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This is a spider we picked up... sat in previous owners yard for 5 years... supposedly ran up to that point when car was in a fender bender. We're struggling to get it started. We have been reading through most posts for the past month with no success. (including Eric's diagnostic essay). All calls for advice please!
What we've done so far:
1. Removed and cleaned out tank.
2. Tank pump replaced (including strainer) and tested at 25 to 30 psi.
3. Blew out all sending and return fuel lines (lots of old dirty gas).
4. Replaced external fuel pump (tested at >60psi).
5. Replaced external fuel filter.
Tested fuel pressure,in-line, at input of fuel rail (36psi) and after fuel regulator (>60psi with no thru flow).
6. Removed fuel rail and injectors, tested and cleaned them (including rail by itself). Each will squirt fuel when a signal is present. We purchased 1 new injector to compare the fuel output during test and the spray pattern looks very similar to the original 4. I'll discuss this more at the end of this post.
7. Verified all injector connectors were getting the same signal from ECU.
8. Checked all vacuum lines and everything looks OK. Some small vacuum lines were broken and these were repaired.
9. Checked cylinder compression and the 4 ranged from 110 to 125 psi. Seems good enough to run the engine.
10. Checked that all spark plugs are sparking.
11. Verified firing order from spark plug wires / cap / rotor... all OK.
12. Checked all other electrical/sensor/controller components in engine bay and everything seems to be intact. Including the clean-up of ground connections.

Now, our suspicion is something fuel related. When we add fuel or starter spray to throttle body the engine will run for a few seconds with lots of power. We then did a dirty test that I would not advise to anyone because of risk of damage: we crimped the return line to build up pressure and tried to start; sure enough, it ran... though not extremely smooth but it did run because of the forced fuel.
Our conclusion is that something is not allowing enough fuel to go through the injectors.
To test the signal we removed one of the injector connectors (#1) and connected externally to our extra (known good) injector. We bridged the fuel line to it to feed 36psi fuel. To get a signal to it we removed the distributor and with the key on, rotated it manually. This simulates the rotation of the engine. What we noticed was that this signal is only sent to the injectors only twice during a full rotation of the distributor rotor.
I thought I had read that it should get 4 hits at every complete rotation, one for each cylinder/spark plug? Anyone have anymore info on this?

The only other possible causes we could think of are:
1) Our new injector is defective, not spraying enough fuel, making us think the others are working just as good. Though it seems to be just as good, comparable to sprays I've seen on other vehicles. But we may be wrong.
2) The ECU is not telling the injector to stay open long enough. Though again, it seems very similar to what we've seen in other vehicles.
3) The ECU is not sending the 4 signals it needs before each compression stroke.
Our next task is to go through the ECU to check connections and grounds.

If anyone has any suggestions, please advise, this is going to make us lose hair in places where light has never been!
-Brutus
 

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If anyone has any suggestions, please advise, this is going to make us lose hair in places where light has never been!
I was doing OK until I read that line. Yikes - TMI!!


To test the signal we removed one of the injector connectors (#1) and connected externally to our extra (known good) injector. We bridged the fuel line to it to feed 36psi fuel. To get a signal to it we removed the distributor and with the key on, rotated it manually. This simulates the rotation of the engine. What we noticed was that this signal is only sent to the injectors only twice during a full rotation of the distributor rotor.
I thought I had read that it should get 4 hits at every complete rotation, one for each cylinder/spark plug? Anyone have anymore info on this?
I never thought to try turning the distributor to fool the ECU into squirting the injectors. My assumption was the flywheel position sensor is what told the ECU the engine was turning. Speaking of flywheel sensors - did you test them as described in the L-jet diagnosis page? There are two sensors - they are identical but must be connected to the wire harness correctly.

The ECU is not sending the 4 signals it needs before each compression stroke.
The injectors are batch fired - not sequentially in any firing order.

Our next task is to go through the ECU to check connections and grounds.
That is vital - the ECU controls the injectors by switching their ground circuits.
 

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Discussion Starter #3
Eric,
Yea, the distributor trick is pretty cool for most basic tests.
But my concern is that it only sends a signal on every other spark that the plugs get. For example, only when 1 and 4 get hit by the rotor. If I understand you correctly 1 should inject at the same time 2,3,and 4 inject. In other words, each cylinder should have gotten 4 hits of sprays when it's turn comes up. Is this correct?

Another concern is the crank sensors you mentioned. I can see the connectors hanging down but nothing is connected to them. I can't even see the sensors existing anywhere back there. I assumed this spider didn't use crank sensors. Is this possible?

- Brutus
 

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Eric,


Another concern is the crank sensors you mentioned. I can see the connectors hanging down but nothing is connected to them. I can't even see the sensors existing anywhere back there. I assumed this spider didn't use crank sensors. Is this possible?

- Brutus
Can you clarify this? The connectors are back by the fire wall and near the top on the passenger side. The sensors are attached to the bell housing by blocks. Check the L-Jet diagnostic for pictures.
 

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I can see the connectors hanging down but nothing is connected to them. I can't even see the sensors existing anywhere back there. I assumed this spider didn't use crank sensors. Is this possible?
If the original Bosch distributor and ignition ECU have been replaced by another 'stand-alone' system then I think it is possible to do away with the flywheel sensors.

