1986 90hp johnson primer bulb collapsing..hear me out

[roonie]

I have 120 psi x4.was just rebuilt before I purchased.
I've pulled the bulb, it pumps fine either horizontal or upright.
I've pulled the tank pickups,CLEAN/CLEAR.
I've pulled the fuel filter
,clean it....it screws apart(nice)
I did find the 8" hose from filter back to the engine fuel conn. Was Grey (liner), yes it was collapsed/disssinagrated... so I've replaced that hose.
Is there a slight chance a piece of that collapsed hose could have gotten lodged, somewhere?
Not sure where to look next.
The pieces of liner can't go any further than the fuel filter....pieces can't flow backwards. Runs like a champion when the bulb is pumped...but won't stay running.
I did disconnect the vro and I'm mixing my fuel but that was long before this issue popped up.thanks in advance.the 8 inch fuel line from fuel conn. At engine to fuel filter.

 

[havoc_squad]

Use test tank with its own hose and connection to see if primer bulb collapses due to engine running.

If issue remains, then your fuel issue is in the outboard side of things. There's no point in chasing after the fuel lines and tank because you just proved the issue is in your outboard.

If issue stops, you have a restriction on your permeant fuel tank setup.

What is the vacuum reading on the fuel hose behind the water seperating fuel filter while the engine is running when the primer bulb collapses?

If it is higher than a value of 4 inches of mercury, the restriction is in the fuel tank.

If the vacuum level is lower than 4 inches of mercury, put the gauge after water separating fuel filter but BEFORE the primer bulb. Otherwise you may damage your low pressure/vacuum gauge if you squeeze the primer bulb due to the gauge being on the pressure size of things.

Does that show a vacuum of higher than 4 inches of mercury? If so, the issue is either with the water seperating fuel filter assemby, fuel hose, primer bulb, or fuel line connector to the outboard.

Where there is a restriction of fuel flow/high vacuum pulling, you will have high vacuum. Where there is little restriction to fuel flow the vacuum is low.

 

[brodmann]

If you have access to an air compressor, I'd blow out all the fuel lines starting at motor and blowing toward the tank. Also, need to check the vent hose. Also, if one section of hose has deteriorated, you may have the same problem between the tank and filter. Also check the screen on the fuel pump. When you say you've cleaned the filter, was that a fuel/water type filter or inline filter under the cowling? If one hose has started breaking down, I'd replace everything. If primer bulb is collapsing, then a fuel blockage is between tank and bulb. I'm assuming that it's a built in tank.

 

[roonie]

Only other question i have is...., if i manually tested the bulb in water, could it still be a faulty fuel bulb, like weak spring inside but works fine on bench test?
Thanks folks, that's quality answers I was looking for, now I have something to go on.
My tanks are 6 imp gal. Portable older metal tanks, very clean considering their age.
I am at a bit of disadvantage cashwise as I have a disability.
I will post back in a couple days hopefully with results.

 

[roonie]

brodmann, its in line under cowling.
The fuel filter fuel level inside filter seems only half full in use.
It's a serviceable filter.i got it very clean

 

[jimmbo]

If the`Primer Bulb is collapsing, then there an Restriction, in the Fuel Line, Fuel Pickup, Pickup Strainer, or in the Tank's Ventilation. Loosening of the Filler Cap, can verify/rule out Tank Ventilation.

 

[guy48065]

If you have access to an air compressor, I'd blow out all the fuel lines starting at motor and blowing toward the tank.

There are check valves in the fuel line assembly that prevent flow in that direction.
It might take some juggling but I would disconnect the line and hold open the spring-loaded balls in both connectors while blowing low pressure air in the normal direction.

Another thing to try is remove the engine-end connector, set the tank on a table, then squeeze the bulb to get fuel flowing towards a container on the floor. Then see if it continues to flow on it's own. I'm pretty sure fuel it's supposed to siphon through all the valves & bulb just by gravity flow.

