1986 Ford F150 302 v8 Hard to start - Ford Truck Enthusiasts Forums



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1986 Ford F150 302 v8 Hard to start

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Old 06-18-2017, 11:27 AM
8brian1 8brian1 is offline
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1986 Ford F150 302 v8 Hard to start

once you run it and gets to operating temp. and i cut it off its hard to start. i have double checked my timing with a timing light both times.

Any help will be greatly appreciated.

Thanks
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Old 06-18-2017, 12:45 PM
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Is this a fuel injected engine?
If so, did you check the fuel pressure at the rail to see if (1) it is correct, and (2) to see if the pressure leaks down when the engine is off?


If carbureted, have you looked at the choke setting? Does the engine crank fast but wont start - or does it crank slowly when hot?


What is the timing set to now?
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Old 06-18-2017, 12:51 PM
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If it is fuel injected, how are you setting the timing? Just making sure you know how to do it, there is a few different things you need to do.
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Old 06-18-2017, 01:08 PM
8brian1 8brian1 is offline
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Quote:
Originally Posted by CountryBumkin View Post
Is this a fuel injected engine?
If so, did you check the fuel pressure at the rail to see if (1) it is correct, and (2) to see if the pressure leaks down when the engine is off?


If carbureted, have you looked at the choke setting? Does the engine crank fast but wont start - or does it crank slowly when hot?


What is the timing set to now?

its fuel injected and it cranks slowly when hot
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Old 06-18-2017, 01:16 PM
8brian1 8brian1 is offline
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Also could this have something to do with it having a hard time starting. I cant figure out where it goes
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Old 06-18-2017, 05:00 PM
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Might have had a rubber cap on it (which cracked and fell off).
If you have a C6 tranny, is there a vacuum line going to the modulator?


If a hose fell off, it should not be too far away.


Does your truck still have the sticker on the radiator support showing the vacuum line routing? Should look something like this:


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Old 06-19-2017, 05:48 AM
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Originally Posted by CountryBumkin View Post
Might have had a rubber cap on it (which cracked and fell off).
If you have a C6 tranny, is there a vacuum line going to the modulator?


If a hose fell off, it should not be too far away.


Does your truck still have the sticker on the radiator support showing the vacuum line routing? Should look something like this:


Photo borrowed from another member's post

yes it does. But somebody painted halfway over it. My was aod and I changed it to a 4speed last year
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Old 06-19-2017, 08:41 AM
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When you say it is hard to start, is it cranking freely or has the crank speed slowed down?
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Old 06-19-2017, 10:48 AM
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Quote:
Originally Posted by 8brian1 View Post
its fuel injected and it cranks slowly when hot
Quote:
Originally Posted by bcamill View Post
When you say it is hard to start, is it cranking freely or has the crank speed slowed down?
See above.
Dave - - - -
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Old 06-19-2017, 11:28 AM
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See above.
Dave - - - -
the crank speed is slow. When the motor is cool. It will spin over freely. Just after you drive it and cut it off. Spina really slow. Sometimes it won't start unless you jump it
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Old 06-19-2017, 11:33 AM
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That can be a symptom of timing too far advanced. When you set the timing did you pull the "spout connector"?

Also don't forget to check the battery condition and battery cables. You could drive over to one of the chain auto parts stores and have them do a battery/starter test while the truck is hot.
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Old 06-19-2017, 11:49 AM
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Quote:
Originally Posted by 8brian1 View Post
the crank speed is slow. When the motor is cool. It will spin over freely. Just after you drive it and cut it off. Spina really slow. Sometimes it won't start unless you jump it
Ah, this would have been good to mention in your first post. My mind-reading skills aren't what they used to be. Since you didn't mention the starter was slow, I assumed you had normal cranking speed.

Normal crank speed when cold and slow when warm is a common fault. With a cold engine, compression is lower so there is less strain on the starting circuit. When warm, compression returns to normal and a marginal starter system falters.

Notice I said "starter system", not just "starter". Follow this troubleshooting guide, written for your exact scenario:

https://www.ford-trucks.com/forums/1...w-starter.html

Don't change any parts just yet. Three simple tests with a voltmeter will tell you all you need to know in under five minutes.
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Old 06-19-2017, 01:21 PM
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That is also a sign of a bad solenoid. When they are on the way out, they are tempermental to the heat under the hood and slow the crank speed. Have you replaced this before? Do not use Autozone parts. Motorcraft is best, but Napa is good too. Try to jump the solenoid and see if it starts OK when hot. Be careful Have a wrench ready to disconnect the battery. If it is close to going, it may stay on and keep cranking.
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Old 06-19-2017, 08:24 PM
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Quote:
Originally Posted by bcamill View Post
That is also a sign of a bad solenoid. When they are on the way out, they are tempermental to the heat under the hood and slow the crank speed. Have you replaced this before? Do not use Autozone parts. Motorcraft is best, but Napa is good too. Try to jump the solenoid and see if it starts OK when hot. Be careful Have a wrench ready to disconnect the battery. If it is close to going, it may stay on and keep cranking.
Never have seen that symptom before. I have seen the solenoids stick or not work at all, but never have seen them subject to heat and cause a slow crank. The connections on the solenoid maybe.

Fords with the solenoids on the fender are not subjected to heat like the ones mounted on the starter like other brands. Of course Ford eventually went to that design also.
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Old 06-20-2017, 12:00 AM
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Quote:
Originally Posted by bcamill View Post
That is also a sign of a bad solenoid. When they are on the way out, they are tempermental to the heat under the hood and slow the crank speed. Have you replaced this before? Do not use Autozone parts. Motorcraft is best, but Napa is good too. Try to jump the solenoid and see if it starts OK when hot. Be careful Have a wrench ready to disconnect the battery. If it is close to going, it may stay on and keep cranking.
Not too crazy about the idea of jumping the solenoid. Do you mean between the two big terminals? If so, you will need to use something heavy like jumper cables, as it must handle several hundred amps. An ordinary piece of wire, 14ga for example, would quickly burn in two under such a load.

Also, there's not really any need to jumper it. The voltage drop test referenced in post #12 will quickly tell you if the solenoid (and rest of the starter circuit) is good, or further investigation is warranted.
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