92' Volvo 740 no tach = no start

Old Jan 9, 2021 | 01:11 PM
  #21  
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Further investigation, timing belt is fine. The fuel pump will prime for 3 seconds every time you turn the key to accessory but will not get power when cranking the engine. I better check for spark.. Has to be a bad connection somewhere or maybe a bad ignition control unit..
 
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Old Jan 9, 2021 | 06:01 PM
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if the fuel pump isn't restarting when you crank the car, thats an indication its not getting any timing., and you probably don't have any spark, either. The timing comes from a CPS, Crank Position Sensor, which provides the timing for both the ICU and ECU. the CU's rarely fail on these cars, failures are almost always something external to them.
 
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Old Jan 10, 2021 | 02:04 PM
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Checked again and we have spark
 
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Old Jan 10, 2021 | 02:18 PM
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if you have spark, you should have tach, since the tach is directly connected to the ignition coil pin '1' which is the signal that fires the coil.
 
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Old Jan 10, 2021 | 02:21 PM
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Dave b. mentioned rewiring the fuel pump, the only thing that concerns me is that I dont see any tach movement and if the fuel pump is still priming wouldn't that mean there isn't a ground issue? Also when the car did run, no check engine light which leads me to believe my cps is fine. I have a universal fp wiring kit that I was going to use for my other project, tempted to wire this up with a switch tonight if it's really as simple as the pump not getting power intermittently for whatever reason..
 
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Old Jan 10, 2021 | 02:22 PM
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Originally Posted by Kaiden
Further investigation, timing belt is fine. The fuel pump will prime for 3 seconds every time you turn the key to accessory but will not get power when cranking the engine. I better check for spark.. Has to be a bad connection somewhere or maybe a bad ignition control unit..

wait, ACCESSORY ? there should be no fuel system power at all in position I (Accessory), the fuel injection system should only be powered in II (Run) and III (Start). this suggests perhaps your ignition switch is worn out (not the key part, but the electrical switch behind the key lock).

thats this part, https://www.fcpeuro.com/products/vol...-940-9447805oe

 
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Old Jan 10, 2021 | 02:33 PM
  #27  
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Originally Posted by pierce
wait, ACCESSORY ? there should be no fuel system power at all in position I (Accessory), the fuel injection system should only be powered in II (Run) and III (Start). this suggests perhaps your ignition switch is worn out (not the key part, but the electrical switch behind the key lock).

thats this part, https://www.fcpeuro.com/products/vol...-940-9447805oe
Apologize I meant position II is when itll prime.
 
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Old Jan 13, 2021 | 06:46 PM
  #28  
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Going ahead with an ignition switch tomorrow, will update
 
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Old Jan 23, 2021 | 06:43 PM
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I narrowed it down to water in the fuel tank. I really hate to admit this, but I'd say around Aug 2020 I was filling up gas one day and leaned against my fuel door (it broke off) normally where I hang the gas cap; I go to fill up gas again sometime in August and set the gas cap on top of the car. Eventually, I drove off and the next day is when i noticed it was missing. During that time it was raining heavily in Florida, and I left it off for about a month until I started to have this issue. I now realize this was very stupid on my part, but we drained the old gas and threw in some HEET additive. Been fine for about 4 days now with no hiccups. Such a headache, lesson learned...
 
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