RUNS GREAT AT 3/4 THROTTLE, STUTTERS AND SLOWS DOWN AT FULL?

rpengr · **Posted:** Tue Aug 06, 2013 11:02 am

LouC wrote:

I don't for sure know how to test these valves because there isn't really any information in the factory shop manual from OMC that I have (I guess because the valve is part of the tank assembly installed by the boat builder). I would guess that you use a vaccum pump and pull a vaccum on it and see what the results are. If it requires a lot of vaccum to open the valve its probably bad. I'd google "how to check an anti siphon valve" and see what comes up. I know about the valve because when I first got this boat, it ran OK the first season and the second it would start, idle, rev up in neutral but would not plane the boat. I did everything I could myself and then gave it to the best OMC shop around. They fixed the shift system and also went through the whole boat fuel and ignition. They found that the carb was dirty but also it had a stuck anti siphon valve. The mechanic explained to me that the boat builders use a cheap aluminum one but he used a better quality Evinrude/Johnson one. No problems since then (2003-4).

My understanding is that these valves are a check valve that uses a SST ball and a weak spring. The fuel pump draws over the week resistance of the spring. You could check for a stuck anti-syphon valve by attaching some clear tubing (at least 2-3') and sucking on it by mouth. You should be able to suck fuel up the tube, and of course stop before it gets to your mouth. An alternative would be to use a rubber ball pump like used on outboard engines. Do not use any type of shop vac or electric vacuum to do this test!

LouC · **Posted:** Tue Aug 06, 2013 12:58 pm

Good advice I was thinking a hand vaccum pump like a mightyvac that you use to bleed brakes.

wkearney99 · **Posted:** Wed Aug 07, 2013 3:46 pm

Correct, anything that's not SPECIFICALLY RATED to be able to handle fuel would be a HUGE mistake.

Liquid gas burns, but gas vapor EXPLODES. The last thing you'd ever do (or want to do) would be to atomize the fuel and then send it hurtling toward a sparking electric motor.

Ka-BOOOM!

I think those valves fall into the category of "you've fixed every other possible thing, so the valves are the last poassible piece of the puzzle". Testing them on the boat is just not practical, nor safe. It's just a whole lot cheaper and safer to just assume they don't work and replace them, but only after doing all the other likely repairs first.

Mark T · **Posted:** Mon Aug 12, 2013 1:51 pm

Just heard from the marina,

Good news, diesel ( 8 gallons to 55 gasoline ) does not appear to have done anything. 2 Seafoam and 4 Octane boost pints did its job. They emptied my fuel filter and while the color was a little more amber than normal gas, there did not appear to be any debris / particles floating around. They said leave the 45-50 gallons ( 65 capacity )in the tank as opposed to draining it and top it off with more fresh gas and another couple pints of octane boost.

The low pressure fuel pump was dead, so new one on order. Apparently, there is still enough pressure from the high pressure pump to get gas into the cylinders just not enough to run full throttle.
Learned that high pressure pump was tested at 40psi which they said was great pressure. As for the low pressure pump, normally that should be at about 3-5psi and it was doing nothing.

You guys were correct in that the anti siphon valve also had some issues and will be replaced as well. The said it had some debris ( ? ) in it and appeared to be worn as well. Fuel lines to the cylinders were fine, ( stainless ), and they are putting in a new fuel vent since mine was original and falling apart.

Hopefully they will get the new fuel pump in and take it for a test drive ( hard wide open throttle ).

The service department was impressed that I was able to give them a better idea than most boaters of what was wrong. They said they had one dropped off last week and all the guy could tell them is it doesn't run like it used to and it sounds funny. So THANKS TO EVERYONE for their suggestions as it seems to have helped the service department and hopefully saved me some money on needless searching for the problem.

LouC · **Posted:** Mon Aug 12, 2013 3:37 pm

Well if some of us didn't have such old boats, we wouldn't know so much LOL....

wkearney99 · **Posted:** Mon Aug 12, 2013 6:18 pm

Diesel? How'd THAT happen? That would certainly cause problems. But it was good they actually found the problems and fixed 'em.

