Tps?
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Freshman User
Joined: Sep 2005
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From: Vicksburg, MS
Tps?
I have an 85 F150, with a 5.0 liter efi. It starts and idles fine, it runs wide open fine. But when I'm in the mid range of the accelerator, it cuts out. The best way I can explain how it sounds is it sounds like a top fuel dragster idling. The truck has set up for about two years or so and I have replaced the fuel filter, the in tank fuel pump, the spark plugs, wires, distributor cap and rotor button. I'm out of ideas. I'm thinking it may be the throttle position sensor but I don't know how to check it, and I imagine that is a pretty expensive part to just replace to see if it helps. Any info would be useful, thanks
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From: Northwest, Arkansas
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We are glad you chose to visit our site. In order to make it easier to navigate please read the following. Please view the main forum page to find the best forum to ask any Technical questions
Also, below some of the titles of forums there is text that explains what the forum is either for or what shouldn't be posted in it.
Then ,Inside certain forum's there could be a Read First: thread or threads attached to the top.
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In Addition to the Tech Forums all user's can make their relationship closer to others by visiting & joining the State/Province Chapter that relates to their location.A complete list of Chapter's is located on the main forum page, near the bottom.
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Elder User
Joined: May 2004
Posts: 506
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From: Edwards Air Force Base
Get a code scanner at any parts store or a Wal-Mart for about $30 and run the scan and memory codes. You could spend a fortune just changing parts until you hit the right one.It could be a lot of things, especially on a motor that has been sitting a long time. Who knows what is sticking, the mice chewed the wires on etc. Run teh scan then let us know what it said.
Good Luck,
Lee
Good Luck,
Lee
Senior User
Joined: Oct 2003
Posts: 480
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From: Elyria, Ohio
Engine is EFI, no carb. Try some Fuel Injector Cleaner in Gas Tank and give it a good steady run before you start removing and repairing. Might same some time or money. But I think your next step after injectors might be TPS or something with emissions; defective EGR, PCV, O2 Sensor possible. Any Codes stored; Check Engine Light on?
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From: Vicksburg, MS
Update on 85 F150
I have yet to buy a code reader but I did take the throttle body off and cleaned it. I ohmed out the TPS and didn't find any spots in the potentiometer range where it was reading open or short so I assume it is good. While I had this off I looked into the fuel injection and it is filled with a black **** type of stuff that looks like it is coming from the egr valve, exhaust/carbon builup. I cleaned all I could thru that small opening and it ran fine for about 30 minutes. it started it again and I parked it.
I plan on taking the fuel injection off and cleaning it entirely. Also I am going to take off all of the emissions junk, ie. smog pump, egr valve, etc. I looked on my dash and I don't even have a check engine light. I do have a 'emissions' light. Any way, I'll post another update in about a week or so.
I plan on taking the fuel injection off and cleaning it entirely. Also I am going to take off all of the emissions junk, ie. smog pump, egr valve, etc. I looked on my dash and I don't even have a check engine light. I do have a 'emissions' light. Any way, I'll post another update in about a week or so.
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Junior User
Joined: Jun 2005
Posts: 90
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From: virginia
last weekend on my 86 5.0efi i pulled off most of my fuel system parts and cleaned out, not to mention the throttle body, w/IAC, and upper intake... there was a lot of carbon/sludge build up... definitly worth doing.
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Thread Starter
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Freshman User
Joined: Sep 2005
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From: Vicksburg, MS
How did you clean yours out. I don't have a bucket big enough to submerge my upper intake in gas or something. I thought about taking it to a car wash and pressure washing the sludge out of it. Or I guess I could just buy 20 bucks worth of carb/fuel injector cleaner.
Elder User
Joined: Feb 2005
Posts: 526
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From: Spokane, WA
TPS's are fairly cheap (20 to 30 dollars). You check them with an old analog mulimeter. Disconnect the TPS, put a probe end in each wire, set the meter to ohms (you will have to experiment, I don't remember the scale), then slowly work the throttle from idle to full. If there is any hitches, dead spots, etc, you need a new TPS. They usually wear out just off idle (where you operate most of the time), so if it idles and you stomp it, and it runs OK, then I would say TPS (i.e. if you run it slowly, it stumbles or dies).
Did that help? Mine seemed to wear out around 100,000 miles.
Kenny
Did that help? Mine seemed to wear out around 100,000 miles.
Kenny
Junior User
Joined: Jun 2005
Posts: 90
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From: virginia
Originally Posted by lugnut1009
How did you clean yours out. I don't have a bucket big enough to submerge my upper intake in gas or something. I thought about taking it to a car wash and pressure washing the sludge out of it. Or I guess I could just buy 20 bucks worth of carb/fuel injector cleaner.
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Freshman User
Joined: Sep 2005
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From: Vicksburg, MS
It Was The Tps!
Hey,
For those of you that were keeping track of my progress with my '85 F150, I got it running right! I cleaned out the upper intake and made a block plate for the EGR valve so it wouldn't put any more carbon buildup back into my intake. I also removed the smog pump and blocked off all the vacuum lines that were associated with it. You wouldn't beleive how much the smog pump had the engine bogged down! Anyway, that didn't do much for the original problem.
I had finally ran out of cheap-n-easy options so I went to my local Autozone [where they know me by name] and got a TPS. The lady told me that she would take it back if it wasn't it anyway. So, I got it home and had it replaced in about 15 minutes, and it only cost me $34. And it runs great!
Now if I can just get someone to sponsor me to fix the rest of the truck...
For those of you that were keeping track of my progress with my '85 F150, I got it running right! I cleaned out the upper intake and made a block plate for the EGR valve so it wouldn't put any more carbon buildup back into my intake. I also removed the smog pump and blocked off all the vacuum lines that were associated with it. You wouldn't beleive how much the smog pump had the engine bogged down! Anyway, that didn't do much for the original problem.
I had finally ran out of cheap-n-easy options so I went to my local Autozone [where they know me by name] and got a TPS. The lady told me that she would take it back if it wasn't it anyway. So, I got it home and had it replaced in about 15 minutes, and it only cost me $34. And it runs great!
Now if I can just get someone to sponsor me to fix the rest of the truck...
Last edited by lugnut1009; Sep 29, 2005 at 09:18 AM.
