1990 F150 5.0 engine problems
Lead Driver
Joined: Feb 2002
Posts: 7,958
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From: Greater Austin, Texas
The TPS is adjustable, can you not adjust it to get the required voltage?
BTW I say Bah! Humbug! to not messing with the base idle screw. I've done it, your truck won't blow up, but you do have to readjust the TPS after and also if you are trying to knock 500 RPM off your idle, the base idle screw is not your problem.
BTW I say Bah! Humbug! to not messing with the base idle screw. I've done it, your truck won't blow up, but you do have to readjust the TPS after and also if you are trying to knock 500 RPM off your idle, the base idle screw is not your problem.
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Joined: May 2010
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The TPS is adjustable, can you not adjust it to get the required voltage?
BTW I say Bah! Humbug! to not messing with the base idle screw. I've done it, your truck won't blow up, but you do have to readjust the TPS after and also if you are trying to knock 500 RPM off your idle, the base idle screw is not your problem.
BTW I say Bah! Humbug! to not messing with the base idle screw. I've done it, your truck won't blow up, but you do have to readjust the TPS after and also if you are trying to knock 500 RPM off your idle, the base idle screw is not your problem.
The truck will now idle at around 900 rpms after it's been sitting for a minute--which makes me think it's still got a vacuum leak somewhere. I've been finding and replacing cracked hoses left and right.
When I say "after it's been sitting for a minute" I mean even after it's been warmed up. For example, if I'm driving around and stop at a red light it will idle around 1500 rpms. The longer I sit, the lower the rpms go until it eventually reaches about 900 rpms.
Lead Driver
Joined: Feb 2002
Posts: 7,958
Likes: 592
From: Greater Austin, Texas
I used to have a 1990 F150 with 302 and 5-speed, just like yours only it was 4x4. IIRC the correct idle speed in neutral was 900 RPM. It was at least 800 because I remember thinking that was too high but after I looked it up, it was correct.
Still, it needs to return to that idle as soon as you push in the clutch, not several minutes later.
Still, it needs to return to that idle as soon as you push in the clutch, not several minutes later.
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Joined: May 2010
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I used to have a 1990 F150 with 302 and 5-speed, just like yours only it was 4x4. IIRC the correct idle speed in neutral was 900 RPM. It was at least 800 because I remember thinking that was too high but after I looked it up, it was correct.
Still, it needs to return to that idle as soon as you push in the clutch, not several minutes later.
Still, it needs to return to that idle as soon as you push in the clutch, not several minutes later.
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