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Old 05-27-2019, 10:26 AM
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Quadrajet issues

Ok, I’ve got two 454 Crusader motors in my boat. Basically 350 hp bbc run of the mill motors.
There is only 1000 hours on them so they are in good shape.
Both have rebuilt marine Qjets on stock manifolds. I’m not sure of the ignition but it looks like old Mallory point style no vac advance.

Three weeks ago I had both running perfectly. Idle at 600 with good throttle response.

Typically we let these run at about 1500 for about ten minutes to get to operating temp. It’s very low on these marine motors. Usually about 150 and 170 underway.

Idle quality is essentual as it’s used for docking and maneuvering in tight spots.

So two weeks ago the port motor starts acting up, poor idle, poor response. So I opened the hatch and sure enough it’s flooding, gas coming out of the accelerator pump rod and out of the vent tube. I lightly tapped on the front of the carb and restarted. It cleaned up and purred nicely.

Last week the exact same thing happened to the other motor. Ran terrible, smells of gas. So again I lightly tapped the carb with my boat knife and restarted and it cleaned up.

I simply can’t have this. Other guys don’t even look at their motors more than once a year to change oil. Some barely know where the motors are.

Both motors have fresh fuel/water separators . Gas is non oxy premium. That’s all that is sold on marinas here.

My el Camino has the same basic carb and run every day, no problems except for boat gas mileage.

Anybody got suggestions.

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Old 05-27-2019, 11:36 AM
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The best I can offer is Cliff's High Performance. I've been sending fellows there for years and never had bad feedback.....
https://cliffshighperformance.com/
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Old 05-27-2019, 12:56 PM
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Thanks. I registered on the site. I’m waiting for approval.

I forgot you have that nice 59 el Camino.

I have a black 77 SS that’s been restored. It’s my daily driver until I get the Buick fixed.

The river is going up again. Third crest. By tomorrow it will be over the walkway to the pier. I have my knee boots in the el Camino. Just got word that the fuel dock is closed until the river goes down. Not predicted in the next week. It’s pouring rain for the next couple days. Oh well I won’t be cruising with these carbs the way they are. Both are near new rebuilds too. I’m disappointed. My suspicions are that the floats are a bit too high. Getting them off is a lay down job over the hatch. Like laying down over the fenders of a truck. Not fun. I thought Streetrods were hard to work on . At least if you have problems on the road you can call AAA.
Boats on the big river you weasle over to the side of the channel and drop the anchor. Then either call your marina if you have cell coverage or get on the VHF and call the coast guard. Be prepared to bend over and grab your ankles when the bill comes.

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Old 05-27-2019, 01:10 PM
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I bought some parts from Cliff and everything was up to par. Just don't mention anyone's "thumper cam"! (he goes off on how stupid they are, (to which I agree)) I have his book and it has come in handy.
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Old 05-27-2019, 02:16 PM
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could the bouncing in a boat shorten the the life of the needle and seat?
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Old 05-27-2019, 02:40 PM
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could the bouncing in a boat shorten the the life of the needle and seat?
That seems like an intelligent question to me. I can see how it could.
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Old 05-27-2019, 02:52 PM
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I believe the QJ's have occasional problems with their floats, check this site out for parts;
https://www.carburetor-parts.com/4G-...bbl_c_161.html
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Old 05-27-2019, 04:38 PM
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I believe the QJ's have occasional problems with their floats, check this site out for parts;
https://www.carburetor-parts.com/4G-...bbl_c_161.html
Once a float loses buoyancy, it doesn't "fix itself" when you rap on the carb. The only thing that does this is a piece of crud stuck in the needle and seat. Do both motors draw fuel from the same tank? Is it possible that you have some debris that got sucked into one carb first, then the other?
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Old 05-27-2019, 06:49 PM
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Ahhhhh, DA! LOL!
My bad....
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Old 05-27-2019, 07:35 PM
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I’m on the Mississippi River north near St.Paul. This is a big heavy boat..about 20k pounds. The biggest waves we see are from wake boats maybe 2 feet or a big barge about 3 feet if you are too close. Since I’ve had it last year about a foot is the highest. Maybe there or four in a row. For the most part this boat is like riding on air cushions. There is a little vibration from the motors but nothing like our roads.

I most certainly is possible something got into the carbs. However I have changed fuel water separators at least three times. Each motor has its own pickup in the tank. These are about 4-5” off the bottom.

I think the best solution is to take the tops off the carbs, see what floats are in them and replace both. Then replace needles and seats.

The site noted has a good choice. I’ll call and ask Mon.

Thanks everyone.

The flood continues so very limited cruising. They opened the fuel dock Sat then closed it until further notice yesterday due to high waters. The only thing open are the new showers and laundry.....if you can wade up to them.LOL
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Old 05-28-2019, 05:23 AM
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When the water separators get full of water they still bypass water. If that happened in the past, the water sits in low spots in the fuel pumps and creates some corrosion which works it's way up to the carbs. At the inlet of each carb, where the metal line hooks up is another filter which should catch this stuff. But over time the little gasket shrinks down and let's stuff by. I would pull those filters and check those gaskets. It takes a 1" wrench to unscrew those, I have a short one I use.

