1995 850 turbo will not start after rebuild

gwoiler · Post by **gwoiler** » 15 Nov 2015, 13:29

After too long of a 3 year rebuild, I have the engine back in the 850 wagon and everything hooked up and ready to go. Turning the ignition key to the on position has the tachometer going up and hovering at 1700rpm, but the engine is not running. I have gas to the injectors. There is a pale green relay in the center and next to the after cooler outlet on top of the radiator that makes a racket with the ignition on. I tested the spark while cranking and it seems to be a continuous stream of spark - yellow orange... not blue... not separate strikes. I disconnected the Cam sensor and the stream of electricity going from the coil wire to ground was the same. I have exercised the electrical connectors on many things to make sure it was not an oxidized bad connection. Ohms on the crank sensor was 262. Any suggestions? The engine cranks over fine.

Sommerfeldt · Post by **Sommerfeldt** » 15 Nov 2015, 15:27

There shouldn't be any racket from a relay there - are you talking about the fan relay, or something else? In addition - is your distributor cap/rotor doing OK?

- S

gwoiler · Post by **gwoiler** » 15 Nov 2015, 15:53

There are 3 electronic items on top of the aftercooler. The center relay has the chatter. I have not been able to see what it is. The rotor cap was almost new when I took the engine out. It ran fine except for the bad exhaust valve in one cyl. I been jiggling connectors and looking and looking for something wrong. Why the tachometer goes up to 1700 with on ignition? The sensor checks OK ohms.

gwoiler · Post by **gwoiler** » 15 Nov 2015, 15:54

The spark from the coil should be blue, but it is yellow orange and continuous... This must be a tell tale sign? The spark discharge does not change when unplugging the cam sensor

Post by **Ozark Lee** » 15 Nov 2015, 18:20

The relay you are describing is the master fuel system relay. The car will not run unless it is properly functioning since it provides power to the fuel injectors. It also provides power to the idle air control valve.

Check the connector to the relay closely. The connector has all of the wiring exposed going into it and it has been the source of many problems on many cars. Tug on the wires at the connector to make sure that they don't just pull apart. During an engine change there are many opportunities to snag one of the wires.

The ECU and TCU provide the signal to the relay to turn on and it might be that the connectors on the modules has corroded since the car has been parked for so long. Pulling the modules out and giving the connections a shot with contact cleaner might clear it up if the they have oxidized.

If you deal with the chattering relay then the car will likely start and run. I don't know about the tachometer issue but it might clear up and behave after the relay is dealt with.

...Lee

gwoiler · Post by **gwoiler** » 15 Nov 2015, 21:06

Thank you Lee. uhhh... I spent so much time getting that part of the fan shroud back in position on top of the intercooler and now have to pull it back out to check that relay! lol... Is there an easy way to get that unit out and back in without forcing it? I am speaking of the plastc unit that has kind of a over hanging cover on the fan shroud with the vacuum unit on the right side, the relay you speak of, and the power connector for the fan motor. I wrestled with that unit to get it in position. I will check it closely. I did pull both computers out today and re-seated them. All the contacts looked clean. Maybe I should get some electrical spray cleaner. Thanks for your suggestions.

Sommerfeldt · Post by **Sommerfeldt** » 16 Nov 2015, 07:36

Can't you just pull the relays out towards the engine? That thingamajig you're talking about that covers them is a PITA for sure - I've never figured out a better way than a little wiggling and a lot of force.

Check your engine grounding while you're at it - that yellowish and continous spark sounds a little strange.

- S

gwoiler · Post by **gwoiler** » 16 Nov 2015, 10:32

The 2 grounding wires on top of the engine are good. I am wondering if I should try to reach the 2 grounds on the side in the starter area. Maybe I should have cleaned them before bolting down? The coil wire is strange in that, it is a continuous spark... not strikes as the car cranks. I will see what I can do with that relay now.

Post by **jimmy57** » 16 Nov 2015, 10:36

Definitely symptoms of grounding issues.
Cycling relays can create EMF and that is why you have 1700 rpm tach. Since the RPM sensor is getting signal the ignition is responding and creating coil signals.
There is a wire not hooked up or not tightened somewhere.

gwoiler · Post by **gwoiler** » 16 Nov 2015, 12:16

I disconnected that relay and the tachometer stayed down at zero. The coil wire was also silent and when I hook up the relay with key on, the coil wire is making a continuous stream and the tachometer is up but not as far. I did notice that all 4 relay wires were bare where they bent around the shroud. I separated them but no change. One thing I noticed more normal, was with the relay hooked up the fuel pump sounded more normal than before because when turning the ignition on the pump would come on and then go off which is normal before the engine starts. I checked the grounds to the body on top of the engine and their connections are clean and shiny. There are actually 3 grounds to the block on the lower front of the engine. I can see the lower one near the dipstick tube. Ahhh... frustrating.