1999 Mercury 150 Xr6-primer bulb callapse after sitting

[Umgettinbetta]

First off I'm very thankful for this site... The info and advice is truly priceless. But back to the subject matter. I posted here few weeks ago concerning my "new to me" mercury 150 xr6. At the time I was unsure of the yr but since then I've found out it is a 1999(serial# 0G912040). But the problem I'm having is fuel related. I pump the primer bulb and after following the procedures I've learned from this site she starts up on second turn of key. So awesome!! I proceed to go to my first stop and she gets me there in no time with no cause for concern. She runs beautifully. I'm on my spot, I fish for a while and if I'm off her for better than 20-30 minutes... I have to re-prime the primer bulb as it has lost all fuel/pressure. And the interesting kicker on the restarts is she's harder to get going and needs more idle time. I fish tournaments and this as you could assume becomes time consuming..will someone direct me into the right direction... Your advice will be greatly be appreciated

Btw: on those re-primed re-starts.. Do I treat it as a cold start and perform same cranking procedure??

Bryan

[leonreno]

After running the motor the primer bulb will lose pressure because the motor sucks fuel from tank so the bulb will be under slight vacuum. It should still have fuel in it though. It shouldn’t be really flat, should hold its shape especially after sitting. If it’s completely flat you may have a problem with the tank vent.

You should pump bulb after sitting for awhile, it helps re prime the lines and helps where the gas has formed vapor bubbles from heat soak in the fuel lines.

[Umgettinbetta]

Pump after long periods... Could you give me an estimate on what's considered long? Also how would I determine and solve the tanks venting problem... Sorry if this is a dumb question...

Bryan

[bdmilam84]

always pump the primer bulb before every start. Works for me.

[JOE54]

may need linkage adjustments and timming check also look at pulse diaphragm (check valves)rebuild pump with oem kit

[mxmike]

When I replaced my fuel lines and primer bulb on my XR-6. I moved the primer bulb into the battery compartment and have it positioned so that it stays in a vertical position( flow arrow pointed up) I think it helps to keep the check flapper in the bulb seated and also cooler without the sun beating on it causing the gas to vaporize. It seems to stay "primed/firm" much longer this way.

[leonreno]

Long time sitting would be 10-15 minutes plus, anything that allows the motor heat to soak into the fuel system.if you can get a portable fuel tank, that would be a good way to determine if you have a tank problem. As joe said, pulse fuel pump should be looked at, rebuild kit is less than $30 and easy to do.

[Umgettinbetta]

I will definitely try the spare tank method next... I replaced all the fuel lines from the tank to the motor and replaced check valve... The primer bulb definitely holds pressure lot longer and after fishing for better than 45m I hit the key sometimes it would crank and sometimes it wouldn't. Times it crank it sounds starved of fuel and I have to throttle it up to keep it going. But when I go to idle and try to put her in gear she stalls... Can't seem to get her going right unless I pump ball again... Is this problem still sounding to come from tank/lines or possible fuel pump... Again when she's running... She runs!!!

Bryan

[Umgettinbetta]

Ok another update... I went out on the water all day yesterday...today I go out this afternoon to clean boat up and I decide to check the primer bulb... It's really firm. I pumped it to check it out and it wasn't even one full squeeze b4 it was hard...approaching 24hrs and ball still firm... What you guys think

Bryan

[EuropeanAM]

Primer bulb should be pumped firm before EVERY engine start. Every meaning each one... cold, first, second, hot or otherwise.

Have engine at level trim when you start or idle. As you begin to apply throttle to take off, drop trim down.

Restarts may not require "choke" (which is actually an enrichener).

[Umgettinbetta]

Primer bulb should be pumped firm before EVERY engine start. Every meaning each one... cold, first, second, hot or otherwise.

Have engine at level trim when you start or idle. As you begin to apply throttle to take off, drop trim down.

Restarts may not require "choke" (which is actually an enrichener).

So is this technique(pump ball before every start)for this particular motor? Or is this a practice that should be employed on all 2 strokes... Thanks

[EuropeanAM]

If it has a primer bulb, it should be used. ESPECIALLY critical on these carb-engines.

[Umgettinbetta]

10 4

Thanks

[Umgettinbetta]

If it has a primer bulb, it should be used. ESPECIALLY critical on these carb-engines.

One last question... May sound silly.. But after priming bulb is this just a turn key start? If it doesn't start should I hold for 10 sec and apply throttle.. How should I go about this

Bryan

[EuropeanAM]

Cold starts you already have down, based your above description (with the exception of applying throttle). Cold starts normally do not require throttle (throttle may actually hamper the cold start enrichment from doing it's job).

Warm starts are often turn-key. If engine does not fire off, and you know it's warm, crack the throttle open a bit.

Pump bulb firm for all starts, engine at level trim.

[Umgettinbetta]

Thank you

Bryan

[turfy49431]

I have the same thing with my XR6. Every boat I have ever had, I have only had to prime the bulb in the morning on the first start, then it was fine all day. My XR6 I have to prime it everytime

[Umgettinbetta]

I have the same thing with my XR6. Every boat I have ever had, I have only had to prime the bulb in the morning on the first start, then it was fine all day. My XR6 I have to prime it everytime

Yea... Good info! This is my first high performance outboard... I've owned other boats throughout the yrs and all the outboards were much older than my current xr6. I normally primed the ball first thing in morning and I'm normally good rest of day. But I'm okay with priming it every time as long as I know it's the norm

[lpugh]

When I replaced my fuel lines and primer bulb on my XR-6. I moved the primer bulb into the battery compartment and have it positioned so that it stays in a vertical position( flow arrow pointed up) I think it helps to keep the check flapper in the bulb seated and also cooler without the sun beating on it causing the gas to vaporize. It seems to stay "primed/firm" much longer this way.

A lot of problems can be avoided with this approach, this method pretty much assures not having a large vapor bubble in the bulb. When vapor bubbles are downstream of the pulse pump it will not move much if any at all at low rpm (I.E. vapor lock). The pulses just expand the bubble size and then contract

[EuropeanAM]

I'm not subscribed to the "primer bulb must be mounted vertical" approach. It needs to be able to ROTATE so the arrow points vertical, while pumping the bulb.

Once primed it should be fine laying in any orientation.

The situation with pumping the primer bulb is a FUEL and FUEL BLEND related problem. RVP ratings and overall fuel blends have changed IMMENSELY since the mid 2000's, folks back in the years of MTBE fuels got away with the "once in the morning" approach. Not so with today's fuels, which may vaporize in the fuel line at room temperature (or below).