1989 Mercruser 5.7 will not get over 2000 rpm

[dmiles452]

I just replaced the water fuel separator filter and drained a lot of water out of the bottom of the fuel tank. Motor starts fine and has good oil pressure, water temp is 160F. I open the throttle wide open and all it will do is 2000 rpm.

 

[Bondo]

I just replaced the water fuel separator filter and drained a lot of water out of the bottom of the fuel tank. Motor starts fine and has good oil pressure, water temp is 160F. I open the throttle wide open and all it will do is 2000 rpm.

Ayuh,...... Whatcha workin' on,..??..??

If it's got a carb, it too, is probably fulla crap,......

 

[Scott Danforth]

run the motor from a separate portable fuel tank after you clean the carb. by clean, not talking an exterior spray of carb cleaner, however taking it apart, cleaning all the passages and verifying they are clear by passing fishing line thru them prior to installing a new gasket set.

 

[dmiles452]

Ayuh,...... Whatcha workin' on,..??..??

If it's got a carb, it too, is probably fulla crap,......

year and type of engine is in the title

 

[Bondo]

year and type of engine is in the title

Ayuh,..... Carbed,..?? 2bbl., 4bbl.,.....

'89, is possibly a Quadra-jet,..??

 

[QBhoy]

Outwith you perhaps not knowing if she was in better form previously, she’s just new to you and something like her being over propped is at play…it’s got to be the carb that’s first on the suspect list, in such a situation. Good luck

 

[dmiles452]

I just replaced the water fuel separator filter and drained a lot of water out of the bottom of the fuel tank. Motor starts fine and has good oil pressure, water temp is 160F. I open the throttle wide open and all it will do is 2000 rpm.

New development, I found a wire that looks like it goes to the sending unit just to the left front of the distributor. If this is the oil pressure sending unit and this wire was off, could that be the problem with getting more than 2000 rpm?

 

[Scott Danforth]

Your motor doesn't care if you have an oil pressure gauge or not

That is not your problem

 

[dubs283]

1989 mercruiser 5.7.

Yes that is some info but there is more info you can provide. Best info is serial numbers and actual model ID. Model will be something like MCM 5.7 Liter.

Nobody here knows exactly what setup you have. Is it oem/stock? Pictures help a lot if you can't get s/n or model info

Agree with bondo and Scott. Based on provided info you most likely have an issue with fuel supply/carburetor and the oil pressure sender, wiring and guage on a carbed motor will not affect rpm in any way