85 f150 problems
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85 f150 problems
hello everyone! I have a 1985 f150 5.0 that has been giving me some issues. This truck had sat for 7 years and the gas was garbage. I have replaced the tank, the fuel pump( in tank and under the driver door), the filter. Tested all the sensors they are all within the normal operating range. But for some reason the truck labors a lot with the air charge temp sensor plugged in? If I unplug it the truck runs great. There is the occasional "miss" or stutter. But other than that it sounds and runs great with it unplugged. I have also replaced the spark plugs. If you guys have any input I would be grateful!
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Joined: Jul 2010
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From: Northeast, OK
Welcome to FTE! Where are you located?
I don't know much about that system, but assume it is EFI. The schematics and some minor info is shown here: Electronic Engine Control - ???Gary's Garagemahal. But if you go to the stickies at the top of the main page you can find the instructions on how to pull codes as well as what the codes mean. That's where I'd start.
I don't know much about that system, but assume it is EFI. The schematics and some minor info is shown here: Electronic Engine Control - ???Gary's Garagemahal. But if you go to the stickies at the top of the main page you can find the instructions on how to pull codes as well as what the codes mean. That's where I'd start.
FTE Legend
Joined: Jul 2010
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From: Northeast, OK
AFR is air/fuel ratio. You may very well have a timing issue. As said, usually the computer locks the timing at 10 degrees is there is the slightest problem. And by "bypassing the small system", whatever that entails, you have given it plenty of provocation. So I would put a timing light on it and see if the timing advances when you rev the engine. I'll bet it doesn't.
At that point you have a choice to make. You can either live with it the way it is, put it all back stock, or pull the entire EFI system off and put something else on - like a carb or an aftermarket EFI. I say that because there is no half-way with the computerized systems. You either have none or everythin
At that point you have a choice to make. You can either live with it the way it is, put it all back stock, or pull the entire EFI system off and put something else on - like a carb or an aftermarket EFI. I say that because there is no half-way with the computerized systems. You either have none or everythin
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Well by by pass I mean the belt for the air pump is removed and the egr valves vacuum line is removed which should keep the egr closed. I'm not doubting you but I have seen this truck run 7 years ago with the same setup and it ran perfect the only thing that has changed was the knock sensor has been broken and the gas was bad.
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FTE Legend
Joined: Jul 2010
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From: Northeast, OK
I'm not a guru, so may be wrong. But the proof will be in the timing. If it changes with RPM you may be ok. However, some of the systems had feedback on the EGR, and on those the computer knows when the EGR valve isn't working. So, ....
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Yes you are right wished this had a carb but it's a project. So you think the timing doesn't advance when I increase the Rpms just to be sure what I'm looking for. Would it not do good acceleration though?
Posting Guru
Joined: Apr 2011
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From: Orlando area
What about the injectors? Did you do anything to test/clean them?
There are professional injector cleaning kits available (but probably not worth the cost to buy one for a one-time cleaning, but you can take truck to a shop for this). If also seen some "one-use" kits available for the DIYer but not sure how well those work (probably pretty good).
The cleaners you add to the fuel tank do nothing to clean injectors. The cleaner is just not strong enough when diluted with a tank of gas.
On a fuel injected truck you would plug the fuel lines to/from the tank (pull the fuel pump relay so the pump doesn't run) and connect the pressurized cleaning canister to the fuel rail pressure test port. Then you run the engine only on the cleaner (and change spark plugs afterwards).
There are professional injector cleaning kits available (but probably not worth the cost to buy one for a one-time cleaning, but you can take truck to a shop for this). If also seen some "one-use" kits available for the DIYer but not sure how well those work (probably pretty good).
The cleaners you add to the fuel tank do nothing to clean injectors. The cleaner is just not strong enough when diluted with a tank of gas.
On a fuel injected truck you would plug the fuel lines to/from the tank (pull the fuel pump relay so the pump doesn't run) and connect the pressurized cleaning canister to the fuel rail pressure test port. Then you run the engine only on the cleaner (and change spark plugs afterwards).
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Thank you all for the replies! I'm getting a timing light at the moment to try that. I like the idea of the injector cleaning your referred too I will also see if I can find one of those kits. And yes that's what my warmup is like it's within the range you just mentioned and the act has high resistance when cold and then low when warm. Can't remember the exact number. The plug on it has 4.8 volts