45hp mariner Oiler/Fuel Pump

[KevinTee]

Nubee here:<br /><br />I have a 1988 Mariner 45HP that has had the oil injection bypassed. Since I purchased the boat last year I have been fighting a fuel starvation problem. I am an auto mechanic but not familiar with outboards. I have replaced the fuel line complete with bulb and fittings. After rebuilding the fuel pump (I think I reassembled it correctly) it ran through a full take at full throttle with no problem. Got to the lake and it would only run at 3/4 throttle. Manual pump of the bulb and it runs fine. I assume the manual will not show me how the oilier can be bypassed. Where can I find info (drawings) on how to do this? I want to make sure the bypass was done correctly, replace fuel lines and go through the pump again with Merc parts. No Merc Dealer close so where is the best place to order parts?

 

[Ralphie3_2]

Re: 45hp mariner Oiler/Fuel Pump

have same engine with same problems. would like to compare note. send Pm. Ralphie

 

[Scali]

Re: 45hp mariner Oiler/Fuel Pump

I doubt the fact your oil pump is bypassed has anything to do with your problem.<br />I have a 1994 40 hp 4 cyl. Merc, I believe the same basic motor as yours & I'm considering bypassing mine before next season as I just dont trust these injection systems especially after a decade.. <br />The oil pump is driven by a gear off the crankshaft & supplys oil to the fuel pump I may be wrong as I believe your motor has the earlier oil injection setup but I cant see how the oil injection being bypassed has anything to do with you not getting full RPM's ..<br />First thing that comes to my mind is gas tank vent clogged open ? Correct prop ? Linkage properly adjusted for full RPM's ?<br />Fuel filter backwards ? Carbs dirty out of adjustment ? Stuff like that..<br />First post for me but long time lurker

 

[KevinTee]

Re: 45hp mariner Oiler/Fuel Pump

Bulb goes soft and RPM returns to full when I pump the bulb. I have 2 fule tanks and it does it on both. Does not seem to be a carb problem unless the float don't drop but I don't think I could pump the bulb and override the floats. I ordered a service manual and will double check the fuel pump when I get it. Ralphie I will be happy to compare notes when I get some. I think I will put in a clear fule line to check for air leaks.

 

[KevinTee]

Re: 45hp mariner Oiler/Fuel Pump

Found my problem.<br /><br />I had rebuilt the fule pump and that cured the problem for one outing then it started running out of fuel again. After carful inspection this winter I found a kinked input fuel line. This is the line from quick connect to the fuel pump. There is not much room for this line so be carfull when routing it. The engine ran good at WOT last week. Since then I performed a De-Carb and carb/timing sync. All adjustments were way off so I can't hardly waite to get it on the water again.