Injectors not spraying when starting

[bsimonson]

Would very much like some input on what might cause this.

Background
Engine was starting and running well but a leaking #8 bearing made me decide to do a rebuild. I took the engine out myself, stripped it to the long block and sent it off to my mechanic. Got the rebuilt engine back, put everything back on and installed it. The only changes I made to the injection and ignition systems while the engine was out was to replace a few bad wires in the main engine harness. It's a US-spec 1980 SC.

Current situation

• Engine is turning over on the starter but does not fire. I've had a few backfires.
• I've checked for sparks, they are there (at least on the #2 cylinder)
• If I turn the ignition on and lift the meter plate, the injectors spray. While cranking, however, the injectors does not spray, even if I lift the meter plate. They should, right?

I have checked that the 87 input on the fuel pump relay has voltage while cranking and that the relay itself is ok.

I assume I've made a mistake when I messed with the engine harness or I've made a mistake when putting things back on the engine but I don't understand what it could be that would cause this behaviour. Any ideas?

Cheers,
Björn

[boyt911sc]

Björn,

Before we go on discussing the details for troubleshooting, please check the operation of the FP relay and socket. There is thread by DKLever48 about about troubleshooting the FP relay socket. If all the 5 terminals are confirmed good, then we could go on further and look for other possible culprits.

What electrical works have you done to the harness? Did it involve the FP circuit? Please advise. Thanks.

Tony

[LJ851]

Originally Posted by bsimonson

[*]Engine is turning over on the starter but does not fire. I've had a few backfires.


Cheers,
Björn

Your distributor could be installed 180 degrees out (firing on exhaust stroke instead of compression)

[bsimonson]

Hi Tony,

Thanks for the input, I will have a look at the thread around the FP relay.

I only worked on the harness that connects the starter, alternator and 14-pin connector. Replacing worn/hardend wires etc. Could of course have made a mistake and crossed some wires somewhere while doing it.

/B

[walt]

I had a similar problem the last time the engine was out. Did you label the connectors on the harness to verify where they go.

[bsimonson]

Hi Walt,

Yes, I had labels on all the CIS-type connectors like CSV and WUR etc.

/B

[Jase77]

Hi Björn,

I have recently rebuilt my 2.7 and I was having exactly these symptoms when I was trying to get the first fire up.

Does the 1980 SC have a fuel pump safety switch on the back of the Air Flow Sensor housing, behind the large rubber boot? If so try unplugging it and see if it will start.

This part had failed on my car and prevented me starting it for weeks whilst I went through the CIS componentry with the help of boyt911sc (Tony, couldn't have got this far without him). Once unplugging it it started up and has been running well since.

Give it a go, it may be something simple.
Cheers,
Jason.

[bsimonson]

Hi Jason,

Yes it does, and I should have thought about removing it to see what happens. Thank you for reminding me!

I'm a bit busy this week but will report back once I've tested more things.

Cheers,
Björn

[ossiblue]

It doesn't make sense to me that the injectors don't fire while cranking, even when you lift the meter plate. Your test with ignition ON and lifting the plate confirms that fuel is injected. By lifting the plate during crank, you are essentially repeating that test because lifting the plate switches the relay to 87a, power with ignition ON, and the fuel distributor is engaged by the pin on the plate arm.

Unless...you have a fault at the relay terminals. If power to 86 and 87a is interrupted while the START circuit is applied, then fuel would not be injected. Interrupting that power would immediately cause the relay to switch to 87a because the relay coil is shut off also. 87a would then have no power to the fuel pump so the fuel would not be injected even if the plate is lifted and the plunger pin activates the fuel distributor.

Use a test light. Test to see if there is power at sockets 86 and 87a while the engine is being cranked. If not, there is a problem.

BTW, be very careful lifting the plate during cranking. You are placing yourself very close to a possible backfire should enough fuel be injected by either the injectors or the CSV. Backfires have been known to blow apart air boxes. If part of your issue is timing or ignition, a sudden backfire could be very dangerous.

[JSZ]

Check the two yellow wires that plug into the starter and make sure you dont have them reversed.

[boyt911sc]

Originally Posted by bsimonson

Would very much like some input on what might cause this.

Background
Engine was starting and running well but a leaking #8 bearing made me decide to do a rebuild. I took the engine out myself, stripped it to the long block and sent it off to my mechanic. Got the rebuilt engine back, put everything back on and installed it. The only changes I made to the injection and ignition systems while the engine was out was to replace a few bad wires in the main engine harness. It's a US-spec 1980 SC.