What is inside your distributor? The original has nothing except the rotor - no points, no hall sensor, etc. It is basically just a four-way switch. The L-jetronic ignition ECU tells the coil to fire and the distributor sends the output to the appropriate spark plug wire.
 

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Discussion Starter #6
The connectors are there by themselves... nothing connected to them.
I still cannot see the sensors or blocks. Can you see them from above or only from below? Are they directly inline with firewall or farther back towards the tranny? Are they supposed to be near the starter? I think we need better pics to show the exact location; we're dumbfounded!

Also, I believe the distributor is the original. Only the rotor and the hall effect sensor, with the 4 tooth gear is present. The distributor cap even has made in Italy molded on the top, looks original.
 

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Only the rotor and the hall effect sensor, with the 4 tooth gear is present.
This is not an original distributor. As such, the Motronic ignition ECU is just along for the ride and the flywheel sensors are not needed.
 

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Discussion Starter #9
Wow, that is something new for us!
Is there a way to identify this through the coil/module assembly? Or through the ECUs in the back seat?
 

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Hey, Jim, doesn't one of the sensors provide the signal to keep the fuel flowing?
No. The fuel ECU gets it's engine running/engine speed signal from the ignition coil negative terminal. Both of the flywheel sensors, reference point (lower sensor) and the RPM sensor (upper), are for the ignition system.

Brutus,
If you'd like some color wing diagrams, please send me your email address in a private message. They include the L-Jet wiring and the stock Motronic ignition wiring.
On a side note, the 'spin the distributor' trick would not work on a stock system as there is nothing in the dizzy to trigger the coil.
 

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Discussion Starter #11
Thanks for the info, John and Jim.
Assuming this is Motronic distributor and back to my original question, should the injectors receive only 2 batched signals during 1 complete rotation of the rotor or should they receive 4 since there are 4 teeth on the distributor?
 

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Discussion Starter #13
Rogerspeed,
Excellent! That means we are getting the pulses we need. So now assuming the duration of the pulses is correct, and we have the required pressure (36psi), and we have spark at the spark plugs, then the only things I can think of are:
1) The injectors are defective/clogged, not letting in enough fuel.
2) The fuel rail injector lines are partially clogged.
3) The entrance to the the intake port is clogged.
4) The signal to the injectors is not a full 12V.
5) The ground to the injectors is not sufficient.
etc...?
Any other suggestions?

Since we had done preliminary tests on injector output, I'll leave those till the end and we'll concentrate on the 12V signal and Ground.
I'll look at the drawings Papajam sent me, but any one know off the top of their heads where the Ground originates?
Also, how do I verify the full 12 volts on the supply side at the injector, since it pulses?
Thanks in advance!
 

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The injectors are supplied battery voltage with key on via the main relay (the small one) by the fuel ECU. The fuel ECU provides the injector grounds to pulse the injectors. Check injector voltage at any/all injector connector with KOEO (Key On Engine Off). You'll find that BOTH wires will be hot! :eek:
 

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Discussion Starter #16
Papajam,
OK, on the schematics I see the 12V come from pin 87 on the Main Relay... will be checking that, just in case the full 12 is not at Inj connectors. For the Ground, I only see pins 16, 17, and 5 going to Ground at the valve cover (I believe). I'll check those.

rogerspeed,
We tested each interface/connector individually with an extra injector we had and it seems to operate fine with all wires but not sure if it's enough output.
We wanted to leave the valve cover to the end since the compression measured 110-125 psi across the 4 cylinders. This indicates good valve timing. Unless normal compression should be much greater?
 

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Discussion Starter #17
OK, we tested the voltage at the 4 injector connectors and both wires measured 12.9V. We checked this voltage through the 3 grounds: 2 at the Aux Air Valve on the valve cover and 1 under the valve cover, on the head next to Fuel Inj #1. I believe these are the ones going to the ECU?
We checked the connector with our extra backup Injector and it still outputs the same amount of fuel; not sure if it's enough.
Is there any other way to test the negative part of the signal to ensure we're getting the complete signal?
Otherwise where do we go from here?
Pull out Injectors again?
Remove Valve cover? check cams?
Is it possible the Air Flow Meter could be messing with it? I just realized, we haven't checked the Air Filter Assembly.
 

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I will be following this as i picked up a 82 Spider with pretty much the same symptoms. I just ordered new injectors now to get them so i can see if this solves the no start.
 

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HELP!! 84 SPIDER Fuel pump run on and timing issues?? HELP!!

Can someone tell me what controls how long the in tank pump runs when you turn the key to on? This ones running like hell.There are other issues, which I'm pretty sure from reading other posts and the excellent FAQ are, 1. timing is 180 out (won't run with starting fluid pops etc. 2. Not enough voltage to wake up the ecu to pulse the injectors. which I'll be checking with a meter. Have power to both sides of injectors and fuel at the rail. engine was just rebuilt both fuel pumps are new. Went bad from sitting too long with crap fuel.
 

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Assuming the 84 is like an 87, the drive relay located under the parcel tray behind the passenger seat is what powers the in-tank and the main pump (under car). Its the bigger of the 2 relays in that area. In the key on position, the pumps should only turn on for 1 second. I'd be curious to know if its a KAE brand relay.
 
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