Speedaemonc4

Hi all, I have an 86 NA Rx7, Ive been workin on the cars for a lil while but am stumped at this point. The situation goes like this....3 years ago I fixed an RX7 for some friends, they drove it around about a month then there was a fuel leak and so they parked it. Finally they decided to get rid of it so I bought it.However I am having issues getting it to run. I can start the car pretty easy but it will run 3-4 secs then die, if i give it any gas during that 4-5 secs It will die faster with absolutly NO rise in rpm or even effort towards that. Ive checked my maf and its hooked up..The following things I found bad on the car.....Leaking fuel injectors,Broken wire to O2 sensor, and several rat nests under there as well( got them out mostly). Anyhow all these problems existed before I parked the car and it still ran fine, so Im not sure what it could be..Also during the 3-4 secs itll run it smokes heavily. So thanks for any help offered Im hoping to get it up and goin quick for work.

RotaryRocket88

iTrader: (7)

If it had rats in it, then there's no doubt you have chewed up wiring. Check that area.

tmoon

for those few seconds how does it run, smooth or not, and have u done a compression test yet?

Templeton

iTrader: (10)

check your wiring then injectors, sounds like your not getting enough fuel

Speedaemonc4

Ok heres the update, compression is good, I checked it, I was able to check most of the wires and they are all good minus the wire to the O2 sensor it was broken.As far as the few secs it runs it depends, if its hooked up to the maf it runs fine then dies, if not hooked up it runs longer....5-10 secs but very poorly. Heres a new catch, the fuel pumps are lasting about 20 starts before they stop working and I have to get a new one....Gone through 3 now, 2 which were brand new from stores in different cities so I dont think its the pumps. Gonna change the fuel filter out and hope maybe that was it and that somthin was just blocking it maybe. Thanks for the suggestions any more would be greatly helpfull.

Templeton

iTrader: (10)

i believe the fuel pumps use the gasoline in the tank to cool themselves, how much gas is in the tank? shine a light down into the tank and see if its full of rust, fuel filter would def be a good idea, since youve swapped out the pump so many times make sure your fuels lines are run correctly, again you may need you injectors cleaned, it seems like your fuel pump is pushing fuel, and its not going anywhere, so your fuel pump keeps burning itself out try filter first, if that doesnt do it check to see if your injectors are firing, not just slowly leaking fuel into the motor.

Speedaemonc4

Ok, the fuel had been low and I thought about it and filled it up, so far ive messed with it about 20 minutes without the pump dying, also yes the injectors are still leaking pretty badly and the o2 sensor is still broke also. Changed the fuel filter also and its still the 3 second starts, actually its more like 2 secs..

hanman

Troubleshoot the MAF per the factory manual and make sure it is good. Also make sure the MAF door is opening and closing easily.

misterstyx69

iTrader: (142)

check the lines at the engine.in between the fuel filter and the engine.If they are mixed up you get Some fuel,but it won't start up and run.

Speedaemonc4

Checked the lines they are fine. Not sure on the maf, however a friend just blew the motor on his 87 rx and is putting a 302 in, so I am buying his motor and gonna start swappin stuff in and out. Also check the maf, got a manual as well.

Speedaemonc4

Ok heres the next update, Ive switched out all the rails and the injectors as well as a few other minor sensors etc. Anyhow now it wont start at all. Every now and then it will attempt it but never succeed. However I found this interesting, if i swap in a leaking injector it will start for longer,so I think the only reason it starts period is because an injector leaks in.So, the pump,filter, and most fuel injector parts are new now. The only possible thing now is somthing that is stopping the injectors from firing, they definatly arent. But with carb cleaner it will start right up so I know I have spark. What could stop the injectors from firing?

Leafy

I went to a local RX7 shop for help for something similar to your original issue, the car would fire up and idle for a little more than a minute (stutter idle ranging from 750-100rpm) first thing he did was unplug the cold-start system. The problem was solved then and there.

hanman

I would test for fuel pressure at the rail. No fuel pressure = no fuel for the injectors.

Second, things that will cause the injectors to not fire:
No or bad CAS signal
Bad ECU
Bad injector grounds (two grounds, both under the intake, one is the small wire that connects to the firewall, but the really important one is on the engine block near the EGR valve.
Bad injectors
No fuel (see above)
Bad wiring to the injectors (no 12v or no intermittent power from ECU)

I am sure there is more, but this will get you started.

hanman

Also, take a look at the injectors. With the key on, you should have 12v on one side of the connector, at each injector. With the engine turning over you should have a pulsing 12V at the other pin. If not, see my post above about what would cause injector failure.

Speedaemonc4

Ok I tested the wires running to the injectors and there is a steady 12v to one side but no pulsing 12v to the other while turning over. Ill look at the ground wires and ecu next then.

MetalPGT

a bad ground is often the root cause but are not easy to troubleshoot

Speedaemonc4

Ok grounds are good, I also checked under the dash and noticed a pretty big plug with quite a few wires of various sizes and colors, mostly blue.. Just hanging there, couldnt find where it could possibly plug into though. Also looked at the ecm and it looked fine on the outside, dont know how itd just die since I used it last.

Speedaemonc4

Ok as is my problem is that the pulsing wire from the computer is not firing off to the injectors, the only reason it started before was because my old injectors were leaking so bad. So I guess its off to find an ecm.

fcforlife

iTrader: (9)

well if your friend had an 87.5 to 88 and you swapped the wiring or injectors from it they won't work at all with the ecu you have. and check your tps to if its not reading anything then you putting to much air into the mixture. and i don't know if this has been asked but what color is the smoke?

mikevoch89146

iTrader: (1)

Don't worry about the smoking issue at this point, the oil is injected into the rotor housing to prevent apex seal chattering. It is normal for a rotary to smoke for a few after sitting for even a couple of days. I can imagine it will go away after about 3 to 5 minutes when you get it running.

Dark_Knight

iTrader: (1)

Right in the middle of my rebuild as well hope you get it running.

Speedaemonc4

Its the right year model, same motor and stuff. Right now Im pretty much waiting for a good deal on a used working ecm, then Ill go from there I imagine.