It really does help when you can offer useful diagnostic info, for just about anything that ever needs someone else's help.

Mark T · **Posted:** Tue Aug 13, 2013 3:18 pm

wkearney99 wrote:

Diesel? How'd THAT happen? That would certainly cause problems. But it was good they actually found the problems and fixed 'em.

It really does help when you can offer useful diagnostic info, for just about anything that ever needs someone else's help.

The Diesel happened when I pulled up to a gas station pump, hit the premium button, but grabbed the diesel handle. Had it been one of the pumps where you have to flip the lever to turn on, that would not have happened. It was one of those days, where I had hoped to get out on the lake by 10 am and it was already 11:30 so was rushing and not paying attention.

Nice to know that as long as you don't put too much in, the boat can still run.

wkearney99 · **Posted:** Tue Aug 13, 2013 5:06 pm

Well, wait, you KNEW this happened and didn't mention it?

While the engine may fire, it's really not a good way to let it run. The timing can get all screwed up, as can fuel injection systems. The engine computer, assuming it's gasoline, may end up really screwing up the fuel mixture. This can lead to all sorts of problems with the valves and such. Count yourself lucky.

Just be sure to keep changing the fuel filters. It'll take several of them. You're still dealing with a screwy mixture in there, so take it easy. Avoid WOT or pulling skiers/floats until your filters are free of contamination.

rpengr · **Posted:** Tue Aug 13, 2013 9:17 pm

wkearney99 wrote:

Well, wait, you KNEW this happened and didn't mention it?

While the engine may fire, it's really not a good way to let it run. The timing can get all screwed up, as can fuel injection systems. The engine computer, assuming it's gasoline, may end up really screwing up the fuel mixture. This can lead to all sorts of problems with the valves and such. Count yourself lucky.

Just be sure to keep changing the fuel filters. It'll take several of them. You're still dealing with a screwy mixture in there, so take it easy. Avoid WOT or pulling skiers/floats until your filters are free of contamination.

wkearney99: The Diesel conversation started in a different thread... here:
http://www.smwebhead.com/phpBB3/viewtopic.php?f=2&t=12109
Marina mechanic advised him that it was OK to run with Seafoam and octane boost.
Sounds scary to me, I think I would have pumped it out. I agree that I would avoid full throttle until it is all out.

Mark T · **Posted:** Sun Aug 18, 2013 8:03 am

I'm feeling better about the diesel in the tank now. Talked with a second marina who is repairing my fuel pump and they said they have not seen any issues until the mixture gets up around 25-30%. my mistake was about 10-12%. They also agreed with the other marina that by adding the seafoam ( 2 bottles ) and octane boost ( 4 bottles ) I brought the octane rating back up to a point where there should be no damage. The mechanic said it actually may help lubricate the cylinder rings ??. I have changed the fuel filter and will continue to do so every 15 gallons or so until I burn thru all 65 gallons.

mechanic also noted when changing the fuel filter, and pouring the gas into a clear glass it was still very clear, but it was about a shade or two darker than normal gas.

Mark T · **Posted:** Sun Aug 18, 2013 8:03 am

I'm feeling better about the diesel in the tank now. Talked with a second marina who is repairing my fuel pump and they said they have not seen any issues until the mixture gets up around 25-30%. my mistake was about 10-12%. They also agreed with the other marina that by adding the seafoam ( 2 bottles ) and octane boost ( 4 bottles ) I brought the octane rating back up to a point where there should be no damage. The mechanic said it actually may help lubricate the cylinder rings ??. I have changed the fuel filter and will continue to do so every 15 gallons or so until I burn thru all 65 gallons.

mechanic also noted when changing the fuel filter, and pouring the gas into a clear glass it was still very clear, but it was about a shade or two darker than normal gas.

TX H210SS · **Joined:** Thu May 27, 2010 9:10 am **Posts:** 1488

I think you should be fine with some diesel in there with all your doing, but considering the cost of seafoam, octane boost, multiple fuel filters and stress I would think draining the tank and replacing with fresh fuel would be cheaper.

