Inconsistent Start / 10 Second Run - 86 Spider - Alfa Romeo Bulletin Board & Forums
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post #1 of 8 (permalink) Old 07-09-2017, 04:07 PM Thread Starter
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Inconsistent Start / 10 Second Run - 86 Spider

Hey Folks,

New to the forum and to Alfas. My old man has an 83 Spider and we stumbled upon an 86 barn find! Ive been cleaning and checking things according to the shop manual as well as the guides for the L-Jetronic guide from Greg (many thanks!).

My issue with the 86 Spider is an inconsistent start, One out of 5 cranks seems to start the engine. It begins very rough and eventually stabilizes out then stops running. Once it runs, I get somewhere between 5 and 10 seconds of runtime before the engine stops. The majority of the carpet and insides are out (for cleaning). I believe I am hearing the Jetronic master relay switch / trip right before the engine stops.

As mentioned, I have followed the guides and shop manual. I have exhausted ideas for troubleshooting and am hopeful that more capable folks can suggest next steps to try!

First off there was some poor wiring under the dash and in the engine bay, I believe I have corrected that, just replacing melted wiring with larger gauge cabling, frayed or taped wires replaced with new, soldered and heatshrinked back to life.

The following have been metered and found in spec:
Cold Start Injector
Aux Air Valve
Engine Fuses
Fuse Panel Fuses
Both Flywheel Sensors
VVT - Solenoid also fires as expected with ignition
Cooling Temp Switch
Thermal Time Switch
Fuel Pump - getting voltage

The Air Flow Meter and the Aux Air Valve have also been swapped with known working (from 83). The vacuum lines and fuel filter have been replaced.

As mentioned any advise or next steps would be greatly appreciated. Thank you in advance for any guidance.

Best Regards,
Austin
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post #2 of 8 (permalink) Old 07-09-2017, 05:11 PM
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My guess is that the Drive Relay (AKA Fuel Pump Relay) is either defective or not getting the expected tachymetric signal. The tachymetric signal comes from a sense wire at the coil so the Drive Relay 'knows' the engine is running. It then sends power to the fuel pumps. There is a bypass circuit that powers on the fuel pumps during cranking to ensure the fuel pumps are powered up when you are trying to start the engine. Once it starts and you release the key to the 'run' position the drive relay is supposed to take over.

The Drive Relay is not inexpensive or easy to find locally so the first thing is to clean & secure the connections at the coil. The sense wire is either white or yellow (I forget offhand) and goes into a shielded cable (sort of like a cable TV cable). The shielding wire is grounded. There is a replacement relay made by KAE but I have read reports that it does not function exactly right - it might keep the fuel pumps powered on when the engine stalls - a missing safety item.

Next would be to temporarily connect 12V directly to the fuel pumps. If the engine then runs it is likely the drive relay was faulty. I do not suggest driving the car with the fuel pumps so wired - again a safety issue.
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- - Eric
don't read this
~ 1984 Spider Veloce ~
- -~ 1981 GTV-6 ~
Mebane, North Carolina


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Last edited by ghnl; 07-09-2017 at 05:17 PM.
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post #3 of 8 (permalink) Old 07-10-2017, 03:50 PM Thread Starter
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Hey Ghnl,

Ive gone ahead and swapped the Main Drive Relay with a similar and get the same results. The coil was nice and crusty so went ahead and cleaned that up. The grounds are installed and now nice and clean. Also checked the pump and it indeed is sending gas. That did make me think about the fuel / ox mixture. Its had a bit of a gassy odor after testing and cranking, but the engine may be getting flooded. About a week or so I replaced the spark plugs, and for kicks pulled one off for inspection, and its full of carbon one of which was wet with fuel. Also did a quick test with the O2 sensor off and received the same results. Im pulling a first day as a mechanic, but am really scratching my head. Any more suggestions that pop off the top of your head?

Thank you,
Austin
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post #4 of 8 (permalink) Old 07-10-2017, 05:51 PM
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If you are certain all the L-jet bits are working properly (intake air or vacuum leaks are usually the #1 issue, followed closely by dirty grounds) the next thing is to be sure that system voltage remains above ~ 10.5V during cranking. It can sound like it is cranking over fine but available voltage can drop below that threshold. The computers do not power up if voltage is below ~ 10.5V. Don't go by a dash gauge (if it has one) as they do not measure system voltage during cranking. Connect a voltmeter to the battery and report what it reads. With everything off a fully charged battery should show 12.6V. 12.3 is about 1/2 charged. Our Spider shows ~11.8V during cranking.

