1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

S4 fuel issue

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Old 09-12-07, 12:21 PM
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Kim
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S4 fuel issue

I have an series 2 with a Series 4 N/A motor in it.
The last nine months ive been fixing her up, rust, suspension and such.
About 6 months ago i moved her out of the garage and in to the shop, no problems she fired right up.

Now as she is ready to go out in all her pride and joy, the damn bitch wont start.

I've got:
Fuelpressure
New plugs with spark
fresh rebuild with 1500 miles on it and 110psi compression
lots of cranking power ---- But no bang.

If I use "startgas", You know the ether based spray ****, it will fire right up, go to 3000rpm for a second and then die out.

I have checked the plugs, they are dry and has no signs of ever having been in contact with fuel
Could my injectors have seized up just by sitting for six months?

Any suggestions are eppreciated.

Kim
Old 09-12-07, 06:33 PM
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Highly unlikely that both injectors would freeze up in 6 months. More likely they aren't getting a signal to open if you've covered everything else.
Old 09-12-07, 07:21 PM
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Kim
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Still have to check:
AFM
Injector Resistors ( 2,5 OHM right? )

Ohh man I used to rock at this when I was a 2nd gen guy, guess i'm getting older
Old 09-12-07, 07:31 PM
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Get a noid light set and check signal to the injectors.
Old 09-12-07, 07:41 PM
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Kim
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I will nig.. ehh ghettorig a bulb tester for the injectors.
Now it's bedtime, been online for too damn long to figure this one out.

Thx
Old 09-12-07, 08:21 PM
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You don't need a noid light for this. 1st check the fuseable links for the injection system

You can do a pin test at the ECU to verify power and ground to the injectors.
How did you verify that you have fuel?
Old 09-12-07, 08:49 PM
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Originally Posted by Kim
Still have to check:
AFM
Injector Resistors ( 2,5 OHM right? )

Holding the AFM door open a little is always a good trick to try.

2-3 OHM only applies to the 86-87.0 engines.They still get 12 OHM to the ECU,but its because the resistor pack takes care of it.The 87.5-92 engines have 12 OHM injectors and no resistor pack.

This is very common,be sure the fuel feed and return lines are plumbed right.If the feed is sent to the wrong steel line on the block,it will dead-head behind the FPR and youll never get any fuel.The inlet should feed to the primary rail and return from the secondary rail.
Ive also heard of guys putting the feed line on the vapor recovery line that sits next to the 2 fuel lines.They then proceed to fill their crankcase with gas while wondering why it wont start.
Old 09-13-07, 03:43 AM
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Kim
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Originally Posted by rx7doctor
You don't need a noid light for this. 1st check the fuseable links for the injection system

You can do a pin test at the ECU to verify power and ground to the injectors.
How did you verify that you have fuel?
Thanks, i will test at the ecu before taking all the manifold and stuff off.
I can hear the fuelpum and when i removed the feed hose after cranking, there was definately pressure inthere
Old 09-13-07, 07:46 AM
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Well, before testing the AFM, ECU, etc. You need to see if to got a signal to the ECU. Most common problem is that your trailing ignitor died or became disconnected. If this happens, you get fuel in the line, but never a signal to fire the injectors. Do you have spark on all plugs? If you are getting spark on the trailing side, then this isn't the problem. I am assuming that you are running an S4 ECU, AFM, ignition, etc.

Another possibility is a lack of power to the injectors (or lack of signal). This could be due to a blown fusible link that powers the injectors or a problem with the ECU.
Old 09-13-07, 01:13 PM
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Kim
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Trailing is firing just fine, I doubt its the problem anyways since I run N322 ecu, the european engine with dizzy and butterfly aux.ports.

There is power at the resistor pack plug.
The pack shows 8.some ohms.
12 Volts at the ECU primary pins.
Injectors are clicking like a ****.

Im sure this is just some wire that got fucked up somehow, just needs to find it.
If anything fails I will slap on the IDA Weber. and be done with EFI.
Old 09-13-07, 02:42 PM
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Since it has a dizzy (much like our GSL-SEs), you can have spark on the trailing without the signal to the ECU. For instance, there should be a wire the runs from the trailing coil - to the ECU. If that became disconnected/broken, you would get no signal to the ECU and no firing of the injectors.

You do say they are clicking, so it sounds like they are at least trying to fire. It may be a good idea to throw on a noid light and see for sure. So if the injectors are getting signal to fire, and are getting power. The only things that I can think of as to why you are not getting fuel are:

- fuel lines plumbed wrong (as Steve pointed out above)
- both injectors are seized (seem unlikely, though)
- you're out of gas

For fuel pressure, how did you test for it? Pulling the line off? Squeezing the line? Actually measure it? When you try the key on and prop open the AFM, do you hear the fuel pump running? Try squeezing the fuel lines to feel if fuel is being circulated? Just trying to come up with different possibilities.

Another thing, the fuel pump (at least on the SE and the 2nd gens that I have looked at), will run under the following conditions:
1. AFM door open
or
2. key turned to 'START'

So, say you prop the AFM open with the key switched to 'ON', you could test #1. As for #2, it is a bit harder to test (unless you can hear the fuel pump run when cranking). You could remove the trigger wire from the starter, turn the key to 'START' and see if the pump runs (this test is with the AFM door closed).

It does sould like more of an injector problem, though. Because if you had some fuel in the line (I assume you do since you said you had fuel pressure) and the injectors were working, you should get some pops or start for a few seconds and then die.
Old 09-13-07, 04:46 PM
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Kim
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So far I have checked that I have fuel.
In the tank
Pump runs during cranking
Pressure in the fuelhoses (hard to the squeeze nad fuel all over when I pull the hose off)
Theres also fuel in the secondary rail before the pressure regulator, but not after

I will look for the trailing wire tomorrow.

Thanks once again.
Old 09-14-07, 05:49 AM
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trailing signal to the ecu is there too.
approximately 10Volts to the injectors during cranking, my papers says 12Volts.
Old 09-14-07, 01:05 PM
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Screw it, i'm pretty sure it should fire right up, If it would just get some fuel.
I've come to the conclusion that the injectors may be gummed up with premixed fuel residue. Going to pull them out Monday to get them cleaned.

I need to get it to work, don't wanna run a non choke carb during the Danish wintertime
Old 09-18-07, 05:17 PM
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Kim
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Woohoo...

Got the damn thing fired up today, turns out that it infact was lacking fuel(as in empty tank)
I must have mistaken the fuel/air mist spewing out of the hoses for just being fuel under pressure

Anyways the car had a quart of a tank of fuel when she went into hibernation last year, and now theres nothing in it. Seems like the, allways broke, guy I share my shop with is about to be kicked out. He's a ******* BMW tool anyways
Well, not everything sucks about this dumb issue, I got some of all that wiring mess cleaned up and ripped out.

After 6 months of just sitting, she fired right up to 3000 rpms then settled down and purr'd like a kitten

Video from my cellphone, sry.
http://www.youtube.com/watch?v=fHgaPuzn7MM

Last edited by Kim; 09-18-07 at 05:38 PM.
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