PROXS 175 idle issue for a while on the water the other day, now it’s fine?

[bman5150]

I recently replaced my spark plugs. Took the boat out using leftover but treated gas from November 2021 and it ran great. Idled well; started just fine and ran well.

My last outing referenced above was early last week. During that outing, I finally used most of my old gas from November 2021. So, when I went out this past Friday I put in 15 gallons of 87 octane, which I treated with mercury fuel treatment and Mercury cleaner which I’ve also used each time I’ve ever gassed up the boat. Early on, the motor started, idled and ran well. Then after fishing for about 90 minutes, I went to start it and it started but idled horribly. It would not stay idled-would die after sputtering for a few seconds. I attempted to start it several more times and got the same result. Then, I started it and while it was sputtering, I quickly put it in gear and hit the gas. This allowed me to get going and once I was above around 1800 rpm it ran perfectly fine. Also idled fine after the run. Fished for 30 more minutes, the tried to start it and had the same sputtering idle. Got it going the same way.

Then the remainder of the evening, I had no issues.

Think the fuel cleaner broke something free and temporarily caused a fuel flow issue in the pump, fuel rails or an injector? I had no warning beeps. Engine serial number is in my signature.

[SilverFox579]

Did you pump the bulb prior to either of those starting events?

[bman5150]

Yes, I did prior to all but the last two starts where I didn’t have a problem.

[crawlerHarness]

Was the 87 octane Ethanol Free?

The reason I ask.....is it is darn near impossible to find Ethanol free 87 octane in Wisconsin and Michigan. It is all 89 or 91 octane.

[bman5150]

It was 10% ethanol 87 but that’s what I always fill up with. I also always add mercury fuel treatment to the gas.

[SilverFox579]

Not the E-10. Should be running this cocktail in every tank...

-1oz Mercury QuickCare +
-1oz Mercury QuickLeen
----------------------------
Per 5 Gallons of Fuel (in EVERY TANK).

In addition to the above, it is acceptable to add 150:1 mix of Premium PLUS in the fuel tank (for OPTIMAX engine models). This has been proven to benefit fuel system components by providing additional lubrication ONLY to the fuel system components (especially the direct injectors- which are often left DRY after engine shutdown).

(If leaving fuel in boat for more than 30 days, be sure to also add Mercury QuickStor).

IMHO, the Premium Plus @ 150:1 should be strongly recommended to protect the DIs.

[JOE54]

^^^^^^+1

[bman5150]

Still chasing this problem, but I think I’ve narrowed it down a bit. Same deal-pump bulb to start day, motor starts and runs great. Fish for a while, try to start motor and it won’t stay started and seems fuel starved. I figured out that if I pump the fuel bulb before every start, I have no issues. So, it’s losing vacuum somewhere in the fuel line. Another possibility is that after stopping the motor and letting it sit, the fuel line is getting heated up more than usual and causing vapor lock. But I’m not sure if that would make the bulb soft? It’s soft before every start so something is going on. In my entire time I’ve had the boat, I’ve never had to pump the bulb more than 1-2 times in an entire day of fishing.

What could cause a leak down of the fuel line? Do bulbs have any sort of check valve that prevents fuel from draining away from the motor past the bulb?

Bulb flow arrow is pointed towards the motor.

Any thoughts on some things I can easily troubleshoot?

[leonreno]

Bulbs have check valves. But the bulb will not remain hard after the motor is running, the fuel is sucked from the tank by the motor. The bulb will become soft but remain mostly full after running the motor. It is a common problem with the fuels of today that when the motor is cut off the fuel sits in a hot motor and vaporizes some and can cause vapor bubbles in the fuel system. Pumping the bulb helps compress out these vapor bubbles. Now that maybe the solution but you could have other problems too. Have you checked your fuel lines for deterioration on the inside. Also have you checked your fuel pressure at start up and idle?

