1996 Elantra 1.6L GLS slow crank no power to injectors
 

HI,
i am very confused with this vehicle as the car dropped all power while driving and wouldn't start again , it cranks slow but no start.
i have replace the cam and crank sensors , MAP sensor , coil pack , leads and spark plugs.
the fuel pump is running , the fuel is going through the filter , through injector rail and returning perfectly fine.

There is 0.26ohm on the Injector connector going to ECU but no 12V when the ignition is ON.
I have checked all the fuses in the engine compartment and the fuses inside the kick panel at the driver side.

The car manual talks about an MFI Relay that should be located inside the vehicle.
I can't seem to find any such relay.

any help would be appreciated thanks.

First a silly question: Do you have 12 volts at the battery?
Next silly question: Did you check the fuses visually or electrically??
Use a test light?
Last silly question: Did you test for voltage at the fuel injectors while the engine is cranking??

If there isn't enough power to crank engine at proper speed then crank sensor will not provide a good signal to ECM
ECM will then not put out 12 volts for injectors, fuel pump
Also, if the cranking of engine makes the voltage of the battery drop below 9.5 volts then ECM will not function properly

Okay... So I replaced the MFI sensor (fuel injection relay)... After that we tried to crank the car again. Cranked normal but no start. Checked fuel on spark plugs, strong smell. Checked for spark, none but there was smoke coming from the spark plug hole in the head meaning heat so there must of been fuel.

We checked all fuses electrically and they are all good, the fuel pump is running as usual. Our electric tester went flat so we got to wait to get a battery for it to test the car battery and make sure there is 12v on the injectors.

I will reply as soon as we do that.

Basically we are one step closer in my books.

If the battery isn't giving 45amp I'll replace
If battery isn't giving more than 9.5v on crank I'll replace.
If there is 12v on injectors then that is fixed.

I'll keep the progress posted. But thanks for that point of view, we never checked battery.

​​​​​Although the battery could of died out with all the testing and the MFI relay is fixed.

Getting igniting sounds from engine now but again, need to check battery now.

Okay, so i have some news... replaced the MFI relay and put back the old cam and crank sensors.
The battery is 100% fine , got 12.7V on it , 45AH and it drops to 10.7V when cranking the car.
The injectors have power and are pulsing when i crank the car.
There is Blue spark from all the plugs.

one problem though... took of the fuel line at the fuel filter and cranked the car... it doesn't squirt out with pressure... it just bubbles out ... i could push more pressure with a damn straw.

So what do you guys think? backtrack the problem by either:
1) replace fuel filter and test again...
or
2) spend more money on a tool to test the PSI of the fuel pump before i replace anything else?

EDIT:
ps. the engine is Cranking perfectly now after charging the battery fully , although it is almost time to replace the battery. (but as it stands the battery is still 100%)

If you still have the no start problem, from what info you provided , it is time to verify power and ground to the in tank fuel pump.You could start the procedure by confirming power going out of the fuel pump relay, to the fuel pump. Verify good ground at the fuel pump. If you have both of those requirements, chances are pretty good you are looking at a fuel pump replacement.

Thanks Hanky , but i listened to the fuel pump running. there is fuel coming through to the injectors , just not at the pressure it should. There is almost no pressure at the fuel filter and the pump is running. so my suspicion is that the filter is bad as i had the car now for 2+ years and my dad drove the car for like 8 years and he says he doesn't remember changing the filter at all... (that is very bad , over 10 years old fuel filter, i know)...

The fuel pump relay is working and so is the pump in tank.

So changing the filter is a must anyway after such a long time.

Seems you know what to do, let us know how you make out , OK, thanks.

Something of which you should be aware,
Some fuel pump modules (Punp assy and gauge sending unit assy in the tank) developed leaks within the internal tubing of the module. The pump would run at the correct speed, but did not develop sufficient pressure because the tubing within the pump module had a hole in it and was leaking internally. You could replace a good pump and still have no pressure..Entire module replacement was the solution.

Hanky is right. Check for power and ground at the fuel pump
(Engine must be cranking. Safety feature. If car is in an accident and engine stops. Pump stops)
Sometimes the fuel sock in the tank gets clogged or one of the hoses breaks or a clip will break
Then the fuel pump doesn't build up enough pressure for the injector to work properly.
So, you have almost got it fixed. Looks like you didn't need help.

Okay Gents , i have progress... there is fuel now , there is spark and there is compression since the car is damn backfiring out of the intake and manifold... so that is timing on the crank sensor if i am not mistaken.

Now i checked for voltage at the plug at the crank sensor and there is no power... FOUND THE DAMN PROBLEM!!!

(yes there is power at the injectors , cam sensor , map sensor ... all over... not at the CRANK)

so my question is , is there a fuse or Relay the Crank Sensor runs through and if so , where might it be?
There is no power at all on the plug for the Crank sensor at all.

(ps. i did replace the fuel filter and the pressure is perfect now.)

Most vehicles use a 5 volt reference voltage to various sensors.
Suggest you unplug the throttle position sensor and check if you find a 5 volt reference voltage at one of the pins in the plug. If present, do same for crank sensor.
You can also use the plug at the MAF sensor.
Let us know what you find.
Do you know when the timing belt was last replaced ? How many miles ago ?