7.5 performance issues
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Junior User
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From: Central Va.
7.5 performance issues
My 92 f350 has an engine on code 34. The truck runs very rich and uses tons of gas (5mpg). It starts and runs ok but seems sluggish. It idles at a perfectly steady 18.5 inches of vacuum and 30lbs. Of fuel pressure. 42 lbs. Without vacuum to the regulator. The timing is at 12° static. The truck also smokes blue after any idling. Plugs are near perfect looking. Maybe just a little more brown than tan. Any suggestions would be appreciated.
Lead Driver
Joined: Jul 2007
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From: Rhode Island
I'd start by verifying the MAP sensor's vacuum line is hooked up and crack free. The next thing I would try doing is unplugging the coolant temperature sensor and seeing how it runs. It's the one with a two-wire connection, not the 1 wire. The 1 wire sensor is for the gauge, not the computer.
With the coolant temp sensor disconnected, it will be hard to start cold.
With the coolant temp sensor disconnected, it will be hard to start cold.
Thread Starter
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Junior User
Joined: Dec 2013
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From: Central Va.
I'd start by verifying the MAP sensor's vacuum line is hooked up and crack free. The next thing I would try doing is unplugging the coolant temperature sensor and seeing how it runs. It's the one with a two-wire connection, not the 1 wire. The 1 wire sensor is for the gauge, not the computer.
With the coolant temp sensor disconnected, it will be hard to start cold.
With the coolant temp sensor disconnected, it will be hard to start cold.
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Junior User
Joined: Dec 2013
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From: Central Va.
Yes, fumed up my garage immediately. Just as it did when plugged in.
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Lead Driver
Joined: May 2011
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Sounds like you have an injector stuck open. Check fuel pressure after you shut it off. If the pressure drops steadily, there is an injector (or more than 1) that won't close.
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Junior User
Joined: Dec 2013
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From: Central Va.
Interesting. ...I'll try that asap. How long should the system stay pressurized?
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Junior User
Joined: Dec 2013
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From: Central Va.
Installed EGR eliminator .Fuel pressure at idle is 31lbs. After turning engine off for 25 minutes still at 31lbs. Ran scan got a 51 and 85. Cleared codes plugged in old coolant sensor. Scanned again with only the 85 showing back up. Truck runs exactly the same.
Last edited by FREDDAY; Apr 27, 2016 at 07:51 PM. Reason: Forgot something
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