starts and dies - Alfa Romeo Bulletin Board & Forums

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post #1 of 8 (permalink) Old 02-17-2017, 09:25 AM Thread Starter
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starts and dies

Hi - I have looked through previous posts and have not found an answer to my question so I am posting a new thread in the hopes that you all may be able to help.

I have a '86 spider veloce with 75,000 miles. Currently it will start and then die and I have kind of run out of options as to what it might be. To date I have:
- replaced the coil, cap, rotor, wires and plugs
- replaced the flywheel sensors
- replaced all the various air/vacuum hoses under the hood and in the trunk
- replaced the plenum connection hoses (the ones that are a pain to get to)
- new battery
- new relays
- tested the main ECU (there is a company in FL that will test and repair them) and found to be working
- replaced fuel injection ECU with known functioning unit
- replaced MAS with known functioning unit
- replaced fuses and refurbished contact points in fuse box
- new fuel pumps
My question is: what have I missed that I should check that can cause this?
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post #2 of 8 (permalink) Old 02-17-2017, 09:37 AM
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Starts and stops... like runs for 1 sec and dies, or for how long before it dies.
Are you missing fuel or spark?
How about the inline fuse under the parcel tray that supplies power to the fuel pumps?
When you turn the key to the on position do you hear each pump buzz for the 1/2 second they should?

Mike

'87 Quadrifoglio
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post #3 of 8 (permalink) Old 02-17-2017, 09:51 AM
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FPR? (fuel pressure regulator)

pull small vacuum hose off and check for signs of fuel, or for a split anywhere along this hose (if not replaced in your list above, that is!)

pinch off fuel return hose and see if it'll stay running (hose # 5 in diagram here)
Extreme pressure in fuel tank

Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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post #4 of 8 (permalink) Old 02-17-2017, 10:02 AM
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When you say you replaced 'relays' which ones? And what brand are the replacements?

There are two relays next to the FI ECU. They are called the main relay & drive relay. The main relay switches on the fuel injectors (the ECU then controls them by switching their connection to ground). The drive relay controls power to the fuel pumps (and the main relay, too, I think - but my memory isn't very reliable...). The drive relay gets a signal from a sense wire at the coil to 'know' the engine is running. If the engine should stall the lack of signal shuts off the power to the fuel pumps. If the signal is missing then the drive relay never powers up the fuel pumps. There is a bypass circuit that powers on the fuel pumps when the key is turned to the 'start' position. Thus, you could get fuel pressure enough to run the engine for a few seconds via the bypass circuit but, if the signal to the drive relay is missing or if the drive relay is faulty then the lack of fuel will cause the engine to die.

I asked what brand relays you used because I have read that some non-Bosch relays will physically fit but they don't work properly. I think those are 'KAE' brand.

One clue as to whether the problem is lack of fuel or lack of spark is to watch the tach needle. If the needle drops (to its needle rest) and then the engine dies the issue is lack of spark. If the needle reads as it is dying then likely problem is lack of fuel.

Also, the two flywheel sensors are identical but must be connected to the wire harness correctly. The harness connectors are color coded black & grey. Be sure they are connected correctly.
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- - Eric
don't read this
~ 1984 Spider Veloce ~
- -~ 1981 GTV-6 ~
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- fuel injector cleaning
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post #5 of 8 (permalink) Old 02-17-2017, 10:45 AM
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Fuel filter clogged?

Fuel tank pick up clogged?

Pete

'71 1750 Series 2 GTV:
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156 Series 1 v6 ... and remember it's all just opinions
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post #6 of 8 (permalink) Old 02-17-2017, 11:16 AM
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Do a search on 'Starts then Dies'. It's an unfortunate, common thing with the FI models. IIRC, most of the time it was the coolant temp sender or the thermotime switch...

86 spider Veloce
74 TR6
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post #7 of 8 (permalink) Old 02-18-2017, 07:18 AM Thread Starter
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UPDATE: Thank you for the quick responses.
- yes, fuel pressure regulator was replaced along with the fuel lines and vacuum lines. I have tried pinching the fuel line and can feel the fuel pressure but it doesn't change the starting and stopping
- yes, I have replaced the fuses and I can hear the fuel pumps come on as they should when I turn the key
- the fuel tank was replaced with a new one and then taken out and cleaned when the pumps were replaced along with the fuel filter
ghnl - I replaced and connected the flywheel sensors as they were but it probably couldn't hurt to switch them around - there is only one right and one wrong answer there. I have tried fitting the distributor cap 180 degrees as that has been suggested but that made things worse. I will go out and check the brand of the relays and provide an update. I will also check the wiring at the coil - I may have inadvertently gotten the wires mixed up (the ones that bolt on to either the positive or negative terminals).
John533i - I have not checked out the thermotime switch or coolant temp sender. In my searches of starts then dies, those two items seem to be buried underneath the other possible factors.
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post #8 of 8 (permalink) Old 03-23-2017, 01:50 PM Thread Starter
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So... sorry for the delay I have had a lot going on. I ended up not being able to find the problem so I had it towed to my local Alfa specialist in Orange CA and it ended up being that the fuel injectors were stuck closed and just needed to be cleaned up. Car runs fine now. Thanks!
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