87 crew cab R20 weak spark and won't start

[halusmc71]

I'm new here to the forum and hope I'm doing this right!

Anyways, yesterday I took my 87 Crew cab to the car wash and decided to wash the engine bay along with the truck to degrease it and clean it up a bit. After I was done you guessed it, it wouldn't start. The truck is all stock 350 TBI with 400 turbo 2WD R20. I took the cap off and attempted to dry it out and put it back on and still nothing. Then I noticed the plug in the center of the cap was almost completely gone, so i went to the parts store and got a new cap rotor and a coil. Still would not run. Then I read a forum about the pick up coil being back. So today I pulled the distributor and replaced it. No easy task there. Still won't run. The thing is , it is getting spark to the plugs it's just weak and the injectors are spraying fuel. When I would try to start it and I would give it some gas it would try and start then it would just grind the starter. I even pulled it into a shop close by and had some help and now i think I fried the starter because nothing happens now when i turn the key. I mean, Nothing! Any help would be appreciated.

God Bless,
Ed

 

[Jims86]

Make sure the 2 plugs going into the coil are dry, and try to tighten the bolts holding the coil to th intake manifold. if you have a tester, turn the key on and see what voltage is coming through the large pink wire going to the coil. also, chick the system grounds at the thrmostat housing bolt....clean and tight.
Check Battery connections too, make sure they are clean and tight. check positive cable connection at starter, and negative cable connection which should be on the block or to annaccessory bracket.

 

[halusmc71]

I tested the voltage going to the Coil and it tests at a little over 12 volts. While cranking the engine over trying to get it to fire I think something else went wrong and it wouldn't turn over or do anything. I replaced the fuse that says crnk and it started turning the engine over again. Not sure what the bottom fuse is to but after some trying to get it started again, it ran for a moment and then died and tried to start again and the same thing happened. Nothing is happening. I turn the key and get nothing. I have good voltage to the starter but can not get anything to the switch leg of the starter solenoid. Also, I did not mention it but I did replace the ignition switch on top of the steering column as well. I went to check the fuses again and noticed when I pulled the crnk fuse that there is no voltage to the posts that the fuse plugs into with the key to the on position. I'm stumped.

 

[Jims86]

I tested the voltage going to the Coil and it tests at a little over 12 volts. While cranking the engine over trying to get it to fire I think something else went wrong and it wouldn't turn over or do anything. I replaced the fuse that says crnk and it started turning the engine over again. Not sure what the bottom fuse is to but after some trying to get it started again, it ran for a moment and then died and tried to start again and the same thing happened. Nothing is happening. I turn the key and get nothing. I have good voltage to the starter but can not get anything to the switch leg of the starter solenoid. Also, I did not mention it but I did replace the ignition switch on top of the steering column as well. I went to check the fuses again and noticed when I pulled the crnk fuse that there is no voltage to the posts that the fuse plugs into with the key to the on position. I'm stumped.

Check the connections at the starter solenoid, you may have blown a fusable link. Thats where the fuse box gets its power.

 

[halusmc71]

Are you talking about the red wire from the starter that is about a 10 or 12 ga. and goes up to the junction block on the firewall ?

 

[89Suburban]

Are you talking about the red wire from the starter that is about a 10 or 12 ga. and goes up to the junction block on the firewall ?

That junction block with the 2 posts on the firewall is actually a large fuse. That metal in between will melt away if something major shorts out.


Look at the wire at the alternator, there should be a fusible link in the wire there. Mine went bad last year and was giving me the same symptoms you are experiencing right now. I would wiggle that part of the wire and the truck would light back up. I cut it out put and hard wired it to get me back on the road.

 

[halusmc71]

Thanks , I'll look at that wire tomorrow. Late now!

Another question. What does the fuse marked CRNK power? I'm still not sure on why I don't have power to it with the key in any position.

Thanks,
Ed

 

[Jims86]

Holllld the phone here...Ed, when was the last time you pulled the battery cables off, and cleaned them and the battery. We have been diving into complicated **** on this forum lately, without checking the simple stuff. My fault totally!

