no start condition with a wild twist- completely stumped
06-05-16, 03:51 AM
#1
no start condition with a wild twist- completely stumped
i got my car back together and i turned the key, it started but was rough and nasty. come to find out i had the fuel feed and return swapped with the feed going to the primary and return going to the secondary. switched them and boom perfect start. with no idle controls and a cold motor, it shut itself down after a couple seconds since i didnt have my foot on the gas. ok no big deal. next day, no start. it just spun the motor. nothing changed but the day on the calender from the previous start. figured it was flooded from the short run time. did a few different deflood procedures to ensure it was good and got the same result: no start. i was lead to check to see if my injectors were stuck. i put a 9v battery to them and boom, started right up but then it shut itself down after a few seconds even with my foot on the gas.
i immediately tried to start it up again and no luck. did a thorough deflood and no luck. i called injectors rx since they cleaned the injectors. they advised that the injector wasnt the problem since i can get them to click with the battery and to search elsewhere. no surprise with that answer. they gave a very detailed explanation as to why they felt that way but still, it was expected. at least they offered to test them again if i so desired.
since the 9v worked to get it started before, i tried again and no luck. i havent been able to get the car to start again after hours upon hours of shooting. the list below is what i have tried to remedy:
check ignition- coils, brand new plugs, wires, harness
check cas
check power to injectors
fuel pump rewire
removed injectors to verify condition and correct installation
checked relays and fuses
checked grounds
calibrated tps
checked fuel pressure
checked map sensor and all other vacuum lines
checked 4x y z and 1b on ecu plugs
added fuel- i have half a tank
fuel pump relay bypass just to verify
i have verified that there are no shorts in the engine harness by chasing a power signal to multiple places. i have a spare harness thats torn apart so i can see which wire goes where then i chase it down in the harness in the car. i go from the point of origin to the component(s) that wire runs to.
something that was suggested by a friend of mine was to pull the primary rail and crank, just to see if the injectors were firing. i used a rag and mirror under them to verify. after cranking, the glass on the mirror had a VERY light mist on. enough to call it residual from a firing injector. next, i removed all 4 injectors and jumped the fuel pump just to see if fuel was flowing through the rail. it is not. i imagine this is normal operation as the fpr may need to see vacuum to open the diaphragm. im guessing of course since i have no idea. i have a vacuum pump but its only capable of positive pressure which im pretty sure the fpr sees anyway. i dont think thats its the injectors not firing, i think its fuel not flowing into rail somehow. the feed line pressurizes. i put it in a bottle and jumped the pump to verify. fuel just isnt getting into the rail. after cranking it, the rail isnt pressurized at all.
so what the car is doing is its cranking super strong and i can hear the fuel pump wine as its cranking and i can hear the ignition pulses in the exhaust. whats NOT happening is even the slightest effort to start. the motor is just spinning. having a power fc makes this troubleshooting a little easier but i am at a loss at this point. i feel as though i have tried everything. the only thing i need verification on is if the fpr is doing what its supposed to by not letting fuel into the rail without a vacuum source. i also have a spare fuel rail and i removed the injectors from it and tried to get flow into the rail and could not.
the most aggravating part of this is the fact that it started and idled perfect..... twice now. before i figured out the fuel lines were backward it made an effort to start every time. now it doesnt even try. sorry for the long post but i wanted to be sure that no one suggested something that i have already done or tried to say that it was flooded. i am hoping that there is a simple fix and i am missing something super obvious
i immediately tried to start it up again and no luck. did a thorough deflood and no luck. i called injectors rx since they cleaned the injectors. they advised that the injector wasnt the problem since i can get them to click with the battery and to search elsewhere. no surprise with that answer. they gave a very detailed explanation as to why they felt that way but still, it was expected. at least they offered to test them again if i so desired.
since the 9v worked to get it started before, i tried again and no luck. i havent been able to get the car to start again after hours upon hours of shooting. the list below is what i have tried to remedy:
check ignition- coils, brand new plugs, wires, harness
check cas
check power to injectors
fuel pump rewire
removed injectors to verify condition and correct installation
checked relays and fuses
checked grounds
calibrated tps
checked fuel pressure
checked map sensor and all other vacuum lines
checked 4x y z and 1b on ecu plugs
added fuel- i have half a tank
fuel pump relay bypass just to verify
i have verified that there are no shorts in the engine harness by chasing a power signal to multiple places. i have a spare harness thats torn apart so i can see which wire goes where then i chase it down in the harness in the car. i go from the point of origin to the component(s) that wire runs to.