[JOE54]

vapor lock in this heat is a problem for sure

[bman5150]

This issue started only after I fueled up a month ago. I haven’t purchased gas since. I’m wondering if the gas station I bought the fuel from had more than 10% in the gas. It’s my understanding that ethanol decreases the temperature at which fuel will vaporize.

I’ve used most of the 20 gallons of fuel I bought, so I’m going to fuel up with some non-ethanol gas as my next step and see if that fixes it. Looks like the marina on the lake I fish has some and so do area Sheetz gas stations.

I haven’t tested the fuel pressure at startup and idle - but will if new gas doesn’t fix it.

Thanks guys. LMK if anyone has any other ideas.

[adchunts]

Take a look at Don’s sticky post regarding fuel lines.

http://www.bbcboards.net/showthread.php?t=22490

I ran into this on my 2007. If you have the old lines, you need to replace them ASAP.

[EuropeanAM]

This issue started only after I fueled up a month ago. I haven’t purchased gas since. I’m wondering if the gas station I bought the fuel from had more than 10% in the gas. It’s my understanding that ethanol decreases the temperature at which fuel will vaporize.

I’ve used most of the 20 gallons of fuel I bought, so I’m going to fuel up with some non-ethanol gas as my next step and see if that fixes it. Looks like the marina on the lake I fish has some and so do area Sheetz gas stations.

I haven’t tested the fuel pressure at startup and idle - but will if new gas doesn’t fix it.

Thanks guys. LMK if anyone has any other ideas.

Fuel from over a month ago probably isn't even a suitable blend for today's use. Blends are changing CONSTANTLY now days.

It is important to pump that primer bulb firm before EVERY engine start. This is even more critical in temps that reach 60F or above (some blends may literally boil and vaporize in the fuel supply line at or above 60F).

[bman5150]

My fuel line between the bulb and motor is gray with blue lettering. I had it replaced in 2014 as preventative maintenance. From the bulb to the tank is a bigger diameter black fuel hose likely the original that came with the boat (2008). But I would think that if I was having debris breaking off in the fuel from the hose, I couldn’t “fix” my issue with just pumping the bulb before each start. I also have no issues when running at speed.

based on Don’s comments, I’m now really starting to think the issue is vapor lock. Me pumping the bulb before each start fixes that issue. The only thing that seems odd to me is I never used to have to do this. I’m the original owner too. Maybe my motor is running a little hot after shutdown. I do see it “pee” for a short period after shutdown like I often have seen in the past. I’m assuming this is by design so it helps prevent overheating once you shut down the motor after a long WOT run.

[leonreno]

I believe it is best to not turn off the motor as soon as you finish a long run. It’s best to stop short a bit and then idle to the specific spot you are headed to. This allows the motor to cool down a bit before you shut down. If you see it peeing and the motor is off, it’s just draining not actually running any cooling water through the motor. The pump only works when the motor is running, it’s on the driveshaft, so the driveshaft has to be spinning for the water to be pumping.

[EuropeanAM]

Although I would definitely recommend replacing those lines as a maintenance measure (5-6 years on the gray line and bulb is probably prudent), the real variable that would account for why you might not have previously done this is this liquid "gold" we buy at the pumps. Some call it "fuel"... (term used very loosely).

[SilverFox579]

I believe it is best to not turn off the motor as soon as you finish a long run. It’s best to stop short a bit and then idle to the specific spot you are headed to. This allows the motor to cool down a bit before you shut down. If you see it peeing and the motor is off, it’s just draining not actually running any cooling water through the motor. The pump only works when the motor is running, it’s on the driveshaft, so the driveshaft has to be spinning for the water to be pumping.

^^^^+1^^^^

[bman5150]

Update for those that might have the same issue.

Bought some ethanol-free gas from Sheetz. Since adding this gas, no issues with starting and no issues period. Something was up with the gas I bought prior to buying the ethanol free gas from Sheetz. Strange. Who knows what the deal was with that gas but maybe it had too much ethanol in it. Just glad my motor is running great. Ran it fri-sat and had zero issues.

[JOE54]