60 HP Merc Fuel problem

[Outlaw]

Fuel doesn't want to prime with primer bulb.Had it working first try of the year,wouldn't today,with this being an ongoing issue.Tried backflushing Autoblend(which seemed to have cured the problem last year),new fuel lines,fuel fittings,etc. but just doesn't want to draw.Any suggestions on what to try next?

[WHITEINDIAN]

the bulb won't firm up? new fuel line i'm assuming you got a new hose with a new bulb? won't pressuer up you have the inlet end of the hose on the motor side.
lol i dunno but the question confused me. isn't hard to do.

[Outlaw]

The bulb won't firm up with no fuel being drawn from either carry on or main(bow) tank.At least last year the fuel would draw from the carry on tank.No fuel getting to the Autoblend oil injection tank or motor.Yes new lines and primer bulb.

[WHITEINDIAN]

stuck needle? fuel just flowing through the bowl? sorry man i might be able to help better if i could see it.

[Outlaw]

no stuck needle as no fuel is even getting to oil injection(mix)tank,it runs when fuel gets to carbs.Problem is in getting fuel to pull to the Autoblend oil mix tank,and therefore beyond to fuel pump on motor and then to carbs.Primer bulb will not harden like it should.

[StupidSheet]

Problem with the air valve on the tank?

[Outlaw]

No,been there done that bow tank is vented and carry-on tank air valve is opened.
I'm kinda wondering if the problem may lie in the Autoblend "pump", as it is supposed to have a diaphram inside, but I'm not sure it helps to "pull" fuel?
Fuel pump diaphram(s) on the Merc has been rebuilt but it needs to get fuel to be able to pump.

[pipes]

Is the auto-blend part of the carry on fuel tank.Can u post a pic of ur motor and fuel tank.Something i have also tried was pulling the fuel line off at the top of the primer bulb and holding ur thumb on the end and prime it a couple of times and releasing your thumb to vaccum the fuel up to the bulb then installing the fuel line back on.

[silverback]

do like pipes said. if you can prime that far than you're problem toward auto blend tank. is there a selector valve between bow tank and carry on tank, was it replaced? it may be drawing air.
you could also try LIGHTLY pressurising the fuel line and checking for a leak. this is likely not the "recommended" procedure.

[Outlaw]

Originally Posted by pipes

Is the auto-blend part of the carry on fuel tank.Can u post a pic of ur motor and fuel tank.Something i have also tried was pulling the fuel line off at the top of the primer bulb and holding ur thumb on the end and prime it a couple of times and releasing your thumb to vaccum the fuel up to the bulb then installing the fuel line back on.

AutoBlend unit is separate from either fuel tank and mounted inside on the transom.First noticed fuel problem(few years ago) when fuel delivery wouldn't keep up with WOT using the bow tank.Problem progressed and I tried switching to carry on and situation was remedied.I just took apart the Autoblend and diaphram looked intact and in good shape.Fuel is drawn from carry-on tank but bulb doesn't firm up completely like I was used to it being.Boat didn't see water last year as high waters kept it on land.Good hint on pressuring up and priming the fuel up to the bulb.Thanks.
From what I can tell the diaphram just pulls oil into mixing chamber but I could be wrong as I'm not familiar with the units operating principals.

Originally Posted by silverback

do like pipes said. if you can prime that far than you're problem toward auto blend tank. is there a selector valve between bow tank and carry on tank, was it replaced? it may be drawing air.
you could also try LIGHTLY pressurising the fuel line and checking for a leak. this is likely not the "recommended" procedure.

No selector valve as I just unclip connectors and switch to other fuel tank by line connection.

I will see if I can get some pics soon as I had computer repaired and have to install program(s) yet so may be awhile.

[Outlaw]

Seems like there is no draw now even with hand over primer bulb.Tried using a vacuum guage and found no vacuum even with tank vent closed leading me to believe diaphram or faulty filter as hoses are all tightened and replaced.I did get a small amount of fuel drawn with the vacuum guage but no where close to what it should have been.Gonna replace the diaphram and fuel filter in the "Autoblend"as I believe this is where the problem lies.Filter has a broken mounting tab but doesn't seem to leak but you never know.It does flow through and is not blocked.
Any other suggestions welcome as I am out of ideas now.
Motor is 1990 60 HP.

[pipes]

look's like fuel pump was rebuilt.pressure test auto blend from primer bulb back.Should at least hold 5-10 psi.I would suggest this first then pressurize to the fuel pump.Those check valves that come in the rebuild kit need to be installed correctly or will give 3 unexpected fuel starvation symtoms.Thank's for the pic.when turning over unit do u feel pulsation from the fuel line.When these unit's are running they should show 3-5 psi at idle.

[Outlaw]

No pulsation or any flow is happening.Would not hold any psi(of vacuum) immediately after pumping any vacuum pressure.Should have tried rigging up a bypass of Autoblend unit and checking if any fuel flow was present but was way too hot outside at the time.

[Outlaw]

Originally Posted by pipes

look's like fuel pump was rebuilt.pressure test auto blend from primer bulb back.Should at least hold 5-10 psi.I would suggest this first then pressurize to the fuel pump.Those check valves that come in the rebuild kit need to be installed correctly or will give 3 unexpected fuel starvation symtoms.Thank's for the pic.when turning over unit do u feel pulsation from the fuel line.When these unit's are running they should show 3-5 psi at idle.

What's the correct way to install those check valves?Had the boat out today with Autoblend unit off(running mix fuel in the large bow tank) and had fuel starvation numerous times.The primer bulb(new) now siphons up fuel and you can hear the vacuum drawing in the fuel line.Gonna rebuild that Autoblend unit as I got the diaphram coming and fuel filter will be replaced.
What are the numerous symptoms?The boat would run WOT then suddenly run out of fuel,or starve,surging sometimes or sputter.I'm betting those check valves are shot.

[Outlaw]

Think I found the problem tonight........took apart the fuel pump and looks like the rear spring/cap(inside fuel pump) towards the engine(pulse/vacuum) port was missing.Found it funny as there were 2 spring/caps in the kit and only one inside the fuel pump.Upon researching pump assembly online I quickly learned where the second spring assembly was supposed to be.I installed a spare spring/cap I had in a diaphram kit I had kicking around the parts shelf.Will finish line hook-ups in the morning and test run although I'm now sure that the problem is solved as this spring must control diaphram pulse flow movement of fuel.

[Outlaw]

Amazing how much drivability problems one missing little spring and cap can create.Performance is back to A-1 @ WOT.No fuel starvation.This Merc always did like running WFO and still doesn't putt well at low idle..Gotta bump up the idle as it likes to stall after any extended idling.

[StupidSheet]

Glad to see you have it fixed. Congrats!

[pipes]

Awesome glad u corrected ur fuel starvation problem.Did someone have the fuel pump apart before.Just guessed at the fuel pump ,but seen that scenario many times.Thumbs -up.

[Outlaw]

Gotta fess up and admit I had it apart for rebuild.I do remember installing both spring/cap assemblies along with the new diaphrams and gaskets.Must have fallen out at some point when installing back on outboard when screwing everything back together.Funny thing is I recall finding this spring/cap assembly at some point like a year later,as the boat didn't get used too much at the time,and wondering WTF that piece was and where it came from as it never dawned on me as to what it was.This is why I never took that pump apart sooner.All running problems pointed towards fuel delivery but I was so sure it wasn't that pump unit.Live and learn.