something that was suggested by a friend of mine was to pull the primary rail and crank, just to see if the injectors were firing. i used a rag and mirror under them to verify. after cranking, the glass on the mirror had a VERY light mist on. enough to call it residual from a firing injector. next, i removed all 4 injectors and jumped the fuel pump just to see if fuel was flowing through the rail. it is not. i imagine this is normal operation as the fpr may need to see vacuum to open the diaphragm. im guessing of course since i have no idea. i have a vacuum pump but its only capable of positive pressure which im pretty sure the fpr sees anyway. i dont think thats its the injectors not firing, i think its fuel not flowing into rail somehow. the feed line pressurizes. i put it in a bottle and jumped the pump to verify. fuel just isnt getting into the rail. after cranking it, the rail isnt pressurized at all.
so what the car is doing is its cranking super strong and i can hear the fuel pump wine as its cranking and i can hear the ignition pulses in the exhaust. whats NOT happening is even the slightest effort to start. the motor is just spinning. having a power fc makes this troubleshooting a little easier but i am at a loss at this point. i feel as though i have tried everything. the only thing i need verification on is if the fpr is doing what its supposed to by not letting fuel into the rail without a vacuum source. i also have a spare fuel rail and i removed the injectors from it and tried to get flow into the rail and could not.
the most aggravating part of this is the fact that it started and idled perfect..... twice now. before i figured out the fuel lines were backward it made an effort to start every time. now it doesnt even try. sorry for the long post but i wanted to be sure that no one suggested something that i have already done or tried to say that it was flooded. i am hoping that there is a simple fix and i am missing something super obvious
06-05-16, 07:52 AM
#2
RX-7 Bad Ass
iTrader: (55)
First off, I don't think you have a good grasp as to how the FPR works.
Fuel pressure is at a base rate of 38.5 psi - that's with no vacuum or boost applied to the FPR nipple, atmospheric pressure. The pressure will drop with vacuum applied, or rise with boost applied. You always have to have that fixed pressure differential so fuel will squirt out of the injectors. Think about it - let's say you had 10psi of fuel pressure, and 10psi of boost in the engine. No fuel would squirt out - you need to go from high pressure to low pressure for a fluid to squirt out.
The stock FPR does a good job of regulating fuel pressure. Most likely you will be getting enough flow to the FPR that a good amount should be returning to the tank. The FPR will restrict the flow back to the tank enough so that 38.5psi (at atmospheric pressure) is between the FPR and the fuel pump.
It could be possible that your fuel lines are clogged. I've seen that on an FC I worked on ages ago, the banjo bolts had some sort of crap in them and it kept fuel from flowing through the rail and back to the tank. With the FPR off of the fuel rails, you should VERY easily be able to blow through the system.
Fuel goes from the fuel pump, to the inlet on the primary rail (side closest to the firewall), to the front of the secondary fuel rail, to the FPR at the back of the secondary fuel rail, then back to the tank.
Another possibility is that the plugs are fouled. Fouled plugs can happen VERY easily when trying to start a cold, fresh motor and it only runs for a few seconds. I would get a NEW pair of leading plugs (don't worry about trailing) for troubleshooting. Get 7's, 9's are probably what you want to be running the car on, but 7's will foul much less easily and will be good for troubleshooting and getting the car going.
Is this a freshly rebuilt engine?
Dale
Fuel pressure is at a base rate of 38.5 psi - that's with no vacuum or boost applied to the FPR nipple, atmospheric pressure. The pressure will drop with vacuum applied, or rise with boost applied. You always have to have that fixed pressure differential so fuel will squirt out of the injectors. Think about it - let's say you had 10psi of fuel pressure, and 10psi of boost in the engine. No fuel would squirt out - you need to go from high pressure to low pressure for a fluid to squirt out.
The stock FPR does a good job of regulating fuel pressure. Most likely you will be getting enough flow to the FPR that a good amount should be returning to the tank. The FPR will restrict the flow back to the tank enough so that 38.5psi (at atmospheric pressure) is between the FPR and the fuel pump.
