My 86 fires but wont keep runing

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My 86 fires but wont keep runing

blazz86 blazz86
I watched Corvette Summer | Posts: 7 | Joined: 08/12
Posted: 01/16/13
04:00 AM

Hi, When I try to start my 86 it fires but then dies straight away, if I hold the key on for a second longer it continues to run untill I let go of the key, It only seems to do this in the wormer months, some cool mornings it will start and run fine. although it seem to be getting worse. I have replaced the fuel filter and checked fuel presure wich is fine. its always the same fires then dies, after a couple of atemps it wont even fire.
Please Help Im going off my head.  

waynep71222 waynep71222
Duntov Incarnate | Posts: 241 | Joined: 04/12
Posted: 01/16/13
06:28 AM

thats easy to diagnose...   change the ignition switch...    under 20 bucks in parts...


this is the inside of one that did exactly that...


you can see how its mounted in this drawing up on top of the steering column and you have to remove the dimmer switch to get to it..


its normally easier to drop the column a few inches and pull off the mounting bracket to get at it... but thats only 4 bolts that hold it to the column..  and two probably 15MM deep socket nuts to get drop the column after you remove the knee pad under the dash...   do place a piece of tape on one side of the steering column bracket so you know which way it goes back on..   it will almost fit both ways..  but almost is not close enough...

you will want to disconnect the battery and have the car where the drivers door can open fully...

pay attention to the push rod for the dimmer switch...  and when reassembling.. you will have to set the dimmer switch position.. by checking the stalk actuation...

if you need more instructions just ask..  

lonewolf11 lonewolf11
Duntov Incarnate | Posts: 105 | Joined: 04/09
Posted: 01/16/13
10:29 AM

I had a similar problem with my 1987 Corvette. Wayne has directed you correctly, as he has countless times with my issue's. I did this about 6 months or so back and my only advice is give yourself at least half a day to work on this project. The tightness of the area in which you will be working is as I said, VERY tight. I might add also, if you have Cruise Control, as most of us do, be careful to not disengage this. I did so mainly when I had to replace my Power Brake Booster but that is another story. I only mention this caution as it is located in the same area where you will lower the steering column. Good luck with your project.  
Gregorio Lonewolf

blazz86 blazz86
I watched Corvette Summer | Posts: 7 | Joined: 08/12
Posted: 01/17/13
02:30 AM

thanks heaps, have orded one from the states ( they are a bit scarse here in Australia ) will let you know how I go.  

waynep71222 waynep71222
Duntov Incarnate | Posts: 241 | Joined: 04/12
Posted: 01/17/13
03:36 AM

Ignition switch


If equipped, disable the SIR system, as outlined in Chassis Electrical , then disconnect the negative battery cable.
Remove the column to instrument panel trim plates and attaching nuts.
Loosen the steering column mounting bolts.
Remove the steering column mounting bolts, lower and properly support the column. If access to the switch is not sufficient, remove the column from the vehicle.

Be sure the steering column is supported at all times in order to prevent damage to the column.

Remove the hex nut and washer head screw securing the dimmer switch to the column.
If equipped, remove the horn ground strap attached to the dimmer/ignition switch mounting stud.
If equipped, remove the cable bracket.
Disengage the switch assembly from the actuator rod, unplug the wiring harness connector and remove the dimmer switch assembly.
Remove the dimmer and ignition switch mounting stud.
Remove the ignition switch from the actuating assembly and disengage the switch wire connector.

To install:
Make sure that the key cylinder is in the OFF-LOCK position.

Install the ignition switch to the jacket with the switch in the "OFF-LOCK" position, as shown in the accompanying figure. New switches will be pinned in the "OFF-LOCK" position. Remove the plastic pin after the switch is assembled to the column. Failure to do this may cause switch damage.

Install the switch with the rod in the hole and adjust as necessary. To verify the switch is in the lock position, adjust the ignition switch assembly as follows:
Move the switch slider to the extreme right position.
Move the switch slider one detent to the left "OFF-LOCK" position.
Install a 3 / 32 in. drill bit in the hole on the switch to limit travel.

Ignition switch adjustment


Install the ignition switch to the actuator assembly. Install the ignition and dimmer switch mounting stud and tighten to 35 inch lbs. (4.0 Nm).
Remove the drill bit from the switch.
Install the dimmer switch assembly to the actuator rod.
If equipped, install the cable bracket and the horn pad ground wire.
Install and finger-tighten the washer head screw and the hex nut.
Adjust the dimmer switch and tighten the screw and nut to 35 inch lbs. (4.0 Nm).
Position the steering column, then engage the ignition and dimmer switch connectors. Secure the column in the vehicle
Connect the negative battery cable and enable the SIR system.   ( SIR is Air bags on early 90s models. )

i was looking for the parts diagrams for the RIGHT HAND DRIVE corvettes.. i know i saw the RHD dash diagram someplace..  or was yours  a conversion... so its all custom..  

blazz86 blazz86
I watched Corvette Summer | Posts: 7 | Joined: 08/12
Posted: 01/29/13
03:35 AM

I picked up the switch today and a hour later BANG! she fired up straight away, I must have loosened a wire in there somewhere because the dash goes out sometimes but that will give me somthing to do tommorow. Thankyou guys so much for your help, I had a few mechanics puzzled, if you lived around the corner i'd bring you  a slab of beer.
Thans again,

waynep71222 waynep71222
Duntov Incarnate | Posts: 241 | Joined: 04/12
Posted: 01/29/13
07:53 AM

there are several articles and forum posts out on the web about repairing the C4 cluster..

there are multiple layers of circuit boards that have straight pin interconnects.

the interconnects get corroded... the solder joints come loose... once in a while..  you could have gotten a bad ignition switch.. does anything else not function???

there is only power out on the IGN 1... ACC and the IGN3...   does everything else work..

take a look at this pinout of the cluster connector..

C4cluster 32Pin

if you have to PROBE anything.. please use either a digital volt meter or a logic probe.. both are cheep... you don't want to blow out any data circuits...  please invest in a static discharge wrist strap also... and hook it to a properly selected ground point on the circuit board/cluster when you have it out and are working on it..  you don't want to let the smoke out of the electronics..  

blazz86 blazz86
I watched Corvette Summer | Posts: 7 | Joined: 08/12
Posted: 01/30/13
03:07 AM

everything seems to work fine, it was just the display that disapeared for a few seconds, today I went for a drive and it didnt do it .  

waynep71222 waynep71222
Duntov Incarnate | Posts: 241 | Joined: 04/12
Posted: 01/30/13
07:01 AM

the movement of the car down the road over bumps causes the circuit boards to jiggle and can solve the flickering issues... but eventually it MAY... get worse...

if you know how to solder and have a decent soldering station you can take it apart and resolder the various interconnect pins..  

there is a really good article on it out there on the web... step by step...