Rpms dropping down then engine cutting off
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Joined: Jul 2015
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Rpms dropping down then engine cutting off
I have a 1994 5.0 F150 and a few days ago I started it up and after about 3 seconds the idle dropped down to about 500 then it cut off from low idle of course. When I put it in gear it tries to drop down but not too bad because I keep hitting the gas, but after it warms up it runs perfectly fine then I cut it off and start it back up and it idles fine in park and while in gear. A few weeks ago I had a problem where I had to turn the key on and off 2 times so the fuel pump sent fuel twice. Then it would start and run fine. That problem randomly went away but do y'all think this new problem is the same thing just worse?I was thinking fuel pump or fuel pressure regulator? Maybe it has something to do with intake? Plugs? I have no idea but thanks in advance.
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Joined: Jul 2007
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From: Cape Girardeau MO
Fuel pressure is checked at the Schrader valve on the manifold fuel rail. Would like to see 35 psi or better. Have used a tire guage I didn't care about to get the reading, be careful as fuel may spray.
One other thought is the IAC (idle air control) solenoid. The previous gen ('87-'91) tended to gunk these up causing idle speed control issues. May be worth a look to ensure the piston moves freely, and a possible cleaning - use regular carb cleaner. This looks like a roll of quarters with an electrical connection which straddles the main throttle butterfly.
One other thought is the IAC (idle air control) solenoid. The previous gen ('87-'91) tended to gunk these up causing idle speed control issues. May be worth a look to ensure the piston moves freely, and a possible cleaning - use regular carb cleaner. This looks like a roll of quarters with an electrical connection which straddles the main throttle butterfly.
Thread Starter
Member
Joined: Jul 2015
Posts: 61
Likes: 3
Fuel pressure is checked at the Schrader valve on the manifold fuel rail. Would like to see 35 psi or better. Have used a tire guage I didn't care about to get the reading, be careful as fuel may spray.
One other thought is the IAC (idle air control) solenoid. The previous gen ('87-'91) tended to gunk these up causing idle speed control issues. May be worth a look to ensure the piston moves freely, and a possible cleaning - use regular carb cleaner. This looks like a roll of quarters with an electrical connection which straddles the main throttle butterfly.
One other thought is the IAC (idle air control) solenoid. The previous gen ('87-'91) tended to gunk these up causing idle speed control issues. May be worth a look to ensure the piston moves freely, and a possible cleaning - use regular carb cleaner. This looks like a roll of quarters with an electrical connection which straddles the main throttle butterfly.
Senior Member
Joined: Jul 2007
Posts: 3,805
Likes: 480
From: Cape Girardeau MO
Yes, and yes.
The thing that brought to mind the IAC was your comment about the idle dropping down when put into gear. Granted, the idle should drop some, but not so low as to need feathering with the pedal.
Don't mess with the set screw on the main butterfly. While it's tempting to use this, it's really only meant to keep the butterfly offset from sticking in the throat - not for controlling idle speed.
Thread Starter
Member
Joined: Jul 2015
Posts: 61
Likes: 3
Yes, and yes.
The thing that brought to mind the IAC was your comment about the idle dropping down when put into gear. Granted, the idle should drop some, but not so low as to need feathering with the pedal.
Don't mess with the set screw on the main butterfly. While it's tempting to use this, it's really only meant to keep the butterfly offset from sticking in the throat - not for controlling idle speed.
The thing that brought to mind the IAC was your comment about the idle dropping down when put into gear. Granted, the idle should drop some, but not so low as to need feathering with the pedal.
Don't mess with the set screw on the main butterfly. While it's tempting to use this, it's really only meant to keep the butterfly offset from sticking in the throat - not for controlling idle speed.