Fuel Problem

[Trout Tamer]

Greetings all,
New here and have a fuel question. This is on a DF250 / 2013 model.
After stopping for a time (15 - 30 Minutes) and trying to restart, the engine will crank fine, run about 20 seconds and die. When this happens the hand bulb is soft, and the motor will not restart until the bulb is pumped up.
Have changed the fuel lines, replaced all of the spring hose clamps, and water separator. This is the fourth bulb, and no one has been able to solve this problem. The motor is on a Carolina Skiff 25' center console bay boat.

Any suggestions will be appreciated.

[Moonlighter]

I would check the anti-siphon valve on the fuel tank. They sometimes fail and you get those kinds of symptoms, we had a similar situation on mates Striper.

The valve is actually in the barb that the fuel line attaches to on the tank. You should be able to take the fuel line off and then unscrew the barb from the tank fitting. We then took it to the workbench and punched out the little ball, spring and seat from inside it so that it was then just a straight-thru barb, and reinstalled it on the tank. That solved our problem.

[Trout Tamer]

Thanks.

Have already removed ball. Didn't help. Actually thought it may be a crack in the pick-up tube, so since this boat has two pick-ups ( for twin outboard applications ) I changed over to the other one. Still no success. This doesn't happen consistently, sometimes it may be several trips before it fails to run after startup. I do notice that when this motor starts correctly it will briefly rev up upon starting. If it doesn't rev up when it starts, it is going to die in about 15 seconds.

[Harper]

Well, in your last post, it's starting to sound electrical. Every connector, battery terminal connections, battery switch and connectors, virtually EVERYTHING needs to be checked, cleaned, and tightened. Batteries need to be in good shape and to the extent possible, kept fully charged. Our motors are very sensitive to any voltage drop, particularly at start-up.

Perhaps as a test, if you are able, put the start battery on an automatic charger overnight before each of your next few trips, and see if that prevents the problem. If so, then you need to concentrate your efforts on the battery and electrical system.

[Trout Tamer]

Mike,

Thanks for the input, but all electrical connections were removed and treated with corrosion x prior to the boat ever getting wet. The motor battery is on a charger when in the garage, but this boat is usually out about three days a week. Not a guide, just enjoy fishing. I have just read a post on here about an electric fuel pump being added by Suzuki to remedy what appears to be the same problem. Perhaps I can find out more about this and install one.

[nelbur]

Mike,

Thanks for the input, but all electrical connections were removed and treated with corrosion x prior to the boat ever getting wet. The motor battery is on a charger when in the garage, but this boat is usually out about three days a week. Not a guide, just enjoy fishing. I have just read a post on here about an electric fuel pump being added by Suzuki to remedy what appears to be the same problem. Perhaps I can find out more about this and install one.

The Suzuki fix for the vapor lock problem was an electric fuel pump AND a pressure regulator, so the combination of electric and mechanical low pressure pumps does not over pressure the float, needle and seat, in the vapor separator. If this vapor lock is your problem, starting the engine and firming up the primer bulb before you throttle up should solve the problem for that acceleration. Replacing your anti-siphon valve should keep the vapor from pushing the fuel back into the tank, and might help. Suzuki has come out with a new low pressure pump with a V in the new part number. I have not been able to determine if the V is related to the vapor lock problem. If you look at the fuel line once it goes into the engine, it snakes between the intake manifold and the block where heat soak could heat the fuel when the hot engine is shut down. I have thought about running the line down below the block and back up to the low pressure pump, avoiding the hot block. Just a few things to try.

[Moonlighter]

Is there any sign of air in the fuel filter on the engine?

It does sound possible that there could be an air leak in the fuel system somewhere.

Some people have had issues with the gasket on the water separating fuel filter, so check that. Also seen a couple of filters where the brass barb fittings (inlet and outlet) in the filter head had been fitted using plumbers tape on the threads and this fails with fuel contact. We use liquid gasket on the threads to prevent any air or fuel leaks from there.

And also re-tighten all those hose connections. We sometimes use the liquid gasket compound on the hose barbs to seal up better as well.

The best fuel primer bulbs are the high end OEM ones made by Mercury, as they have a proper valve in them that totally stops fuel running backwards. The Suzuki ones have the old flapper style valves that are nowhere near as good, so if you replace it again try the Merc one.

You do have the primer bulb held vertical don't you?

Final thought- check the fuel lines in the engine itself to make sure all the clamps are in place and no kinks in the hoses. We have seen a couple where the hoses were kinked around a corner, causing problems.

Hope these thoughts help.

[Trout Tamer]

Solved the problem, I think.

There is a vent hose coming from the top of the HP fuel pump to a servo, which opens a solenoid to dump vapors back into the engine. This servo fails and allows a vapor lock situation to occur. Replacing the servo is an option, however they tend to fail again soon after replacement.

The fix that my Suzuki guru came up with is to cut three slots ( just a nick in the vent hose, only visible when you bend the hose ) about 1 inch apart to allow this hose to vent vapor pressure. This was done with a pair of side cutters, and the slits are only about a quarter of the way through the hose. When I cut the first slit, an audible hiss from escaping pressure was heard.

So far, after three trips with numerous starts and stops, no more problem.

Still want to make a few more trips before declaring a victory, but as of now this is way better than external fuel pumps and pressure regulators.

Will post again after more trials.

Thanks.

[Drrnjns]

Hiya Trout Farmer, wouldn't it be "neater" to put a "T" connector in place of the nicks? and lead the vapor away from hot thingies?

[Trout Tamer]

Has been awhile since I posted here but just wanted to let everybody know, after numerous trips I have not had any more problems with the engine shutting down. Apparently the fuel pump and regulator weren't needed, after I relieved the pressure from that vent tube all has been well.