It could be possible that your fuel lines are clogged. I've seen that on an FC I worked on ages ago, the banjo bolts had some sort of crap in them and it kept fuel from flowing through the rail and back to the tank. With the FPR off of the fuel rails, you should VERY easily be able to blow through the system.
Fuel goes from the fuel pump, to the inlet on the primary rail (side closest to the firewall), to the front of the secondary fuel rail, to the FPR at the back of the secondary fuel rail, then back to the tank.
Another possibility is that the plugs are fouled. Fouled plugs can happen VERY easily when trying to start a cold, fresh motor and it only runs for a few seconds. I would get a NEW pair of leading plugs (don't worry about trailing) for troubleshooting. Get 7's, 9's are probably what you want to be running the car on, but 7's will foul much less easily and will be good for troubleshooting and getting the car going.
Is this a freshly rebuilt engine?
Dale
06-05-16, 09:05 PM
#4
Eats, Sleeps, Dreams Rotary
For the record, the feed line is the one of the left (looking from the side of the car), the hose in the middle is for the charcoal cylinder, and the return line is on the right.
If you have an aftermarket FPR, it goes on the return line.
For the record, if an engine is flooding BADLY (i.e., due to severe overfueling or a weak spark), regular unflooding procedures will not work. Neither will cleaning/drying/blow torching the plugs. You might need to use brand new plugs.
If using brand new plugs starts the car immediately, you either have a flooding issue or a weak ignition system.
If you have an aftermarket FPR, it goes on the return line.
For the record, if an engine is flooding BADLY (i.e., due to severe overfueling or a weak spark), regular unflooding procedures will not work. Neither will cleaning/drying/blow torching the plugs. You might need to use brand new plugs.
If using brand new plugs starts the car immediately, you either have a flooding issue or a weak ignition system.
06-10-16, 08:50 AM
#5
RX-7 Bad Ass
iTrader: (55)
So....had some good suggestions here, any updates?
Dale
Dale
06-10-16, 11:56 AM
#6
For the benefit of the OP, or anyone reading this, there are three basic things needed for a car to start. Fuel, Spark (at the right time), and Compression. Seems most people are aware of this, but always start chasing gremlins before confirming the basics. Fuel needs to be confirmed going into the engine. This is kind of a pain because that means taking out your primary rail (don't need secondaries to start) and confirming the injectors fire, so the next best is to confirm fuel pressure. However, if compression and spark check out, the injectors will need to be checked. Spark needs to be a good firing spark plug at the right time. Compression needs to be on all faces.
06-10-16, 05:54 PM
#7
First off, I don't think you have a good grasp as to how the FPR works.
Fuel pressure is at a base rate of 38.5 psi - that's with no vacuum or boost applied to the FPR nipple, atmospheric pressure. The pressure will drop with vacuum applied, or rise with boost applied. You always have to have that fixed pressure differential so fuel will squirt out of the injectors. Think about it - let's say you had 10psi of fuel pressure, and 10psi of boost in the engine. No fuel would squirt out - you need to go from high pressure to low pressure for a fluid to squirt out.
The stock FPR does a good job of regulating fuel pressure. Most likely you will be getting enough flow to the FPR that a good amount should be returning to the tank. The FPR will restrict the flow back to the tank enough so that 38.5psi (at atmospheric pressure) is between the FPR and the fuel pump.
It could be possible that your fuel lines are clogged. I've seen that on an FC I worked on ages ago, the banjo bolts had some sort of crap in them and it kept fuel from flowing through the rail and back to the tank. With the FPR off of the fuel rails, you should VERY easily be able to blow through the system.
Fuel goes from the fuel pump, to the inlet on the primary rail (side closest to the firewall), to the front of the secondary fuel rail, to the FPR at the back of the secondary fuel rail, then back to the tank.
Another possibility is that the plugs are fouled. Fouled plugs can happen VERY easily when trying to start a cold, fresh motor and it only runs for a few seconds. I would get a NEW pair of leading plugs (don't worry about trailing) for troubleshooting. Get 7's, 9's are probably what you want to be running the car on, but 7's will foul much less easily and will be good for troubleshooting and getting the car going.
Is this a freshly rebuilt engine?
