sykohank

HI. I know alot of you on here are actual mechanics and are probably annoyed by posts like this, but i am an 18 year old kid and dont know where else to go. I have an 86 z28 with an 87 305 tpi motor. It worked fine until it started to grow sluggish untill fiunally it died, convieniently enough right in front of my house. Ever since then it will not start. It will start if i use ether, but i have been told often by people not to do that with this type of engine. At first i thought it was an electrical problem so i checked for spark (i have spark) and made sure my timing was correct (it was way off but it was previously runing advanced like this so i am not moving it because i am afraid that will complicate things. I think the guy before me messed up on the distributor.) Anyway when i discovered it was not an electrical problem i thought it was fuel. So i was looking around and noticed that the idiot who swapped my engine forgot to put a fuel filter in the car, thus my injectors were shot. Slowly but surely i figured out how to take the old injectors out and put new ones in. I was pretty proud of myself for doing the job right, but when i got in to start the car...nothing. I then started talking to people for any ideas they had. I checked the pressure in the fuel rail, it was 45lbs so that should be ok. Then i used a check light to see if my injectors were getting power. They are not. To make sure the light itself and my method worked i used to light on my buddy's mustang and it lit up but on my camaro it did nothing. I also checked the fuse for the omputer that was located towards the battery and that was fine. I am not familiar with fuel injection and i dont know what the problem is. My freind had a computer out of around an 88 5.7 which we put my chip into and put into the car which didnt help me either. Now i have my own computer back but i dont know what my next step should be... I would really appreciate help from anyone. thanks! -hank

jv9999

iTrader: (1)

Are you getting +12V to the injectors with the key on? You should get +12 (to ground) on both terminals of all injectors. If that's OK, then the ECM isn't firing them (it grounds one terminal to fire them). I'm assuming no security system in an 87, if it did have it that would be the first place to look. The next place is the distributor since that's how the ECM knows when it needs to fire. You might try reseating the connectors.

sykohank

no thats the thing, i'm getting no juice to the injectors. I highly doubt i have a security system in the car, but even if there was something wrong with the distributor, shouldnt i be getting something to the injectors?

white rider

iTrader: (2)

If your car has a knock sensor look into that. If your getting spark but no injector pulse then it might be your knock sensor. It should be located on the left side of the engine right above the starter. That would also be the cause of lost power and might be the reason the timing on the car was so advanced when you got it. If the knock sensor is going bad it will retard the timing to save the engine from internal damage. I dont remember the correct way to test it, its been years since I worked in a shop!!! LOL! Good luck with that.....

lunaticinaZ

did u check the fuse for the injectors in the fuse box?

jv9999

iTrader: (1)

Check the two injector fuses. There's one for each bank.

sykohank

Yea the fuses are not the problem, the guy bypassed them somehow. Does the knock sensor have a press on connecton that a wire goes to, and is that the same as a crank sensor?

jv9999

iTrader: (1)

The knock sensor has nothing to do with it. Do you get +12V on either side of the INJ1 and INJ2 fuses with the key on? If not, you have a wiring issue. See the attached scans for how it's supposed to be wired.

sykohank

The thing is though that the car ran before it died. It was moving right along (with a bad MAF sensor that i didnt know about) but running nonetheless. I dont think it is a wiring problem, i think it is a sensor that went bad or got fouled up cause it didnt just suddently die, i got worse and worse with less and less power and then wouldnt start for 5 months...Alot of people i talk to tell me that it is the crank sensor (not the knock) whatever that is and whatever that does that is the problem...could that be?

jv9999

iTrader: (1)

But you said you have no power to the injectors. There are no sensors involved in that. If you don't have +12V at the injectors and the fuses are good, it's a wiring problem (or possibly a bad ignition switch).

sykohank

yea i dont think it is a sensor or anything like that anymore. I looked at the wiring diagrams you gave me and that inspired me to check out the wiring that I have under the dash. I found out that the dumbass i bought it from doesnt like to use solder or wire nuts, but rather electrical tape with barely twisting two wires together...(thats the kind of car this is...) so i followed the pink and black wire and found a connection like this. I fixed it but it will still not start. I'm about to give up on it because all of his wiring is terrible and am so frustrated with the car. He chopped the hell out of the pink and black wire and put different colors onto it so it is really hard to follow. What i think the problem is now has to do with the fuses. I found the two fuses. For some reason he chose to take them out of the fuse box and let them hang under the dash. When i took the electrical tape that he had on them off, i found that there were only three wires between the two fuses...i guess this means that i am missing a wire somewhere because the circuit would not be made using two fuses with only three wires coming out of them. I looked all around under the drivers side dash and found no loose wire that looked as if it belonged as part of the fuse setup. Being that the whole situation is out of wack I was wondering if there was any way that I could just leave his wires all alone and start over with all new stuff. The thing that i dont know about this is that i dont know how it attaches to the computer and at times it is very hard to follow the harness as they weave through the firewall to try to figure stuff like this out...have any ideas about what i should do next?

