1985 Spider starts rough and dies

[Daveje]

I've made some progress here but still stumped right now,Saturday afternoon. The short story is that it's running,but crippled.
I took the fuel rail off last night and made an attempt to clean the injectors, only no.4 was spraying when I tried it.
I took the injectors off,put a 3" pc. of 5/16 hose on the pintle,and filled the hose pc. with cleaner. I then stuck a compressor hose with 20 lbs. pressure on that and cycled the injectors with a 9v battery. Anyway,this seemed to worked like a charm and I soon had 4 injectors spraying good when I did the same thing with the hose & cleaner on the input side of the injectors. I put the whole thing back together with new hoses,everything thoroughly clean,and put it back on the car. Unfortunately only no.'s 3 & 4 seemed to be spraying, when i hook just the 9v battery up to no.'s 1 & 2 injectors they seem to spray fine. I check for a signal on no's 1 & 2, now there is no signal although there was a .5v pulse the other night. There is 12v on both contacts with just the key on. I did put the rail back on the car and hooked up the ground tab to the manifold etc.
So, even though I think all 4 injectors are functional, I'm running on 2 cylinders(is that possible?) because injectors 1 & 2 are not getting a signal to fire. Does any one know what could cause this? The car start right up and will even sit there and idle,when I disconnect the spark plug wire to either 1 or 2 there is no difference in the way the car runs. Any help or ideas would be appreciated.Thanks

[pope]

Sounds like you have a 2 cyl. 1 L engine. Should be good on gas!

With the key on, constant voltage should be going to the injectors. The computer turns the injectors on and off by adding or subtracting the ground. Injectors 1 & 2 wire up to the double relay together and 3 & 4 wire up together. Check that there is not a problem with the ground wires along the way or the double relay.

[Daveje]

Thanks for that Pope,I'll look into it. I've been at it again and things keep changing. Now running on 3 cylinders, 1,2 & 3. No.4 seems to be dead now although there is good spark. I started messing with the coolant temp. sensor, sometime it won't start until I disconnect it, other times it will. Mostly runs better with it disconnected,when it's warm and I plug it back in the car immediately dies like I shorted something out. Would a bad coolant sensor cause my problem? I've tried putting the 3000 ohm resistor across the connector(when warm) but that just made the car die. The car will idle along pretty decently on 3 cylinder.

[So Cal Mark]

umm, I don't have my spec manual here at home, but isn't supposed to be a 300 ohm resistor, not 3000?

[rlux4]

Good memory for an old man Mark. 300 ohm should be normal run temp resistance.
3000 ohms is giving cold condition signal to the ECU.
Ron

[Daveje]

My mistake but I did go back and try the 300 and it didn't help. I don't know if it rules that out. I'll take another look at the injectors tomorrow.

[So Cal Mark]

the fact that your symptons seem to change sounds like either a ground connection problem or voltage drop on the power side. I'd use a voltmeter and measure volts at the ecu. There should also be a ground on the rear exhaust cam plate to the firewall

[BrianAz]

Mark,
I am reassemblying my 1980 FI spider and checked for that ground wire on the rear cam plate. There isn't one on my wiring harness, just the two that are connected to the plenum chamber.
Dave. check that you have reconnected all the grounds and check that the relay is sitting correctly.

Brian.

[Daveje]

I do have a ground going from the rear cam plate to the coil bracket but I only see 1 on the plenum, on the driver's side rear. I've been going around cleaning grounds wherever I find them. At this point the car is running on 4 cylinders and idling to the point I can move it,but wthout the coolant sensor plugged in. I can start it when it's cold with the coolant sensor plugged in but after it warms up I have to unplug it or the car dies, so the car is running on four cylinders with a little bit of pop in the exhaust but not bad. The sensor has about 5000 ohm resistance when cold but gets in the meg ohm range when warm, so I think thats going in the opposite direction. I'm ordering a new coolant sensor today hoping to have it Thursday.

[rlux4]

The coolant temp sensor is the most critical one in the system. If it's bad, the car will run, but very poorly. With any of the others you'd barely notice it even if they were unplugged, except in mileage and emissions. There should be two ground wires going to the intake plenum's back two bolts, They are the grounds for the injectors. If you only have one and all the injectors are pulsing, then the one that's missing has been combined into it. If so, it's a change from the earlier FI cars. I'd be interested to know if that's what happened.
Ron

[Daveje]

It looks like that's what they did then Ron. The only ground I have there is attached to the rear plenum bolt on the left side. I also have the one that's attached to the cam plate. This car was built 7/85.
I'm hoping it's the coolant sensor. What throws me is it doesn't help when I put a resistor in there to replicate the signal. The car won't start at all now even after running halfway decent on Sunday. Came out the next day,no start. Looks like the plugs are fouled, who knows.Thanks

[So Cal Mark]

fouled plugs could be caused by the wrong signal from the temp sensor, but just as likely is a leaking cold start injector or pressure regulator

[Daveje]

I guess the pressure would be too high then? I don't have anything to check that right now but I'll get something if the new coolant sensor doesn't solve it. The cold start i can check though. Thanks Mark.

[So Cal Mark]

not a stuck regulator, but a leaking one. Pull the vacuum hose and check for fuel there

[Daveje]

So I guess that would mean fuel was getting sucked into the manifold through the vacuum hose and fouling the plugs,right?
I did taste some fuel when I sucked on the end of that hose,but it did hold vacuum. (Hate to admit I do these kind of things)