I finally got my idle air bypass from Ford for my '89 F150 5.0. It keeps it from dieing but this thing still runs like total crap. I used to think it was simply a EFI problem but I am starting to think that this rebuilt 5.0 with 30K on it is junk. It really really runs rough and I keep having a problem where you touch the gas and it hesitates so bad that it dies. If it does that you have to wait about 20 minutes until it will start again. Even if you use starter spray on it, it still will not start. Because it runs so rich I am assuming that it is flooding.
I have a 302 of unknown origin and condition that is suppose to a fresh rebuild from Shucks or something. I’m starting to think about maybe swapping EFI parts on to it and put it in this truck just so I can sell it and get it out of my hair!

I think that this truck has burned me so bad that I will never buy another late 80's-early 90's 5.0 again!

 

Running too rich could be quite a few things. I didn't see any other posts from you regarding problems with this truck, so lets start at pulling codes and checking your fuel pressure.
You know we'll all be glad to help ya diagnose and turn this around for ya!
Popa Tim

 

Overall, Ford trucks are fairly reliable. However, if you didn't buy the vehicle know or know its maintanence history, there might have been some misinformation (or fibbing) from the seller. It's one of those "who knows" things.

And EFI problems aren't that difficult to troubleshoot, you just have to kick the computer into test mode and get the codes out of the truck.

Turn the truck off, jump these wires that are under the hood on the driverside fender near the hood hinge...


Turn the key to "on" but not "start", then count the check engine light blinks, keeping track of blinks and spaces between blinks... then look up the codes here:

11 - System pass
12 - RPM unable to reach upper test limit
13 - RPM unable to reach lower test limit
14 - Pip circuit failure
15 - PCM read only memory test failed
15 - PCM keep alive memory test failed
16 - IDM signal not received
18 - SPOUT circuit open or spark angle word failure
18 - IDM circuit failure or SPOUT circuit grounded
21 - ECT out of self-test range
22 - BP sensor out of self-test range
22 - BP sensor or MAP out of range
23 - TP sensor out of self-test range
24 - ACT sensor out of self-test range
25 - Knock not sensed during dynamic test
26 - VAF/MAF out of self-test range
26 - TOT out of self-test range
26 - TOT sensor out of self-test range (E4OD)
28 - Loss of IDM, right side
29 - Insufficient input from vehicle speed sensor
31 - PFE, EVP or EVR circuit below minimum voltage
32 - EVP voltage below closed limit
33 - EGR valve opening not detected
34 - EVP voltage above closed limit
35 - PFE or EVP circuit above closed limit
41 - HEGO sensor circuit indicates system lean
41 - No HEGO switching detected
42 - HEGO sensor circuit indicates system rich
44 - Thermactor air system inoperative-right side
45 - Thermactor air upstream during self-test
45 - Coil 1, 2 or 3 failure
46 - Thermactor air not bypassed during self-test
47 - 4WD switch closed (E4OD)
48 - Loss of IDM, left side
49 - 1-2 shift error (E4OD)
51 - ECT/ACT reads -40°F or circuit open
52 - Power steering pressure switch circuit open
52 - Power steering pressure switch always open or closed
53 - TP circuit above maximum voltage
54 - ACT sensor circuit open
56 - VAF or MAF circuit above maximum voltage
56 - TOT reads -40°F or circuit open (E4OD)
59 - 2-3 shift error (E4OD)
61 - ECT reads 254°F or circuit grounded
63 - TP circuit below minimum voltage
64 - ACT sensor grounded or input reads 254°F
65 - Overdrive cancel switch open, no change seen (E4OD)
66 - MAF sensor input below minimum voltage
66 - TOT grounded or reads 290°F (E4OD)
67 - Neutral/drive switch open or A/C on
67 - Clutch switch circuit failure
67 - MLP sensor out of range or A/C on (E4OD)
69 - 3-4 shift error
72 - Insufficient MAF/MAP change during dynamic test
73 - Insufficient TP change during dynamic test
74 - Brake on/off switch failure or not actuated
77 - Operator error
79 - A/C on during self-test
79 - A/C or defrost on during self-test
81 - Air management 2 circuit failure
82 - Air management 1 circuit failure
84 - EGR vacuum solenoid circuit failure
85 - Canister purge solenoid circuit failure
86 - Shift solenoid circuit failure
87 - Fuel pump primary circuit failure
88 - Loss of dual plug input control
89 - Converter clutch solenoid circuit failure
91 - Shift solenoid 1 circuit failure (E4OD)
92 - Shift solenoid 2 circuit failure (E4OD)
93 - Coast clutch solenoid circuit failure (E4OD)
94 - Converter clutch solenoid circuit failure (E4OD)
95 - Fuel pump secondary circuit failure - PCM to ground
96 - Fuel pump secondary circuit failure - battery to PCM
97 - Overdrive cancel indicator light - circuit failure (E4OD)
98 - Electronic pressure control driver open in PCM (E4OD)
98 - Hard fault present
99 - Electronic pressure control circuit failure (E4OD)
111 - System pass
112 - ACT sensor circuit grounded or reads 254°F
113 - ACT sensor circuit open or reads -40°F
114 - ACT outside test limits during KOEO or KOER tests
116 - ECT outside test limits during KOEO or KOER tests
117 - ECT sensor circuit grounded
117 - ECT sensor circuit below minimum voltage or reads 254°F
118 - ECT sensor circuit open
118 - ECT sensor circuit below maximum voltage or reads -40°F
121 - Closed throttle voltage higher or tower than expected
122 - TP sensor circuit below minimum voltage
123 - TP sensor circuit below maximum voltage
126 - BP or MAP sensor higher or lower than expected
128 - MAP vacuum circuit failure
129 - Insufficient MAF or MAP change during dynamic responded test
144 - No HEGO switching detected
167 - Insufficient TP change during dynamic response test
171 - Fuel system at adaptive limit, HEGO unable to switch
172 - HEGO shows system always lean
173 - HEGO shows system always rich
174 - HEGO switching time is slow
179 - Fuel at lean adaptive limit at part throttle; system rich
181 - Fuel at rich adaptive limit at part throttle; system lean
182 - Fuel at lean adaptive limit at idle; system rich
183 - Fuel at rich adaptive limit at idle; system lean
211 - PIP circuit fault
212 - Loss of IDM input to PCM or SPOUT circuit grounded
213 - Spout circuit open
224 - Erratic IDM input to processor
225 - Knocked not sensed during dynamic response test
311 - Thermactor air system inoperative
312 - Thermactor air upstream during self-test
313 - Thermactor air not bypassed during self-test
327 - EVP or DPFE circuit below minimum voltage
328 - EGR closed voltage higher than expected
332 - Insufficient EGR flow detected
334 - EGR closed voltage higher than expected
337 - EVP or DPFE circuit above maximum voltage
411 - Cannot control rpm during KOER low rpm check
412 - Cannot control rpm during KOER high rpm check
452 - Insufficient input from vehicle speed sensor
511 - EEC processor ROM test failed
512 - EEC processor Keep Alive Memory test failed
513 - Failure in EEC processor internal voltage
519 - Power steering pressure switch circuit open
521 - Power steering pressure switch did not change state
525 - Vehicle in gear or A/C on during self-test
536 - Brake on/off circuit failure, switch not actuated during KOER test
538 - Insufficient RPM change during KOER dynamic response test
538 - Operator error
542 - Fuel pump secondary circuit failure: PCM to ground
543 - Fuel pump secondary circuit failure: Battery to PCM
552 - Air management 1 circuit failure
553 - Air management 2 circuit failure
556 - Fuel pump primary circuit failure
558 - EGR vacuum regulator circuit failure
565 - Canister purge circuit failure
569 - Canister purge 2 circuit failure
617 - 1-2 shift error (E4OD)
618 - 2-3 shift error (E4OD)
619 - 3-4 shift error (E4OD)
621 - Shift solenoid 1 circuit failure
622 - Shift solenoid 2 circuit failure
624 - EPC solenoid or driver circuit failure
625 - EPC driver open in PCM
626 - Coast clutch solenoid circuit failure (E4OD)
627 - Converter clutch solenoid circuit failure (E4OD)
628 - Converter clutch error (E4OD)
629 - Converter clutch control circuit failure
631 - Overdrive cancel indicator light circuit failure
632 - Overdrive cancel switch not changing states (E4OD)
633 - 4WD switch is closed
634 - MLP sensor voltage out of self-test range, A/C on
636 - TOT sensor voltage out of self-test range
637 - TOT sensor circuit above maximum voltage
638 - TOT sensor circuit below minimum voltage
654 - MLP sensor not in park position
998 - Hard fault present

