Let me start out by saying I am not a factory trained marine professional. I'm an over-educated, certified to the hilt automotive professional. Worse yet, this is not a problem I have been able to personally verify, though there is a catch to that.
This is a 2018 Mercury 115/80 4 stroke injected jet outboard. The engine is full serviced/maintained and runs PERFECTLY, until it is shut off, sits for a few minutes while you go get the truck/trailer, then won't restart. Of course, the ONE TIME I was with him when it did this, the instant I removed the cowl to check for spark, it started up and would NOT act up again the rest of the night.
My mind has me wanting to investigate the coolant temp sensor and possibly see if it isn't losing spark, but I can't get this to fail without it being on the water, and being a disabled veteran whose back has been a train wreck all year long, just getting a day when I can stand up and he's available has been an exercise in futility.
Last year this did the same thing, but one night completely died and after it was at 2 marinas to be checked and neither was able to get it started again I went over everything I could without a marine scanner and I found the low pressure fuel pump fuse blown. I figured that fixed it as it didn't seem to act up again afterwards, though this was towards the end of the season and it was cooler out which once again make me think temperature affecting something, but without a scanner, I'm guessing.
WHY it instantly started the one time this happened with me there when I removed the cowl and plugged in an in-line spark tester may very well be coincidence, but I don't think so. I ran that outboard for 2 hours after that happened that evening though the cowl was on the shore, in the back of his truck the entire time I was trying to get it to act up! I ran it for 10 miles, shut it off, waited 5 minutes, instant restart. Ran it a few more miles, shut it off, let it sit for 8 minutes, instant restart. Ran it the few miles back to the ramp, let it sit for 11 minutes and again, started the second I hit the key.
I've inspected the cowl, twice. There is no damage to ANYTHING on this, not even a scratch on it. I checked the air induction openings for any restriction and they're perfect. It can't be a gas tank issue as this will run for hours on end. I encountered a bot a few years back that had a plugged tank vent that would starve for fuel after running for a few minutes and then run well again until it began to develop a slight vacuum in the gas tank. That was a pretty simple diagnosis/repair but this one is pissing me off. NOT having a scanner is killing me with this although I know there have been countless times I've had an ignition module act up in a similar way on quite a few cars/trucks that showed nothing on the scanner....no codes and even with a dead ignition module NO INFORMATION that would tell you (or give an inexperienced tech reason to look) that the module puked.
My hope is that one of the pro guys here have come across this issue and have an answer. For now I have him running it without the cowl as I physically have been incapable of going down with him the past month and of course it won't act up without the cowl on it!!
BTW...IF any of the pro guys here ever have any automotive issues/questions, feel free to hit me up. I had to sell my shop years ago but I have a pair of degrees and dozen of aftermarket and OEM certs. I still go to schools simply because I've been a "gearhead" my entire life and I still make $120-$150/hr, cash, doing diagnostic/drivability work for shops that used to send that work to my shop anyway, so I have to try to stay as current as I possibly can. Besides, drivability work is one of the few things i can reliably do as I can do it sitting in a wheelchair ASSUMING that the base engine and all basics were properly inspected, which in most cases that's where the problem lies anyway! People know that today's technology is ultra complicated and INSTANTLY blame most issues n the "computer" when no computer on Earth can make up for a broken vacuum line, cracked valve spring, low fuel volume (these were the last 3 causes I was called out to do diagnostic work for, none of which needed to have the electronics diagnosed!) so I've ensured the basics on this have been covered although I have no way of measuring fuel volume/pressure on this outboard.
IDEAS?
This is a 2018 Mercury 115/80 4 stroke injected jet outboard. The engine is full serviced/maintained and runs PERFECTLY, until it is shut off, sits for a few minutes while you go get the truck/trailer, then won't restart. Of course, the ONE TIME I was with him when it did this, the instant I removed the cowl to check for spark, it started up and would NOT act up again the rest of the night.
My mind has me wanting to investigate the coolant temp sensor and possibly see if it isn't losing spark, but I can't get this to fail without it being on the water, and being a disabled veteran whose back has been a train wreck all year long, just getting a day when I can stand up and he's available has been an exercise in futility.
Last year this did the same thing, but one night completely died and after it was at 2 marinas to be checked and neither was able to get it started again I went over everything I could without a marine scanner and I found the low pressure fuel pump fuse blown. I figured that fixed it as it didn't seem to act up again afterwards, though this was towards the end of the season and it was cooler out which once again make me think temperature affecting something, but without a scanner, I'm guessing.
WHY it instantly started the one time this happened with me there when I removed the cowl and plugged in an in-line spark tester may very well be coincidence, but I don't think so. I ran that outboard for 2 hours after that happened that evening though the cowl was on the shore, in the back of his truck the entire time I was trying to get it to act up! I ran it for 10 miles, shut it off, waited 5 minutes, instant restart. Ran it a few more miles, shut it off, let it sit for 8 minutes, instant restart. Ran it the few miles back to the ramp, let it sit for 11 minutes and again, started the second I hit the key.
I've inspected the cowl, twice. There is no damage to ANYTHING on this, not even a scratch on it. I checked the air induction openings for any restriction and they're perfect. It can't be a gas tank issue as this will run for hours on end. I encountered a bot a few years back that had a plugged tank vent that would starve for fuel after running for a few minutes and then run well again until it began to develop a slight vacuum in the gas tank. That was a pretty simple diagnosis/repair but this one is pissing me off. NOT having a scanner is killing me with this although I know there have been countless times I've had an ignition module act up in a similar way on quite a few cars/trucks that showed nothing on the scanner....no codes and even with a dead ignition module NO INFORMATION that would tell you (or give an inexperienced tech reason to look) that the module puked.
My hope is that one of the pro guys here have come across this issue and have an answer. For now I have him running it without the cowl as I physically have been incapable of going down with him the past month and of course it won't act up without the cowl on it!!
BTW...IF any of the pro guys here ever have any automotive issues/questions, feel free to hit me up. I had to sell my shop years ago but I have a pair of degrees and dozen of aftermarket and OEM certs. I still go to schools simply because I've been a "gearhead" my entire life and I still make $120-$150/hr, cash, doing diagnostic/drivability work for shops that used to send that work to my shop anyway, so I have to try to stay as current as I possibly can. Besides, drivability work is one of the few things i can reliably do as I can do it sitting in a wheelchair ASSUMING that the base engine and all basics were properly inspected, which in most cases that's where the problem lies anyway! People know that today's technology is ultra complicated and INSTANTLY blame most issues n the "computer" when no computer on Earth can make up for a broken vacuum line, cracked valve spring, low fuel volume (these were the last 3 causes I was called out to do diagnostic work for, none of which needed to have the electronics diagnosed!) so I've ensured the basics on this have been covered although I have no way of measuring fuel volume/pressure on this outboard.
IDEAS?