Help me resurrect my '86 X. (fuel injection system troubleshooting)

[AnthonyG]

Due to an accident and related circumstances, my car has unfortunately been sitting for several years.

On the bight side, I had it running quite well before, and it has been parked indoors and in a dry climate.

I have so far:

- *** reconnected the black wire from the ECU to the negative post in the coil *** (YES, I really remembered to do it!)
- replaced the battery
- checked all the fluids (they're still full and look good, but I will replace them one by one once I get the car running)
- checked the coolant hoses (still look good)
- checked the spark plugs (still look new) and fogged the cylinders
- re-inflated the tires (but will be replacing those too, once the car is running)

- drained out the old gas where the low pressure 12mm ID fuel outlet hose attaches to bottom of the tank
- flushed some fresh gas though the tank
- replaced the fuel pump
- added a 149ppm (larger particle) pre-pump filter to protect the new fuel pump
- replaced the fuel filter
- replaced all the fuel hoses (except for the injector hoses, which I will do when I remove the intake manifold to clean the injectors)

The car WILL now start and run when I spray starting fluid into the air intake flap.

But it will not start otherwise. (The starter is running strong and it will turn over like crazy.)

The fuel pump hums fine when I push open the air intake flap with my finger. But as far as I can tell, the fuel pump does NOT engage when I try to start the car. Apart from being triggered by the air intake flap opening, isn't that the only other time the pump is supposed to kick on? (And might that implicate a bad signal from the FI double relay or the ECU?)

I am now using the FI troubleshooting guide to work my way to finding the problem(s).

1) Check ignition - Spark plug wires sparking fine (still new)
2) Check air intake - Looks good; haven't spotted any leaks

3) Check fuel feed pressure - Whenever I press the air intake flap, the pressure shoots to 42psi. When I release the flap it drops to 40psi. then over the course of about 4 minutes, it gradually falls from 40psi to 20psi.

Spec is 36psi + or - 3psi, so I'm about 1-3psi over spec when the pump is engaged.

My guess is.. that small overage is probably okay, if not ideal. Am I wrong?

More concerning to me is the steady not so slow drop. I know the pressure is supposed to decline over a long while, but it shouldn't hold at that initial 40psi for at least about 20 minutes or so?

So an internal fuel pressure leak would possibly implicate:

1) bad fuel pump check valve
2) leaky injectors
3) bad fuel pressure regulator

Is this correct? Am I forgetting anything?

It seems to me that if I pinched the hose off at the inlet line before the fuel manifold, and took the pressure reading from just before that point, and the pressure still didn't hold, that the fuel pump check valve would be the culprit. But if it did hold, I could rule that out, and narrow it to the injectors and the regulator.

Am I on the right track here?

I realize the pressure would be much higher on this reading because I'd leaving out the regulator, but it should at least hold constant if the fuel pump check valve isn't flawed, right?

Would doing this higher pressure test (I'm guessing it MIGHT go as high as 50-60psi and hold there) harm the pump? I doubt it, but I figured I should err on the safe side and ask, before I risk wrecking my brand new pump.

The next step in the guide when the pressure is over spec, is to disconnect the return hose from the regulator, and to attach a test hose there and let the fuel run into a container. If the pressure is still over, it implicates the regulator. If it returns to spec, it implicates a blocked or damaged return hose.

My pressure was still over spec. In fact, it now spiked up to 43psi. So it's seems I have a not-so-hot pressure regulator that should probably be swapped sooner than later.

But I'm doubtful it's the reason the car won't start and run.

Today I'm on to #4 -- testing injector voltage.

To be continued.. ..

Feedback is welcomed and encouraged.

By all means, school me.

Thanks, Xperts.

 

[lookforjoe]

So, if it won't run or stay running without external fuel supply (starter fluid) then the issue has to be fuel side, as you have determined.

Fuel pressure as is should run the car, the (rest) pressure drop off I wouldn't worry about - unless it's instantaneous, I find that it can vary - sometimes holding for hours, sometimes dropping to >20 in less than 20 min.

Anyway, what it would seem to be is either the ign signal to the ECU is missing (check at coil), or something else connected or related to the main relay, since your injectors are not being triggered.

