I pulled codes on my 1987 F-150 302 today, here's what I got:

KOEO: 3 Tests
-11: System Pass
-10: Seperator Code
-87: Primary Fuel Pump Circuit Failure

KOER: 4 Tests
-12: RPM Not Within Self Test Upper Limit
-25: Knock Not Sensed During Dynamic Response Test
-42: System Rich
-44: Thermactor Air System Inoperative
-52: Power Steering Pressure Switch Open Circuit
-73: Insufficient Throttle Position Output During Dynamic Response Test

If anybody could share some insight on where I should start, I would really appreciate it. If you need any further details about my truck and what it does while running, please feel free to ask.

 

I'm guessing you didn't perform your part of the KOER tests - goose the throttle, then push the brake pedal down while turning the wheel half a turn. There's an explicit time in that test when you're supposed to do those actions, it will be after the computer raises & lowers the engine speed but before it spits out codes.

If you didn't do those things, ignore:

-25
-52
-73

of the KOER tests.


The 87 will be coming from the CM codes - something the computer encountered in the recent past while driving.

 

Thank you for the response. That's good to hear, I've never heard about pushing the brake pedal while turning the wheel before, I will definitely remember that step of the testing. I only got the code 73 on one of my 4 tests, so I guess I must not have hit the throttle hard enough that time.


The code 87 is one I really don't know what to think of. The pickup has good fuel pressure and the pumps turn on and then off like they should with the key at the "on" position. This truck's biggest problems are being very hard to start (hot and cold), hard to keep idling until it gets somewhat warmed up, starts misfiring and cutting out when given throttle (normally in gear, very rarely in park or neutral), refuses to go over 40 mph, and is very hard to get up to that speed. The transmission feels fine; especially since I changed the fluid and filter in the pan and replaced the bad vacuum modulator, sadly I did not have the time to drain the torque converter today. It runs great other than those problems. I have gave the truck a full tune-up, new fuel filter, air and crankcase breather filters, cleaned the IAC valve, replaced faulty wiring, new starter, new oxygen sensor, and started repairing vacuum lines. I really like this pickup and badly want to get it on the road, but I'm stuck and not really sure where to look next.

 

If you're handy with a multimeter pull your fuel pump relay out and check what kind of voltage you have at the different pins, you should have two pins that are both near battery voltage, if not you have a wiring issue. If you have good power try trading the relay for another one nearby and see if your problem gets any better.

Code 87 is for the primary circuit used to control the fuel pump relay by using grounds controlled by the engine computer, the tests above are very basic ways to troubleshoot common issues with that wiring.

 

Thanks for the reply, I will give that a shot next time I get to work on the pickup. The pickup had been parked for 2 or 3 years by the previous owner and got some mice under the hood, so faulty wiring is very possible. I got the pickup running and driving finally, but it has the exact same problems as it always had for the previous owner and more than likely the original owner (only 2 owners previous to me). Whoever had been working on it obviously wasn't the most competent mechanic so these problems have more than likely been with the pickup for 10-15+ years. The pickup doesn't show it thanks to old man dents, sun beat paint in places, and the under hood dust from spending most of its life on gravel roads; but judging by pedal pad wear, interior wear, and mechanical condition; the truck appears to have just under 54,000 original miles. I hate to see how abused it was, but I'm trying to bring her back 100%.

 

The book says to fix the KOER and KOEO problems before going after the CM codes.

Code 12 for the 5.0L engine is the Idle Speed Control... first diagnostic step is to connect a tachometer and start the engine, then disconnect the ISC (aka IAC) harness... does the RPM drop, or the engine stall? If yes, first investigate EGR... you're not listing those codes, so, onward....

It then has you checking the wiring from the ISC motor to the computer and doing some diagnostic work to determine of the ISC motor has failed or not.



Code 42 has you checking the oxygen sensor and its wiring.

Code 44 has you checking the vacuum system to the TAB, TAD & Thermactor system.

FWIW,, for Code 87, it has you checking power to the fuel pump - relays, grounds, etc. but only after first correcting the other problems (the cavities).

This would be invaluable to you:


http://www.ebay.com/itm/1987-Ford-Engine-Emissions-Diagnosis-Service-Manual-Cars-Trucks-/110886107109?pt=Motors_Manuals_Literature&vxp=mtr&hash=item19d153b7e5

 

Thanks for the info, I will be using it next weekend.



I just put a new Standard Motor Products oxygen sensor in today, but I will check the wiring.

I know for sure that there are more vacuum lines to fix and some looking to be missing, so this is more than likely a huge part of my problems.

I highly agree with you here. I have a goal to get every factory service manual for this pickup eventually, but it's not quite fitting my budget right now; so I'm stuck with my Chilton and blue cover Haynes.