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Hard starting, idles good, poor acceleration

Tiny
GWVANALLEN
  • MEMBER
  • 2003 FORD F-150
  • 4.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 121,000 MILES
I'm not original owner, bought about 2 months ago. Service engine soon light is on. Replaced all 4 catalytic converters. Sprayed can of seafoam through throttle body, and can of seafoam through gas tank, 1 bottle of fuel injector cleaner through gas tank.(Was told truck sat for awhile when I bought it.) AutoZone scan tool reports (sometimes it just says read error) but when it did read it, I got 2 codes saying running lean in banks 1 and 2. Before changed catalytic converters I got a temperature of 500 on front driver side catalytic converter. I changed all 4 and absolutely no change in the performance. Still hard to start, idles fine, drives okay but no power to accelerate. Now I'm tight on money after spending $1,000.00 on catalytic converters, $400.00 on brakes, $500.00 on wheels. Therefore my trouble shooting ability has been financially hampered. Any help with this would be awesome. I have used this site before and it's simply amazing. P.S. I'm not a mechanic, I have some experience however I do have access to a mechanic who lives here on the property (when ever they aren't busy) 1 to 2 hours a day.
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Tuesday, June 30th, 2020 AT 10:54 AM

23 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Hi,

The lean mixture can be caused by a couple things and can cause a hard start and lack of power.

Often times, a lean mixture is caused by engine vacuum leaks. Basically, the engine receives unmetered air into the combustion chamber causing it. Start by checking for leaks. Here is a link to help:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Next is fuel pressure. can be a concern. Low fuel pressure resulting from a weak pump or partially plugged fuel filter can cause these same issues. Have you checked fuel pressure to make sure it is within the manufacturer's specs?

Here is a link that explains in general how it's done. You will need a fuel pressure gauge, but most parts stores will lend one to you.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Here are the manufacturer's pressure specs:

Fuel Pressure
Engine Running .................... 193-310 kPa (28-50 psi)
Key On Engine Off .................... 240-310 kPa (35-45 psi)

Check these things and let me know what you find. Also, if you could find out what the codes actually were, it may be helpful.

Take care,
Joe
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Tuesday, June 30th, 2020 AT 10:42 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Thanks Joe for the information. Looking for vacuum leaks I replace three questionable hoses, however that did not change the performance at all. Did the fuel system pressure test and here's what I got: Turning the key to the on position does nothing the gauge stays at 0 tried it half a dozen times. After cranking three times to get it started as usual it went up to 28 PSI. And it took about 15 to 20 seconds to get from 0 to 28. When I rev the engine a little the gauge might have moved 1 lb. When I did the load test by putting in reverse and revving up to 1,500 RPM's the gauge meter moved another pound or two. It never went hire than 30 PSI on the gauge. Well I finally feel like I made some progress in this endeavor. Thanks for the tip. If you could guide me into what I need to do from here be much appreciated.
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Wednesday, July 1st, 2020 AT 1:48 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
It sounds like you either have a plugged fuel filter or the pump is weak. When you first turn the key on, do you hear the pump engage for a second or two before turning the key to start?

Let me know. Based on what you described, I suspect the pump is bad, but I just want to confirm.
Joe
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Wednesday, July 1st, 2020 AT 9:48 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Thanks Joe, okay when I listened from the fuel cap it sound like it came on for about one second and was sucking air and I only had one pound on the pressure gauge.
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Wednesday, July 1st, 2020 AT 9:52 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Is the fuel level low? I wonder if something has come apart in the tank. The idea that is sounded like it was sucking air could be the entire issue. At the bottom of the pump module assembly is the pick up sock. This functions as a filter to help keep dirt from the tank from entering the system. Take a look at the attached pic.

I have to be honest, I feel the tank needs removed and the pump at a minimum needs inspected. Is that something you are comfortable doing? Take a look through this link and let me know. I have specific directions if needed.

____________________________________

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

Let me know.

