Diagnosis no start

DanielForest

DanielForest

True Classic
Last fall, my 1987 X1/9 engine died on the highway, at night with heavy rain. So it shouldn't be starter related.No way to restart it. Engine was turning fast but not starting. So I need to call the towing.

Back home, my first guess was the fuel pump since it's location was close to the road and there was heavy rain. But the fuel pump was pumping fine. So I started changing parts since I have a lot of them as spares. Change for new distributor, distributor cap and rotor, spark plugs and wires change for used but good coil and ignition control module. Nothing.

Got my best friend Dan, who's also my mechanics (don't remember which one came first) to come check it. We spend a day and a half on it to finally settle on no fuel to the injectors. So my friend said it was the FI computer. Other option was the double relay, but since it was clicking when we were turning the ignition switch, we had a small clue it may be allright. I'm a carb guy, so I have no Fi spares. Talk with Jean-Marc Nadeau (Most Québec members know him) and he was sure it was the double relay. Finally got the double relay today. Swap the double relay and still no start. Smelling fuel, battery full, spark to the plugs. So it will leave me with the Fi computer. Or when I tested the car today, I didn't bolt the computer to the wall, so could it be it needs ground? I don't think so but I maybe wrong. So next step will be to get a used Fi computer. Is my logic right?
 
Yes, check valve timing. Also shot some starting fluid into the intake. If the problem is no fuel you should get something from the starting fluid.
 
No fuel from the injectors, or to the injectors? Is the fuel rail pressurized? If fuel in the rail but nothing past the injectors...

Ohm distributor pickup coil. Make sure its not open or shorted.

Spec is 700-800 OHMS between pins of the connector. Also check the pins to the distributor body to be sure it's not internally shorted.
 
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Interesting suggestions. Thanks to all.

I don't think it's the timing belt because the car was just driving fine without "correction". No braking, no acceleration, just continuous speed. But still, I will check timing but I think I already did (it's been 8 months sitting now).
There is fuel before the injectors, but nothing in the intake.
I changed the pick-up coil, but will check for OHM, could be bad lucj with a bad spare.
Large connector was removed and no water or rust. Seems like it was open in the past (some clear silicone to seal) but look good.
 
There are testers that plug into the injector connector to verify pulse "noid lights" - they are made in a variety of configurations to fit Bosch, GM, etc., style harness plugs. That will tell you right away if the problem is the ECU, since they won't show a pulse when cranking if the ECU signal is absent. Unlikely to be the injector itself, since it was running at the time. I would assume you have already verified continuity on all the ECU and component grounds. I think the two main ones are on the valve cover. Not a great place in my opinion.

EDIT - don't recall if L-jet needs an ignition pulse to turn on - you should verify that signal from the ignition if it is required.
 
lookforjoe said:
EDIT - don't recall if L-jet needs an ignition pulse to turn on - you should verify that signal from the ignition if it is required.
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L-Jetronic does need to see ignition pulses to work. This is the infamous piggyback connector on the coil; JimD has posted photos of this in the past, but Photobucket is hiding them. The piggyback connector coming off fits the symptoms, so definitely worth checking. Photos recovered from JimD's post below.

86_coil_1.jpg
86_coil_2.jpg
86_coil_wire.jpg
 
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The Electrical Diagnostic Manual doesn't explicitly state the pickup coil is part of the injector control. But it does say the coil sends signal to the ECU which does control the injectors.

It also says the coil current is regulated by the ECM, which is triggered by the pick-up. The pick-up sends impulses to the module.

Pgs 14 and 25 of the Diagnostic Manual.

It's a 2 minute test to check the pickup. If nothing else, rule it out. But if it is bad....hey easy and cheap fix!
 
ng_randolph said:
L-Jetronic does need to see ignition pulses to work. This is the infamous piggyback connector on the coil; JimD has posted photos of this in the past, but Photobucket is hiding them them. The piggyback connector coming off fits the symptoms, so definitely worth checking. Photos recovered from JimD's post below.

