1996, 850 Turbo, No Start

Rbaratt · Post by **Rbaratt** » 13 Jan 2015, 11:02

I am beginning this thread to document upcoming efforts to determine the root cause for the latest issue with my 1996 850 Turbo.

Yesterday I drove the vehicle 30 miles to work, it started fine and completed the trip without any signs of an impending problem. In the evening I left work and tried to start the car, but the starter would only crank over the engine without firing up.

I tried a few things, on the remote chance that I might get lucky and avoid the tow, but as it turned out I called AAA to get both myself and the car home.

I will not be able to troubleshoot much until I finish the work week, but when I do, I plan to follow many of the suggested procedures in this forum. I believe the best approach is to confirm fuel delivery, spark and compression, in that order.

Things I have quickly looked at before the tow:

1. I swapped the fuel control relay with two other spares.
2. Swapped the position of the J relays
3. Released all the pressure at the fuel rail. Turned the key and noted that the fuel pressure was again evident, though until I put a gauge on it, I won't know if it's enough pressure.
4. Removed the fuel pump cover and confirmed that I could hear the pump running.
5. Sounded like I still have compression, but again not confirmed.

Next Steps:
1. Since I am always by myself when working on my vehicles, I will purchase a remote start switch to attach to the starter to allow me to turn over the engine from under the hood.
2. Confirm fuel pressure, maybe try some starting fluid in the air intake.
3. Check grounds and electrical cables.
3. Confirm spark or no spark condition.
4. Pull timing cover and check timing marks.
5. Depending on what I find, maybe a compression test.

I will report back with my progress as I get into this, and as usual any suggestions would be appreciated.

rhalkyard · Post by **rhalkyard** » 13 Jan 2015, 12:05

My 850R had an issue like that when I bought it. Most of the time, it would start and run just fine with no symptoms at all, but every so often it would refuse to start, even after sitting for just a few minutes. Sometimes it would start successfully an hour or so later, but other times, it would go on for days, and then miraculously recover.

In my case, I had plenty of fuel pressure, but no spark and the injectors weren't firing. I finally tracked it down to the cam position sensor. Whatever intermittent fault that it had never caused any codes, or any problems while the engine was running, but without a good signal from it, the ECU can't determine where the engine is in its cycle, hence no fuel or spark. I swapped it out with a junkyard one, and it's been fine since.

Post by **erikv11** » 14 Jan 2015, 07:37

I agree, at this point go straight to checking spark and if there isn't any, then first suspect the cam sensor followed by the crank sensor.

Rbaratt · Post by **Rbaratt** » 18 Jan 2015, 07:21

Triple A flat bedded me home and put my 850 in the driveway. Saturday morning I started to check out what might be the cause of the no start condition. It was very cold (About 14 Degrees F) and since I do not have a garage I needed to try to solve this problem quickly. I figured since I had fuel pressure at the fuel rail prior to being towed this would eliminate fuel delivery as the problem. As the previous posts suggested, ignition spark was the next thing to look at.

I first checked to see if I had power at the bl/wht wire at the coil and this checked out okay. I bought an inexpensive remote starter switch from AutoZone but couldn't find enough room between the engine and the fan shroud to hook this up to the starter. I have a spark tester that can be placed between the ignition wire and the plug but when I need to crank it over I can't see it. I opted to use a test light with a longer lead. I wasn't sure if this would work, but I had to try something. The test light didn't light up and I didn't fry the bulb either, so I figured no spark.

Since I have a couple of spare junkyard camshaft position sensors, I decided to check this first. I removed the sensor and brought it inside to compare the resistance with the one of the spares. The sensor was definitely gone, as it showed an open circuit, no matter which leads I probed. The spare had resistance so I went out and installed it.

With all my attempts to start the engine I began to notice a change in the cranking, similar to my '95 when it gets "lawnmower" syndrome. With the new sensor installed it fired up but immediately stalled out. I used my lawnmower syndrome starting procedure (foot to the floor and a long cranking time) and it finally fired up. It ran rough for a minute but then it cleared up.

My plan is to put together a "no start" tool kit to carry in the trunk and I am curious what items others carry with them. On my list I have spare relays, spare CPS, spare fuel pump assy, spark tester, various tools to access these items. Can't carry the whole toolbox but just curious what others think are the essential items to have on board.

Thanks to erikv11 and rhalkyard who correctly pointed me in the right direction.

Post by **Ozark Lee** » 18 Jan 2015, 08:15

You have a service starter wire that sticks out of the loom just next to the left front strut. As I recall it is a Green and Red wire with just a connector on the end. Tie that wire to + battery through the switch and it routes through the PNP switch to the starter solenoid.

Do you hear the idle air control valve buzzing when you put the key in position II? The master fuel system relay, or more specifically the connector to it, has been a historical problem. It provides power to the IAC valve and the injectors. That relay is the one on the fan shroud on the opposite side of the fan from the fan relay. If the IAC valve is buzzing you can pretty much check that one off the list.

...Lee