Recently rebuilt 2nd gen suddenly won't start - where to begin?
 

Okay, here's the deal -

I'm driving an S4 (87) n/a, stock for all practical purposes, got about 25k miles on a rebuilt engine, and at the same time got new fuel pump, new injectors, new ignition coils, etc.

I drove the car two days ago, and it ran 100% normal. Tried to start it today, and it'll sit there and crank and crank but won't actually fire up so I think I'm either not getting fuel or not getting a spark.

What's a good starting point as far as things to test?


**I should note, the guy who rebuilt my engine installed a kill switch (pretty sure it's for the fuel injectors, in case the engine floods)

Did you try "flood" starting it, put the pedal in the floor and crank it? See if it turns over then.

This does not work for any S4 vehicle.


-Ted

Oops, works on my S5. I forgot. Pull the plugs and crank for 15 seconds, reinstall plugs and see if it starts up.

Shouldn't the tach 'bounce' if it is getting spark?

I forget.

Yes, but that only indicates a specific coil is firing.

Pull the plug wires and put a screw driver to the tip of them and see if there is a spark arcing.
If there is, pull your two leading plugs, and yer EGI fuse and turn it over and blow all the gas out of it. Squirt a little motor oil in there while yer at it.
Try that.

Thanks for jumping in here!

What will that do? If it's a cure for flooding, the kill switch works for that. If it's supposed to cute something else, lemme know and I'll try it!

My tach 'bounced' all of once in the whole time I was trying... so it does sound like I may not be getting spark. What would I do to test/confirm this?

As in, screwdriver in one hand, and one plug wire end in the other, right? how far apart should I hold them?

If there's no spark arcing, that means my trailing coil is not functioning, then, right?

I typically just leave a plug in the end of the wire and ground it, have a helping hand to turn it over, and while that is going on you can observe whether or not there is spark. Screwdriver works too, just a little cumbersome to me.

This.
But, having been zapped before, I'm now paranoid and I use a set of pliers with an insulated handle to hold the plug by the boot on the wire.

Watch the tach needle while trying to start the engine. IF the needle makes small movements that tells you a lot. It tells you that the ENGINE fuse, both EGI fuse are all good and that the main relay is pulling in.

Engine will not start with a blown EGI fuse(s), engine fuse, period.

IF the needle does make movements try deflooding it by the usual methods. I assume you don't have a blown apex seal when saying this and you have gas in the tank and there is no fuel cut switch in the OFF position.

EDIT: And or ...........put a jumper in the fuel pump check connector and the key put to ON. The fuel pump should be heard running. If not.......too bad, something is amiss.

Pulling the fuse does essentially the same thing your fuel cut switch does. Putting oil in the engine helps build compression if it's been flooded.

I'll check the EGI fuse. -checked and all fuses with EGI in the title are fine.

Tach is making the tiniest of bounces once each time I start the ignition, then nothing.


**engine isn't flooded, there's practically no way an apex seal is blown, etc. - Fred's assumptions are all fair.

Where is the fuel pump check connector? Not coming up with that one easily in the Haynes manual

Just put the plug wire on the windshield and prop a screw driver in place so it is about 1/4" away form the plug wire opening. Make it so you can see it from inside the car. Get in and crank it while watching for spark.

Great suggestion! I'm definitely getting a spark, so we can rule out a bad leading coil.

Gotta figure out how to run the fuel pump test now.

[QUOTE=MmSadda;145206]Where is the fuel pump check connector? Not coming up with that one easily in the Haynes manual[/QUOTE

On the right hand side of the engine bay find the pressure sensor attached to the front side of the right front strut tower area. The elect plug is yellow in color and has two sockets. It is not attached to anything. Get a piece of elect wire bare at each end. Put one end in each socket of the plug. Key to ON. Listen for the fuel pump noise running all the time.

This yellow fuel pump check connector might have black heat shrink around it. Possibly.

If the pump runs you Know the ENGINE fuse in the interior fuse box is good (third row up from the bottom and second fuse over on that row counting from the left as you look into the box. 15amp fuse).

Usually the tach needle will make one bump if you just turn the key ON. Normal. But it sounds like you have no tach action after that when you spin the engine with the starter. Odd.

This is when I'm facing the engine bay from the front of the car? It's on the right?

I see a little box labeled "pressure sensor" on the left, as well as another wiring harness. On the right, I just see the main fuse box.


Nope, no tach action after that.

Trailing coil is where you get yer tach signal from. Make sure you have spark to those.

If you are facing the car, it is on the LEFT side of the engine bay.

Right is the right side of the car. Left is the left side of the car.

The yellow two socket plug is not connected to anything and you may have to fish around the area where the pressure sensor is to find that YELLOW colored plug.

If you turned the key to ON and saw the tach needle make one small bump...........the trail ignitor did fire that one time along with one of the fuel injectors. All one has to do to prove this is put a LED on one of the primary fuel injector wires at the ECU and turn the key to ON and see the LED make one blink. You can only get a blink if the ECU puts a gnd on that primary wire. One LED wire to a constant batt voltage and the other LED wire to the primary injector wire at the ECU (I'm not suggesting the thread owner do this, make that clear).

EDIT: I found the jpg attached on the internet. The yellow connector is circled in the jpg.

To clarify further, the check connector is on the passenger side of the engine bay.

Okay, so the trailing coil seemed to be fine when I ran the test, too. I tried checking the fuel pump and it was fine.

In frustration, I tried starting the car once more and it fired up just fine! I took it for a drive and it ran well, and started again perfectly once I shut it off and restarted!

Thanks for all the help, guys! I dunno what the issue was, but it's resolved so I'm happy. Tech help here is a WHOLE lot better than 7club, it seems.

I just hate it when problems fix themselves... they always reserve the right to come back again later on those terms.

Glad you got it running.

Yeah, I fought one of those for over a year with the O2 sensor - I think it was the wiring. Ultimately, it's been well over a year since I've seen symptoms, but they used to show up once every couple weeks.

Thankfully, I think this may have been a loose connection. If nothing else, I know pretty well where the issue is.



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Ok, thread is done, and OP seems to have the problem solved for now.
This is getting way OT, so I'm closing it.
Remember folks, this is a TECH section.


-Ted