 

[roonie]

OK,will do these things guys.
Yes ,I have tested the tank and the fuel does flow on its own " down to the floor"

I no longer have a collapsed primer bulb, I do still have to pump the bulb to keep the engine running now though.the collapsed bulb happened only at the start of these issues.
Would it be possible with fuel line connector attatched to engine, to have the Grey fuel line particles get pulled back BEHIND the fuel line connecter ball and plug it along with the small holeshifaft on engine that the connecter plugs onto...it's a very small passage way
Also, should my fuel filter be fuller than this?
I never have been able to find a connector that fits tightly onto the tanks or engine side....they all seem to spring back on an angle but never caused an issue before this.
I appreciate all the help folks

 

[havoc_squad]

Other than what Jimbo mentioned in loosening the fill cap on fuel tank to rule out tank vent issues, everyone's recommendations have been dancing around the necessary test.

Do you have higher than 4 inches of vacuum on the fuel line going to the outboard when engine is running?

If so you have a restriction behind that test fitting towards the tank, if not then you have either a pump issue or restriction further up to the outboard.

Throwing guesses with parts cannon is going to be more expensive than buying a low pressure fuel/vacuum gauge and some brass npt barb fittings to diagnose the problem and know facts, not maybes.

If OP wants to save money, buy those tools to diagnose because 1 hour of shop labor to diagnose cost double what those tools would cost to do this test once.

Maybe a local auto parts store has a vacuum gauge available using the loaner tool program that some offer with deposit.

 

[jimmbo]

OK,will do these things guys.
Yes ,I have tested the tank and the fuel does flow on its own " down to the floor"

I no longer have a collapsed primer bulb, I do still have to pump the bulb to keep the engine running now though.the collapsed bulb happened only at the start of these issues.
Would it be possible with fuel line connector attatched to engine, to have the Grey fuel line particles get pulled back BEHIND the fuel line connecter ball and plug it along with the small holeshifaft on engine that the connecter plugs onto...it's a very small passage way
Also, should my fuel filter be fuller than this?
I never have been able to find a connector that fits tightly onto the tanks or engine side....they all seem to spring back on an angle but never caused an issue before this.
I appreciate all the help folks

So now the bulb is no longer collapsing, but fuel still not getting to the Carb. Air leak in the Hose prior to the bulb, or No leak, and now the fuel Pump is Pooched.

 

[flyingscott]

Is the arrow on the bulb pointing to the engine?

 

[roonie]

Yes, arrow pointing toward engine, ..first thing I checked, also held bulb upright

 

[roonie]

Perhaps I should hook the vro back up. The reason I disconnected vro is first start up this spring I had terrible smoking...worse than ever...so...maybe fuel pump not working?.i always have too much smoke and poor starting issues with vro. I took the fuel/oil pump apart not long ago, she looks like new inside. After this season, I'm going back to vro disconnect and manual fuel pump.
to me ,vro is like a accident waiting to happen, she smokes and I can't troll down as it runs too rich, poor starting...just too many things to go wrong....including a small electronic circuit board

 

[brodmann]

If pumping the primer bulb keeps the motor running, you have a bad fuel pump. Pretty cheap/easy fix.

 

[kbait]

My ‘84 90hp VRO was converted to premix by prior owner. He said a ‘83 90hp type fuel pump was used (‘84 was first VRO year)..

 

[brodmann]

The fuel pump and oil pump are completely separate pumps, right? Is fuel pump for VRO different than standard fuel pump?

 

[havoc_squad]

The fuel pump and oil pump are completely separate pumps, right? Is fuel pump for VRO different than standard fuel pump?

VRO fuel pump used by Evinrude/Johnson for this engine is a single unit assembly. For more questions involving this, I suggest opening a new topic. Otherwise it may be considered thread hijacking by the moderators.

The parts diagram used for ordering parts would be a powerful clue if looked at, very simple compared to the larger V6 carbed engines and ones with fuel injection.

 

[racerone]

Agrreed the VRO is a combination fuel / oil pump and it mixes the 2 according to engine load.-----The early one did not have " no oil warning " feature.----Those should be thrown out and updated with a new pump / wiring kit.

 

[roonie]

Yes, mine is smaller vro pump.it works by the diaphragm sliding back and forth, one side being fuel, the other side being oil. As stated above, not a big fan of vro, too many things can go wrong.i like the simple KISS (keep it simple stupid) method in life.
starts poorly, smokes lots,won't idle down. It's no other problem, ove verified this by disconnecting the unit already.starts great, no smoking...idles right down for trolling!!

 

[jimmbo]

Sounds like a ruptured diaphragm/leaky shaft o-ring in the VRO pump