1970 GTO won't start after mild tuneup. - Pontiac GTO Forum
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post #1 of 9 (permalink) Old 04-27-2019, 05:56 PM Thread Starter
 
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1970 GTO won't start after mild tuneup.

Greetings,

This is my first time posting. I have an original 1970 GTO with the 400 engine. The engine was running fine until I changed some parts out.

I replaced the thermostat, and the gasket. I replaced the fuel filter, and I replaced the spark plugs. I did not touch the distributor/cap, or anything else.

The engine will turn over, but not start. The fuel filter will fill with gas clearly, so it's getting fuel. I even tried dumping some gasoline in the carb, but that did nothing. I double checked that the spark plug wires were connected, and they seem to be fine, though maybe the terminal is too far in the boot after I took them off??

I'm at a loss, and I only have basic tools (nothing to test electrical or power). I'm thinking at this point of just replacing all of the spark plug wires because they are fairly old.

Any guidance would be appreciated.
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post #2 of 9 (permalink) Old 04-27-2019, 06:16 PM
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I suspect you messed up the firing order when you did the plug install. Verify that first. Also, you can pull the coil wire from the coil tower and hold it in place about 1/2 inch from the tower and have someone crank the engine to verify that you ARE getting a spark.
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post #3 of 9 (permalink) Old 04-27-2019, 06:17 PM
 
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Originally Posted by bwayney View Post
Greetings,

This is my first time posting. I have an original 1970 GTO with the 400 engine. The engine was running fine until I changed some parts out.

I replaced the thermostat, and the gasket. I replaced the fuel filter, and I replaced the spark plugs. I did not touch the distributor/cap, or anything else.

The engine will turn over, but not start. The fuel filter will fill with gas clearly, so it's getting fuel. I even tried dumping some gasoline in the carb, but that did nothing. I double checked that the spark plug wires were connected, and they seem to be fine, though maybe the terminal is too far in the boot after I took them off??

I'm at a loss, and I only have basic tools (nothing to test electrical or power). I'm thinking at this point of just replacing all of the spark plug wires because they are fairly old.

Any guidance would be appreciated.
These cars pretty much only need fuel and spark to start. so since you dumped fuel down the carb with no effect, check for spark at the plug end. remove a spark plug wire and connect a screwdriver into the plug boot end. Then hold it close (1/4")to metal on the on the engine,then have someone crank the engine and look for the spark jumping from the screwdriver to the metal. Be sure not to touch the metal on the screwdriver. If you have no spark look at the plug wire connections on your distributor or check your coil by using the same method.
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post #4 of 9 (permalink) Old 04-27-2019, 06:33 PM Thread Starter
 
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I made sure I did one sparkplug at a time, so I know the order is not messed up.

Unfortunately, I live alone and don't know when I would be able to have someone come by and help start the engine while I check for spark.

I have a feeling it has to do with the spark plug wires at the plug ends. Some of them did not come off easily and I really had to tug on them, which may have affected the terminals.

But, even if a few spark plug wires were loose, the car should still be able to start with at least, lets say, 5 spark plugs and wires/correct? it would just run very poorly?
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post #5 of 9 (permalink) Old 04-27-2019, 07:33 PM
 
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Originally Posted by bwayney View Post
I made sure I did one sparkplug at a time, so I know the order is not messed up.

Unfortunately, I live alone and don't know when I would be able to have someone come by and help start the engine while I check for spark.

I have a feeling it has to do with the spark plug wires at the plug ends. Some of them did not come off easily and I really had to tug on them, which may have affected the terminals.

But, even if a few spark plug wires were loose, the car should still be able to start with at least, lets say, 5 spark plugs and wires/correct? it would just run very poorly?
If your cars in a garage close the door shut the lights and look for spark. Or set the screwdriver wire set up higher and stand outside the car while you crank and you may see the spark. Or wait till evening. Abad wire or two will run bad or may not start and backfire somewhat.
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post #6 of 9 (permalink) Old 04-28-2019, 06:46 AM
 
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It is easy to install boots not all the way......you can re-Pull each boot one at a time and reset,..you should here and feel the click as the boot seats....just do one by one.

Also if your new spark plug gap is too wide it will cause a hard start, make sure you use a wire gauge spark plug gapped....if unsure of the gap regap....too wide and it will not crank easy
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post #7 of 9 (permalink) Old 05-02-2019, 08:54 AM
 
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I'm guessing power connection to the coil. It would be easy to check with an ohm/volt meter. There are cheap ones, like $5, at Harbor Freight...
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post #8 of 9 (permalink) Old 05-02-2019, 02:18 PM
 
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https://www.walmart.com/ip/IN-LINE-I...BoCjFoQAvD_BwE

Hello ... and welcome
I am in favor of doing 1 thing at a time if I am not confident in something ...
and just doing plugs and trying to restart is a smart idea ...

so the plug wires were tough to pull off eh ... we always like to SPIN the boot to break it loose b4 pulling it off or even to try n pull em off... if they are tuff to pull and the ones you think you may have had issue with put the light on that wire maybe first
no spark ?? move to another plug wire

DO NOT PUMP THE GAS pedal

I would check for spark 1st with the above tool

then we can move on ... since you have fuel to the carb it sounds like.... and it ran b4
the plug change ...
this is your buddy ... I use it on my lawn mower ... chain saw ,,, neighbors rigs etc ....weed wacker or your GTO .... I have the harbour freight ones napa auto zone ...sell em too . for under 10.00

built cheap ... but it sure is a time saver ....
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Last edited by BLK69JUDGE; 05-02-2019 at 02:32 PM.
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post #9 of 9 (permalink) Old 05-04-2019, 02:58 PM
 
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Originally Posted by bwayney View Post
Greetings,

This is my first time posting. I have an original 1970 GTO with the 400 engine. The engine was running fine until I changed some parts out.

I replaced the thermostat, and the gasket. I replaced the fuel filter, and I replaced the spark plugs. I did not touch the distributor/cap, or anything else.

The engine will turn over, but not start. The fuel filter will fill with gas clearly, so it's getting fuel. I even tried dumping some gasoline in the carb, but that did nothing. I double checked that the spark plug wires were connected, and they seem to be fine, though maybe the terminal is too far in the boot after I took them off??

I'm at a loss, and I only have basic tools (nothing to test electrical or power). I'm thinking at this point of just replacing all of the spark plug wires because they are fairly old.

Any guidance would be appreciated.
Just curious, did you figure out your issue?
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