Joe
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Wednesday, July 1st, 2020 AT 10:10 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Thank you so much for your time and I think we're on the same page with the solution. Thank you. I'll get back to you and let you know if that works.
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Wednesday, July 1st, 2020 AT 10:18 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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You are very welcome. Here are the directions specific for removal of the tank on your truck. I don't know if you need them, but I thought I would add them in case.

______________________________________

2003 Ford Truck F 150 2WD Pickup V8-4.6L SOHC VIN 6
Fuel Tank
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Tank Service and Repair Procedures Fuel Tank Removal and Installation Standard Models (Non Bi-Fuel) Fuel Tank
FUEL TANK
High Lift Jack

Pic 1

SPECIAL TOOL(S)

REMOVAL

WARNING:
DO NOT SMOKE OR CARRY LIGHTED TOBACCO OR OPEN FLAME OF ANY TYPE WHEN WORKING ON OR NEAR ANY FUEL RELATED COMPONENT HIGHLY FLAMMABLE MIXTURES ARE ALWAYS PRESENT AND MAY BE IGNITED, RESULTING IN POSSIBLE INJURY.
FUEL IN THE FUEL SYSTEM REMAINS UNDER HIGH PRESSURE EVEN WHEN THE ENGINE IS NOT RUNNING.

1. Relieve the fuel pressure.
2. Disconnect the battery ground cable.
3. Raise and support the vehicle; refer to Maintenance/Service and Repair.

Pic 2

4. If equipped, remove the fuel tank skid plate.
5. Drain the fuel from the fuel tank.

Pic 3

6. Remove one hose clamp on the fuel tank filler pipe support.

Pic 4

7. Disconnect the fuel tank-to-filler pipe hose from the fuel tank.

Pic 5

8. Disconnect the fuel tank filler pipe vent hose from the fuel tank.

Pic 6

9. Position special tool under the fuel tank.

Pic 7

10. Remove the fuel tank support straps and partially lower the fuel tank.

Pic 8

11. Disconnect the fuel tubes from the fuel pump.

Pic 9

12. Disconnect the fuel tank front connections.
Disconnect the Evaporative Emission (EVAP) hose.
Disconnect the fuel tank pressure transducer electrical connector.

Pic 10

13. Release the rear EVAP hose clamp and disconnect the hose.

Pic 11

14. Disconnect the fuel pump electrical connector.

Pic 12

15. Lower and remove the fuel tank.

INSTALLATION
1. To install, reverse the removal procedure.

__________________________________

I hope this helps. Let me know if you need anything.

Take care,
Joe
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Wednesday, July 1st, 2020 AT 10:26 PM
Tiny
GWVANALLEN
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  • 32 POSTS
You guys on this site are amazing. I'm just amazed and for free. Thanks a million.
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Wednesday, July 1st, 2020 AT 10:34 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Not a problem. Let me know if I can help.

Take care,
Joe
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Wednesday, July 1st, 2020 AT 10:39 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Hi Joe. Happy Fourth of July. Well, it turns out that the fuel pump do you have a crack its hose. So I replaced the fuel pump and now it starts right up. But it still doesn't have much power. I'm getting codes p1131 and P0174. Would you be able to give me a order of attack for this? I've already changed the fuel and air filters, PVC valve, and fuel pump.
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Saturday, July 4th, 2020 AT 6:41 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Hi,

Both of the codes together indicate a lean fuel mixture. Were these present prior to replacing the pump? If they are new, I need you to check for engine vacuum leaks. Here is a link that explains how to do it:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, by any chance is there an exhaust leak where the exhaust manifold attached to the engine? Often times it will sound like a ticking rather than an actual leak.

By the way, do you have access to a live data scan tool? If you do, could you let me know what the short term fuel trims are?

Let me know.

Joe
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Saturday, July 4th, 2020 AT 10:15 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Hi.

