RotaryMazda

I did use the search option for my question, however the answer I found related to the S5 series and I have a S4. Also I got a little confused... so, here's my question.

My fuel injectors are not firing. All fuses are fine. The injectors ARE getting power, but there is no "pulse." I know the ECU works, as I swapped it into another S4 and that started right up. The fuel pump is brand new and I know for a fact fuel is getting to the injectors. I did check that myself. However, the injectors are just not injecting fuel. I have spark and they are new plugs and wires.

This may sound ridiculous to request, but I'm not familiar with all the terminology that some people use on this site. Therefore, if you could respond but make the answers "simple" that would be awesome!

Here are some things that might matter though. The engine in the car is from an '87, while the chassis and wiring harness are an '86. The ECU that is also being used in from the same car as the chassis and wiring harness, an '86. Again, I did put the '86 ECU in my other '87 and it started up. I also tried putting the ECU from my running '87 into the car I'm having problems with and it did not start. It cranked over faster... but no pops or anything.

I think that covers it.

arghx

iTrader: (3)

does the car have spark? unplug one of the wires at the coil and see if it flashes or not. if it doesn't have spark you could have a crank angle sensor issue

RotaryRocket88

iTrader: (7)

You won't be able to see the "pulse" with a multimeter, since the injectors open and close in milliseconds. All you can really do is test for 12V and assume the ECU is opening them properly.

Test for spark like arghx mentioned, and you can also pull a spark plug to see if it's soaked with fuel. If you have fuel but no spark, they'll be covered in gas.

RotaryMazda

I know I have spark, tested that. And I have pulled out the plugs a couple of times, and none of those times was there fuel on the spark plugs.

Again, I know fuel is getting pumped through the fuel lines, just not being injected from the injectors.

Raid3n

have you tested the fuel pressure either before it goes under the manifold (after the filter but before the block) or at the fuel rails?

your pump could be doing a damn good job pumping fuel out of the tank, but if there is no pressure at the engine, then something is wrong (possible plugged filter)

J-Rat

iTrader: (2)

Makes me wonder if there are high imp injectors in the car being hooked up to a resistor pack? That would nuke your inj signal good....

RotaryMazda

I'm quite certain the fuel pressure is fine and the filter is not clogged.

Any other suggestions?

HAILERS

Buy a common LED from RADIO SHACK. Put the positive wire on one of the two wires on the far left of the small ECU plug (shove it in the back of the plug ). Put the negative lead of the LED in the back of the LIGHT GREEN wire in the small plug.

Turn the key to START and watch the LED. The light will blink each time the injector operates, proving the ECU is good and the injector is getting power. It also might prove you have your pressure and return lines on backwards at the engine. Having fuel pressure does not mean/prove the fuel lines are routed right.

1988vert

iTrader: (1)

I was going to suggest a check of the FP regulator as mentioned in the haynes manual.

hellisholds77

all injectors arent firing? they may have power but the ecu may not be grounding them out to complete the circuit like its supposed. do the led check like HAILERS said. to my knowledge, theres a common ground wire thats spliced to all 4 injectors, which could cause all 4 to fail at once. i may be wrong because this may be different from the way other cars are and im to lazy to actually look it up at the moment. ill get back when i do.

Spectator

iTrader: (1)

Are you sure you didn't hook your fuel lines backwards on the rats nest? (If you unplugged them in the first place...)

Spec.

HAILERS

.

RotaryMazda

HAILERS, I tested the injectors to see if they were firing with your method. They are firing. The light flashed repeatedly. I don't really understand the problem still. I recently learned from the seller of the vehicle this information:

"I do remember that one of the things they told me when I had the car [at Mazda] to sort out my starting issues was that the injectors were leaking, leading to a "wash down" of the "cylinder" walls and leaving them bare and reducing the seal formed by the apex seals and making compression harder to achieve."

Is my problem really as simple as replacing the injectors? Again, they seem to be firing, or at least that LED flashed.

Thanks for the help thus far.

RotaryMazda

Also, I have a couple injectors from an '89 lying around. Would those be able to work for me?

arghx

iTrader: (3)

Again, are the fuel lines hooked up correctly?

RotaryMazda

Yes, they are and I recently replaced the fuel pump, too.

HAILERS

IF the LED flashed while cranking the engine, the injectors are opening/shutting.

Don't replace the injectors. The washing down of the cylinder walls makes sense, but not a reason for replacing the injectors.

Find the fuel filter and it's outlet hose. Follow that hose to the engine. Leave that hose on the engine but remove the OTHER hose next to it. Now jumper the fuel pump check connector and put the key to ON. Fuel should flow FROM THE Engine hard line that return hose was connected to. If the fuel does not flow from the engine hard line, then swap those two hose. How you handle the fuel spill is up to you. At least it wasn't a new floresent light bulb and you won't have to call OSHA to clean up the spill of mercury.

If the fuel did flow from the hard line on the engine, then put things back as they were. and we won't ask again if the fuel hose are on right.

So if you have spark and the injectors are operating.........Heck, I don't know. Pull the bottom plugs out of the engine. Put some oil into the sparkplug holes and crank the engine by hand so each chamber gets some oil in it. Replace the sparkplugs. Pull the fuel pumps plug off.
Spray starter fluid into the intake manifold/snorkel for two/three seconds max. Start the engine. If it starts momentarily, then repeat. Then reconnect the fuel pump plug and try again.

IF it does not try to start with the starter fluid........got me. Push start I guess. Last resort imho.

RotaryMazda

Wow, I definitely overlooked the fuel lines issue and made a terrible assumption.

I had been comparing the fuel lines from my '87 to the '86, thinking everything would be the same. I was wrong.

I switched the fuel lines, the car started up. I let it run for about 5 minutes and then shut it off to do some final touch ups on the car. When I went to start it back up, it wouldn't start. I have no idea what to do now.

But anyhow, thank you guys so much for the help. For those few minutes while the car was running I was ecstatic! Now I just have my final question about why it won't start back up again?

RotaryMazda

Alright. So I assumed I may have flooded the engine, so I de-flooded it. The procedure I used was removing the ENG INJ fuse and cranking it over with both the clutch and gas pedal completely depressed. I did this twice, with a break in between and then put the ENG INJ fuse back it. It then started.

Unfortunately, I still hadn't added enough coolant so after letting the car run for a short while, I shut it off and added coolant. I did this process a few times, and each time I had to "de-flood" the engine. Now even with the de-flooding procedure it won't start back up. For the first 1 or 2 seconds, it seems like it is about to... but doesn't. I'm letting the car cool off now, and letting myself cool off as well. I just don't know what to do and all I wanted to do was just drive to the gas station to get more gas! (Yes, there is gas in the car, by the way)

Thanks for help!