Fuel pump doesnít come on while cranking.

  #1  
Old 05-28-2019, 06:49 PM
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Default Fuel pump doesnít come on while cranking.

I have a 1994 Volvo 940 turbo with Bosch ignition. My car just stalled out on me the fuel pump doesnít turn on while cranking. It turns on for 3 seconds when I hit the ignition switch. I replaced both relays the fuel pump and the radio suppression. I replaced plugs, wires, distributor cap and rotor. I also replaced the speed sensor. They where all original and it was justifiable to replace everything. It still doesnít trigger the fuel pump during cranking. Wtf. Iím so frustrated I feel like setting it on fire and using it for charcoal. Kids will get a kick out of it. Anybody got any suggestions?
 
  #2  
Old 05-28-2019, 07:47 PM
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. Nice set of possabilities
 
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Old 05-28-2019, 08:11 PM
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Default Thanks, but um?

The fuel pump doesnít turn on while cranking. The fuel pressure regulator is probably the next thing Iíll buy. I just think that it probably wonít help if the fuel pump is not pumping.
 
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Old 05-29-2019, 06:05 AM
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The fuel pump is supposed to run for a second or two when you turn the ignition to the II position. Then while cranking, if the ECU detects pulses on the crank position sensor it will fire up the pump again. If it doesn't detect pulses it will not run the fuel pump.

Have you checked your engine codes? Have you checked for spark? If the crank position sensor was not providing the ECU with pulses then you won't get spark either as it provides a signal to both.
 
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Old 05-29-2019, 07:31 AM
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Did you try to hot wire the fuel pump to verify if it works. This by passes the relay and will tell you if you have a relay problem or a fuel pump problem. I traced a similar problem a few months ago on my 740 which turned out to be the ECU.
 
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Old 05-29-2019, 07:40 PM
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It turns on for 3 seconds with the key and yes it turns on if I power it directly itís not even a year old. I have not checked the one in the tank but I donít really think that would cause it not to start. The pump comes on but not while cranking.
 
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Old 05-29-2019, 07:41 PM
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Also no codes. Just 1-1-1
 
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Old 05-30-2019, 10:38 AM
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Originally Posted by Mrjonsmith1 View Post
Also no codes. Just 1-1-1
How did you check for spark. Verify that a spark plug has spark . Next use a noid light to verify that your fuel injectors are working during the start process. Also if you shoot some starter fluid into the throttle body does it start.
 
  #9  
Old 05-30-2019, 07:34 PM
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For some reason sheís not sending spark or pulsing the injectors. That kind of goes along with the fuel pump not turning on while cranking. The Ecm is not sending signal to anything. I replaced the speed sensor. I tested the old one and the new one and they where both good. I donít know if the ecm is bad, the wiring between, or if thereís anything else on that circuit that could cause this kind of problem. Maybe the maf or coolant temp? I think I need to test the wiring between the speed sensor and the ecm. Iím not sure that Iím not missing something else.
 
  #10  
Old 06-21-2019, 09:03 PM
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Default Possible problems with no fuel or spark

I was having same issue with my 740 no fuel and no spark which after a few test led me to the ignition control unit underneath dash black box. Purchased used on on eBay and started right up
 
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