No the codes aren't new. I previously had (not sure of the actual code numbers) been running lean on banks 1 and 2 according to AutoZone scan tool, and the recommendation was to replace the PVC valve. Not sure about exhaust leak at manifold and my mechanic friend who has been helping me hasn't mentioned anything about that. I will go and purchase the appropriate scan tool today. I hear what sounds like sucking air coming from engine compartment, but 2 cans of brake cleaner later and can't locate it. Also, the exhaust pipe is cut right before the muffler but after the catalytic converters.
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Sunday, July 5th, 2020 AT 10:07 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
If you hear it, something is leaking. Let me know what codes you find. Also, be really careful with brake clean if that is what you are using. If it hits something hot enough, it can catch fire.

As far as the exhaust manifold, if the system has no muffler, then it's going to be hard to hear. Ford has had issues with exhaust manifold leaks. As a result, air enters at the leak and sets a lean code.

Let me know.

Take care,
Joe
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Sunday, July 5th, 2020 AT 8:38 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Thanks again Joe. I wasn't able to get the right scanner today.I will have to try again tomorrow.
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Sunday, July 5th, 2020 AT 10:44 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Hi. I'm getting codes P071 and P1000.
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Sunday, July 5th, 2020 AT 11:10 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Hi Joe, I got the scanner in inNova 5210. It is giving me the code p0171. In these readings with the engine at idle-engine temperature 144 it didn't get any warmer:
Ltftb1-25%
Ltftb2-25%
Maf-.73
Tips-19.2

Engine rev to 2500
Ltftb1-28%
Ltftb2-28%
Also the scanner is reporting that the cat and the Eva monitors have not finished their testing, they're flashing red. I have had the battery disconnected recently.
The message prior to this point was done about one to two hours earlier. Now I'm back out here trying again and the readings are different as follows
Ect150 degrees f
At idle
Ltftb1-29.7%
Ltftb2- (-15.6%)
At 2500rpms
Ltftb1 29.7%
Ltftb2- (-6%)
++++ Note all above measurements are positive except the 2 in parentheses.
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Monday, July 6th, 2020 AT 2:25 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Hi.I just re-read one of your answers to my questions and I gave you the long-term fuel trim. So I will get you the short-term fuel trims here in a minute.
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Monday, July 6th, 2020 AT 5:53 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,709 POSTS
Hi,

Let me know what they are. The LTFT are indicating a rich fuel mixture. Let me know.

Joe
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Monday, July 6th, 2020 AT 9:59 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Hi Joe, thanks again for your help.
Here are the numbers:

Engine at idle
Stftb 1*27.3
Ltftb 1*24.7
Stftb 2* -.8
Ltftb 2* -12.5
Maf *.85
Tps * 19.2%
O2sb1s1 *.35-.8v
Stftb1s1 * 15-35%
O2sb1s2 *.02v
Stftb1s2 * 99.2%
O2sb2s1 *.1-.7v
Stftb2s1 * (-1.6)-.8%
O2sb2s2 *.3-.5v
Stftb2s2 * 99.2%
Engine at 2500 rpm
Stftb1s1 * 28-38%
Ltft * 24%
Stftb2 * (-14.1)%
Ltftb2 * (-9.4)
Maf * 2.14
Tps * 22%
O2SB1S1 *.2-.7
Stftb1s1 * (-3.1)-8
O2sb1s2 *.75v
Stftb1s2 * 99.2%
O2sb2s1 *.8v
Stftb2s1 *(-2)-2%
O2sb2s2 *.4v
Stftb2s2 * 99.2

Any negative value is surrounded with. ( )
For example stftb2s1*(-2)-2%is read as negative 2 through 2%.
No disrespect and not trying to insult your intelligence sir. Just letting you you know what I'm meaning, as these can get confusing. Also I'm in the progress of making a smoke machine to check for vacuum leaks.
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Tuesday, July 7th, 2020 AT 2:56 PM
Tiny
GWVANALLEN
  • MEMBER
  • 32 POSTS
Hi.I made a mistake in the above figures. Third and fourth line down should have been;
Stftb2 * (-.8)
Ltftb2 * (-12.5)
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Tuesday, July 7th, 2020 AT 7:04 PM

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