Current situation

• Engine is turning over on the starter but does not fire. I've had a few backfires.
• I've checked for sparks, they are there (at least on the #2 cylinder)
• If I turn the ignition on and lift the meter plate, the injectors spray. While cranking, however, the injectors does not spray, even if I lift the meter plate. They should, right?

I have checked that the 87 input on the fuel pump relay has voltage while cranking and that the relay itself is ok.

I assume I've made a mistake when I messed with the engine harness or I've made a mistake when putting things back on the engine but I don't understand what it could be that would cause this behaviour. Any ideas?

Cheers,
Björn

Bjorn,

Why does your engine have two (2) decel valves? Take a closer look at the attached picture of yours. Are you aware of this strange set up?

Tony

[jjeffries]

Obviously you're in great hands with Tony consulting. Only thing I'd add is to check you haven't reversed the wires on the temp sensor located on the driver's side cam chain cover. Best of luck, John

[T77911S]

tony, one may be the DV and the other looks like a AAV.


you say if you turn the key on and lift the sensor plate the injectors spray. that is good. means FP and all is working., only unknown and I don't think is the issue is does the pump run when cranking.
you are getting backfires.
sounds like your dist may be in 180 out or plug wires on not correct. check firing order. its very easy to get mixed up. I always count #4 as #3.

no spray when cranking is probably not a big deal either. mainly because the engine starts from the CSV. check the connections at the starter. that is where it gets its power.

if the plug wires are correct you should be able to lift up on the sensor plate then start it. you may have to hold it up to keep it going. if so then you could just be too lean. (another reason why the injectors wont spray when cranking.).

backfiring is tell tail sign of either the dist is in backwords.
verify #1 intake valve closes then Z1 comes to the top.
rotor is pointing to #1 plug wire and line on dist.

[bsimonson]

Hi all,

Sorry for my long absence. I had a long vacation and have been busy since coming back. I have read all the suggestions given and tried a few more things over the weekend:

I've measured the relay socket with the relay disconnected as suggested by Tony and everything was to spec.

With the relay connected while cranking it was a bit different however with power on 87 but not on 86 / 87a. So there is most likely something wrong with the wires to the socket. I'm also not sure that the connections in the socket are fine as it looks quite worn, will probably replace it while sorting out the wires.

What I also tried is to run the fuel pump continuously with a (fused) wire straight from the battery to the 30 hole in the socket. Then tried to crank the starter to see if it would run. No luck there either except for another backfire.

I'm hesitant to mess with the mixture adjustment as it ran well before, but I guess it could be worth a shot since I can set it myself later as I have an MTX-L installed.

My old ignition lamp broke but I will get a new one to verify the ignition when cranking, I've checked and double-checked the wires and timing but I can of course have messed it up somehow. The light will guide me

Thanks a lot for the help and I'll report back more frequent from now on.

Cheers,
Björn

[T77911S]

backfiring is crossed plug wires or dist in backwords.

if the socket checked fine per what tony said it is probably ok. not sure what your other test was

[theiceman]

could your safety shut off and csv plugs be reversed?

[bsimonson]

Originally Posted by T77911S

backfiring is crossed plug wires or dist in backwords.

if the socket checked fine per what tony said it is probably ok. not sure what your other test was

As far as I remember Tony's test's didn't include any tests with the engine cranking, so I basically added that.

Backfiring could be what you said but also a general lean condition created by the CSV injecting fuel but not the other injectors.

Originally Posted by theiceman

could your safety shut off and csv plugs be reversed?

Anything is possible but they were labeled and the color coding is correct. And since a bit of fuel is injected I guess that is coming from the CSV. I'll double check with my voltmeter.

Thanks for helping out!

/B

[theiceman]

well when you say they are not spraying I'm assuming you have them in glass jars or something and you see no fuel coming out while someone cranks ? so that would eliminate distibutors, spark , all that other stuff
so something is killing the fuel pump while you crank.
so you did not touch your intake system other than the wiring harness ?

[boyt911sc]

Bjorn,

Have you confirmed and tested that the fuel pump relay is good and working? If you have tested the FP relay socket per DKLever’s post, you should not worry about the wiring connections. Another test you have to verify is your CSV’s operation during cranking of the starter. The motor is basically driven initially by the fuel coming from the CSV followed by the injectors. This is not a convenient test to perform.

Pull out the CSV and place it in a container. Crank the starter and observe the CSV’s fuel spray. While the engine is cold and turning the ignition switch to START will cause the CSV to be energized and deliver fuel. Keep us posted.

Tony

[theiceman]

"This is not a convenient test to perform".

understatement of the year .. I HATE testing that thing !!! lol