Suzuki DT100 losing gas pressure in the bulb

[Willhuntforfood]

Hello Everyone,

Yesterday I experienced a loss of pressure and fuel in the primer bulb and the engine stalled.  I squeezed the bulb and it filled up and I took off but after about 1 minute it stalled again.  I had someone with me and they kept pumping the bulb and we could make some headway but it kept stalling.  Went it got real soft he had a hard time getting fuel to it, we found that if I accelerated for a few seconds and then backed off the fuel was readily available and the bulb would fill up quickly with a few pumps.  I had a spare bulb and replaced it thinking it was a possible pin hole but that did not work.  Boat has been running fine with nothing noticeably wrong.

Is this a fuel pump issue or possible a restriction?  Also, maybe not by coincidence the fuel gauge has stopped working right around the same time?

Any thoughts would be greatly appreciated!

WHFF

[John Jones]

If it is sucking the ball flat my guess would be a restriction between the bulb and tank.  If the tank has an anti-siphon valve it's probably the culprit.  It looks like just a hose connection but they have a ball and spring in there and it's quite common for them to corrode or catch some trash.  The pickup tube in the tank probably has a screen and they can get clogged as well.

If it's not sucking the ball flat then probably the fuel pump.

[Capt. Bob]

viewtopic.php?p=39053#p39053

[seabob4]

http://www.classicaquasport.com/phpbb3/viewtopic.php?p=39053#p39053

There you go again, CB, using the search function...  

[Willhuntforfood]

Awesome, you guys and this forum are the best!  I found it strange that I could fill the bulb and it would run it dry and still be a fuel pump issue.  I think the gas gauge failing has something to do with it, something must be causing a restriction.  

I have a smaller outboard can and am going to try that and bypass my in floor tank to see if that totally eliminates the fuel pump issue and then I can dig into a possible restriction.  I am told the  tank was replaced 18 months ago and it is plastic.  I cannot see any way to get to it without taking the whole floor section under the console out, does not look easy!  Too bad there were no access hole put in strategic locations for any type of tank service.

Thanks again!

[Willhuntforfood]

Sorry John just re-read you message.  You said sucking the bulb flat, i took that as sucking it dry.  It is not physically flattening the bulb, just emptying it.

Sorry for my confusion.

[MarshMarlowe196]

Fuel doesn't flow through the sending unit so that couldn't have anything to do with it.  Like you said, it failing too is probably just a coincidence.  As mentioned, there is an anti siphon valve in the pick up tube that may be contributing to a fuel delivery problem but the primer bulb really ought to be able to overcome that, unless you've got a chunk of something causing an obstruction.  How old is the tank?  Disconnect the primer bulb and squeeze it all the way flat, then stick your finger over the engine side outlet to create a seal, then release the bulb. Does it pull gas or stay flat? If it stays flat, or pulls noticeably slowly, you've probably got a blockage somewhere between the bulb and the tank.  It's a good idea to try to run the engine from a different tank.

I cannot see any way to get to it without taking the whole floor section under the console out, does not look easy!  Too bad there were no access hole put in strategic locations for any type of tank service.

The pickup tube is located at the very rear of the tank, on the starboard side (If you still have the original tank). Getting to it and attempting to free up an obstruction inside the tube may only required you to "raise" the console (unscrew, place on blocks/supports), remove the tank hatch and slide it forward enough to give you access.

Since you have same tank hatch and rigging chase/trough setup as my boat, I wouldn't be intimidated by the idea of pulling the tank out.  This job is made easy (comparably) for you by the removable tank hatch and rigging hatch - many other fuel tanks in other boats are only accessible by cutting a large portion of your floor out.  I've pulled my tank a few times and its really not so bad.  If you diagnose to that point, there's plenty of threads and members here who can help.

[Willhuntforfood]

Thanks MM 19-6,

I picked up a fuel pump and will be conducting some tests later in the week.  The boat is new to me and the tank was replaced 18 months ago.

I will try the tests you have mentioned to see a result.  

Thanks for your help!

Happy 4th to all!

[Willhuntforfood]

Ok guys here is what I got.  As you all know I am a newbie and learning new things everyday.

I removed the hatch below the console to get to the fuel tank.  First I found corrosion on the sending unit common terminal so I cleaned that and it worked again, second I found that the tank is a 35 gallon plastic unit.  The tank is 8" deep and 55" long.  The pick up for this tank is near the fill toward the bow.  What was happening is that all the fuel was collecting in the back of the tank when the boat was not on plane and therefore sucking air.  I went and filled the boat to find that I had almost 10 gallons in the tank but I was acting like it was empty.  I even was out the other day and had it stall because I was running at headway speed and had passengers and gear at the stern and it grabbed some air, I had over 1/2 tank in it.

Does anyone know if I can put and elbow on that pick up tube and extend it towards the stern to minimize this issue?

Thanks,
WHFF

[Capt. Bob]

Does anyone know if I can put and elbow on that pick up tube and extend it towards the stern to minimize this issue?

My first thought would be no.....

Is the tank baffled?
If you remove the pick up, how do you attach the elbow? (braze, silver solder, thread)
With the elbow attached, will it fit back through the opening?
Elbow attached, fits through opening, how long can the extension be with a tank depth of 8" but a length of 55"?

If this was my problem..... and the tank is in good shape.
Drain fuel
Remove tank
Fill with water (safety overkill)
Drill (by hand) new opening for alternate fuel pick up at opposite end.

Thinking (well sorta) out loud.

[fitz73222]

Turn the tank around and replace/ splice the fill and vent hoses.

[Willhuntforfood]

Hey Guys,

The tank is not baffled and is only 18 months old and in good shape.  I was thinking I could cut the pickup, slip it in, then possibly attach an elbow through the sending unit hole, but that might be wishful thinking.  Maybe a longer pickup tube could be inserted and then slightly bent towards the stern to help with this issue?

I thought about spinning the tank.  I might save this for a winter project as it would only take an extension on the fill and then shortening of the vent line.  I guess for the rest of the summer I can just make sure not to fall below 1/2 tank.

Thanks again!

[carldoc]

I have the same situation with my boat. New tank, but an elbow was needed for the fill to reach the back, Moeller did not make one so the tank fill/vent are bow way. I didn't want another aluminum tank. We will construct a stainless tube to flow to the back of the tank. Sounds like you have the same tank I do. I ran into the same problem with about 10 gallons of fuel left. There are no baffles in my tank. I'm expecting this to be an easy fix, but you never know

[Willhuntforfood]

I have just been keeping it topped off.  I took a good look and it should not be a major undertaking to spin the tank.

I would be interested in how your fix comes out.  Are you going to make this stainless tube yourself?

[carldoc]

A marine mechanic friend will do it. He will place a brass fitting at the bottom to keep it weighed down. Should be easier than removing the whole tank.