Burnin_streets

I have a spark problem on my 86 NA. Can someone suggest anything? I am going to recheck the CAS tomorrow (checked it before and it was within factory specs). Anything else I should do?

~148000 miles.
Known to be working lead and trail coils.
Known that the previous spark plug wires had a huge gash in them that may have caused a short.


ANY SUGGESTIONS?

I know I have GAS and I'm pretty sure air.

Chuck

iTrader: (2)

I don't know for sure, but after reading your thread post, I still don't know what the problem is. Can you describe symptoms or what the car is doing (or not doing) that leads you to believe that you have a spark problem.

Whizbang

agreed, more information is needed. As many details as possible

HAILERS

You won't have spark if either of the EGI fuses is blown in the engine bay and you won't have spark and fuel if the ENGINE fuse is blown in the interior. See the FAQ thread for a picture location of the above fuses.

We assume the starter is turning the engine over.

EGI fuses provide 12v to the coils and 12v to the ECU. Either power sources blown means no start. ENGINE fuse puts power on the MAIN relay and the Circuit opening relay. Bad ENGINE fuse means no start.

You can prove the ENGINE fuse is good by putting the key to ON and shoving the vane in the AFM aft a quarter inch or so. Fuel pump will run if that is done, proving the ENGINE fuse is good. You will be able to hear the fuel flowing in the fuel rails if the pump runs.

Burnin_streets

Ok. so the engine will turn over. It has good compression. My buddy and I tested the spark plugs for spark and we got nothing from any of them. The fuses from the top side look good. I guess I'll swap them out, but i doubt its as simple as that. I also unplugged the lines from the fuel pump and turned the engine over, it shot gas every where so thats why I don't think its the fuel pump. Battery reads over 12 amps. Anything else I should try?

Burnin_streets

I also feel it may be a connection issue. The previous owner hacked the ground to the alternator and spliced in a wire.

Burnin_streets

Hailers, is there more than one EGI fuse in the engine bay? I'll do a qucik search.

Burnin_streets

Ok, I understand why you said there were two EGI, the comp and injection.

eage8

iTrader: (9)

just because the fuel pump is working doesn't mean the injectors are firing, put your finger on one when you crank it and try and feel if it clicks.

Also, Are you sure you hooked the spark plug wires up right when you replaced them? leading is on the bottom. How did you test the spark plugs?

HAILERS

If the fuel pump runs, then it's a given that the ENGINE fuse is good and most likely that the Main Relay is also being pulled in. I've yet to see a bad Main Relay.

The Main Relay feeds the EGI fuse(s) power to the fuel injectors and the ECU itself. My remark about the fuel pump running was just to affirm the ENGINE fuse is good or not.

And somewhere above is mention of a gnd to the alternator. That's confusing because the alt internal get their gnd from the alt body making contact with the engine/brackets. No wire on the alt is a gnd. Talking stock car.

You really should aquire a digital meter of some sort. You could just go to the white, two wire plug at the Lead coil assy and check for batt voltage at the BLACK/YELLOW wire. That confirms the EGI INJ fuse and Main Relay are good and doing their job. To check the EGI COMP fuse you just check one of the black'/white wires on any of the solenod plugs for batt voltage. Got it, then the EGI COMP is good. Car should start.

If you had a spare CAS you could just attach the elect plug that is presently on the engine CAS to the spare CAS. Key ON. Spin the CAS bottom gear and listen for the injectors clicking. You'd disconnect the Lead and Trail coil plugs so you won't mistake sparkplugs clicking for fuel injector clicking. You don't put the key to anything other than ON. You don't spin the starter at all. Just the CAS bottom gear.

Or if you had a meter and a 86 car, you could pull the solenoid resistor plug off to see if there's batt voltage at the black/yellow wire on its plug. Confirms the EGI INJ fuse is good.

Or you could pull the CAS in the engine out but leave its elect plug on it. KEy ON and do the above. You could also check for spark doing that. Just lay ONE of the LEAD sparkplug wires near one of the left strut towers studs. Spin the CAS bottom gear. Spark will occur. Just the key to ON. Do not spin the engine with the starter. Just key ON, spin the CAS BOTTOM gear. All sorts of clicking will occur. Sparkplugs and injectors clicking as you spin the CAS bottom gear.

Burnin_streets

Alright Hailers, I'll do this tomorrow morning when I get off of work. I will check back with you later. Thank you for the advise.