Either way I hope your probs are over and keep swapping filters.

Mark T · **Posted:** Sun Aug 18, 2013 10:05 am

TX H210SS wrote:

I think you should be fine with some diesel in there with all your doing, but considering the cost of seafoam, octane boost, multiple fuel filters and stress I would think draining the tank and replacing with fresh fuel would be cheaper.

Either way I hope your probs are over and keep swapping filters.

Not sure the cost of the stress ( $$$$$ ) but the seafoam, octane boost and 4 filters was less than $100. Did not ask what cost was to pump out and dispose the gas, replacing 65 gallons would be $ 250-325 or so. So once I had more than one mechanic say that it was not going to be an issue, I elected to just burn through it. I will admit, my wife is right, I am cheap, but I did ask 2 marinas, one autoparts store and 1 auto mechanic before making my decision.
The gas station attendant where I put the diesel in told me I HAD to pump it out, but she also had more tattoos than teeth, so I'm not sure about her qualifications....

rpengr · **Posted:** Sun Aug 18, 2013 4:15 pm

Mark T wrote:

TX H210SS wrote:

I think you should be fine with some diesel in there with all your doing, but considering the cost of seafoam, octane boost, multiple fuel filters and stress I would think draining the tank and replacing with fresh fuel would be cheaper.

Either way I hope your probs are over and keep swapping filters.

Not sure the cost of the stress ( $$$$$ ) but the seafoam, octane boost and 4 filters was less than $100. Did not ask what cost was to pump out and dispose the gas, replacing 65 gallons would be $ 250-325 or so. So once I had more than one mechanic say that it was not going to be an issue, I elected to just burn through it. I will admit, my wife is right, I am cheap, but I did ask 2 marinas, one autoparts store and 1 auto mechanic before making my decision.
The gas station attendant where I put the diesel in told me I HAD to pump it out, but she also had more tattoos than teeth, so I'm not sure about her qualifications....

Ah...a old tatoos to teeth ratio greater than .7 is bad, but greater than 1.0 cannot be trusted. :lol:

This is interesting new information about what is safe regarding diesel in the gas. I have heard that the opposite is usually OK also (some gas in a diesel engine within a low ratio)>

I don't follow why fuel filter changes would be necessary?

Mark T · **Posted:** Mon Aug 19, 2013 11:12 am

rpengr wrote:

Mark T wrote:

TX H210SS wrote:

I think you should be fine with some diesel in there with all your doing, but considering the cost of seafoam, octane boost, multiple fuel filters and stress I would think draining the tank and replacing with fresh fuel would be cheaper.

Either way I hope your probs are over and keep swapping filters.

Not sure the cost of the stress ( $$$$$ ) but the seafoam, octane boost and 4 filters was less than $100. Did not ask what cost was to pump out and dispose the gas, replacing 65 gallons would be $ 250-325 or so. So once I had more than one mechanic say that it was not going to be an issue, I elected to just burn through it. I will admit, my wife is right, I am cheap, but I did ask 2 marinas, one autoparts store and 1 auto mechanic before making my decision.
The gas station attendant where I put the diesel in told me I HAD to pump it out, but she also had more tattoos than teeth, so I'm not sure about her qualifications....

Ah...a old tatoos to teeth ratio greater than .7 is bad, but greater than 1.0 cannot be trusted. :lol:

This is interesting new information about what is safe regarding diesel in the gas. I have heard that the opposite is usually OK also (some gas in a diesel engine within a low ratio)>

I don't follow why fuel filter changes would be necessary?

I am probably being a little too cautious on the multiple filter changes. Traditional Diesel is pretty dirty in that it is not as filtered and distilled ( ? ), so it has more pieces and parts floating around in it. What I put in, turned out was ULSD, Ultra Low Sulfur Diesel, which is a more processed and refined fuel, which again is probably why it is working fine in the engine with the additives I put in.

www.iFourWinns.com

RUNS GREAT AT 3/4 THROTTLE, STUTTERS AND SLOWS DOWN AT FULL?

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