 

[halusmc71]

Yes I have checked and cleaned the battery terminals. I have reset the computer a couple of times as well.. The only code that i have seen was a 45. I did have it running for a minute yesterday and it moved under its own powwer for about 20 feet then died again and wouldn't start again. Today I went back throught the basics and disconnected and cleaned all my grounds and made sure the injectors were spaying. When I finally did get it to start was after i rechecked my timing. it didn't run for long before it died and then i tried to restart and it let out a little back fire and now i have nothing going on. I also took off the egr and checked it, it seems to be moving freely and i took off the IAC and cleaned it with some Tb cleaner. ?????? Where should i check for voltage coming from the ignition switch at to verify if I have voltage leaving the switch? Where does the wire go from the switch to the starter solenoid? Is there a place in between somewhere?

 

[Jims86]

Yes I have checked and cleaned the battery terminals. I have reset the computer a couple of times as well.. The only code that i have seen was a 45. I did have it running for a minute yesterday and it moved under its own powwer for about 20 feet then died again and wouldn't start again. Today I went back throught the basics and disconnected and cleaned all my grounds and made sure the injectors were spaying. When I finally did get it to start was after i rechecked my timing. it didn't run for long before it died and then i tried to restart and it let out a little back fire and now i have nothing going on. I also took off the egr and checked it, it seems to be moving freely and i took off the IAC and cleaned it with some Tb cleaner. ?????? Where should i check for voltage coming from the ignition switch at to verify if I have voltage leaving the switch? Where does the wire go from the switch to the starter solenoid? Is there a place in between somewhere?

The starter wire goes from the ignition switch, to a neutral safety switch, to the starter soleniod.
If you get it fired up again, unplugbthe MAP sensor 3 wire connector, and see if it runs better. if so, you need a new map sensor...or at least check the plug to make sure its not wet and fouling things up. Pop your dist cap off and dry that out too.

 

[halusmc71]

I don't know what I did but I unPlugged the ECM and battery, then took off the starter and bench tested it because I was getting power frOm the switch to the solenoid but nothing was happening. The starter tested ok on the bench so I re-installed it and decided to try and find the 3 amp fuse that the schematic shows going from the solenoid to the ECM. No luck. Then I decided tO re install the ECM and reconnected the power checked fuses again. Then suddenly I turned the key and off she goes. It starts, but was idling rough so I let it run and it seemed to smooth out. So I decided to check and see where the timing was at.

This is still troubling me. I turned it off. Installed the light, disconnected the wire and started it again and it was at 28 degrees. So I turned the dizzy and got it to zero and checked the timing mark and was good at 0. So I shut it off and Plugged the tan wire back n and started it. It ran like crap now? Then it dies, I try starting it again and it back fires a little bit and suddenly it is dead at the switch again. I turn the key and dont get anything. Same symptoms . I tried pulling the starter then unPlugging the ECM and then reinstallIng it all and repowering and it's still dead.
It's almost like the little back fire tripped the ECM but I'm not sure. One of the guys thinks its a bad starter solenoid? What do you guys think?

 

[halusmc71]

Any help would be appreciated.

I did get it started today and the symptoms its having are as follows:

First i started it with the timing wire unplugged and and the timing was at about 28 degrees. After started I adjusted the dizzy till the mark on the balancer and the light were at zero. I then shut it off and plugged the tan wire back in and it won't start. It does back fire and shoot flame out through the throttle body. Then if I unplug the tan wire and move the dizzy back counter clockwise to where it read about 28 degrees it will start and run rough for a minute then it smooths out a little.

After getting it started I decided to take it out for a drive and it had hesitation and low throttle and would not take off when i pushed the throttle down like it used to prior to me washing it.

Keep in mind i have replaced the coil, coil pick-up, cap, rotor bug, ignition switch, ignition module, plugs and have cleaned all grounds and battery terminals, also replaced starter solenoid. Also I have unplugged all sensors and dried them out using a compressor and air gun. Also checked all vacuum connections, and intake and throttle body gaskets for leaks with carb cleaner. No leaks.

What's next? I'm thinking the ecm, or elec spark control module?

Thanks, Ed