Will not stay running?

Tiny
CHASE1041
  • MEMBER
  • 1998 MAZDA B4000
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 220,000 MILES
Okay, I replaced my fuel pump, fuel filter, and all the EGR components. My truck cranks up but stalls out either by itself or when I give it gas. I’m wondering if I should look at the fuel injectors now. Keep in mind I’m doing all this myself. Any idea what may be going on?
Monday, September 6th, 2021 AT 8:33 AM

44 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,640 POSTS
Hi,

The first thing I would check for is an engine vacuum leak. Also, make sure there are no restrictions in the catalytic converter.

Here is a link the explains how to locate vacuum leaks:

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

Also, if you remove the upstream oxygen sensor, that will allow an extra location for the exhaust to exit. If the converter is plugged, this should be enough to make a difference.

Take a look through this link and let me know if anything mirrors what you experience:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

One last thought. If possible, record what it is doing and upload it for me to hear. Hopefully, that will helps. And if you haven't checked for diagnostic trouble codes, do that as well.

Take care and let me know what you find.

Joe
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Monday, September 6th, 2021 AT 7:30 PM
Tiny
CHASE1041
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I am getting this code but I have replaced all my EGR sensors, so I guess now I need to replace the wiring. I’m going to look at the vacuum leak portion first.
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Monday, September 6th, 2021 AT 10:52 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I'm Danny.

Here is the information relating to your code P0453 Fuel Tank Pressure Sensor Malfunction. Here is a tutorial on how to test electrical wiring:

https://www.2carpros.com/articles/how-to-check-wiring

I've attached a picture step diagnostic flow chart below for your Mazda truck. Let us know what you find and we'll go from there. Hope this helps and thanks for using 2CarPros.
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Tuesday, September 7th, 2021 AT 5:39 AM
Tiny
CHASE1041
  • MEMBER
  • 35 POSTS
Here are some videos:
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Tuesday, September 7th, 2021 AT 6:45 AM
Tiny
CHASE1041
  • MEMBER
  • 35 POSTS
Another does the B4000 have a fuel regulator or does it have a Fuel Tank Pressure Sensor? I get mixed answers when trying to shop this part.
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Tuesday, September 7th, 2021 AT 7:41 AM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello again.

Yes, your truck has both a fuel pressure regulator and fuel tank pressure sensor. The fuel pressure regulator is incorporated into the in-tank fuel pump assembly. The fuel tank pressure sensor is mounted in the top of the fuel tank. I've attached pictures below on the location of the fuel pressure regulator circled in red and steps on how to replace the fuel tank pressure sensor. You will have to remove the fuel tank to gain access. If you like I can attach instructions on how to remove and replace the fuel tank. Hope this helps and thanks again for using 2CarPros.

Danny-
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Tuesday, September 7th, 2021 AT 8:22 PM
Tiny
CHASE1041
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  • 35 POSTS
I can remove my truck bed like I’ve done in the past right instead of removing the tank right?
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Tuesday, September 7th, 2021 AT 9:53 PM
Tiny
CHASE1041
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This is the correct FTP right?
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Tuesday, September 7th, 2021 AT 10:18 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello again.

Yes, if you choose to remove the bed and do it that way the sensor as I stated is on the top of the tank. Yes, that is the correct sensor. Keep us updated and let us know if you have any further questions on this issue. Hope this helps and thanks again for using 2CarPros.

Danny-
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Tuesday, September 7th, 2021 AT 10:24 PM
Tiny
CHASE1041
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I bought a new FTP Sensor. I’ll let you know how it goes.
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Wednesday, September 8th, 2021 AT 1:32 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello again.

Sounds good. Thanks again for using 2CarPros.

Danny-
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+1
Thursday, September 9th, 2021 AT 4:57 AM
Tiny
CHASE1041
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You guys are always a big help.
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Thursday, September 9th, 2021 AT 5:51 AM
Tiny
CHASE1041
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The new FTP Sensor did not fix my problem. I have been wonder what it could be?
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Thursday, September 9th, 2021 AT 1:42 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

If the vehicle is still doing the same thing, have you gone through the FTP sensor diagnostics that Danny provided above? The problem may not be the sensor, but rather a wiring issue or even the PCM.

Is it possible for you to record what it does in the engine area and upload it for us to hear?

Let us know.

Joe
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Thursday, September 9th, 2021 AT 3:26 PM
Tiny
CHASE1041
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Here you go:
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Thursday, September 9th, 2021 AT 4:32 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,640 POSTS
Hi,

Thanks... Believe it or not, that helps. When I listen to it stalling, the idle drops until it finally just stalls. I have a feeling we either have low fuel pressure or a big vacuum issue.

Have you confirmed fuel pressure? Also, have you checked the EGR to see if it holds a vacuum? Have you removed the EGR to see if it responds to vacuum?

If you remove the fuel cap from the filler tube, does that chance anything?

One thing I noticed, and correct me if I'm wrong, it takes two tries for it to run for any length of time. That is what is leading me to think low fuel pressure or fuel pressure drop off.

Let me know if you have done these things. Keep in mind, a stuck EGR or one that doesn't hold a vacuum can be causing this as well. However, by pressing the throttle, you should be able to keep it running. That takes me back to the fuel pressure possibility. Here is a link that shows in general how to test pressure:

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

If you look below at the attachment, it provides the pressure/drop-off diagnostics specific to this vehicle. The directions indicate the use of a scan tool.

Let me know.

Joe
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Thursday, September 9th, 2021 AT 5:11 PM
Tiny
CHASE1041
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I replaced the EGR valve and all the sensors that are linked to it a few weeks ago so I am assuming it has nothing to do with that. However, it started the same with the gas cap on vs off. No codes are showing now on my OBD2. But maybe it fuel pressure. I’ll need to test the pressure, what should the pressure be at?
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Thursday, September 9th, 2021 AT 6:01 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

I attached the manufacturer's specs for fuel pressure below. When testing, make sure to check drop-off. When the key is turned off, the system shouldn't lose more than 5 PSI in the first minute.

Let me know what you find.

Joe
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Thursday, September 9th, 2021 AT 8:53 PM
Tiny
CHASE1041
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Do you guys see anything here that would be causing my truck to stall out by itself or when I press the gas? I think this obd2 shows fuel pressure.
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Friday, September 10th, 2021 AT 6:15 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,640 POSTS
Hi,

It won't identify fuel pressure. However, it does provide fuel trims. I saw them for a second but you moved and I couldn't see them again. I think it was around 18%. That indicates the computer is trying to add fuel to the mixture. Can you tell me what the short-term fuel trims are?

Joe
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Friday, September 10th, 2021 AT 8:01 PM

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