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Possible fuel pump issue?


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tilopa
User

Feb 19, 2014, 9:17 PM

Post #1 of 10 (1280 views)
Possible fuel pump issue? Sign In

1995 Mazda Protege
1.5L 4 cyl
Automatic
158K miles

The car was running fine. One day it rained heavy and later I drove and the car started to sputter a bit, like it was going to stall, and I'd give more gas and it would be ok. It did that for a few miles and then it stalled and would not start.

I could not get down to tow it for a few days, when I did I tried starting it and it started right up. It had stopped raining for a couple days and the ground was dry. I tried to drive it home but only got about a mile or so and it stalled and has not been able to start since.

I tested that the spark plugs were firing. Then I rented a fuel pump pressure tester and fuel pressure read about 20 psi, the manual said it should be around 80 psi. I replaced the fuel filter and tested again and it read 50 psi. I tried to start it at this point and still no go. Before I go ahead and replace the pump I wanted to get advice about other things to test as the pump is expensive (about $120) and once I put it in I bought it.

I mention the rain to include all clues and variables but I personally think the rain was just coincidental. check engine light is on with code 0510 "closed position throttle switch". My understanding is that would not prevent starting.

Any advice is appreciated.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Feb 19, 2014, 10:52 PM

Post #2 of 10 (1267 views)
Re: Possible fuel pump issue? Sign In

? Caused or brought on by wet. Two different pressure with just fuel filter. I tend to think this could be fooling you with a weak connection not able to deliver proper current to pump and would check those that can get wet first,


T


PS: $120 for a pump is cheap as some can be mega times more than that.......



Hammer Time
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Feb 20, 2014, 3:45 AM

Post #3 of 10 (1249 views)
Re: Possible fuel pump issue? Sign In

That is not the correct fuel pressure spec for this car.

Regulator Vacuum Line ON(engine running)
200-240 kPa (29-34 psi) Line Pressure With Pressure

Regulator Vacuum Line OFF 280-310kPa (40-45 psi)

The pressure needs to be read inline with a "T" so you are reading regulated pressure.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tilopa
User

Feb 20, 2014, 11:20 AM

Post #4 of 10 (1231 views)
Re: Possible fuel pump issue? Sign In


In Reply To
The pressure needs to be read inline with a "T" so you are reading regulated pressure.


ok, thanks, I was wondering about that, was not sure if I needed a T. So, if I do the test inline with a T does that NOT isolate the fuel pressure regulator being the problem? In other words, if I get a low reading with a T how do I know if the problem is the fuel pump or the fuel pressure regulator?

Not sure what my manual was referring to when it said the fuel pressure should be between 76 and 92 psi, would that have been tested not inline, just the fuel pump alone?

I'll test inline and post results.


Hammer Time
Ultimate Carjunky / Moderator
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Feb 20, 2014, 1:12 PM

Post #5 of 10 (1224 views)
Re: Possible fuel pump issue? Sign In

They were referring to maximum capacity of the fuel pump and I have no idea why they even did that. The regulated pressure is the only thing to be concerned with. If it's low, then you have to determine which it is. The regulator failure is rare and usually just causes a rich mixture when it goes bad.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tilopa
User

Feb 20, 2014, 10:30 PM

Post #6 of 10 (1211 views)
Re: Possible fuel pump issue? Sign In

Yes, I looked at the book again and it did say max, my bad.
I did the test inline with the T and it showed about 42 PSI, the book said it should be between 37 and 46, I believe, when the switch is turned on, so I guess it is not the pump. I took the vacuum hose of the pressure regulator and it was not wet and the regulator does not look damaged in any way, so maybe I can rule out the fuel system?

I took one of the spark plugs out and it was wet, not a good sign. Tomorrow I will test the wires to the plugs and make sure they are providing electricity and test the plugs to make sure they are sparking.

I took the distributor cap off and it looked fine, it was dry and so was the rotor. Not sure how else to test that, but I'll start with the wire to the plugs and work backward I guess.


Tom Greenleaf
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Feb 21, 2014, 12:49 AM

Post #7 of 10 (1209 views)
Re: Possible fuel pump issue? Sign In

To add: Notes on this...... It had a problem being wet. Later started but quit and would not start again. Now since once you said you had spark and are finding wet plugs they alone may not fire if soaked from a lot or failed attempts making this more confused to zoom in on the original problems and a fix.


Plugs do NOT always plain air dry well but will take the electricity but not make that critical jump to fire. Heated carefully or new may be in order for those or you could get all messed up,


T



Hammer Time
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Feb 21, 2014, 3:28 AM

Post #8 of 10 (1205 views)
Re: Possible fuel pump issue? Sign In

You need to go back to basics where you should have started.

You may have already done some of this but you need to complete the rest of the testing.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.



Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.


2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.


3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tilopa
User

Feb 22, 2014, 11:36 PM

Post #9 of 10 (1183 views)
Re: Possible fuel pump issue? Sign In

Hammer, I just found your sticky the other day, thanks for putting that together. I went through the list. Here is what I've done:

- replaced fuel filter
- tested fuel pressure and did basic test on fuel pressure regulator.
- tested the injectors with a noid light.
- tested the spark plugs for spark at the plug.

All these tests past. You mentioned that 3 things must be present for an engine to run but shouldn't air be included in that. My gut is telling me at this point that I'm not getting proper air flow.

Tom,
I pulled out all the plugs and dried them tested and put them back. The car will start but it is very difficult to get it started. And I found that when I give it gas during crank it will not start but if do not pus the throttle it will start but not easily. But when it starts it will idle smooth and well. But then if I just touch the gas it stalls. This seems like air intake problem, no?

No MAF codes (not sure how to test this). Idle air control valve? Could that TPS code have anything to do with this? What about a vacuum leak, but I guess that would not cause it to stall really.

Thank you both for all your feedback, I'd appreciate if you could help me with the next step of troubleshooting.


(This post was edited by tilopa on Feb 22, 2014, 11:38 PM)


Hammer Time
Ultimate Carjunky / Moderator
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Feb 23, 2014, 5:21 AM

Post #10 of 10 (1179 views)
Re: Possible fuel pump issue? Sign In


Quote
You mentioned that 3 things must be present for an engine to run but shouldn't air be included in that. My gut is telling me at this point that I'm not getting proper air flow.



#4?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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