Firm yet spongy bulb first start 95 175hp opro

[angus63]

Boat sits a day or two (must be raining )and when I pump the bulb when it's cold I can feel fuel being drawn into the bulb. What I also feel is a sponginess as if air is trapped between the bulb and the bowls. I know there are vents on the carb bowls, but I still feel trapped air. I also believe there is some type of vapor separator in the fuel system, but I am not familiar with its function. When I try to start, it kicks off but dies immediately (1-2 sec). When I try to squeeze the bulb, I am able to pump it 2-3 times before it is firm again (still a little spongy). I may do this 2-4 times before finally kicks off. It's as though each time I try to start, a little of the trapped air is expelled. What could cause this? New OMC fuel line and bulb, no obvious leaks, no problem starting the rest of the day. It used to start first twitch of the key until this started about 2 weeks ago.

 

[Silvertip]

Re: Firm yet spongy bulb first start 95 175hp opro

The primer bulb does not stay firm when the engine runs. It gets firm before you start the engine because the float closes the inlet needle which prevents overflowing the carbs. As soon as the engine begins to draw fuel the inlet needles open and the fuel will be drawn from the line. You probably need to bump the choke (push in on the key) a time or two during warm up.

 

[angus63]

Re: Firm yet spongy bulb first start 95 175hp opro

Up, thanks for the reply. I am aware of what you said. The odd part what I am experiencing is that the bulb draws up fuel but does not get firm before ever trying to start the motor. It feels as though there is air trapped between the bulb and the bowls when first pumped up. It takes 3 or 4 start attempts before it feels like the trapped air is expelled. When it starts and warms up, I can pump the bulb and it get firm. What I am trying to uncover is how to purge air in the fuel system for the first start attempt of the day, or even better, what is causing air to be trapped in the system in the first place. Again, close inspection revealed no leaks and motor runs well after starting.

 

[clanton]

Re: Firm yet spongy bulb first start 95 175hp opro

My guess on this is. The vapor seperator is not vented, it has a small pump tp remove the vapor, the pump works off of crankcase pulses, which is not great at starting rpms. So I think the vapor is not removed until the engine is running.<br />The seperator also has a float and needle assy, just like a carb. If the carbs need cleaning, the seperator probley would need cleaning. I would remove the seperator and inspect the inside,clean, replace the float/needle assy, and the small pump diaphram/o-ring. there is one other way to fix this, but not approved by EPA.

 

[umblecumbuz]

Re: Firm yet spongy bulb first start 95 175hp opro

Two things I would add:<br /><br />First, the bulb needs to be in an upright position (vertical) with the outlet at the top, before it will prime properly or get hard. Yes, it works in other positions, but not as efficiently (no old jokes please!).<br /><br />Second, it may be that you have an air leak somewhere along the line from tank to carbs, causing air to be drawn in when the motor's not being used. It doesn't need much, and can be a pig to trace. It will not always show up as an obvious fuel leak, because the whole line is under negative pressure while the motor's running, but it can also cause the symptoms you describe. <br /><br />Easy way of checking is to smear grease round every joint. The grease seals the leak, and you can remove the greae joint by joint until you've isolated which joint's leaking.<br /><br />If that doesn't work, then we're probably talking carbs or pump.

 

[angus63]

Re: Firm yet spongy bulb first start 95 175hp opro

Clanton and Still<br />Thanks for the replies. <br />Clanton, I briefly reviewed the OMC manual and saw no description or breakdown of the separator. Could you describe procedure for removal, cleaning, and reassembly? Oh yeah, location would help too!!<br />Still<br />Regardless of orientation of the bulb, it still occurs. I would bet the air is trapped at the highest point (VRO I believe). I will try cleaning separator first and then try cleaning and reclamping every connection. The ones near the tank require the flexability of a Romanian gymnast, unfortunately I'm built more like fire- hydrant.<br />Clanton If all this fails, could you email me the method that may work rccktc@hotmail.com<br />Thanks

 

[angus63]

Re: Firm yet spongy bulb first start 95 175hp opro

One other thing, I am willing to bet that record temperatures 90°F+ with high humidity for two weeks and 10% ethanol fuel has something to do with this.

 

[Goodoleboy]

Re: Firm yet spongy bulb first start 95 175hp opro

Manual for my 87 40hp says!<br /><br />Alchol extended fuel may result in engine running quality problems.<br /><br />1...Vapor lock<br />2...fuel starvation<br />3...moisture absorption (phase seperation)<br /><br />Manual advises switching to straight gasoline and see if sympton persist.<br /><br />Good luck!

 

[angus63]

Re: Firm yet spongy bulb first start 95 175hp opro

Hey Goodoleboy<br />Yeah, that's what I was thinkin'. What I'd like to do is add a manual release vent at the top of the fuel system just after the fuel pump to eliminate this issue. Or maybe the separator is just clogged like Clanton suggested. Sure would be nice to figure this out before the weather cools and it reoccurs next year.<br />BTW 10% ethenol fuel is the only fuel available within a 100 mile radius. Even though the factory states up to 10% is okay for this model engine, I was pretty sure it would be an issue in the hot humid months. I'm embarrassed to call myself an engineer (propulsion) after recent industry stunts.<br />Thanks

 

[clanton]

Re: Firm yet spongy bulb first start 95 175hp opro

The VS located behind the air silencer, between the carbs. The VRO comes off with the VS. Chapter 2 page 2-24, manual 503151. You have to push the hoses off, if you pull, the plastic will break. The ones that I have worked on V4/6s are all hard starting after it sets for a day. I would check the primer, insure its working, then drill the primer nipple .015 oversize. The nipples are on the intake manifold.

 

[angus63]

Re: Firm yet spongy bulb first start 95 175hp opro

Thanks Clanton<br />Will recheck the manual. Clean the seperator. Clean and reclamp all connections. Post the results. I hope it's just not inherent and reoccuring due to temp,humidity, and 10% ethanol.<br />I did try manually priming with the same result. Do you think opening the manual primer and squeezing the bulb will purge the air without flooding or putting too much gas w/o oil in the intake for a cold start?

 

[angus63]

Re: Firm yet spongy bulb first start 95 175hp opro

Hey.... just noticed I can now dine at the O club. Anyone who served knows a "butterbar" can not possibly have more to offer than an E8!!!!<br />Sorry off topic

 

[CATransplant]

Re: Firm yet spongy bulb first start 95 175hp opro

RHIP...rank has its problems...<br /><br />Going from a senior chief to an ensign...what a letdown. Where you were once highly respected, now you're an object of mockery, eh?<br /><br />And so it goes. But...be of good cheer. You'll soon rise in rank again.