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Old 12-14-2018, 07:57 PM   #1
jcondo
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Location: estherville, IA
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engine wont start

My fathers plow truck has been having some issues lately. Its a 79 with a 400 sbc but I don't know the year of the engine, its been 20+ years since I installed it.
I got it running enuff to pull into the shop and replaced the hot air choke on the carb with an electric upgrade kit. Had it running good afterwards and backed it out, plowed a bit of snow in front of the shop, maybe 20 mins of running time. Then put it back in the shop and worked on another truck I have.
Today I went in to see if the choke was gonna be closed and would open back up like its supposed to, and it wouldn't start up. It turns over and has fuel to the carb but just wont fire. I had a poof of smoke come out of the carb and thought well maybe the carb is messed up cuz its over 20 years since it was redone. I took my edelbrock off my 1980 Malibu that I know runs and put it on the plow truck.
It is doing the same thing minus the poofing of smoke out of the carb. If I manually move the throttle linkage I can see gas going into the carb so I don't think its a fuel pump or filter issue.
What else could be my issue?
We have done nothing to the engine electronically or mechanically for it to not run. Fuel pump in mechanical and I took the quadrajet off because the oem gas line had been jb weled and was loose, so I couldn't put it back on, is why I put the edelbrock on.
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Old 12-14-2018, 08:08 PM   #2
KDO
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Re: engine wont start

Did you verify you have spark? When was the last distributor cap and rotor installed?
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Old 12-14-2018, 08:16 PM   #3
jcondo
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Re: engine wont start

well I had spark a week ago but no I didn't verify it.
I ran out of time when I noticed the broken fuel filter threads on the old carb, and replaced it with my edelbrock.
Ill swap out the cap and rotor from the Malibu Sunday when I get time to work on it again.
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Old 12-15-2018, 10:53 AM   #4
nonstop
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Re: engine wont start

Before you start just changing parts, pull a plug wire and make sure you have spark. Cap and rotor might be fine, and it can be a myriad of other problems. Go slow and methodically and diagnose it.
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Old 12-15-2018, 05:15 PM   #5
68gmsee
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Re: engine wont start

If you do the checks above and you don't have a spark, check the cap for burn marks or maybe swap it out with another HEI. I had mine act the same way and found the ground strap under the coil had rusted and wasn't making good contact. It showed a spark with my timing light attached to the plug wire but evidently it was a weak spark because I replaced it with a spare and it started right up.
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Old 12-16-2018, 12:32 AM   #6
jcondo
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Re: engine wont start

Quote:
Originally Posted by nonstop View Post
Before you start just changing parts, pull a plug wire and make sure you have spark. Cap and rotor might be fine, and it can be a myriad of other problems. Go slow and methodically and diagnose it.
Yes I just meant changing the cap and rotor wouldn't be a bad idea as its not been done in 20 years. Other then a little maintenance, oil changes and easy things like that, my father hasn't done much to it sine I gave him the truck those 20 years ago.
But now that someone says cap or rotor, I remember having to pull my 85 cap off and dry it off every time there was a heavy rain or high dew point as it got moisture under the cap.
The only reason I swapped carbs was because when I went to touch the original fitting for the fuel filter on the quadrajet it was not tight at all. I remember him telling me he used JB weld on it cuz the threads on the carb were stripped out for that piece.
Hopefully I can get back to do some inspections on it sunday.
Thanks for the ideas on where to start everyone.
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Old 12-16-2018, 11:52 PM   #7
jcondo
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Re: engine wont start

Thanks everyone for the info and ideas on what to look for.

I changed all the vacuum lines, mostly cuz it should have been done anyway.
Inspected the rotor and cap and noticed the Cap center connection point was no longer domed but flat with a half moon groove in it. So I borrowed the cap from my Malibu for the time being.
Also took a spark plug out to look inspect and it was all carboned up on the end with a itty bitty electrode. I happened to have 9 r44tsx plugs on the shelf for my Malibu and decided to throw those in as well.
She fires right up and runs as good as I can allow it to, as I need the correct adapter plate for a GM intake to edelbrock 1405 carb.

Thanks again for everyones input. I am no longer worried bout having to spend a day clearing out my fathers driveway.
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