 

[JimD]

I read the post, I didn't see you mention the wiring at the coil that you found disconnected the other day. Did you address that? That lead being disconnected will give you the "crank all day, but never fire" symptom. Been there, done that. I even let a young oil change tech think he had broke my car. I let him panic for a few minutes before I distracted him, reconnected the wire, then said "Try it again." Its the little things in life.

I noticed your green and black wires were separated. From the factory, they are joined with a piggy back connector which then slides onto a male spade on the coil. Some people put rings on each wire then connect it to the post. How is yours connected... if it is.

 

[AnthonyG]

I read the post, I didn't see you mention the wiring at the coil that you found disconnected the other day. Did you address that? That lead being disconnected will give you the "crank all day, but never fire" symptom. Been there, done that. I even let a young oil change tech think he had broke my car. I let him panic for a few minutes before I distracted him, reconnected the wire, then said "Try it again." Its the little things in life.

I noticed your green and black wires were separated. From the factory, they are joined with a piggy back connector which then slides onto a male spade on the coil. Some people put rings on each wire then connect it to the post. How is yours connected... if it is.

View attachment 37508View attachment 37509View attachment 37510

Yes indeed, Jim, of course I reconnected it.

If I hadn't, not only could you justifiably accuse me of being hopelessly daft, but also of having the worst short term memory in recorded history, since we just just covered the importance of that a few days ago!

I couldn't find a piggyback adapter, or even another adapter like the one on the negative coil post to stack on top of it, so I fabricated a very short connector with a 10 gage loop, a 10 gage wire, and a 10 gage male spade, and stacked it on top of the other one.

Now hopefully I didn't somehow screw that up, or I'm really gonna have egg on my face.

 

[AnthonyG]

Test #3 - test injector voltage

I don’t have a test light, but this does seem like the low power fluctuation that I’m looking for. Can anyone confirm that this looks right?

With a test light, the light is supposed to come on with “weak and fluctuating intensity” when cranking the engine. This reading therefore seems about right. (0.02-0.06V)

UPDATE: Okay, someone loaned me a noid light, and it flickers at low intensity, so all good.

Onward..

 

[ng_randolph]

I hate to ask, but did you get the ECU connection (from your "mystery wire" thread) hooked to the correct (negative) side of the coil?

 

[AnthonyG]

I hate to ask, but did you get the ECU connection (from your "mystery wire" thread) hooked to the correct (negative) side of the coil?

I did! (See reply above.)

 

[AnthonyG]

I’m up to step #7 — checking the cold start valve.

So far everything has checked out.

There’s one little chunk of the step that I don’t understand. Maybe someone can help me out with it.

It’s this paragraph:

“Disconnect electrical connector from thermo-time switch, Jumper wire to terminal 46 of switch to ground.”

I’m having trouble making sense of the second part of that strangely worded sentence.

 

[kmead]

It would be a normal circumstance for the injectors to be clogged after this amount of time.

With someone turning the engine over try tapping each injector in turn as the engine is turning over. This may jog the injector to actually open. If not and you have checked the injectors are getting power (using a noid light) then they may need to be removed and cleaned.

The fact it will run with starting fluid indicates a variety of other failures are off the table like a bad ignition module, broken or missing teeth on the timing belt and so on.

 

[Dan Sarandrea (Phila)]

I’m up to step #7 — checking the cold start valve.

So far everything has checked out.

There’s one little chunk of the step that I don’t understand. Maybe someone can help me out with it.

It’s this paragraph:

“Disconnect electrical connector from thermo-time switch, Jumper wire to terminal 46 of switch to ground.”

I’m having trouble making sense of the second part of that strangely worded sentence.

View attachment 37528

The thermo-time switch is on the forward face of the cyl head vicinity of #2 spark plug, very close to the sender for the instrument panel coolant temp gage. You can tell the difference because the TTS is bigger and has the typical Bosch FI-style plug on it while the temp sender is smaller and just has one wire going to it.

Borrowing a pic from carl's recent post, IIRC it goes in the hole above the cast-in date circle (but I could have that backwards).

 

[AnthonyG]

It would be a normal circumstance for the injectors to be clogged after this amount of time.

With someone turning the engine over try tapping each injector in turn as the engine is turning over. This may jog the injector to actually open. If not and you have checked the injectors are getting power (using a noid light) then they may need to be removed and cleaned.

The fact it will run with starting fluid indicates a variety of other failures are off the table like a bad ignition module, broken or missing teeth on the timing belt and so on.

Thanks, Karl.