If you get codes about the 4wd system or the neutral switch, that won't effect drivability to the degree that you are experiencing, but things like the map sensor, o2 sensor, water temp sensor etc etc etc will seriously impair operation and reliability.

Since you've expressed concerns about the "rebuilt" engine, I'd yank the plugs out one at a time, and do a dry/wet compression test in each cylinder, then depending on the results of that I'd do a vacuum test. That alone would give you at least a decent clue about the health of the engine.

 

See if you can read any numbers off the fuel injectors. Post em here and hopefully someone can confirm the injectors are correct. I have noticed a few people in the F150 community toying with different injectors in the hope of improving performance. BTW, there is nothing wrong with late 80's/early 90's 5.0's as delivered by Ford, the 87 5.0 I bought brand new was the last thing still working when it was traded in. You may have some serious problems, but if you can post detailed observations, and try some basic troubleshooting, I'm sure the people in here can help you fix her. Also, if you think the engine and its performance is your main problem, you should consider posting in the 5.0 forum. How are you doing for tools? Vacuum Gauge, timing light, multimeter, fuel pressure gauge, compression gauge, and a Haynes/Chilton manual are very nice to own.

 

Very nice job Frederic! That makes it a lot easier.

 

It sounds like you're fuel pressure regulator has failed. Take the vacuum line off and see if you detect any gas in the tube. Go to a parts store and rent/borrow a gauge and check the pressure at the fuel rail schraeder valve, 35-45 psig is the range you're looking for.

And Fredrick, Da_n, Man, you are a veritible font of knowledge!

 

The only thing I havn't tried is the fuel pressure thing. I have tried everything else. Replaced lots of sensors and still getting no codes.

 

I'll bet money here that its your FPR. Seems to be a common problem. It's dead easy to fix and not too expensive either.

 

I was gona check it today but with the daylight savings thing I got screwed up and all the shops seem to be closed an hour early! LOL

I am gona check that next! I would be supprised that it would make the truck run rich though.

 

When it went in my F250 it ran the fuel pressure to 80 psig + and idled cobby, blew black smoke, and overwhelmed my O2 sensor. The only surprise was that raw gas was not coming out the duals.

 

My regulator was stuck closed at 65PSI. Horrible mileage. Went from 6-8MPG to 12MPG(which is still horrible ).

 

frederic, can I follow that diagram for my 92 F150 302?

 

Yes you can - it works for any OBD-I truck.

 

Great, Thanks andym!!!

 

Absolutely. Works with any Ford vehicle with that connector.