1978 f150 4.9 starting issues
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5th Wheeling
Joined: Mar 2024
Posts: 29
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1978 f150 4.9 starting issues
How’s it going? So long story short I wasn’t having much trouble starting my truck it would just misfire or when I stepped on gas more so fully in neutral would almost cut out when first turned on. Once it got worse I thought maybe it’s the starter. So I replaced it and to add The alternator, Solenoid and battery are new. At first I thought it was battery cause jumper cables worked but once I got a new battery it stayed on for 20 and died. After it’s gotten to the point where it won’t even turn but the battery is readying 13V off..
at this point without it even starting I’m thinking it’s either the ignition module or spark plugs? Also fuel is getting into carb as I checked to see if any gas would come through with the trigger
Any help would be great this is my first restore!
at this point without it even starting I’m thinking it’s either the ignition module or spark plugs? Also fuel is getting into carb as I checked to see if any gas would come through with the trigger
Any help would be great this is my first restore!
Lead Driver
Joined: Oct 2018
Posts: 7,903
Likes: 2,372
A batter can read 13v and still not be able to crank. any of the parts you replaced could be bad, new doesn't mean what it used to on parts these days. I'd start by charging the battery if you ran it down and go from there, put a breakdown test on it if it won't crank.
As far as running, the control box is always suspect. the pickup coil can cause your issues. your timing and your choke can make it tough to start as well.
As far as running, the control box is always suspect. the pickup coil can cause your issues. your timing and your choke can make it tough to start as well.
Mountain Pass
Joined: Sep 2016
Posts: 171
Likes: 17
An engine needs Gas, spark, and compression to run. Those are the basics. You said it has fuel in the carb, so check for spark at the end of a spark plug. pull a plug, insert it into the end of a spark plug wire, press the spark plug bridge up against an engine bolt and look for a spark while someone cranks the engine. Also 'read' the spark plug end (while you have it out) that enters the cylinder. Is it sooty? Too rich. Is it white? Too lean. Tan color? just right.
It sounds like your choke may not be working. An engine needs a richer mixture (some choke) to start easily. Check that the butterfly valve on the top of the carb is closed when engine is cranking and cold. Starting too lean can make it pop and sputter. Do you know that your timing is where it should be? Could it have very old gas?
It sounds like your choke may not be working. An engine needs a richer mixture (some choke) to start easily. Check that the butterfly valve on the top of the carb is closed when engine is cranking and cold. Starting too lean can make it pop and sputter. Do you know that your timing is where it should be? Could it have very old gas?
Thread Starter
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5th Wheeling
Joined: Mar 2024
Posts: 29
Likes: 1
Starting issues
An engine needs Gas, spark, and compression to run. Those are the basics. You said it has fuel in the carb, so check for spark at the end of a spark plug. pull a plug, insert it into the end of a spark plug wire, press the spark plug bridge up against an engine bolt and look for a spark while someone cranks the engine. Also 'read' the spark plug end (while you have it out) that enters the cylinder. Is it sooty? Too rich. Is it white? Too lean. Tan color? just right.
It sounds like your choke may not be working. An engine needs a richer mixture (some choke) to start easily. Check that the butterfly valve on the top of the carb is closed when engine is cranking and cold. Starting too lean can make it pop and sputter. Do you know that your timing is where it should be? Could it have very old gas?
It sounds like your choke may not be working. An engine needs a richer mixture (some choke) to start easily. Check that the butterfly valve on the top of the carb is closed when engine is cranking and cold. Starting too lean can make it pop and sputter. Do you know that your timing is where it should be? Could it have very old gas?
the butterfly valve is wide open and I don’t know how to shut it? You’re talking about the part right under where the air filter sits? I do not know my timing but it does pop and sputter when I step on the gas at first unless I don’t push too hard. This is all new to me I have an idea but would love help along the way. It is not old gas and I tried finding fuel filter I don’t see anything. I also never have touched the choke
Lead Driver
Joined: Oct 2018
Posts: 7,903
Likes: 2,372
Your choke should be adjustable but it's possible it's not operating at all. open means it's off
when the engine is cold press the accelerator pedal once and then look at the choke, if it's not closed most or all the way it's not working.
