Intermittent not starting issue

1987 FORD F-150
168,500 MILES • 4.9L • 6 CYL • 2WD • AUTOMATIC
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CYNDI PFISTER
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Sometimes it starts sometimes it does not. It will start perfect for a month then one day it just won't. It will start when the fuel pump shuts off, but will not start when the pump runs continuously even though it has 50 PSI at the rail. When the pump continuously runs, it gurgles in the tank. And now it has started cutting out when you mash the throttle. So far have replaced: computer, pickup coil, coil, ignition control module, high pressure fuel pump, fuel pump in tanks, fuel filter, and steering column.
Jan 30, 2021 at 7:38 AM
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KASEKENNY
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Can you clarify the fuel pump issue? When you say it runs continuously the engine does not start but it has 50 PSI? When this happens, what do you have to do in order to get it to start? Also, I assume it is cranking and not starting when this is happening? Meaning the engine is turning over but not starting.

Here are some guides that will help get us started:

https://youtu.be/dCjmRL3p4Cs

https://www.2carpros.com/articles/car-cranks-but-wont-start

Lastly, do you have dual tanks or single? If you have dual tanks does it do this on both tanks or is it always the same one?

Let's start with this and go from there. Thanks
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May 31, 2021 at 5:47 AM
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CYNDI PFISTER
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To start off with answering your questions then I'll look at the attached links.
1.Yes it has 50 psi whether it decides to start or not.
2. Haven't figured out how to get it to start when it doesn't want to which is the problem.
3. Yes it always cranks, but only starts when it wants to.
4. Dual tanks, but have mainly only used the front tank. But we did try the back tank the other day out of curiosity and it did the same thing.
May 31, 2021 at 5:47 AM
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CYNDI PFISTER
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Thanks for the links, but I didn't really find anything helpful in them. It seemed to be mainly aimed towards newer vehicle parts that this truck does not have.
May 31, 2021 at 5:47 AM
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KASEKENNY
  • ✓Experienced Mechanic
  • 18,907 POSTS
Got it. With that information it makes sense why you did not find the solution in there.

I think we can move past a fuel issue with that info. Let's pull a spark plug and connect it back to the plug wire and hold it against the block and crank the engine. We want to see if there is a bright blue spark. I suspect we have no spark but let's confirm that and go from there.
May 31, 2021 at 5:47 AM
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CYNDI PFISTER
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It decided today to start starting again without issues. So would it better to wait until it decides to not start again to test it?
May 31, 2021 at 5:47 AM
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KASEKENNY
  • ✓Experienced Mechanic
  • 18,907 POSTS
Yeah. Unfortunately any test you do now it will not show anything wrong as it is starting. Let us know what happens with this when it starts this again. hopefully that doesn't happen. We love it when things fix themselves but it doesn't happen often. Thanks for the update.
May 31, 2021 at 5:47 AM
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