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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

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  #1  
Old 12-07-2004, 05:19 PM
scottya4 scottya4 is offline
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oil pressure guage drops off when I let off the gas.

93, F150, 302. It's not leaking oil or burning oil. The oil pressure guage reads normal when i first start it up until it warms up. Once all warmed up the oil pressure guage drops all the way down very low when i come to a stop or when left idling, but then if I give it even a little gas it comes back up to normal until i let off again. ANyone know the problem for sure? I had dual exhaust put on a few months ago and it has idled very since then. Sometimes(since the new exhaust) after I give it a shot of gas while idling the idle drops down way low almost shutting the truck off. The oil guage just started. Could they be related?
Any help is appreciated.thanks.
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  #2  
Old 12-07-2004, 05:37 PM
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andym andym is offline
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Ford's lousy oil pressure gauges have been talked to death here. Do a search, you'll get lots of info. Basically, it's useless.
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Old 12-07-2004, 07:07 PM
scottya4 scottya4 is offline
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ya I realize ford's known for the horrible guages, Just wondering if anyones had this happen to them, maybe the guage is working fine...
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Old 12-07-2004, 09:34 PM
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The stock guage reads either zero or a little above mid-scale. Any other reading is a sign of voltage or grounding problems.

If the guage is dropping low (but above zero) at idle, you can expect perhaps a weak alternator or bad grounds. There is a decent chance the engine is OK.

If the guage is dropping to zero at idle, the oil pressure probably really is too low (sub 7 psi) You can try putting a real guage on it, and hope the sender has gone bad, but don't bet the farm on it.

Low pressure at idle is a sign of a worn oil pump, worn main and rod bearings, thin or fuel diluted oil, or a combination of the above. The pressure comes up with RPMs because the oil pump volume is directly proportional to RPM. The more the available volume, the more the pressure.
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Old 12-07-2004, 09:50 PM
scottya4 scottya4 is offline
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"thin or fuel diluted oil"

- I actually smelled the dipstick theother day and it smelled like gasoline, is this the problem then likely? how can it be fixed?help please guys ............
I've changed the oil only about 1500kms ago(about 2 months ago)...
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Old 12-07-2004, 10:25 PM
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I would not jump to any conclusions at all until you find out what the oil pressure really is.
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Old 12-08-2004, 08:50 AM
DcSkater602 DcSkater602 is offline
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i have a 91 5.0L in my bronco. Had the same problem where i would stop or leave it idle and pressure would drop blah blah blah. Looked on the forums here and saw all about how the guages are crappy so i kind of threw it towards the end of my list of things to do. Turns out the guage was fine, my oil pump was shot after only 65,000 miles. Yea thats right and i threw that to the end of my list of things to do....big mistake. Ive been driving w/ low oil pressure for two weeks now... Come to find out oil pump was dead and me accelerating was causing some pressure to build up and draw a little oil into the motor(which is why you see the pressure go up while your accelerating) To make things worse i learned no oil means rubbing metal. I later had to replace not only my oil pump... but all new bearings and the crankshaft. i threw cheap shocks on too while it was being worked on and the grand total was 1800 bux and some change.

GO GET THIS PROBLEM LOOKED AT IMMEDIATLY.

good luck
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Old 12-08-2004, 09:07 AM
ddbuggins ddbuggins is offline
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I had the other prob. Mine would stay at low pressure reading upon start up. Checked and changed oil/filter raised a bitfew min of driving she started reg. normal. May have had crud in the pan.blocking oil pump fillter. Not sure but Now reg. Normal with slight flux. I am thinking sending unit is bad or going bad. ANy thoughts????
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Old 12-08-2004, 10:06 AM
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new oil pump a big job? how much for the pump itself?
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Old 12-09-2004, 12:40 AM
Egor Egor is offline
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Quote:
Originally Posted by scottya4
new oil pump a big job? how much for the pump itself?
Pump itself is cheap, probably 50 or less but a real pain to change and I wouldn't want to go through all that to find out it was a worn out motor anyway. How many miles on this engine? My 351 died at 150,000 about 8 months after I bought it. Same symptoms, Oil pressure dropped at stop lights and idle. Rod started knocking about 2 weeks later.
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Old 12-09-2004, 09:14 AM
scottya4 scottya4 is offline
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200 000 kms. its not making any knocking or anything yet. other then spending a pile to get it looked at, any other ways to tell the motor is on its way to dying other then just the knocking? I'm gonna start looking for a new motor just in case. Mine is a '93, 302. What motors and what year motors will fit easily? just the 302 and 351? Will only the EFI's from 92-96 fit properly?
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Old 12-09-2004, 09:17 AM
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I could probly find an 80's mustang motor fairly easy, but the few i've seen are carbureted, any help is greatly appreciated guys, thanks.
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Old 12-09-2004, 08:28 PM
DcSkater602 DcSkater602 is offline
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the best way to find out what is really going on is either take it to a shop and get them to test your pressure or buy a new real guage. The guage you have is just as good as an oil light. just dont mess around too long... Oh and if u do have to get a new motor that would be a good excuse (to mom and dad or the wife or w/e) to get a H.O.(high output) motor. get a 351 H.o. the 302 motor u have in there now might have 180 hp.Stock.

good luck
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Old 12-09-2004, 08:41 PM
scottya4 scottya4 is offline
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yeah , i'm gonna look around for a 351 if i can find one for the right price. There are tons of 302's around in my area, not as many 351's.
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Old 12-09-2004, 11:52 PM
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my oil pressure was dropping in my 92 f150 so i bought an aftermarket gauge but i never got it installed because i couldnt get to the oil sending unit so i got ****ed with it and left it. i cant get the bolts off the power steering pump to make it easier to get to the sending unit either.
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Old 12-09-2004, 11:52 PM
 
 
 
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