Hoses at fuel pump(s) 90 HP OMC

[mrbarth]

Hi guys,<br />I really try to help myself, but the seloc manual for my 91 OMC 90 HP has exactly 3 slightly underexposed pictures (p 4-28 and 4-29) about the fuel pumps without much explanation.<br /><br />So here is my picture.<br /><br /><br />

<br />I have 4 hoses to these 2 pumps. Am I right the the right one is the VRO pump? (this feature is disabled at my motor) Then, from the manual I think the rightmost hose is the "fuel mixed outlet" hose.<br /><br />What now is the "vacum pulse hose" I read in the manual ?<br /><br />And what are the other 3 coming from / going to ?.<br /><br />And if the VRO is a combination pump, whats he pump on the left side with one hose coming from the bottom only ????<br /><br />I's hard to trace the hoses as this area is cluttered with wires and I'm afraid to break someting.<br /><br />Thanks again for some insight.

 

[R.Johnson]

Re: Hoses at fuel pump(s) 90 HP OMC

The hose at the top of the photo is the fuel outlet to the carbs. Looking at the photo, and going from left to right. The first hose is the pulse hose fitted to the front of the unit, this part of the assembly is called an air motor. It picks up positive-negative pulses from the crankcase, and drives both fuel, and oil pump, in this hose between the crankcase, and air motor is a pulse limiter, it is blue& gold in color. It's purpose is to protect the air motor diaphram from backfire which could damage it. The next hose is the fuel inlet hose. At the very back, and the hose with the nylon view window is the oil inlet hose. Any time I have disabled this system at the owners request, I have removed the VRO pump, and replaced it with a regular fuel pump from the special, or commercial model. I just never liked the idea of all that diabled plumbing hanging around. On the engines where it was possible, I unscrewed the pulse nipple from the crankcase, and closed it with a 1/8" pipe nipple. To me! it just makes it clear, this engine is no longer VRO.

 

[mrbarth]

Re: Hoses at fuel pump(s) 90 HP OMC

Thank you ob,<br /><br />I got this boat awhile ago with the old engine and<br />had some troubles with a rough idle (since I got it) and electric problems after trying to start it on the trailer after being out because of the hurricanes. So bought me a Seloc manual and got "hooked". Engine starts again good, have fixed sveral minor problems and no start exploring with the manual all other features. Would like to try a water pump and / or carb rebuild next. I asssume nothing was done to the motor the last 4 years.<br />Just cleaned it and hope it will start tomorrow <br /><br />One question still. Are these 2 pumps of same build or one VRO that then feed the mix to the next one that feads into the carbs ? Or does it just looks like 2 pumps ?<br /><br />And do Admirals not sleep

 

[mrbarth]

Re: Hoses at fuel pump(s) 90 HP OMC

Thanks RJ,<br /><br />I'll try to follow those hoses tomorrow with the descriptions I have now. By the way, I thought about reactivating the VRO, but maybe I'll follow your advice and replace the pump and close the "pulse nibble" from the crank case. <br />(I'll need to get a technicak dictionary. crank case is there this shaft is rotating that drives the pistons rod I assume (motherlanguage german)) )<br /><br />thanks all so far

 

[ob]

Re: Hoses at fuel pump(s) 90 HP OMC

The pulse hose is the one that connects to the air motor portion of the vro pump,far left in picture ,and runs to a nipple connected to the crankcase of the engine block.The pressure and vacuum pulses created by the engines crankcase is what drives the pump.<br />The vro has three hoses that attach.One fuel inlet,one oil inlet from reservoir in boat,and one fuel /oil outlet to carburetors and primer solenoid .The oil inlet hose will have a white plastic flow indicator inline ,which is clear in the picture ,second from right.<br /><br />Are you having some problem with it or just exploring?

 

[ob]

Re: Hoses at fuel pump(s) 90 HP OMC

The air motor diaphragm pulses to and fro and actuates a common rod that strokes axially and reciprocates both (oil and fuel)pistons.

 

[mrbarth]

Re: Hoses at fuel pump(s) 90 HP OMC

Thanks ob, understood.

 

[seahorse5]

Re: Hoses at fuel pump(s) 90 HP OMC

The FAQ section here has more info on how a VRO works. <br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000028

 

[mrbarth]

Re: Hoses at fuel pump(s) 90 HP OMC

Thank you seahorse,<br /><br />I had "reviewed" this FAQ entry. Its great and very detailed. But I had a problem to identify the parts on my engine as I could not find a description in the manual.<br /><br />With the information I have now, that article start to makes sense to me.<br /><br />Thanks again (and good night for me now)