View attachment 10929 View attachment 10930 View attachment 10931
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Thanks for posting that Bjorn. I have been away from my PC every time I think to post those photos. :)
 
Found nothing yet. L-jetronic correctly plugged to the coil. Still have to check the timing. I tought I had something: In first pic the black sheath with the 2 white wires was stripped (just in front of the orange spark plug wires), probably because of some rubbing. Some metal is visible in the wires but they are not cut, just unprotected. So don't think this is it.

20180505_133740.jpg


In that next pic, I Wonder what is the use of the unplug black wire. This is a female plug, but couldn't find any male to plug in it. Maybe a diagnosis plug?
20180505_133730.jpg
 
This isn't much help, sorry. But some thoughts:
First, in my experience/opinion ECU's very rarely fail. It seems to be the thing no one understands and therefore blame for every problem. That would be my last thought.
Second, electrical connections are a common cause for such issues...especially considering it happened when it was raining. Time consuming and a PITA, but go through every multi-connector, push-on blade connector, ground connection, etc and properly clean them (i.e. scrub with a S/S brush if possible) and spray with electrical contact cleaner before reconnecting. Also make sure they are tight and secure.
On the subject of electrical connections, could those two bare wires (in pic) be touching/shorting?
Third, lots of great suggestions above to test injectors, etc.
Fourth, look at this discussion about that black connector that is loose: https://xwebforums.com/forum/index.php?threads/fuel-injection.34427/#post-293811
Hope the answer to the problem is a simple one, let us know.
 
Thanks. Good to know the ECU rarely fail. Having a spare double relay also eliminate a possibiity since it is also often pointed as the culprit.
No the two bare wires aren't touching. I had the same tought and that,why I cut the black sheath around it and was going to repair the white ones, but since the scratch is mostly superficial, I just separated them and will be taping them individually.

After changing nearly everything that is ignition related and checking the fuel pump, the remaining possibilities are with the Fi system (or timing, but I doubt: the problem being there is no fuel at the spark plugs, not the fuel being available at the wrong time). But the fuel pump is pushing fuel, don't ask me how I know.

So ECU or connector/wires/ground/etc.

I may try the ECU anyway since I could get one to borrow (and to buy if needed). THAT would be the simple solution. Others would be less expensive but much more time consuming
 
If you can borrow a known good ECU to try, then ya why not. My experience with them rarely failing is in general with Bosch systems of that era. But you never know. There are a series of tests with multi-meter on the ECU's contacts, but easier to swap out if one is available.

Is it possible something plugged the fuel line at the fuel rail? Or is that where you found "But the fuel pump is pushing fuel, don't ask me how I know"? I once had a BMW with similar type injection system and the fuel filter came apart internally...the inside filter element broke up and pieces clogged the injectors and other areas. That was fun to clean out. Especially if it suddenly sucked in a ton of water from the rain (but not likely). As someone said spray starting fluid in the intake and see if it fires.
 
Daniel Forest said:
Maybe I shouldn't have pointed the hose toward my face.
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Lucky for you there is nothing there it could damage. :)
Try doing the same thing at the cold start valve hose, to see if fuel is filling the fuel rail. Very easy to do. Be sure you're looking into the end of the hose when the key is turned on.
 
Dr.Jeff said:
Lucky for you there is nothing there it could damage. :)
Try doing the same thing at the cold start valve hose, to see if fuel is filling the fuel rail. Very easy to do. Be sure you're looking into the end of the hose when the key is turned on.
Click to expand...

Sure. Maybe I should put it in my mouth and suck hard to help?
 
You already suck enough. ;)

Joking aside, it might be worth checking for fuel at the rail (cold start valve is easiest place). Good opportunity to hook up a pressure gauge and check the pump's pressure also.

Today I was looking into the fuel injection system on one of mine. Seems like there are issues with the air flow meter. It is causing all kinds of symptoms that keep changing and making things hard to pin down.
 
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