jjacks01

iTrader: (7)

Guys, need some help here...

I have been searching the forum and taking advice and here is the status. I have an 87TII that will not start. I replaced the engine and am building her back up. When I crank the engine she will fire for a brief instant and she fires strong. But within a second she dies. It is not a sputter, its a clean spool down. Throttle position has NO effect. I have checked for vacuum leaks several times. I have jumped the fuel pump override and there is no change. The fuel pump is running and she gets fuel. I have checked the coils and they seemed ok with the check in the FSM. I have checked the AFM and there are some unusual readings. I will likely look to replace.

I have block offs on the BAC, split air, subzero start, and EGR.
Injectors are all hooked up.
TPS is hooked up as is coolant temp sensor, air inlet temp sesor and AFM.
OMP is also hooked up and tight.

This really sounds electrical to me as if the ECU is sensing something is wrong and cutting spark or fuel.

Any thoughts or other tests I can run?

JOn

Aaron Cake

iTrader: (1)

I'd suggest putting the BAC back on as it is what the ECU uses to regulate the idle and there is no reason to remove it.

Are your fuel lines connected backwards?

Check the condition of the AFM connector. If the ECU doesn't see the AFM, you will get the symptom you describe.

jjacks01

iTrader: (7)

Appreciate the help. She is running now but I suspect i am looking at a vacuum leak. She will only run if I manually crack the afm vane open by hand. The resistances check according to the FSM.....yes its my plan to put the BAC valve back on once all the issues are sorted.

jjacks01

iTrader: (7)

Any thoughts on this or anyone have this experience before? Car will fire every time but die. But if you push the air vane open just a tad she will run fine. All resistances on the air meter match the FSM. There must be a switch in the AFM that requires the vane to be opened just a little? Has anyone had an AFM fail in this manner? I would think a vacuum leak is still suspect, but I have checked every joint over and over....

Thanks!
JJ

959595rotor

JJ Hi you said that you changed the engine you might have mixed up the Primary Injector wires ,or, not got the inj and injector seal (new) in the holes straght , the wires are loose on the AFM / or injectors ,also, check your computer open it up top plate first then the board tilt the board over,and look for burnt blue resisters (easy to fix) usually from boosting backwards or incorrect battery install also make sure you are grounded well on your computer eng coils etc triple check your crank angle sensor for TDC as well as broken wires also check for constant fuel pressure if you have gas and good compression and the coils are firing at the right time your car will run PS ARE your spark plugs new too I have seen more dead spark plus than I can count any way good luck....959595rotor

jjacks01

iTrader: (7)

Continued thanks for the help. Checked the things you mentioned again last night again and everything is good. Again when I crank her she will fire almost instantly and very strong, run up to 1500 or so and then just quit. I have checked the AFM plug and it is good. With the ign on, you can lightly press on the AFM vane and you will hear the fuel solenoid energize and hear the fuel going through the rail. I have also tried jumpering the fuel pump override connector with no avail. I understand there is a relay under the steering column that energizes for fuel as well. Someone appears to have cut this and inserted a switch on the black/white wire. I was going to try to repair this. I would think I can jumper this relay to be absolutely sure I have fuel after crank mode. Anyone have other ideas?????. Crank sensor timing is good and obviously she fires and strong. I have 1.08 volts at TPS as I should....

Thanks

959595rotor

JJ Hi the relay under the steering column is the relay for the fuel pump if the black wire is cut or switched off you will not be able to turn on the pump it was cut so that the old low compression engine could be started because they usually flood with low compression if you want try a jumper wire between the black and white wire That will eliminate the need for the fuel system to be turned on from the AFM ps when the key is on the pump works all the time,now when you put the jumper on the yellow underhood plug the fuel will flow non stop with key on,and yes AFM do fail once in a while.I think you are having the fuel shut of and it is killing the englet me know what happens ....

jjacks01

iTrader: (7)

Hello 959595rotor and thanks for the help. I believe I am being shut down by the fuel pump for a couple of reasons. First I clearly hear the fuel streaming through the lines when the ignition is on. Once she fires and dies i do not hear the sound. Also, I ran my meter to the actual fuel pump connector in the rear (red wire) and get about 9v at key on and cranking. She then uickly falls to zero.

