Fuel Pressure

[bgbird]

1998 Suzuki DT100<br />Pump the primer - and get it full. Engine starts great and will idle nicely - no problem with 2K RPM. Bulb starts getting soft. Replaced the fuel filter (big like oil filter). Removed cleanable filter from engine - no dirt visible.<br />When put into gear - starvation and stall.<br /><br />Replaced primer bulb - will test this weekend to see if it stays hard.<br /><br />Anyone have other suggestions?<br /><br />Does the DT100 have a fuel pump?<br />Do they go bad?<br />Can they be tested?

 

[jim dozier]

Re: Fuel Pressure

Have someone pump the fuel bulb while you try to use the engine. If pumping the bulb prevents or cures the problem you likely have a failing pump. Your engine has one (follow the fuel lines from the carb to a round gizmo). They do fail, the diaphragms get old. Go to the bottom of this web page and order a manual. They are easy to rebuild. If you loosen the bolts that hold it to the engine block and it leaks out the back when you pump the bulb the diaphragm has a hole in it.

 

[rodbolt]

Re: Fuel Pressure

the bulb will not and cannot ever stay"hard" it is on the suction side of the system. its sole function in life is to fill the pump,fuel lines and carb fuel bowls before starting. other than that you can throw it away.<br /> have you tested spark and compression.

 

[bgbird]

Re: Fuel Pressure

The bulb will fill up enough to start the engine. The engine will idle smooth - I had it purring for about 20 minutes. When put into gear it seems that not enough fuel is available. I was stuck Sunday. I had my kid drive at about 1500-2000k while I tried to maintain pressure sqeezing the bulb - but the bulb was soft as hell. I picked up a new bulb but haven't tested yet. I also ordered the book today.<br /><br />If anyone can refer me to where I should order the re-build kit and what to order I'll pick up the parts. With the book, I'll do it this weekend. I'm on vacation next week and I'd like to use the boat.

 

[bgbird]

Re: Fuel Pressure

One more thing - Sunday I started and idled for a while. All seemed OK. Took a spin. Ran for 15-20 minutes at 3500-4000 RPM. Turned and the low fuel symptoms came back. Engine would start - but even pumping the bulb wouldn't keep me running in gear. Needed a tow. If the fuel pump was bad any ideas why I'd be able to maintain speed for so long?

 

[jim dozier]

Re: Fuel Pressure

Describe what you are referring to as "low fuel symptoms". If the engine will run smoothly at some speeds but not at others it may not be the fuel pump. You need to begin at the beginning. Again, get a manual. Like Rodbolt says, check compression and spark. Then you might take a look at the carbs. You need to narrow down whether this is ignition related or fuel related or something else.

 

[bgbird]

Re: Fuel Pressure

Sqeeze bulb and engine starts and idles like a dream - smooth. Will idle indefinitely let idle @ 1500 20 minutes. Will rev to 4000 no sputter or any other issue. <br /><br />When put into gear (forward or reverse) - it would stall Saturday replaced fuel/water separator & check carb filter (both separator & filter seemed clean - no suspended stuff - no evidence of any gum).<br /><br />The boat was just bought - so maintenance history unverified. Previous owner said that maintenance was performed under warranty. Plan to call boatyard where maintenance was supposedly performed.<br /><br />Thought that maybe fuel gage was bad and was out of fuel. So, after filter changout, added 15g of fresh fuel (all it took) (tank holds about 60g). Must have had about 45g gas on board - don't know how old (could be over a year) or whether stabilizer was used. <br /><br />Sunday start at first turn of key - idle 15 min no problem. Put into gear several times while tied up - no problem. Left the dock and ran @ 3500-4000 RPM (about 30MPH) no problem for 20-25 minutes. Planed no problem. Reduced RPM & made turn to return to dock - sputter and stall. <br /><br />At this point primer bulb really soft - seemed empty. Pump up (still seemed soft) restart (no problem) and idle nice. Put into gear - pretty much immediate stall. Tried to sqeeze bulb while in gear - still seemed soft - but no go.<br /><br />Towed back to dock. Bought new primer bulb - didn't get a chance to test.<br /><br />This week plan to check all fuel connections. I pulled the fuel separator unit and throughly checked Saturday - no evidence of any blockage. No evidence of any water. Plan to check all fuel line clamps.<br /><br />Plan to pull plugs and check - but would that be it? - fast start & smooth idle.<br /><br />Should I add any fuel stabilizer, carb cleaner, or octane boost? <br /><br />Ordered repair manual. Expect delivery this week.

 

[jim dozier]

Re: Fuel Pressure

Check the vent on your tank to be sure its venting. If it looks like the bulb is having trouble filling from the tank, maybe your anti-siphon valve at the tank is acting up. Do a compression test. If you have low compression or a bad cylinder it will never idle right. Check the spark with a spark tester. Try choking the engine when it starts to sputter, if it picks up you are running lean and most likely need to clean and rebuild the carbs.

 

[bgbird]

Re: Fuel Pressure

How do you check the vent? The boat has a cap that sort of clips and locks over the tank. Is there some way to test this?<br /><br />Also the tank is somewhere under the deck. As far as the anti-siphon valve I haven't a clue as to where it might be located. Maybe it's accessable via one of the pedestal mounts for the driver seat. The main fuel line seemed to disappear into a bulkhead.<br /><br />As far as the fuel situation - should I add stabilizer - or octane boost - or fuel injection cleaner?<br /><br />The Suzuki repair Manual arrived - and I'll take a look in there and see if there is anything germaine in their troubleshooting section.<br /><br />Thanks to all for their advice

 

[Arnold96]

Re: Fuel Pressure

I had identical symptoms on a Yammie and it had nothing to do with the engine. There is usually a check valve right at the connection to the tank. This is supposed to keep all of the fuel from draining out of the lines back into the tank. However, as many have learned it gives problems and will keep gas from going out of the tank also. I spent $200 replacing fuel bulbs, fuel pumps, fuel filters and housings, added an electric fuel pump, all to fix it for $2.28 and pitching the check valve and replacing it with a nipple fitting.