Throttle loss when engine is warm

[Steven Walker]

I have an issue. I was driving the truck today and it was great, no issues or anything while it was cold. Drove for about 8 miles and once it was good and warm it lost all throttle response. Pushed the pedal all the way down, it would barely rev. Then it should run really rough and die. Am I looking at a IP? I dont think its air intrusion since it was running good cold. I could hear the shutdown solenoid click so I know that should be good... help please! Any ideas? Thanks

 

[IDIBRONCO]

I'm not sure that the FSS could cause a low power issue. I think it either works or it doesn't. Was your power loss sudden or was it gradual. I'm thinking that if it was sudden, maybe it happened when your timing advance kicked off after the fast idle cut off. If that's the case, then you could try to advance the pump timing a little bit to see what it does. The only issue that I have with my theory is that 8 miles seems like a long time for the fast idle to be on.

 

[Steven Walker]

It happened suddenly. Everything was fine then all of a sudden no throttle response. I had pushed the throttle completely down and it may have reved up 500 rpms if that. Then it would die. I'd wait a minute and re-start and it'd idle fine, then I'd rev it one time and it would start idling rough and die. It took me 2 hours to make it back that 8 miles... I took a video so I'll try to upload it

 

[Steven Walker]

It won't let me upload it... I can probably send in an email

 

[The_Josh_Bear]

If you host the video on YouTube and then link it here it should work fine.

What an odd situation... did you get under the hood and verify that the cable wasnt snapped? That's about the only thing I can think that would cause such an issue on these mechanical engines.
Try activating the throttle lever on the IP by hand to see if it acts the same way as with your foot.

 

[79jasper]

How much fuel is in the tank?

Sent from my SM-N960U using Tapatalk

 

[Kizer]

I'll bet your lift pump "lifted" some crap out of the tank. When it happened to me, the truck would "surge" ... like it was starving for fuel. But I can see how it could have caused the symptoms that you have described.
After I cleared the lines, with compressed air, everything returned to normal ... so I dropped and cleaned the tanks.

 

[Steven Walker]

If you host the video on YouTube and then link it here it should work fine.

What an odd situation... did you get under the hood and verify that the cable wasnt snapped? That's about the only thing I can think that would cause such an issue on these mechanical engines.
Try activating the throttle lever on the IP by hand to see if it acts the same way as with your foot.

The throttle cable is brand new. I replaced it a couple weeks ago because the other one cracked.

How much fuel is in the tank?

Sent from my SM-N960U using Tapatalk

The tank I was on was full.

I'll bet your lift pump "lifted" some crap out of the tank. When it happened to me, the truck would "surge" ... like it was starving for fuel. But I can see how it could have caused the symptoms that you have described.
After I cleared the lines, with compressed air, everything returned to normal ... so I dropped and cleaned the tanks.

I'll have to take a look and see about the lift pump

 

[Thewespaul]

Check to make sure it does the same thing when moving the throttle lever on the pump so you can eliminate the cable. Then at idle, depress the schraeder valve on the filter head and you should have fuel shooting out. If not, your lift pump is bad. If you have some but not a lot of pressure, try swapping the fuel filter with a new one filled with atf.

 

[Steven Walker]

Check to make sure it does the same thing when moving the throttle lever on the pump so you can eliminate the cable. Then at idle, depress the schraeder valve on the filter head and you should have fuel shooting out. If not, your lift pump is bad. If you have some but not a lot of pressure, try swapping the fuel filter with a new one filled with atf.

I don't have a schraeder valve in the filter head as it was replaced with the sending unit for a fuel pressure gauge. There is a new factory fuel filter installed currently. On that note is the filter bottom supposed to drip at all while running? I've heard yes and no but haven't been able to locate any documentation to confirm it.

 

[Kizer]

is the filter bottom supposed to drip at all while running?

You shouldn't be leaking fuel anywhere. If fuel is getting out, air is probably getting in.

 

[Steven Walker]

You shouldn't be leaking fuel anywhere. If fuel is getting out, air is probably getting in.

It's not leaking I was curious. Some people have said that what it's dripping is water out of the bottom piece that connects to the little tube that runs down the side of the engine down to the bottom of the truck. I don't have the wix filter I have the motorcraft setup. I'm thinking about going to the Wix filter though.

 

[Thewespaul]

How much fuel pressure are you seeing?

 

[The_Josh_Bear]

How much fuel pressure are you seeing?

+1 beat me to it

 

[Steven Walker]

How much fuel pressure are you seeing?

I think its between 5 and 10 psi. I'll look tonight and take another video for yall to see.