The relay under the dash only has two black/white wires, a blue/red, a black and brown. There is no white wire. I beleive the brown wire goes to the Fuel pump per the fsm so I will try jumping them shortly. I am also getting a different afm to try that too. I checked the resistances again on the fuel pump resistor/relay and the circuit opening relay and surprise they are good.... stumped!!!!!

959595rotor

JJ what I mean, is to jump the relay by hooking the blue/red wire to the blackwhite If you have a mazda manual or, clymers repair book, it show the relay and how to jump it for testing the fuel pump circuit ... .later Fred

959595rotor

JJ one more thing you said you recently installed the engine ,double check your wiing harness ......and make sure.... All........the plugs are attached firmly.( listen for a click of the connecter..) because your fuel pump is routed through that upper car harness...................... .................................................. .................................................. ..............................If your car is a custom Install , (not original Turbo) there will have to be a signal wire from the computer to the relay to turn on the fuel pump and a wire from the Ignition Run circuit to the relay for continuious fuel supply...... keep digging you re homing in on the glitch, plus your going to feel a whole bunch smarter once it runs.....good luck

jjacks01

iTrader: (7)

THanks again Rotor!!! I tried jumping the B/W and the blue red wires and i get the same thing. fires and then dies. I think we are almost there and i beleive I have a faulty air meter. The car will crank, fire and die every time. If I push the meter vane and block it open a good part of the way she will start and run. So I figured the fuel switch in her must be dead. I then jumped the pins on the harness side for E1 and fc (supposedly the fuel switch in the air meter) and she starts and runs again. So I guess the meter is not making and holding the connection. Funny thing is when I test with a multimeter the circiut is open and then goes to .2Ohms or so.....but not zero ohms.......New AFM should be here in a few days and we will know more!!!!! Thanks all....JOn

luis07

Check the condition of the AFM connector

jjacks01

iTrader: (7)

Thanks!. The connector looks to be in pretty (though like **** as the afm is not hooked up). I took off the cover of the AFM and the circuits look good and i can see where she makes contact with a small vane movement. I have ordered a new AFM. Is there anyone who really understands this afm? I rechecked the BLUE wire to the fuel pump which I understand to be the power. It is live during crank, firing and appearently after it dies. Are there other triggers for the fuel pump beside the circuit opening relay and afm? Is the pump have a switched ground somewhere.. . i plan to go over every step again this weekend...thanks all....Jon

bbutchart@carolina.rr.com

I have a very similar problem. when you jumpered the afm, did the car stay running? did you drive it with the afm jumpered? On my 85 gsl-se (13b 6port) it has a fuel cut jumper terminal - a black rubber coated terminal (not hooked up to anything) just behind the air box - fuel pump is supposed to run with key in on position when this is jumpered. I've seen similar terminals on 2nd gens.

jjacks01

iTrader: (7)

Yes, our problems are similar, but even jumping the fuel pump bypass terminal it will not stay running. Here what is even stranger....the car will run, but very crappy with the AFM UNHOOKED !!!! and i was under the understanding that the AFM had to be hooked up for the pump to run if it not in start mode. Both AFM's check OK on an ohmmeter at all terminals and the E to Fc pin opens and closes properly with a small movement in the vane... I am absolutely stumped. I am going to look at the ECM next just wondering if something was broken in between.....so a quick summary of status:

Car fires every time I try but dies within a second of firing EVEN IF I HOLD IT IN START
Battery is strong
unhook the AFM and it will run but crappy
jump the fuel pump switch terminals on the AFM harness and she will work

I understood the rest of the pins were a air flow and temp signal, but it acts as if one of them is another cutoff mechanism.
Fuel lines are correct
CTS, TPS, CAS, AIT OTS, coolant level and switch hooked up

Nuts!!!

I will keep looking....

JJ