Engine Cranks but do not start

Tiny
BEIA
  • MEMBER
  • 1996 MAZDA DEMIO
  • 4 CYL
  • FWD
  • AUTOMATIC
I have a ‘96 mazda demio’ EFI engine and the problem is that it cranks but do not start…I have already check the fuses relays and they are all in good condition…I thought there is no spark so I check the electric from distributor to spark but there is spark and also the spark plugs are in good condition. So maybe the problem is in the fuel so I checked the fuel system and found out that fuel is coming in so now I am stuck and frustrated with this problem so if you could help me out tell me if I missed something here please….I really appreciate your help…
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Sunday, February 1st, 2015 AT 12:09 AM

11 Replies

Tiny
KHLOW2008
  • EXPERT
Have the fuel pressure checked.
Try some starting fluid to see if it starts.
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Sunday, February 1st, 2015 AT 12:19 AM
Tiny
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Is there any other methods in checking the system pressure that do not require the pressure gauge and necessary tools?Thnks
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Sunday, February 1st, 2015 AT 4:40 AM
Tiny
KHLOW2008
  • EXPERT
Without pressure gauges, it would not be accurate to test the pressure.

I would use my thumb to close the fuel line and get someone to turn the ignition on. If you can hold the pressure, it is insufficient. You need to be careful if you use this method as fuel can e sprayed onto yourself.
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Saturday, February 14th, 2015 AT 6:55 AM
Tiny
BEIA
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Now when I on the ignition and check the fuel coming from the fuel filter hose the fuel is coming for sometime and then not coming. Is it possible that the pump is weak? Cos I don't know exactly how fast it should run when u bench test it. But when I bench test the electric pump it runs while holding it with my hand.I thought it should like. Jump out of my hand or no?
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Tuesday, February 24th, 2015 AT 4:37 PM
Tiny
KHLOW2008
  • EXPERT
The pump wold work only momentarily when ignition is turned on so there is no problem there. What you need to test is the pressure coming out of it.

The pump would not jump out of your hands when you bench test it. You would only feel it jerking and then hum while running.
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Tuesday, February 24th, 2015 AT 9:43 PM
Tiny
BEIA
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Yeah I think that is the problem. So if possibly the pressure is low what do you think I should do next in order to fix it? Should I replace the fuel Pump with a new one?
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Wednesday, February 25th, 2015 AT 11:28 PM
Tiny
KHLOW2008
  • EXPERT
Since you don't have a pressure gauge to test the pressure, there no way to say if it is bad but if the pressure is low, you definitely need to replace the pump.
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Thursday, February 26th, 2015 AT 9:53 AM
Tiny
BEIA
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Okay thanks I'll try buy a pressure gauge and then test it. But what would be the correct pressure. Is it gona be between 20 kPa to 35 kPa? Appreciate your expertise help
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Thursday, February 26th, 2015 AT 6:09 PM
Tiny
KHLOW2008
  • EXPERT
Fuel pressure changes according to engine running condition as controlled by the pressure regulator but the fuel pump pressure by itself should be more than 50 psi.
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Saturday, February 28th, 2015 AT 2:32 AM
Tiny
BEIA
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Finally, my car is running now.I couldn't find a pressure gauge but I assume that pressure was the problem cos of from the previous tests that I already Did.

So I took out the fuel pump and replace the motor with my toyota corona fuel pump motor and it actually works so again I would like to thank you for your advise all along. My eyes were splashed with fuel when I tried to check it from the hose because of high pressure hahah I should've wear safety goggles.

Ok i'll contact you again if theres other problems
thanks
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Tuesday, March 10th, 2015 AT 5:10 PM
Tiny
KHLOW2008
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You're welcome and glad to know you have the problem fixed.
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Friday, March 20th, 2015 AT 12:35 PM

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