Dale
Fuel pressure is at a base rate of 38.5 psi - that's with no vacuum or boost applied to the FPR nipple, atmospheric pressure. The pressure will drop with vacuum applied, or rise with boost applied. You always have to have that fixed pressure differential so fuel will squirt out of the injectors. Think about it - let's say you had 10psi of fuel pressure, and 10psi of boost in the engine. No fuel would squirt out - you need to go from high pressure to low pressure for a fluid to squirt out.
The stock FPR does a good job of regulating fuel pressure. Most likely you will be getting enough flow to the FPR that a good amount should be returning to the tank. The FPR will restrict the flow back to the tank enough so that 38.5psi (at atmospheric pressure) is between the FPR and the fuel pump.
It could be possible that your fuel lines are clogged. I've seen that on an FC I worked on ages ago, the banjo bolts had some sort of crap in them and it kept fuel from flowing through the rail and back to the tank. With the FPR off of the fuel rails, you should VERY easily be able to blow through the system.
Fuel goes from the fuel pump, to the inlet on the primary rail (side closest to the firewall), to the front of the secondary fuel rail, to the FPR at the back of the secondary fuel rail, then back to the tank.
Another possibility is that the plugs are fouled. Fouled plugs can happen VERY easily when trying to start a cold, fresh motor and it only runs for a few seconds. I would get a NEW pair of leading plugs (don't worry about trailing) for troubleshooting. Get 7's, 9's are probably what you want to be running the car on, but 7's will foul much less easily and will be good for troubleshooting and getting the car going.
Is this a freshly rebuilt engine?
Dale
For the record, the feed line is the one of the left (looking from the side of the car), the hose in the middle is for the charcoal cylinder, and the return line is on the right.
If you have an aftermarket FPR, it goes on the return line.
For the record, if an engine is flooding BADLY (i.e., due to severe overfueling or a weak spark), regular unflooding procedures will not work. Neither will cleaning/drying/blow torching the plugs. You might need to use brand new plugs.
If using brand new plugs starts the car immediately, you either have a flooding issue or a weak ignition system.
If you have an aftermarket FPR, it goes on the return line.
For the record, if an engine is flooding BADLY (i.e., due to severe overfueling or a weak spark), regular unflooding procedures will not work. Neither will cleaning/drying/blow torching the plugs. You might need to use brand new plugs.
If using brand new plugs starts the car immediately, you either have a flooding issue or a weak ignition system.
https://www.rx7club.com/3rd-generati...cation-919013/
sorry for the super late response but i had a lengthy post i wanted to type out in response to yours but completely forgot it. i dont get on here with my computer much anymore and typing longer responses on my phone is just frustrating and kind of impossible. the issue was the crossed fuel lines. the thing that got me was the fact that even after i swapped the lines to feed going to fpr it ran. it ran and then died with throttle input much the same as it did before. with that occurrence, i wrote off the fuel lines being incorrect and at no point during troubleshooting reassessed, which ended up being a huge mistake. i mean, i already switched them once, what are the odds it was right the first time and i just made it bad? very high apparently. hind sight is 20/20 i guess.
the thing that got me to double check was when i pulled the injectors out and primed the fuel system and nothing came in through the rail. all the listed troubleshooting i did verified that all the systems were mechanically and electrically doing their jobs but something was missing. something that also tipped me off was the fact that after all this cranking, the plugs remained bone dry. not a drop of anything on them. if fuel was spraying and it was flooded then there should have been some sort of indication on the plugs and there was not.
i feel like an idiot for messing this up but i can tell you that it wasnt all a loss. the skills i gained from having to do all this troubleshooting are invaluable for future issues. albeit relatively simple, i still had to it. losing my mind and having to think of a new way to verify the operation of a system was difficult but my horizon has been broadened. below is the video of success...
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06-11-16, 09:21 AM
#8
RX-7 Bad Ass
iTrader: (55)
Awesome! Glad you got it sorted out!
Situations like that where you have a 50/50 chance of parts going one way or the other can be tricky. You second and triple guess yourself to death. But, I think you now have a much better understanding of the system which will help you in the future!
Hope to hear about you DRIVING the car and enjoying it soon! And you best be at Deal's Gap next year!
Dale
Situations like that where you have a 50/50 chance of parts going one way or the other can be tricky. You second and triple guess yourself to death. But, I think you now have a much better understanding of the system which will help you in the future!
Hope to hear about you DRIVING the car and enjoying it soon! And you best be at Deal's Gap next year!
Dale
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