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12-10-2021, 01:32 AM | #1 |
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Location: Phoenix Arizona
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Truck will start but won't keep running!
Hi everyone Chris here,
I have a 1967 chevy C20 pickup truck with a SBC 350 1985 engine. Had a oil leak and took the engine out and replaced all of the gaskets and new timing chain, 4 row radiator with dual fans, new water pump, new alternator, new ignition switch and spark plug wires the whole nine yards. Put everything back together and had some issues but nothing to bad. Was driving around for about 2 weeks and noticed the low drop in volts when I tried to start it well below 9-11 volts. I have a new wire harness to be put in but the biggest problem is that the truck will crank over but the volts drop after that. It won't stay running and if it does start and I drive it it will die and can't start it back up. Electric fuel pump works good but think it might be my distributor but dont know for sure. I have a video of the volts dropping but can't get it uploaded. I would appreciate any advice and help to get my truck back on the road. Thanks for your time Chris |
12-10-2021, 02:50 AM | #2 |
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Re: Truck will start but won't keep running!
First thing, I would make sure that the battery is good and that the charging system is working correctly.
2nd would be making sure that starter is not drawing too many amps while cranking. Engine block ground, chassis ground and body ground |
12-10-2021, 01:42 PM | #3 |
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Re: Truck will start but won't keep running!
Battery and alternator are good. The starter is newer but won't know how to find that out. What would I be testing for the starter? The grounds are all there from the tear down.
Last edited by CSchmidt; 12-10-2021 at 01:43 PM. Reason: Added more content |
12-10-2021, 04:08 PM | #4 |
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Re: Truck will start but won't keep running!
What is you voltage on the battery just sitting there? When you say battery and alternator are good, how do you know that? Original style coil or has it been upgraded to HEI distributor?
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12-10-2021, 07:20 PM | #5 |
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Re: Truck will start but won't keep running!
Distributor is a HEI style. Cause the battery has been checked and charged and the volts are 12.53 and alternator is brand new
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12-10-2021, 07:58 PM | #6 |
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Re: Truck will start but won't keep running!
Don't fall into the trap of because a part is new that it's good, I see faulty new parts all the time. You say your battery voltage is 12.5V, is that with the engine running or not? If you are at 12.5V with the engine running, your charging system is not working. You need to be around 13.5V with the engine running.
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12-10-2021, 08:39 PM | #7 |
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Re: Truck will start but won't keep running!
Actually voltage should be 13.8 to 14.2
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12-10-2021, 08:46 PM | #8 |
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Re: Truck will start but won't keep running!
Thats with the engine off.
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12-10-2021, 09:17 PM | #9 |
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Re: Truck will start but won't keep running!
Thats running 14.2..Around 12.4 not running. .When it dies does it start back up with a boost?
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12-10-2021, 09:41 PM | #10 |
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Re: Truck will start but won't keep running!
It cranks and acts like it starts but the volts drop and continues to do so. It doesn't run just cranks. I turn the key and volts go back up its when it tries to start it dies. When it starts its good when in park but when I try to drive it I get a block or 2 and it just dies.
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12-11-2021, 08:10 AM | #11 |
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Re: Truck will start but won't keep running!
90% of the time when your voltage drops that low at start it is a bad cell or so in the battery that looks good until there is a load. I would take it to a store and let them test it. However, most of these older trucks don't need the battery connected to run, so I think you may have other issues besides the battery. I would get the battery checked first. Try and deal with 1 thing at a time. Since you had it all apart, double check all wiring connections and for pinches in wires. AS mentioned, this is especially true of your grounds to the engine and frame.
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12-11-2021, 11:28 AM | #12 |
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Re: Truck will start but won't keep running!
Does your current wiring harness have a fusible link somewhere in the charging system wiring? My truck has one, and it wasn't charging while it was running. Everything was new, as you are saying. It turned out this fusible link had blown and that was my issue.
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12-11-2021, 01:39 PM | #13 |
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Re: Truck will start but won't keep running!
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12-13-2021, 02:27 PM | #14 |
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Re: Truck will start but won't keep running!
+1 to Grumpy Old Man.
You need 12V to run the HEI, the factree 1967 pink wire to the stock coil is a resistance wire that limits voltage to around 7 volts to the stock coil to avoid burning up the points. When the starter is engaged, there is a bypass wire that will run 12V to the stock coil for starting, but it drops down to 7 Volts as soon as the key is off the starter. What voltage do you have at the HEI with key on, but no starter engaged?
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12-13-2021, 02:33 PM | #15 |
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Re: Truck will start but won't keep running!
Sorry everyone I've been busy. I'll get back to you soon.
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12-13-2021, 06:43 PM | #16 |
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Re: Truck will start but won't keep running!
subd good luck lots of good advice from the guys
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12-13-2021, 08:17 PM | #17 |
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Re: Truck will start but won't keep running!
A way to do a quick load test on the battery is to make sure the battery is fully charged, next turn your headlights on for 5 minutes with the engine off then recheck your battery. It should drop a little like maybe half a volt but if it drops way down and is hard to start the battery is bad.
Also as said check the voltage to the distributor, it should be a full 12 volts. Also make sure you have a good ground from the motor to the frame and motor to the firewall. Last edited by garyd1961; 12-13-2021 at 10:35 PM. |
12-14-2021, 02:44 PM | #18 | |
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Re: Truck will start but won't keep running!
Quote:
What output spec does the new alternator have?
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12-14-2021, 08:25 PM | #19 |
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Re: Truck will start but won't keep running!
Yes the fans are brand new came with radiator. I guessing the alternator is either a 63 amp or 78 amp. I'm not really sure.
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12-14-2021, 10:10 PM | #20 | |
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Re: Truck will start but won't keep running!
Quote:
With e-fans & an e-fuel pump, I would want 100amp minimum. Re-check voltage when the fans are on & then off. See what impact they have.
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67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... Cubic inches is like Indiana Jones with a cheap pistol. |
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