Fuel starvation issue

Could be a clogged vent. If you crack open the fuel filler cap when it starts to stall and it keeps running--bingo. Other possibility is a clogged anti-siphon valve assuming it's equipped with one. You've gone through a lot of parts to get to this point and that makes my two guesses a lot easier to make.

Best of luck--we all hope it's fixed ASAP.

The anti-siphon valve was a mandated device to prevent fuel from being drawn out of the tank if the boat fuel line broke and the tank level was above the engine pump. Here's more detail;

It is only necessary if the fuel tank is above the level of the fuel lines.

Have you ever siphoned fuel from a tank? If so, do you remember that the end of the fuel line had to be positioned below the level of the fuel? If you raised the fuel line above the level of the fuel tank then the fuel in the line will simply flow back to the tank. Then, if you lowered the fuel line no fuel would flow out because there was no fuel in the line. To start the siphoning again you would have to suck fuel in the line and keep the line below the level of the fuel in the tank.

Let's assume that you have a fuel tank on a boat that is above the level of the engine. The fuel line runs from the tank downhill to the engine. The line is full of fuel because it has been supplying fuel to the engine. If the fuel line were to break at the engine, the fuel in the line would then siphon the fuel from the tank and dump it on the engine. The engine is hot. A fire might start. The fuel that is continuing to be siphoned from the tank will continue to supply fuel to the fire. Not good.

An anti-siphon valve is a device that requires some amount of negative pressure (suction) to open it and let fuel flow. The engine driven pump, or an electric pump, has sufficient suction to open the valve and let fuel flow. The amount of suction resulting from siphoning does not. So, the valve will let fuel flow if the engine pump is drawing fuel but if the line broke and a siphon tried to start, the valve will close and stop the siphoning.

Sometimes (quite often???) the siphon valves go bad and even the engine pump cannot draw enough fuel through the damn thing to keep the engine running properly.

Maybe the pump is not generating enough vacuum. It's supposed to generate 6" of HG. You're only reading the output. If it cannot draw fuel it won't matter what the output pressure is.

Skicenturion86 wrote: Pleasure Craft V8 the fuel stops being delivered to the motor and the motor stalls.

How are you determining the fuel flow stopping?

After the engine quits, what do you have to do to get it running again?

What's that gauge hooked to? Looks like it's reading engine vacuum, I'd hook it up to the fuel pump discharge and get some readings.

Sounds like you had the issue, then replaced stuff and have the same issue still?

Was the fuel pump a brand new one ? What brand ?

I had an issue like this and it was the fuel pump. You could go slow all day long but give it some gas get to about 2500 rpm and same as you about a minute or so later it would die. It wasn't a diaphragm issue but a valving issue(inside the fuel pump). Some of the discharge was going back to the suction and starving the carburetor at higher RPM. Checking fuel pressure told me a lot.

Cleaned the valves and it worked correctly again.

Sounds like you already tried a separate tank but I'd hook it up again with a fuel pressure gauge on the pump discharge and see what you get

KenO

8122pbrainard wrote: tryathlete wrote: Pete--gotta see the video. They've used a sight glass inline fitting and it shows fuel being replaced by air. Peter, Thanks, I hadn't watched the video! It's not a sight glass but rather one of those inline fuel filters designed to go on the suction side of the pump rather than the high pressure side to the carb. Dan, Ken's got some good suggestions. Try them and report back. BTW, I do hope that filter is just in there temporarily and you are planning on replacing the high pressure line from the pump to the carb with a USCG method. They have some pretty strict rules so people don't drive around in potential bombs like yours.

That's how the boat was setup for decades 8122pbrainard. We will look into how to properly setup the fuel line. Do you know how its supposed to be setup? Video out there maybe? We will do some tests and get back to you guys. Thanks for the help so far.

Ha Ha , Thanks, You one funny guy Pete

Just wanted to show him (jtryon) that it wasn't a hard job to do. The site did get his problem resolved

Keeps my wife chuckling at some of the things I do too.

There are only certain things I know anything about and some topics I won't go near at all.

KenO

The gauge in your video is also a fuel pressure gauge.

Use a tee fitting that fits in your fuel line (probably 3/8 inch) and fits your tubing on the gage (probably 1/4 inch) and put it where the filter is now and you can read the fuel pressure while it's running.

5 to 7 psi should be about right.

I had one that put out a couple pounds and very little volume due to internal valve leakage in the pump and it acted just like yours. (At higher speeds the carburetor used more gas than the pump could supply.)

If you hook your temporary tank to the suction when doing this test, that should take any questions about the suction side out of the picture

Tell us more about this 'replaced' fuel pickup at the tank.

Have you taken the pickup's tube and fittings entirely apart?

Hollywood wrote: can you please just run it off a fresh can of fuel plumbed straight into the pump?

That's the plan but can't work on it for another two weeks.. will update soon as I get back home and test this stuff out. Thanks to all for the ideas.

So, how's your fuel pressure?

Did you check it?

Was it a new pump you put on?

Take that glass fuel filter off and plumb in the TEE and Gauge like KenO showed you on Sept 06 post. See what your fuel pump is actually doing. Then unhook the gauge and TEE and run the line into a SAFE catch can and measure the flow rate (using additional hose to get the catch can outside of the boat). It appears in the second video that you replaced the fuel filter?? You need to throw it away while you are at it.
Assume you have checked the float levels??

edit: while your at it, throw the starting fluid away also

We replaced the pump, it's new, but the next step is checking pressure.i suppose we could have two bad pumps but this seems way odd. I was hesitant to check pressure since I can see the fuel pressure goes away visually so why bother checking it. It must be the pump. But we got the tee and some extra hose and will check the pressure soon as I return back home. Off to work for another week... thanks to those that are helpful.

So looks like we are pushing 7.0 and 8.5 at speed on the fuel pump. My brother ended up adjusting the needle and seat. ...needle and seat? Not sure what that is but he said the pressure was fine and adjusted the needle and seat and the boat ran for 15 minutes above 30 MPH. First time since we rebuilt it. So that was the problem...

Now the clicking sound... Any ideas?
Clicking sound...

fixed....