1988 K5 wont start

[Justin Fleming]

So originally I was fitting a back fire issue. Just got the truck so I don't know the history. I had it running but had no power and back fire issue. So I went a head and put all new plugs, wires, cap and rotor so I know I am starting fresh. Now the truck will not even start. I checked for spark from the coil and that seems to be working, I am getting fuel from the injectors and it would even try to fire. I even sprayed a little either in to see if it would at least try to fire. So what ever the issue was I believe it has now failed 100%.

Usually, spark, compression and fuel source it should at lest fire for a second....

Any ideas guys I am going crazy

 

[TommyD11730]

You have spark from the coil, but do you have it out of the plug wires?

Have seen plenty of those old TBI 5.7s run like dirt/no run with a bad CTS (coolant temp sensor). Might want to see if it will run with it disconnected.

Good Luck

 

[Justin Fleming]

I have spark at the wires also. I have installed a new coolant temp sensor but will unplug for grins

 

[Justin Fleming]

now I have no spark at the coil. I think the intermittent problem is either the coil or what ever tells the coil to fire. I have 12v to the coil large red wire. and I have 12v to the 2 position connector on each leg to ground. What else should I be checking here?

 

[Justin Fleming]

added a new coil and the truck still has no spark. where do I go from here? I have also swapped in a ecm and ignition module from my 1990. When theses items were installed in the 1990 the truck runs so they are good parts. This leaves me down to either wiring somewhere or the distributor pick

where to go from here?

 

[TommyD11730]

Ok, new coil, module and secondary ign parts. Sure sounds like your pickup has gone south in the distributor. It might be as simple to pull the cap and rotor and check those wires on the pickup. I have seen on older distributors with vacuum advance those wires break from age/movement.

Do you have a spare distributor you could try?

You did swap a 4 pin for 4 pin module (or are they 5 pin?)... yes?

 

[Justin Fleming]

Udate

so craziest thing ever... I added the new coil and had no spark. So I went back to the ignition module to take some reading on the pick up. What I found here was that the two prong plastic connector was pretty much hardened up and crumbling. Which allowed for a poor connection. So I hooked it back up, hooked up the old coil and now I was back to having spark where I was yesterday. Truck still would not start. For ****s and grins I plugged the new coil in and it started right up. So it appears to be a weak coil or malfunctioning coil. She purrs like a kitten and is no longer back firing....

Still plenty of bugs in this truck but one at a time I will conquer them.

thanks

 

[ccarley]

I think the Chilton's green/black manual has info on testing the pickup in the distributor; it is very much worth checking out. It's very easy to replace as well; but you do need to pull the distributor to do so. With a bad pickup it will run bad or not run at all.

Good luck,
Clay