At some point you need to check your timing it's important for many reasons.
You should have a filter somewhere in the feed line. you may have one that screws into the carb right as the fuel line enters it.
You have several things going on and they're not related. you may want to check to see if you're charging properly and put a breakdown on your battery.
when the engine is cold press the accelerator pedal once and then look at the choke, if it's not closed most or all the way it's not working.
At some point you need to check your timing it's important for many reasons.
You should have a filter somewhere in the feed line. you may have one that screws into the carb right as the fuel line enters it.
You have several things going on and they're not related. you may want to check to see if you're charging properly and put a breakdown on your battery.
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5th Wheeling
Joined: Mar 2024
Posts: 29
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Starting issues
That’s the thing I’m not sure how to set up the timing. I’m using YouTube to see it and that’s helped but tough to find the same carb and all that. I’ll have to check to see if it closes at all when I step on the pedal. This is my 2nd battery as I had a brand new one trying this yesterday and made sure voltage was good on it. It started it at first but died 20 mins later and then would start and keep turning off to where it wouldn’t make any noise.
maybe the spark plugs are bad?
maybe the spark plugs are bad?
Fleet Mechanic
Joined: Feb 2007
Posts: 1,326
Likes: 48
From: Middle TN
Take the alternator and have it checked to make sure it's still charging. Lots of new alternators seem to be bad now a days.
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Lead Driver
Joined: Oct 2018
Posts: 7,903
Likes: 2,372
Spark plugs are not the problem.
If the battery is dying from cranking is so much that's normal. if it's dying because it's not charging that's a problem.
Check to be sure your battery connections are clean and tight, and that your ground cable is going to the block and that bolt is tight.
there are dozens of things that could be your problems. you just need to fix the easy ones first and then work down the list. some pictures or more detailed information might help. I'm kind of guessing as to what's actually going on.
If the battery is dying from cranking is so much that's normal. if it's dying because it's not charging that's a problem.
Check to be sure your battery connections are clean and tight, and that your ground cable is going to the block and that bolt is tight.
there are dozens of things that could be your problems. you just need to fix the easy ones first and then work down the list. some pictures or more detailed information might help. I'm kind of guessing as to what's actually going on.
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Thread Starter
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5th Wheeling
Joined: Mar 2024
Posts: 29
Likes: 1
Spark plugs are not the problem.
If the battery is dying from cranking is so much that's normal. if it's dying because it's not charging that's a problem.
Check to be sure your battery connections are clean and tight, and that your ground cable is going to the block and that bolt is tight.
there are dozens of things that could be your problems. you just need to fix the easy ones first and then work down the list. some pictures or more detailed information might help. I'm kind of guessing as to what's actually going on.
If the battery is dying from cranking is so much that's normal. if it's dying because it's not charging that's a problem.
Check to be sure your battery connections are clean and tight, and that your ground cable is going to the block and that bolt is tight.
there are dozens of things that could be your problems. you just need to fix the easy ones first and then work down the list. some pictures or more detailed information might help. I'm kind of guessing as to what's actually going on.
I’ll send pics later have some bad weather
Lead Driver
Joined: Oct 2018
Posts: 7,903
Likes: 2,372
If your battery is up and it won't crank then it's the battery connections or cables, or the starter or starter cable or connections. you can test the solenoid by jumping both cable connections with a couple wrenches or whatever, just make sure it's not in gear.
Running poorly is an unrelated matter to cranking. if your plugs are dark black most likely you're using a lot of oil or running too rich. from what you're saying the choke not operating correctly seems very likely as a good place to start.
Running poorly is an unrelated matter to cranking. if your plugs are dark black most likely you're using a lot of oil or running too rich. from what you're saying the choke not operating correctly seems very likely as a good place to start.
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