Fuel System Delivery Issue Mystery HELP

KathyD19

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This is going to be a little long but I want to give all details so please bear with me.
I have a 2016 Grand Island 20 foot pontoon with a 60hp Mercury 4 Stroke Force outboard (same age as boat).
Last August, it started bogging down and acting like it was fuel starved, wanting to die. I squeezed the primer bulb and it got it going again but I had to continue doing that so we could get back to the dock. I noticed the original external gas cans looked cracked and I figured they were the issue so I bought a brand new Sceptor brand 12 gallon gas tank. Still had issues. So I began replacing things in the fuel system. Last year I replaced: all fuel lines and the primer bulb, both of the fuel filters, the spark plugs and the low pressure fuel pump. Still had the same issue.
I put it up for the winter and decided to tackle it when our lake reopened in April. I had emptied the gas and put new in, with stabilizers and injector cleaners. We got a lot of rain this Spring and the boat sits outside so I couldn't do too much more. I called two different marine mechanics to pick their brains and they said all that I had checked and replaced so far was what they would have done as well. They told me to check the VST and that it may be the high pressure fuel pump going bad. So I drained the VST (fuel looked fine, checked the screens in there and they were fine as well). I also checked the fuel pressure and it was fine on the muffs. Put it all back together and was still having the same issue but now I was getting a warning horn. I tested fuel pressure in the water as it was running and it was fine then dropped dramatically as it bogged down and threatened to die.
Gave up on solving this mystery myself and took it to an established marine mechanic. He went through everything I had done to that point and said it was all correct, but he noticed that the gas can was bulging in the heat. With the new EPA requirements, those tanks do swell up and are supposed to self-vent at a certain PSI. But he checked it and said it wasn't venting at all and that the continued swelling had blown out the gasket in the uptake seal and had allowed rain water to contaminate the fuel. He emptied all of that and ran fresh fuel through it. He wasn't getting any error codes from the computer anymore (all the code said was "fuel system" nothing more specific) but it did still have a warning beep. He was puzzled at that but said it seemed to be running fine on the muffs now with good fuel. I purchased a new tank from him, one that he "modifies" from the EPA issue so it vents properly like the old ones used to. Back home and lake tested it and it was still bogging down and had the warning beeps (they varied each time I started it up). I called the mechanic and he said the only other thing he could think would be the high pressure fuel pump was going out and needed replaced. I hauled it back there and paid for him to replace that. While I was there, so sure that this would finally be the last fix, I also had them replace the impeller since they had it there (it was fine but it had been three years....few hours but still). Back home, back in the water and running worse than ever. All kind of different warning beeps upon start up, running so rough that I wasn't sure I could get it bac to the dock to re-trailer it. Called him again and offered to sell him the boat. I am just so sick and tired of throwing money at it and never getting to use it. He said the very last thing would be to replace the ECU and that was almost $1100. There was simply nothing else left. I thought about it for a week, didn't think I could sell it to anyone else if it needed that done and couldn't be used as it was. So I went ahead and told him to order the ECU and I'd take the boat back in. He had it a week and called me to tell me good news. That as he removed the harness to hook up the new ECU, he noticed "brown, heated spots" on the harness over two of the connector areas. He said that two of the connections/pins (can't remember exactly what he called them) on the harness were loose and kind of folded over on themselves. So he took the harness off and to his bench and repaired them. When he put it back on, the motor ran great (again on muffs) and threw no more codes, had no more warning horns or anything. So that was only $350 for that repair vs $1100 for the ECU. I was thrilled. Got it home and took it out on the lake yesterday. She purred like a well-fed kitten and we putted around at a little less than 1/2 throttle for about 45 min. Then when my husband put the throttle up just a little bit, I could hear the tone in the motor change and feel the slight bog. I looked at him to see if he had throttled down and he shook his head no. It was doing it again, although more subtle this time. Whenever he would throttle up even a little, it would bog and surge, bog and surge. I checked the fuel tank cap and even loosened it just in case it wasn't venting and that didn't do anything to help. Out of routine, I pumped the primer bulb a few times to force fuel to the motor. We throttled down and headed back to the dock to give up for the day.

If you've read this far, I greatly, greatly appreciate your interest. I've done all I can do, I've thrown a lot of money at this and I don't know what else to do or what direction to go. If this will let me attach a short video I took yesterday, turn up the volume and you can hear the motor bogging/trying to recover and see me sway in reaction to the change in speed. I welcome all advice. Thank you so much!
 