Some marine carbs have a screen inside instead of the filter. Everyone changes the water separators, but forget about the carbs filters. I prefer to use the 10 micron EFI water separator filters over the 50 micron ones. In Sierra just change the 8 for a 9 like 18- 7844 to 18-7944 for the most popular Merc style filter.

Marine Rochester carbs have a seal around that acc pump shaft, so there shouldn't be any gas coming out of there when it floods. Unless those aren't true marine carbs. We only want fuel coming out of the bowl vents and going down the throttle bores not onto the top of the carbs where it can cause a fire.

I have seen problems with cheap needles sealing, Rochester 4bbl carbs don't like too much fuel pressure, some people add electric fuel pumps which can add problems.

Tomorrow, I have to start sorting out a Donzi with twin 502's. They did some creative wiring when they installed them. The power trims don't work, and when I jumped the port trim pump to lower the outdrive, the stbd engines fuel pump, and MSD box powered up when it reached the bottom! At least it's on the trailer and not on a flooding dock. You definitely want your engines running right when you traverse a flooding river. I live on the Trinity River out here in CA. I have been out there when it was flooding. You have to be really careful.

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Old 05-28-2019, 06:27 AM
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Thanks for the information. I did check the carb numbers and they indeed are Marine carbs. I think the gas may have come from under the flame arresters as there is no gasket there. Now corrected.

There are only marine mechanical fuel pumps on both motors. The gen has an electric pump but there is a solenoid cut off valve in the shutdown circuit.

Due to previous problems with water in the gas I think you may be right about corrosion. I’m going to take the lines off and check the filters there. There are actually two fuel water separators on each motors. Both are 10 micron. These have been changed three times in about 25 hours operation. The last time I did cut the main one open and there was very little water in them, so it’s still present.

I have a set up created to pump the tank out through the sending unit opening. I can get to the bottom of the tank here. That’s the next project.

I totally agree about being carefull out on the big river. It’s not like being down on the road. You can get into serious trouble with dead motors on the river. This is not a small boat. The river has countless wing dams that hide just under the surface. These are concrete and rock not soft sand. Not all are marked. You must stay in the channel excep for noted landings and beaches. Beaching a big boat is not a good idea as the river goes up and down depending on the dam control.

So the motors need to be extra reliable. This boat is new to me but not new itself. Fortunately I can service it myself. The local techs are very questionable. I just need some help from here....everyone helps.

The flood here is continuing. I will have to wade in knee deep water to get to the pier walkway. It will be only 4 feet from the recent record set this year. Working on the third crest.its 16 feet over the normal depth. I had the boat on the hard stands for the winter. The marina has us leave the drain plugs out for the flooding it’s better to get water in the boat than have 300 boats floating around. I only got about a foot in mine. No real damage.

Thanks again.
Byron

Edit: here is my boat, you can see the flooded walkway.
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Old 05-28-2019, 07:01 AM
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Quote:
Originally Posted by 70BossRanchero View Post
When the water separators get full of water they still bypass water. If that happened in the past, the water sits in low spots in the fuel pumps and creates some corrosion which works it's way up to the carbs. At the inlet of each carb, where the metal line hooks up is another filter which should catch this stuff. But over time the little gasket shrinks down and let's stuff by. I would pull those filters and check those gaskets. It takes a 1" wrench to unscrew those, I have a short one I use. lk

That is one of the very few benefits of E-10, it mixes with water so the water is continuously dispensed along with the fuel and there is none left in the tank or the entire fuel system. Yet their are MANY who complain about ethanol, yet they add bottles of dry gas (alcohol based) to their fuel. Dry gas and all the others with different names are never needed unless you are running pure gas with no ethanol.
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Old 05-29-2019, 10:51 AM
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What I find is the ethanol absorbs all of the water it can, then any more water sits on the bottom of the tank. I have a couple of houseboats that I always pump some fuel out from the bottom of the tank in the spring to look for water before trying to start them. In bad cases I will get pure water, then I will see a phase change, and it will appear to be gas, smells like gas but feels funny on my fingers and doesn't fire the engine. It is actually ethanol which has absorbed as much water as it can. If I continue to pump more out, I will get another phase change to pure gas.

Since the fuel pickups are up off the bottom of the tanks, then there is likely to be water on the bottom, which will speraticly be picked up when you go over wakes and waves. So I would definitely pump the tank. I use a piece of copper tubing on the end of the fuel line to control where I am pumping from. Occasionally pump some into a glass jar to look at it. If it appears cloudy at first, then almost immediately clears up, then it is an alcohol water emulsion, keep going.

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Old 05-29-2019, 10:57 AM
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I almost forgot, here's the monster with the twin 502's.

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