My instinct right from the beginning is that it’s clogged/gummed up injectors.

Everyone around me (non Xers) keeps telling me that it’s unlikely, but from what I’ve read about Xs that have sat for a long time, I have a hunch that may be it, especially since everything electrical was working well before it went hibernating.

I’ve been running though all these steps from the FI troubleshooting guide, and will continue to do so cause it's really teaching me my way around the FI system, but I’m definitely eager to get to taking off the air intake and checking them out.

But I’m sure learning a lot doing this, so I'm happy about that. Nothing like hands on experience.

 

[ng_randolph]

I’m up to step #7 — checking the cold start valve.

So far everything has checked out.

There’s one little chunk of the step that I don’t understand. Maybe someone can help me out with it.

It’s this paragraph:

“Disconnect electrical connector from thermo-time switch, Jumper wire to terminal 46 of switch to ground.”

I’m having trouble making sense of the second part of that strangely worded sentence.

View attachment 37528

I would skip this test. The cold start valve is only open for as long as you are cranking the starter, and for no more than 8 seconds (shorter the warmer the engine is), and is only there to assist in starting the engine. Since you are able to start the engine on starting fluid, but the engine wont run on its own, your problem is almost certainly not related to the cols start valve / thermo-time switch.

Adding to that, the wires are all white, and if you ground the wrong one you are creating a short. But should you want to try; find the thermo-time switch as described by Dan above and unplug the wires going to it. The plastic molding at the end of the TTS has a "W" molded into it on one side, and a "G" on the other side.

Have a look at the connector you just unplugged, and note which terminal connects to the "W" side of the TTS. Use a test wire to connect this terminal to ground. The cold start valve should open and spray fuel.

 

[Dan Sarandrea (Phila)]

Thanks, Karl.

My instinct right from the beginning is that it’s clogged/gummed up injectors.

Everyone around me (non Xers) keeps telling me that it’s unlikely, but from what I’ve read about Xs that have sat for a long time, I feel it’s likely. Espivally since everything electrical was working well before, and I’m in a dry climate.

I’ve been running though all these steps from the FI troubleshooting guide, and will continue to do so, but I’m definitely eager to get to taking off the air intake and checking them out.

You could try the "tickle" technique or the "tapetty-tap-tap" technique to try to coax injectors to somewhat function after a long slumber.

The tapetty-tap-tap technique has you placing a longer object (say a wooden dowel or long screwdriver) against a part of an injector you can reach, and then just lightly tap-tap-tap with a small hammer, the idea being the love-taps will help to free up the plungers inside the injector.

The tickle technique harnesses the power of a typical 9v "transistor radio" battery (wow that sounds ancient LOL). You unplug the injector's connector, and then use a fresh 9v battery to energize the plunger coil in the injector. You can rig up a harness with scrap wire or pick up a generic Bosch FI slash EV-1 pigtail connector at a parts store. The tickle part comes from how you energize it---you contact and release one of the wire leads to one of the battery terminals as rapidly as you can, 2-3-4 times per second. In VERY quite surroundings you can hear the injector click.

 

[AnthonyG]

The thermo-time switch is on the forward face of the cyl head vicinity of #2 spark plug, very close to the sender for the instrument panel coolant temp gage. You can tell the difference because the TTS is bigger and has the typical Bosch FI-style plug on it while the temp sender is smaller and just has one wire going to it.

Thanks, Dan. I know which one it is, and I have disconnected it for most of these electrical tests to protect it, as per the guide.

I was just confused about that bad sentence in particular.

But Papa T helped me out, and now I think I get it.

It’s missing few words to make it clear. Bad syntax.

So.. I’m creating a ground at terminal 46 of the ECU, which keeps the thermo-time switch activated, so I can them test the cold start valve.

CORRECTION: I got the above wrong. I'm grounding the "W" side of the TTS connector, and that will enable the CSI to fire away when cranking the engine.

 

[ng_randolph]

Thanks, Dan. I know which one it is, and I have disconnected it for most of these electrical tests to protect it, as per the guide.

I was just confused about that bad sentence in particular.

But Papa T helped me out, and now I think I get it.

It’s missing few words to make it clear. Bad syntax.

So.. I’m creating a ground at terminal 46 of the ECU, which keeps the thermo-time switch activated, so I can them test the cold start valve.

