Oil gauge peaks when turning on ignition

[Epstah]

Hi!
Seems like I have a grounding problem. When I turn on the ignition (not starting engine) my oil gauge peaks to the top(pegs?). When starting engine it drops to somewhat normal. When giving throttle it drops further and kinda follows the throttling up and down! This is a mercruiser 5.0 lx 90- something. The gauge is Faria. New sender. Tried to locate and check all groundings. Any good ideas where to go next?

Ps! Excuse my English if you guys didn't understand any of this, I'm Norwegian ;-)

 

[NYBo]

Re: Oil gauge peaks when turning on ignition

Velkommen til iboats!:welcome:

Checking the grounds is a good place to start.

 

[glenn property of pam]

Re: Oil gauge peaks when turning on ignition

check the grounds on the back of the gauges especially the tach. It sounds like the gauges are trying to find ground and the fuel needle is a nice place to get it

 

[Epstah]

Re: Oil gauge peaks when turning on ignition

400000 members? And no one has had similar problems? as it seems there's a communication problem between sender and instrument. Guess the sender isn't compatible with the faria instrument?

 

[Silvertip]

Re: Oil gauge peaks when turning on ignition

Disconnect the wire on the sender. With the sngine cold (ambient temp) measure the sender reststance. It should read about 40 _ 100 ohms depending on temp. Warm the engine and measure again. Resistance should be somewhat lower. Sender resistance is 30 , 240 ohms. You have Faria gauge si go to their web site for troubleshooting. It is provided there.

 

[Don S]

Re: Oil gauge peaks when turning on ignition

400000 members? And no one has had similar problems? as it seems there's a communication problem between sender and instrument. Guess the sender isn't compatible with the faria instrument?

Actually, out of those 400,000 members only 68 have even looked at this thread at this point. Of those, only 8 are active posting members. Did you verify the grounds as suggested by the previous replies?
personally, I have worked on boats for over 20 years for a living, never seen one do that.

 

[glenn property of pam]

Re: Oil gauge peaks when turning on ignition

I miss read the original post as im sure I read fuel needle not oil needle. Most oil pressure senders work by grounding the wire from the gauge to ground at a set resistance based on oil pressure. Yours seems to be working backwards. There are so many brands of sender units some work 240-33 ohm others work 10-180 I would suggest you ask faria what yours should be. If the fuel needle is also playing up check the grounds.

 

[Epstah]

Re: Oil gauge peaks when turning on ignition

Thanks for all replies. I've done all things you guys mentioned, before posting original post. And as I told you in previous post, I'm certain that the problems is that sender and instrument isn't talking the same language . I have also tested with an analogue gauge directly on engine. The measurements is all good. ( thankfully )
thanks again