Burnin_streets

Hailers, do you think it could be a timing issue?

HAILERS

If it was running before and you have not moved the CAS since it last ran........no.

CAS don't go bad unless you stick a screw driver in them while they're spinning or something similar.

If you pull the top off the CAS off, then thin black cover, and you have the first timing mark on the front pulley opposite the fixed pin on the front cover, the two *pointers* in the top of the CAS should be cutting across the corners of the two block coils in the CAS. As seen in the attached jpg.

Even if the timing was off, you'd still have spark. The CAS turns when the engine spins. It outputs a ac voltage to the ECU. The ECU in turn translates this to spark and fuel injector timing.

For that to work you need the two EGI fuses good and the ENGINE fuse good.

Since you've gone this far, I'd pull the CAS out and spin its bottom gear with the key to ON. Look for spark at the plugs. Listen for spark also. Engine is not turning when you do this. Just key ON, spin the CAS bottom gear.

When finished just align the first mark on the pulley with the fixed pointer on the front cover. Then install and rotate the CAS til the two pointers on top of the CAS are cutting across the corners of the black coils inside the CAS.

Burnin_streets

Alright, I'll do that first thing tomorrow morning! Thank you again for all the help.

Burnin_streets

Hailers, I did exactly as you said and there was no clicking. No spark nothing! I have no clue what is going on and to be honest I'm getting a little frustrated. I took the CAS from the 87 I'm rebuilding and spun the bottom gear. I made sure all the fuses were good again and no spark or fire from the injectors. What should I do now?

HAILERS

Well, if the key was to ON when you spun it, and the CAS elect plug was on the CAS you were spinning........................you will need a digital meter to figure it out.

You'd check for 12v at the black/yellow wire of each coil plug. You'd pull the boost/pressure sensor plug off and check for 5vdc ref voltage at the Brown/White wire. It should be there. It proves the ECU is putting out a ref voltage. No ref voltage equals no spark from the ECU.

Tell you what. Try that twirl of the CAS bottom gear once more. But pull the plug off the AFM before you do that. See what happens.

IF that does not work, get the meter out and go to the ECU and pull it's small plug off. See it there is batt voltage on the Black/White wire on the small plug. Far left of that plug.

You pull the afm plug off just in case the AFM is killing the 5vdc ref voltage. Plug off it can't kill the 5vdc and spark might happen if there was a AFM problem.

Let me ask you this. IF you jumper the fuel pump check connector (yellow,two socket plug near the right strut tower) and put the key to ON, can you hear the fuel pump working? OR not? This affirms whether or not the ENGINE fuse is active or not.

MazdaMike02

iTrader: (4)

Is your ECU grounded properly? Is the ground under the extension manifold bolted to the block?

Burnin_streets

I jumpered the yellow connector and got nothing, but if I take off the hoses right at the pump I get gas being pumped out. Does that count? I have the CPU from the other car. Could I swap it in? ECU is the emissions control unit, thats not the one I'm concerend with is it?

Burnin_streets

extension manifold? I'll have to do a search on that. I have no clue if that the intake or exhaust or something different all together.

Burnin_streets

I also swapped out the AFM from the other car. Still unplug it?

HAILERS

If gas is coming out of the lines, then the pump is running and the ENGINE fuse is good.

The CPU on the drivers side does NOTHING for the engine running.

You tried another afm.........so I guess that lets out the afm being bad. I'd still go remove it's plug and spin the CAS's bottom gear, with the key to ON. Also, this time remove the plug from the boost/pressure sensor also,.

I assumed the gnd for the ECU was good because there was no mention of the engine just being put in and no mention of the upper intake being removed.

You jumpered the yellow with the key ON, and nothing happened???? You should have heard the fuel running thru the fuel rails. Or gone to the gas cap, removed it, and heard the pump whinning. Odd.

Pull the RETURN line off the engine. Jumper the yellow plug. Key to ON momentarily. Did fuel run out the RETURN line?? Should have. Return line is the one that IS NOT connected to the fuel filter below the brake booster area.

HAILERS

Have you tried the other ECU from the other car??????

You almost need a digital meter to figure out what item isn't getting powered up. NO test lights. They burn things up in a heart beat.

Burnin_streets

Ok, well I got called into work so I can't do anything for the next 3 days. I hate this! Ok, well I'll try it again on Monday. Thank you!