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alldodge

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Moved your thread to Merc OB because it's a motor problem, not the toon

They told me to check the VST and that it may be the high pressure fuel pump going bad. So I drained the VST (fuel looked fine, checked the screens in there and they were fine as well). I also checked the fuel pressure and it was fine on the muffs.
What was the fuel pressure reading?

Back home and lake tested it and it was still bogging down and had the warning beeps (they varied each time I started it up).

He wasn't getting any error codes from the computer anymore (all the code said was "fuel system" nothing more specific) but it did still have a warning beep.
I'm wondering just what kind of scanner he has, or even if he has one that will actually read the codes. So far mechanic appears to be a parts changer and not a Marine Tech

A scanner like Rinda's Techmate Pro, or Diacom software needs to be used under load. Also connecting a fuel pressure gauge on muffs is much different when under load

The scanners in the link above is what someone needs to read info from the motor. Need either Techmate Pro kit 94070m or Diacom 94030g and kits include adapters 94029 and 94032
 

KathyD19

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Messages
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Moved your thread to Merc OB because it's a motor problem, not the toon


What was the fuel pressure reading?




I'm wondering just what kind of scanner he has, or even if he has one that will actually read the codes. So far mechanic appears to be a parts changer and not a Marine Tech

A scanner like Rinda's Techmate Pro, or Diacom software needs to be used under load. Also connecting a fuel pressure gauge on muffs is much different when under load

The scanners in the link above is what someone needs to read info from the motor. Need either Techmate Pro kit 94070m or Diacom 94030g and kits include adapters 94029 and 94032
Thank you for moving my post to the appropriate place; I wasn't sure where to post it. When I took the fuel pressure reading, both on muffs AND on the water under load, it was about 41. I don't know what specific computer he uses to check codes but he's been in business about 30 years and has a very good reputation. So I am assuming he uses something good (but again, we know what assumptions do).
 

alldodge

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Thank you for moving my post to the appropriate place; I wasn't sure where to post it. When I took the fuel pressure reading, both on muffs AND on the water under load, it was about 41. I don't know what specific computer he uses to check codes but he's been in business about 30 years and has a very good reputation. So I am assuming he uses something good (but again, we know what assumptions do).
Not knowing how accurate the gauge used was, 41 is good enough for idle, should be closer 43 at 3/4 to WOT. Again it looks like fuel pressure is not the issue

Not putting the guy down, but there are some Marine folks that are great folks and may or may not be Dealer certified. Not that they need to be certified if they keep up with latest Tech. But only way to keep up with the latest is to be a Dealer

There is a guy here @muc which is a master retired Tech and if we can get him involved it will be great. That said if MUC comes he will want the motor serial number to start with and a bunch more to figure it out
 
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KathyD19

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Not knowing how accurate the gauge used was, 41 is good enough for idle, should be closer 43 at 3/4 to WOT. Again it looks like fuel pressure is not the issue

Not putting the guy down, but there are some Marine folks that are great folks and may or may not be Dealer certified. Not that they need to be certified if they keep up with latest Tech. But only way to keep up with the latest is to be a Dealer

There is a guy here @muc which is a master retired Tech and if we can get him involved it will be great. That said if MUC comes he will want the motor serial number to start with and a bunch more to figure it out
Thank you. I will have to go to the boat, which is currently at my dock at the lake to get the model/serial number and all for you/him. I can maybe do that tomorrow. I had taken pictures of it when I was working through all the issues myself but I deleted them from my phone and they've since disappeared. :(
 

KathyD19

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Thank you. I will have to go to the boat, which is currently at my dock at the lake to get the model/serial number and all for you/him. I can maybe do that tomorrow. I had taken pictures of it when I was working through all the issues myself but I deleted them from my phone and they've since disappeared. :(
 

KathyD19

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I have the Model and Serial numbers! The Model #: 1F60453LZ and the Serial # is: 1C481103
 

muc

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I have the Model and Serial numbers! The Model #: 1F60453LZ and the Serial # is: 1C481103
The status of the motor is that it now starts and runs fine up to 1/2 throttle, but starts to surge over 1/2 throttle?

Pumping the bulb doesn't help?

No warning horn when this happens?

Do you still get the single beep when you turn the key on?
 

