thread Starter
Didn't check that. It runs hella cold all the time even after i recently replaced the thermostat. I'll check that today. Thanks funkjaw. I'm tryin to get it back in action for the meet this Sat at Ocean Beach. Are you an yer girl rollin?
05-24-10, 02:59 PM
#6
Excelsior!
Thread Starter
Would that also be called the coolant temp sensor? They look the same. And, would that cause it not to start? Sometimes it sputters like it wants to start but then nothing happens.
Last edited by TripGreeley; 05-24-10 at 03:01 PM. Reason: Added info
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05-24-10, 09:48 PM
#9
lol here is a easy test for the fuel pump. get a plastic bottle and pull of the incoming fuel line to the engine and crank the car if it fills up with gasoline then the pumps fine if not. Then replace the fuel pump. Are you getting and codes stored in ecu and check engine light ?
05-25-10, 11:46 AM
#11
Excelsior!
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No check engine light alread tested the fuel pump with a pressure tester. It seems to be getting compression, but I haven't officially checked it yet.
. So I think I should go to his birthday party.
06-16-10, 11:49 AM
#16
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Found a couple burnt spots in the ECU so I got a used one that is supposed to be legit and still no dice. Time for a compression test just to eliminate it. Anyone know the link to test using a PSI meter not the Mazda BAR one? I haven't had much luck finding it
06-16-10, 12:24 PM
#17
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out of curiosity..you said your fuel pressure is 30psi.
Isnt it supposed to be between 64 and 85.3 psi? Atleast thats what the FSM says.
im having a similiar problem. cant start my car after a swap so we sprayed whatever (brain fart cant rememebr) into the TB and it started but revs kept fluctuating depending on the length of spray. Car died after we ran out of spray fluid. Checked the fuel pressure coming from the filter and it was at 40 - 44 psi. Replcaing fuel pump today to see if anything changes.
Isnt it supposed to be between 64 and 85.3 psi? Atleast thats what the FSM says.
im having a similiar problem. cant start my car after a swap so we sprayed whatever (brain fart cant rememebr) into the TB and it started but revs kept fluctuating depending on the length of spray. Car died after we ran out of spray fluid. Checked the fuel pressure coming from the filter and it was at 40 - 44 psi. Replcaing fuel pump today to see if anything changes.
06-16-10, 06:35 PM
#18
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We thought that at first too, then replaced the fuel pump. That is wide open with a jumper wire. 30psi is legit for normal operating pressure. The reading reading is the same on either side of the filter so the filter is cool. I haven't tried to spray anything in my throttle body (starting fluid, etc) out of fear of what it could do to my engine. A lot of that stuff says on the can not to use in rotaries so make sure you read labels before spraying away.
06-17-10, 12:25 AM
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Your glowing cat suggests a too rich mixture; so does the starting behavior.
They may be due to separate problems.
The hot cat is usually due to the default rich mixture the car goes to if it does not see an O2 sensor. This could be due to a bad sensor, a broken or grounded wire in that circuit, or a fault in the ECU. You can check for all three by checking for closed loop operation. Check for my threads on how to do that.
Check for codes. $3 code checker can be made in a few minutes. See the writeup at teamfc3s.org.
Check the water thermo sensor, and its wiring. It may be the source of the too rich at start.
If all that is ok, look at putting in a hot start switch--a pushbutton wired to cut out power to either the fuel pump or the fuel injectors. You can use it anytime you have trouble with a too rich/hot start.
They may be due to separate problems.
The hot cat is usually due to the default rich mixture the car goes to if it does not see an O2 sensor. This could be due to a bad sensor, a broken or grounded wire in that circuit, or a fault in the ECU. You can check for all three by checking for closed loop operation. Check for my threads on how to do that.
Check for codes. $3 code checker can be made in a few minutes. See the writeup at teamfc3s.org.
Check the water thermo sensor, and its wiring. It may be the source of the too rich at start.
If all that is ok, look at putting in a hot start switch--a pushbutton wired to cut out power to either the fuel pump or the fuel injectors. You can use it anytime you have trouble with a too rich/hot start.
09-18-10, 09:51 AM
#21
You've stated that the fuel pressure on either side of the fuel filter is 30 psi. Did you tee in the pressure gauge on both sides of the filter to get these numbers or was the gauge "dead headed" on the fuel line that would go to the fuel filter from the pump. If it was dead headed then the pressure would be at least twice what you're getting.
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