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Discussion Starter #1
Has anyone out there had this probem. 91 factory oil pressure gage reads "straight across" at idle, all is good. When driving down road and giving it throttle, the gage starts to drop. I let off and it goes back to normal. Yeah I know I should have the aftermarket gages in by now but I just haven't got to it yet. I have seen sending units go out before but this is a new one to me. WTF? :mad:
 

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Mine still does that, i dont know why, it just does. I dont pay any attention to it anymore as i'm getting aftermarket gauges. But it sounds like it could be the sender.

BTW, the forum sure is slow tonight.
 

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The Grim Reaper said:
Has anyone out there had this probem. 91 factory oil pressure gage reads "straight across" at idle, all is good. When driving down road and giving it throttle, the gage starts to drop. I let off and it goes back to normal. Yeah I know I should have the aftermarket gages in by now but I just haven't got to it yet. I have seen sending units go out before but this is a new one to me. WTF? :mad:
How many miles on the motor? The stock sending unit usually dies however it will still go up and down with pressure, even when the unit goes out.

When oil pressure goes up when you let off the throttle it is usually an indication of a worn out main thrust bearing (the bearing that keeps the crank from moving forwards/backwards). If you've got a lot of miles that is probably the case.

However before doing anything at least replace the oil pressure sending unit ($15) just to make sure it's not just the stock guage acting up.
 

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man i had the exact and i mean exact same problem... turned out that the sending unit was bad.. i went and bought an autometer mech oil pressure gauge. its worth the money and piece of mind. at cold i am at 65-70 psi and at warm crusining i am at 50-55.
 

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Discussion Starter #6
I am changing the sending unit until I get the Autometers ordered. I am also changing the oil, filter and anything else that can help me sleep tonight!

To answer the milage question, this my 427ci (351W) with @ 1,000 miles on it. This the cause for concern! If it were one of my mostly stock 302's I wouldn't be as worried. All sound well and I am hoping(praying?) that it is just the sender. Should of ordered up the Autometers before getting this thing up and running. I just couldn't resist to make it go. Thanks for the help so far. I will post a reply with the final conclusion after tomorrow.

:confused:
 
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