One other thought is to replace the fuses. Especially if your car has the 'bullet' fuses. These are known to look OK but somehow fail to pass electrons. Given a choice, get the ones with a brass (not aluminum) strip. Even if your car has the more modern blade fuses, they could all be decades old - just to rule that out consider replacing them.

Although you mention replacing the spark plugs, it is probably a good idea to clean or replace them again. The multiple failed attempts at starting may have fouled them. If you think the engine has 'flooded' due to the failed starts, the way to clear that is to hold the gas pedal to the floor while cranking. This sends maximum air and minimum gas to clear it out.

If that checks out then I wonder if the injectors are clogged. If the car was parked with no plan for storage the old gas left in the injectors may have turned to varnish. There is nothing I know of that you can put in the tank to clear them out. Places like OK Injectors will clean them with solvents and an ultrasonic bath, testing them before & after for flow and leakage.

- - Eric
don't read this
~ 1984 Spider Veloce ~
- -~ 1981 GTV-6 ~
Mebane, North Carolina


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post #5 of 8 (permalink) Old 07-17-2017, 05:11 AM Thread Starter
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Hey Ghnl,

I’m mostly sure the L-jet bits are in working order, at least the resistance on sensors and what not. I believe I have the grounds all clear, (2 top of aux air, 1 #4 injector, 3 next to fuse block, 3 below shift boot, 3 drivers side tail lamp, braiding below trans case, and finally the main battery connection). Please let me know if I’ve overlooked. I did begin with a new battery and charge it before trying…. The old battery was quite tired. I usually float around 11.4V-11.8V through most of the testing before recharge.

Excellent suggestion on the fuses! I had replaced the fuse on the passenger side that is inline to the coil. I had failed to notice the extreme corrosion that the holder had. Retracing my steps I went ahead and tested continuity of the line from the second relay to the terminal on the coil as was getting intermittent results. Cleaned and refurbished the connection, was real hopeful I would have something, but back to the drawing board.

Through testing I have gone and cleaned up the plugs a few times to keep them out of the equation.

The car was parked for a bit from the previous owner, I believe for 3 years. I am told they had planned and put stabilizer in the tank. Not sure what product, if it was ran through the injectors or if it never happened. I believe there was an issue with the fuel pressure regulator, the vacuum had some fuel coming out the top. I’m trying to grab a pressure gauge to make sure all is well off the fuel rail. Ill post results once I have a chance.

I’m hesitant to call the injectors bad just yet. When I do get spark and a short run, I am able to rev the engine up and after the usual sluggish start it runs smooth (10 seconds). After I get a run though it seems to flood out and will resist starting for a few cranks. If I wait about 10 minutes it will usually crank and run once again. Would the ECU have some sort of safety feature baked in for engine oil or temp that would cut the engine? Here in about a week or so I’m replacing a cracked fuel rail on the 83 so I’ll have a set of known working injectors though I have no idea how to refit the hoses. They look compressed, but I’m sure with a little googling I can stumble through it.

Anyways thank you for the help so far. I’ll keep posting as I learn more.

-Austin
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post #6 of 8 (permalink) Old 07-17-2017, 05:44 AM
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Quote:
Originally Posted by austinm007 View Post
I believe there was an issue with the fuel pressure regulator, the vacuum had some fuel coming out the top.
This is a sign of a failed FPR. Inside is a diaphragm - fuel in the vacuum hose indicates the diaphragm has ruptured.

- - Eric
don't read this
~ 1984 Spider Veloce ~
- -~ 1981 GTV-6 ~
Mebane, North Carolina


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post #7 of 8 (permalink) Old 07-17-2017, 02:51 PM
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I wonder if after all the sitting you have a rubber failure/vacuum leak somewhere.
Old rubber parts is what fails on the barn finds, and it would appear your wiring has been checked over and over again.

Maybe you can check all your rubber parts and ensure they are holding all the air you need to keep it running and idling properly.
The start-sequence and fueling will run rich by design, but then when it settles into a proper idle it will lean itself down for emissions and THEN if you have a leak, it will go lean and stall out.
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post #8 of 8 (permalink) Old 07-18-2017, 09:56 AM Thread Starter
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Hey Guys,

Thanks for all the tips and advise! Finally got it running! Ended up being the ECU. After double checking grounding, resistance on the sensors, air leaks and adjustments, I was baffled and thought the computer may be faulty. Swapped it with one from an 83 and within 2 cranks got it running. Im quite relieved. Now on to other issues....

Thanks again!

-Austin
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running problem, spider 1986, starting issues, starting problem

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