engine stalling

  #1  
Old 05-23-2019, 07:13 PM
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Default engine stalling

Hi. My 1990 745 sometimes stalls at red lights and is difficult to restart--or won't restart for 15 minutes. When this happens I have fuel pressure (fuel squirts from the Schrader valve on the manifold. Good, regular spark from the plugs, and battery voltage at the injectors. Today I got a 1-4-3 knock sensor code. I wonder if the knock sensor could cause the engine to die and not restart until after cool down? I worked on these cars for many years, but not on ones this old and with this high mileage. Thanks for any insight. May 22, 2019. Paul Smith. Raleigh, N.C.
 
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Old 05-24-2019, 08:49 AM
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usually warm start problems are related to fuel pressure (low fuel pressure can lead to vapor lock), air intake leaks (ie vacuum lines/air boot cracks, idle air valve), leaky injectors or the engine temp sensor. I'd probably start by looking for any signs of a leaky injector (puff of black smoke on start up? wet plug?) and then consider measuring fuel pressure at the rail before starting and with the engine running, You can also measure the resistance of the temp sensor (google for a resistance by temp chart).
 
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Old 05-24-2019, 06:20 PM
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I'd change the Crankshaft Position Sensor; sounds like it heats up, then once cool the car starts.
 
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Old 05-30-2019, 08:11 AM
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OK. Thanks for that. I put an electric fuel pressure gauge on the dash. It's reading around 40 psi--on my third fuel pump.
 
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Old 05-30-2019, 08:12 AM
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OK. Thanks. That's probably my best alternative. Wiggling the sensor harness didn't help when it went into stall mode.
 
  #6  
Old 06-06-2019, 10:28 PM
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Default Had similar problem mechanics never could figure out

For mine it would stall almost every time I slowed down or pulled up to to stop at red light turned out it was the alternator, but I would make sure to clean the MAF sensor electrical connections as mine were showing some green corrosive build up and will cause issues.
 

Last edited by seafaith; 06-06-2019 at 10:33 PM.
  #7  
Old 06-07-2019, 07:43 AM
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OK. Thanks for the help. I don't have a MAF--it uses a MAP. I've never seen a MAP go bad. I was about to try a new flywheel sensor, but I have spark when it dies and won't restart. I'm thinking of monitoring the drivers on the injectors to see if the computer is not grounding the injectors. Any more advice appreciated!
 
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Old 06-15-2019, 01:24 PM
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if you have a MAP, that means you have a Regina injection system... I've never even seen one of those (I don't think they sold them here in California).
 
  #9  
Old 06-16-2019, 06:31 AM
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Crank Position Sensor! 10 dollars and 10 minute job to change one.
 
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Old 06-16-2019, 05:25 PM
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Originally Posted by sicnarf View Post
Crank Position Sensor! 10 dollars and 10 minute job to change one.
I wouldn't put a $10 CPS. Pay the $40, get an OEM, some parts are too important to go cheap!
 
  #11  
Old 06-16-2019, 06:25 PM
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Probably not, due to emissions restrictions. It was similar to Bosch LH 2.2, but used a map sensor instead of a AMM. The ignition system was called "Rex I)
 
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Old 06-16-2019, 06:27 PM
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Agree on the quality issue. But, I have strong, rhythmic spark when it won't restart, so flywheel sensor must be ok.
 
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