navyCM

iTrader: (3)

lets start over from the beginning...

your timing needs to be set correctly on b4 any troubleshooting can be done.

the fuel filters for our cars are not in the engine bay they are underneath in front of the rear axle. so are you sure that it doesnt have one?

w/ the key in the run position your getting 45psi to the rail and can hear the pump kick on for 2-3 seconds? if so, your pump and relay is good big headache relief there, a real PITA to change.

navyCM

iTrader: (3)

this doesnt make it sound electrical at all. this is sensor related problem.

are cars dont have crank sensors...do they...

sykohank

yea, i checked there on the drivers side near the wheel, but it wasnt there and looked factory like it was never there. I put an inline one in obviously when i put the new injectors in to not ruin the new ones, that would be bad...Anyway yea the fuel situation is fine, and yea you are right about that pump. It is especialy bad cause if i were to drop the tank i'd have to take off my 3'' flowmaster pipes which took me FOREVER to position just right...haha. Anyway the timing is off, but what would that have to do with me not getting any power to the injectors? What i think it is honestly is because of the dumbass i bought the car from. I think the problem now is stemming from the fact that he wanted to race the car. When i bought it he showed me this switch he put in that would stall the car when flipped. When i took the dash pannel off i realized what it does in actuality is cut to power to the injectors. He has everything rigged up as a result (no solder or wire nuts on many thing) because he was a terrible electrician...So i have been so frustrated going through all of his wires trying to correct some of his shabby work but there are just some areas where i just cannot get to because they run through the firewall etc. The biggest problem that i notice is that the two fuses that the car has for the injectors only has 3 wires coming from them, which means to me that a wire is missing somewhere, but i dont know what it should be coming from of where it is. I looked all over for some loose wire that should be on the fuse to complete the circuit, but i had no success. I am so frustrated with his crap work that i am thinking about starting over and rewiring the whole system, bypassing everything he did wrong, but i have a feeling that is going to be a real pain as well...i would love some suggestions. thanks .

sykohank

You see thats what i thought, but i am not familiar with the car that much at all and dont know what kind of sensors it has and which would cause such a problem...Like i was saying this guy did some really bad wiring so what i think it could be too is one of his connections that came loose and got connected and disconnected as i drove around because of bumps on the road etc...i just dont know and dont know how to diagnose it for sure...

navyCM

iTrader: (3)

the ECM is set to fire the injs at a specific time. if the timing is way off they would be firing at the in correct time.

id seriously get a good shop manual w/ a damn good electrical diagram and rewire all the BS that he did. leave alone what is good and jus re-wire the crap. sounds like it is just on the inj. circuit so should'nt be that much of a PITA.

3rd gen Will

iTrader: (8)

there is no crank sensor. The computer gets a signal from the module in the distributor (a cam shaft signal). I know on the TBI cars it uses that signal to fire the injectors. Not sure on the TPI cars, but I would assume it does.

sykohank

Yea, I have a haynes manual, but that is good for nothing. I am going to buy a chilton's manual, I hear they are better. Once i get the manual and the diagrams and attempt to rewire it i'll reset the timing, but it ran pretty good with the timing all out of wack, so i think the guy put the distributor in 180 degrees backwards or something like that. The injectors should still get some sort of power even if they are not firing at the right time though right?

navyCM

iTrader: (3)

do a google search for helms. they sell shop manuals there i think there like 70 bucks and come w/ a kick *** wiring diagram.

JamesLLeary

OK,
With the key on, you should have a constant 12 volts to the injectors. Yes, This power should still be there with the key ON, regardless of what your timing is set at. I would suggest a continuity test between the 2 fuses, from the injector plugs, and the injector side of both fuse plugs in the fuse box. then, do a voltage check on the power side of those fuse plugs. If you get power there, Good. Re install the fuses, and then check for power again at the injector plugs. Then do a continuity test from the ecm plug, at the injector terminals, to the ground side of the injector plugs.

Once you get that squared away, check the ground wires at your ECM, as all of the actuator commands are sent as ground signals. if its bad, fix it.
I am going to assume that you are going to fix the shoddy splices....BUT DON`T GIVE UP!