No start issue
08-18-2019, 08:13 PM
#46
Rennlist Member
Very glad you found it! I had mentioned checking the DME temp sensor above, when it seemed like you might be full rich, but that may have gotten lost in the flood of suggestions. Just glad you got it going and it wasn't anything major. Way to go!
08-18-2019, 10:23 PM
#48
Three Wheelin'
I do this stuff for a living, but I have been in your position on a number of occasions----you have been staring into a black hole for so long that you lose sight of some obvious factors. Sometimes stepping back and taking a break, or asking a fellow technician or my boss for help has been the answer.
09-03-2019, 08:09 PM
#50
Burning Brakes
My '86 951 sat for several weeks, cranks, stumbles a bit and tries to start when the key is relieved from full crank position, and the tach bounces. In other words, turn the key to crank position and she cranks but won't seem to stumble or cough until letting off the key. From this, ref. sensors seem OK, she's getting some fuel or wouldn't even stumble or cough. New fuel pump last year, and she ran fine since, but after replacing the heater control valve, the car stumbled several times while driving, then was parked for awhile and now this no-start stumble.
Thoughts?
Thoughts?
09-04-2019, 08:32 AM
#51
Three Wheelin'
Ask yourself what you "Disturbed" in the process of changing that heater valve.. How Old are the Ref Sensors? what Kind of shape are the connectors to the sensor in? (They tend to crumble because of the heat they see) One time I fixed a problem on one of these cars by simply unplugging and plugging them right back in... The contacts themselves had become somewhat corroded.. Not sure what parts you moved out of the way but I would Def start there...
09-04-2019, 11:21 AM
#52
Pro
Off the top of my head, while I was working in that location, I had the speed sensor, reference sensor and oxygen sensor disconnected.
the car would work if the oxygen sensor was disconnected or not.
I was in the rennlist archive (forgot link) and one person was having start issues because speed or reference sensor connection. I would take GPA951 advice and check the connection. Wiggle those wires, clean/check the connector and see if that makes a difference.
I cant remember if anything else was back there I disconnected.
did you remove the intake manifold to do it?
the car would work if the oxygen sensor was disconnected or not.
I was in the rennlist archive (forgot link) and one person was having start issues because speed or reference sensor connection. I would take GPA951 advice and check the connection. Wiggle those wires, clean/check the connector and see if that makes a difference.
I cant remember if anything else was back there I disconnected.
did you remove the intake manifold to do it?
09-05-2019, 02:54 PM
#53
Racer
Thread Starter
Dash, definitely work backwards as GPA advised. I’m also thinking that testing your ignition switch might be something to check out. I think Clark’s might have a write up.
09-06-2019, 02:58 AM
#54
Burning Brakes
Thanks, all, I also will plug in a spare DME, just in case the one installed has failed like the spare did before I fixed it. Swapped in spare DME relay, no change.
The speed and reference sensor cables were recently replaced, and the connections are clean, but the mating cables at the bracket are original, I think. When these fail, it's the INSIDE plastic in the housing that crumbles with heat over the years, but the outside looks fine. At least that's how it typically is in the mated S&R cables, and when the inside plastic holding the wires crumbles, the electrical connections get loose or fail, then she won't start on that account.
I cranked it tonight several times, could spell fuel, so the injectors are working, evidently.
The speed and reference sensor cables were recently replaced, and the connections are clean, but the mating cables at the bracket are original, I think. When these fail, it's the INSIDE plastic in the housing that crumbles with heat over the years, but the outside looks fine. At least that's how it typically is in the mated S&R cables, and when the inside plastic holding the wires crumbles, the electrical connections get loose or fail, then she won't start on that account.
I cranked it tonight several times, could spell fuel, so the injectors are working, evidently.
09-26-2019, 07:55 PM
#56
Burning Brakes
I've swapped in known good: Fuel relay, DME, fuel fuse, etc. and opened each to clean and check, and all were found good. The fuel pump was replaced last year, as were the speed and reference sensors.
Basic questions, given the above facts:
1. Assuming good DME, fuel relay, fuel fuse, and key to run position, what other than the ignition switch would explain no start?
2. What simple trick works to properly fasten the lower screw of the distributor cap?