I have a 1991 Ford F150 4.9 300 I6. It idles fine but when I try to accelerate it has serious hesitation. It also bucks and surges. It seems worse after I have driven it awhile. I have replaced MAP sensor, TPS, air filter. It has newer (2017) plugs, wires and EGR (2018) and has had less than 20k since these parts replaced. I can't decide if its a fuel filter, issue or maybe catalytic convertor. Do you have any suggestions?
The problem is so old OBD2 scanner doesn't work on them and you'll get very little information. So you got in two things like pressure test the fuel pump see if that's weak do a compression testing of the engine see if the catalytic converter is clogged up that can be tested with a pressure gauge. Often it is a fuel pump or clogged fuel filter though
I had a 90 f150 that had the same problems but for me it was needing the fuel filter replaced then the injectors to be cleaned and a new fuel pump. I recommend starting with a fuel filter change and see if that might help. Its good to start cheap and work your way up.
I will try that!
Have you checked for OBD1 codes?
@chucktobias I finally got codes! it was 327 and 552 code.
Code definitions are in the link below:
https://www.troublecodes.net/Ford/
327 - EGR feedback signal is/was low – EVR or PFE
552 - AIRB solenoid/circuit failure – Solenoids
I looked everywhere for the obd1 port and I couldn't find it. I searched online for the location but it wasn't in any of the locations they said it should be.
If it's not in one of the locations shown in these videos I don't know what to tell you. You'd probably need a mechanic who has worked on F-150s of that vintage to locate it.
https://www.youtube.com/watch?v=cVFpQkl0mnY&t=107s
https://www.youtube.com/watch?v=CnQw6xMAYlE&t=15s
I was able to get 2 codes. 327 and 552.
code descriptions:
pinpoint test charts:
pinpoint tests:
Well find a mechanic like myself to test rather than gas. A catalytic converter can be pressure tested to see if it's bad. The fuel injection system can be pressure tested to see if that's bad start there
Scotty,
I have a 1991 Ford F150 4.9l I6 300 engine with 73,000 miles. It is running poorly and getting poor gas mileage. I have done the following things.
- 4 Years ago (but only 20k miles) new pcm, new spark plugs, cleaned fuel injectors, new EGR
- Last 3 months, new air filter, TPS, MAP sensor, O2 sensor.
- Backpressure check on catalytic convertor says its ok.
When I put in new O2 sensor it started running better and doesn't die as much. It seems to idle fine but when I press gas pedal it hesitates and does not accelerate properly. I can't figure out what is wrong! What do you think?
Backpressure check says catalytic convertor is fine. I will check fuel filter and fuel pressure next. Could a vaccum leak cause a problem?
I ended up changing the fuel filter, and it ran a little better but was still giving me issues. Turns out it was the EGR solenoid. Someone told me to take off the egr vacuum hose and see if it improved. I did and it ran better. He told me that means it was the solenoid. It was a cheap and easy fix. I replaced it and it runs much better.
I did back pressure test the catalytic convertor and it was fine.
1991 Ford F150 300 4.9 with automatic transmission. No OBD-2 port
I have done all the items below and it still runs rough. It seems taking the vacuum off of the egr will help sometimes.
|
8.3.17 |
58266 |
Mechanic Replaced o2 sensor; cleaned fuel injectors, replaced spark plug, replaced pcm, fuel additive. |
525 |
|
12.20.18 |
64789 |
Mechanic put on New EGR and exhaust leak repair |
290 |
|
7.29.2019 |
66431 |
Mechanic put Upper and lower ball joint. Oil change, New brake master cylinder. New Camber/Caster busing front suspension. Alignment. |
837 |
Purchased 73,378
|
Date |
Mileage |
Work |
Price |
|
8.30.21 |
73,378 |
I Purchased Truck |
|
|
9.11.21 |
73,529 |
New MAP Sensor and New Throttle position sensor (TPS) |
$55 |
|
9.13.21 |
73,601 |
New Air Filter |
|
|
9.17.21 |
74,008 |
New O2 sensor. |
$40 |
|
9.22.21 |
74,217 |
Mechanic backpressure test and Catalytic convertor is good |
$41 |
|
10.24.21 |
74,680 |
New air intake sensor, new coolant sensor, new fuel filter |
$51.42 |
|
3.6.22 |
75232 |
New EGR solenoid |
$40 |
|
4.16.22 |
75,616 |
New Battery from O'Reilly's |
$185 |
|
6.2.22 |
76651 |
Mechanic Recharged A/C Tested including recover/evacuate/recharge, tested fuel pressure, tested vacuum, replaced TPS, check timing, |
$736 |
|
6.7.22 |
76672 |
Mechanic set timing to 10degrees (it was 33) |
|
If you could help me figure out what is going wrong I would appreciate it. I like the truck but my wife wont drive because it idles rough and dies sometimes.
Jeremy
@kerux12345 I have merged your question with your other two posts on the same topic. Please read our forum rules about duplicate posting.
I haven't. The check engine light goes off and on at different times.
I looked everywhere for the obd1 port and I couldn't find it. I searched online for the location but it wasn't in any of the locations they said it should be.
Ok I found it, no codes flashed.
I was able to get 2 codes. 327 and 552.