Looking for help…still

boater2018 said:
I replaced this yesterday. Idk what the 2 short wires are for in the picture though. I removed the original sensor, and replaced with a Sierra one that is a replacement for the OEM. The OEM one had 2 wires. The Sierra part had 3, one red/white, one green/white, and one black ground wire. I hooked the ground wire to the main engine ground. A friend helped me and he called the part the pickup coil, but it’s called the ignition sensor in the parts diagram. I’m no mechanic by all means, but I was thinking this was the main electric part of the distributor and would probably be the part affected by Hall Syndrome?
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Have you ran the boat since replacing?
 
NorCalRobert said:
Have you ran the boat since replacing?
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Yes, that was why I posted last night again. I replaced that, distributor cap, rotor, and ignition coil yesterday and ran the boat. After sitting a short bit when it was hot, it did not restart.
 
I also used a spark tester on one of the plugs on top of the distributor cap and it showed that it was firing when the boat would not start.
 
I mentioned in an earlier post to put a spark checker on a plug wire, that will put that question to bed. Next time out with that on and armed with cold water or freeze spray you should be able to figure this out. You should also be able to view the spray pattern by looking into your throttlebody with the arrestor off.
 
Question: when I tested the boat and had the no start condition after it warmed up and sat a bit, the outside temp was around 79-80 and cloudy. It felt cool but comfortable riding in the boat. Does vapor lock still occur when it’s not that hot outside?
 
We chased a similar problem on my brothers 2015 SLX 250 8.2 Mercruiser Magnum all summer last year and went through a lot of what you have trying to figure it out.
We also sat stranded several times after we thought we had it fixed.

It was the fuel pickup tube.
 
boater2018 said:
Question: when I tested the boat and had the no start condition after it warmed up and sat a bit, the outside temp was around 79-80 and cloudy. It felt cool but comfortable riding in the boat. Does vapor lock still occur when it’s not that hot outside?
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The hotter and more humid the weather the more likely for vapor lock -- BUT vapor lock is caused by high temperatures in the engine compartment and even in cooler weather, poor ventilation or routing of fuel lines can cause things to heat up even when the weather is cooler.

Here is a Mercruiser technical bulletin on vapor lock - a good FYI read.
 

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Tucker K5 said:
We chased a similar problem on my brothers 2015 SLX 250 8.2 Mercruiser Magnum all summer last year and went through a lot of what you have trying to figure it out.
We also sat stranded several times after we thought we had it fixed.

It was the fuel pickup tube.
Click to expand...
Was your issue happening only when it was hot?
 
I know it doesn’t make sense.
If the pickup tube was bad you would think hot or cold doesn’t make a difference.

When it was happening I called an old school motor guy I knew and described all of the symptoms and he said “somebody put ethanol in it didn’t they” I said yes then he said “it’s the pickup tube”.
I argued that didn’t make sense he said “shut up and change the pickup tube”
I called Teague Marine in California because I was considering one of their engines for my boat. While I had him on the phone I asked him about this problem with my brother’s boat.
I described all of the symptoms and he said “it’s the pickup tube”.

We had left the boat at Trident Marina because that’s where we broke down last.

Their mechanic argued with me until I finally went and paid their ransom ($2200.00) to get the boat out of jail then took it down the road to another shop which fixed the problem in one day for $150.00
 
The shop called this morning and said they feel it's vapor locking. They haven't tested it by opening the engine hatch and cooling the lines with water or spray, as I suggested, but they talked about it and feel it's vapor lock. I mentioned the pickup tube to them and he didn't feel that would cause the problem although I mentioned another owner had the same problem and that's what it was. He also said they wouldn't be interested in changing it because it's a plastic tank and if something busted, it would be a bad situation since the tank can't be removed. I guess I'm going to test it one more time this weekend and try leaving the hatch open and some freeze spray and cool water to confirm vapor lock. I tried to turn the fitting the anti-siphon valve was on that the pickup tube was attached to, but it is on there super tight and made me nervous that I would break something. I guess I can understand where they're coming from.
 
Does anyone have a link to the correct antisiphon valve? I can't find an actual part number for it. I assume it's pretty universal.
 
Before you spend a bunch of money on a boost pump you can start by putting thermal sleeves on the fuel lines first. Another cheaper option is routing the fuel return line back to the tank instead of back to the filter housing, that round and around with the excess fuel heats it up.

First thing I do with a new boat is throw that anti syphon away
 
scoflaw said:
Before you spend a bunch of money on a boost pump you can start by putting thermal sleeves on the fuel lines first. Another cheaper option is routing the fuel return line back to the tank instead of back to the filter housing, that round and around with the excess fuel heats it up.

First thing I do with a new boat is throw that anti syphon away
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Gotta call you out on this one…

on a gas boat the anti-siphon is a must unless you replace it with an electric cut off fuel solenoid. Other wisw even the smallest leak would empty the tank into the bilge.

same for the injection return, that would be under pressure, can not be a flexible line.

this is why the coolfuel was created
 
Anyone had any luck curing vapor lock issues with heat insulation/tape on the fuel lines or adding a fan to cool the engine compartment? I have seen several threads online that had no luck with wrapping the fuel lines, and a few that said they added a blower to the engine compartment. Curious to whether anyone has seen definite positive results with these methods. Otherwise, the booster pump may the only option. I'm really open to hear any methods that have cured vapor lock.
 
hughespat57 said:
Gotta call you out on this one…

on a gas boat the anti-siphon is a must unless you replace it with an electric cut off fuel solenoid. Other wisw even the smallest leak would empty the tank into the bilge.

same for the injection return, that would be under pressure, can not be a flexible line.

this is why the coolfuel was created
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No on both, fuel doesn't drain out with syphon valve removed and there is no pressure on the return line because the tank is vented. This is how the high performance crowd handles these problems.
 

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boater2018 said:
Does anyone have a link to the correct antisiphon valve? I can't find an actual part number for it. I assume it's pretty universal.
Click to expand...

Here is an anti siphon valve: https://www.amazon.com/dp/B00E21PVE...VkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl&th=1&psc=1

It's a universal thing - pretty sure 1/4 > 3/8 is what you have, but check it first. Also, resist the temptation to use any type of teflon tape when installing this, it should go on and seal without any tape or sealant. Also, regardless of what anyone says, you need to keep the anti-siphon valve. It will prevent a situation when gas starts siphoning out of your fuel tank in the case of a ruptured fuel line. Fairly unlikely scenario, but it can happen if the fuel line came loose or ruptured and fell below the fuel level in the tank.
 
Arminius said:
NASA's problem with their make work moon jalopy is that they have been taking dumb down pills with ESG hiring mandates. This allows us to relate to them although we don't work in clouds of hydrogen, shown to be bad news in the Hindenberg disaster although the future of Airbus. NASA built its long, tall A-bombish on 4 used engines which have to be kick-started during the ignition sequence. This overpressurization vents liquid hydrgen through the engine cooling it further towards the absolute and thus preventing its bearings from skidding. One of the yo-yos pressed the wrong button and injected 4x nominal pressure. NASA complacency syndrome decreed that it should have worked although sensors said that the ignition blast, if allowed, would have been similar to the secret Soviet moon rocket that killed all 36 of their brightest. NASA could help. The other approach is to invite resumes from local mechanics and start interviewing with the most expensive.
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@ttmott
 
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