KathyD19

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Yes it starts easily and runs beautifully but I don't think it made the usual beep at start up. Can't be 100% that it didn't beep, my husband isn't sure either so I'd have to start it again to see. Pumping the bulb did seem to help (it would help it level out and behave a little further then start bogging down again). No warning horn at all when it's happening now. I don't know if it's a "surge" as much as it is trying to die and slows down then tries to get back up to speed so that feels like it's surging. And in general it does NOT do it at low speed only at the mid to higher RPMs

Thank you so much for taking an interest in this.
 

muc

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When you replaced the low pressure fuel pump, was it because testing said it was bad or just guessing? Did you use a Mercury Marine pump from a authorized dealer or off of a place like amazon?

Do you have a Mercury Marine authorized dealer near you? Preferably one on the water or close by water? Because it sounds like this will need to be in the water for testing.


Unfortunately it seems you might have picked the wrong tech for this issue. They might not have the level of training this issue requires. They have raised some red flags, but they do seem honest! Most shady techs would have never mentioned the wiring harness problem and sold you the new ECM.

Depending on the answers to the above question, I'm guessing that to resolve this issue will require a scan tool, a vacuum gauge, a low pressure fuel gauge and the high pressure gauge. Is this something you will want to do?

At this point without the warning horn going off --- I don't see an "easy" fix.
 

muc

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I was typing during your reply.

The single beep is important. Very. Please check.

Pumping the bulb and having it help might mean that you could skip the scan tool and start with the 2 fuel gauges.
 

muc

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The slow down and increase in engine speed could be fuel or it could be the ECM going into guardian mode. This is where the scan tool or warning horn would tell if the ECM is cutting back RPM until the problem goes away and then repeating the cycle. The ECM doesn't monitor the fuel pressure.
 

KathyD19

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Thank you again for your help with this! I will try to answer each of your questions as asked:
I feel like the marine mechanic is a "good guy"; he doesn't push me on repairs or parts and he has a ton of MUCH higher value boats on his lot to work on, rather known to be the guy who is the last resort when others can't figure problems out. Sadly I'm in a rural area of central Illinois so not a whole lot of choice for places to go as far as a certified Mercury Marine tech, let alone one on the water. But I will check the link you added! The only gauge I had was a "fuel pressure gauge" and I attached it at the Shrader valve near the VST, so I am assuming that only tests the high pressure fuel. I wasn't aware that there was a port to attach to on the low pressure pump and I don't know how to check the vacuum with a gauge. Can I use the basic fuel pressure gauge for the low pressure fuel pump as well?
I admit, I bought a low pressure pump on Amazon. I know, probably cheap Chinese crap. I can invest in getting an OEM Quicksilver one for close to $200 or the mechanic said he has good results with the Sierra brand one (for $133). My only boat experience was previously noted on here when I jumped in head first and began rebuilding a 1956 Johnson Javelin outboard a few years back. Like a boss! ;) ) I do a lot of small engine stuff and I am currently also rebuilding a mini skid steer (also a piece of cheap chinese crap) by redoing the hydraulics and now rebuilding all four idler wheels, so I'm handy but very willing to learn.
I've been wracking my brain on this and the only thing I can think of is that if I had water in the fuel when I put the boat up for winter (it's stored in a covered shed at our local fairgrounds but not a heated enviroment) that perhaps the water in the fuel froze over the midwestern winter and that could have damaged the diaphragm in the low pressure fuel pump? Just a potential theory....

I will go to the lake tomorrow and start the motor to see if the start-up beep occurs so I can give you a solid answer.
 

KathyD19

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The slow down and increase in engine speed could be fuel or it could be the ECM going into guardian mode. This is where the scan tool or warning horn would tell if the ECM is cutting back RPM until the problem goes away and then repeating the cycle. The ECM doesn't monitor the fuel pressure.
I just got back from the lake and checked the boat for the start-up beep. It DOES beep briefly when started. I know you said that was important so I wanted to share that with you ASAP. It starts easily and runs smoothly in neutral and low speeds. I also checked to see the brand of low pressure fuel pump that I installed last year and it was marked as EMP (Engineered Marine Products). So it wasn't Sierra or Quicksilver. If you think I should replace with one of those two brands, that's a relatively easy swap out. I just wasn't sure if I should keep throwing parts at this or wait to see if you had any other ideas.
 

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KathyD19

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I just got back from the lake and checked the boat for the start-up beep. It DOES beep briefly when started. I know you said that was important so I wanted to share that with you ASAP. It starts easily and runs smoothly in neutral and low speeds. I also checked to see the brand of low pressure fuel pump that I installed last year and it was marked as EMP (Engineered Marine Products). So it wasn't Sierra or Quicksilver. If you think I should replace with one of those two brands, that's a relatively easy swap out. I just wasn't sure if I should keep throwing parts at this or wait to see if you had any other ideas.
 

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