Not quite. The ECU does not have a terminal 46, and has no idea what you are about to do to the system. You are not "activating" the TSS, you are simply bypassing it to force the cold start valve open.

 

[Dan Sarandrea (Phila)]

Not quite. The ECU does not have a terminal 46, and has no idea what you are about to do to the system. You are not "activating" the TSS, you are simply bypassing it to force the cold start valve open.

Most folks don't realize that the AAV and CSI are simply hang-on units controlled mostly by the TTS (the AAV does take into account the heat from the cyl head its mounted to) and are in no way controlled by the FI controller.

 

[AnthonyG]

I would skip this test. The cold start valve is only open for as long as you are cranking the starter, and for no more than 8 seconds (shorter the warmer the engine is), and is only there to assist in starting the engine. Since you are able to start the engine on starting fluid, but the engine wont run on its own, your problem is almost certainly not related to the cols start valve / thermo-time switch.

Adding to that, the wires are all white, and if you ground the wrong one you are creating a short. But should you want to try; find the thermo-time switch as described by Dan above and unplug the wires going to it. The plastic molding at the end of the TTS has a "W" molded into it on one side, and a "G" on the other side.

View attachment 37538

Have a look at the connector you just unplugged, and note which terminal connects to the "W" side of the TTS. Use a test wire to connect this terminal to ground. The cold start valve should open and spray fuel.

Yes. That makes sense, Thank you. Agreed. Not a cold start valve or time switch issue.

AND.. pretty funny.. It’s currently 99 degrees where I am, and the thermo-time switch isn’t even supposed to turn on above 95 degrees. So when I tested it, it just flickered at low power. At least I know it’s working.

 

[AnthonyG]

Not quite. The ECU does not have a terminal 46, and has no idea what you are about to do to the system. You are not "activating" the TSS, you are simply bypassing it to force the cold start valve open.

Oops, I wrote before I actually got to the schematic and looked it up.

So if that’s the case, what does “ Jumper wire to terminal 46 of switch to ground“ mean?

 

[AnthonyG]

I would skip this test. The cold start valve is only open for as long as you are cranking the starter, and for no more than 8 seconds (shorter the warmer the engine is), and is only there to assist in starting the engine. Since you are able to start the engine on starting fluid, but the engine wont run on its own, your problem is almost certainly not related to the cols start valve / thermo-time switch.

Adding to that, the wires are all white, and if you ground the wrong one you are creating a short. But should you want to try; find the thermo-time switch as described by Dan above and unplug the wires going to it. The plastic molding at the end of the TTS has a "W" molded into it on one side, and a "G" on the other side.

View attachment 37538

Have a look at the connector you just unplugged, and note which terminal connects to the "W" side of the TTS. Use a test wire to connect this terminal to ground. The cold start valve should open and spray fuel.

So the terminal that connects to the “W” side of the switch is “terminal 46”..?

And I was supposed to know this.. how exactly?

Let me guess.. the W side of the switch is labeled terminal 46 in the schematic..?

And I should have looked at that first.

So.. correction.. I’m grounding the terminal 46 side of the thermo-time switch connector, which allow the cold start value to operate when I crank the car. Better..?

 

[AnthonyG]

You could try the "tickle" technique or the "tapetty-tap-tap" technique to try to coax injectors to somewhat function after a long slumber.

The tapetty-tap-tap technique has you placing a longer object (say a wooden dowel or long screwdriver) against a part of an injector you can reach, and then just lightly tap-tap-tap with a small hammer, the idea being the love-taps will help to free up the plungers inside the injector.

The tickle technique harnesses the power of a typical 9v "transistor radio" battery (wow that sounds ancient LOL). You unplug the injector's connector, and then use a fresh 9v battery to energize the plunger coil in the injector. You can rig up a harness with scrap wire or pick up a generic Bosch FI slash EV-1 pigtail connector at a parts store. The tickle part comes from how you energize it---you contact and release one of the wire leads to one of the battery terminals as rapidly as you can, 2-3-4 times per second. In VERY quite surroundings you can hear the injector click.
View attachment 37539

Love it!

I actually tried the tapping technique with a rubber mallet and a small piece of wood yesterday, as the car was running on starting fluid, to no avail. I didn’t wanna push my luck too far and risk breaking something.

And I was indeed planning on using a 9V battery to pop them open when I have them out to clean them.

But hadn’t thought to try it with them still in the rail. Good stuff!