2007 DF150 Suzuki starts and after about 10-15 seconds shuts off.

[Bcribb]

I have a 2007 Suzuki DF150 that will start and after a few seconds it will shut off. It will do this several times and then stay running. When I start to give it throttle it hesitates and runs rough until I open the throttle up more. The gas is good, has new plugs,etc. It runs great after I get the rpm's up.. Wondering if fuel pressure would cause this? Any ideas would be appreciated

[Moonlighter]

Some US built boats have an anti syphon valve on their fuel tank takeoff. It can get sticky and cause problems like this. Best solution is to get rid of the AS valve altogether. Or you can take it off, punch the ball seat and spring out from inside it and reinstall the empty barb.

Worth a try. Can easily do it yourself and even if its not the problem this time, you have prevented a potential future problem anyway.

[artdf175]

the IAC valve controls the idle speed.
I would suggest reading up on adjusting
Art

[Bcribb]

Thanks Moonlighter. I checked the tank fitting and it don't have the as valve.
Thanks Art. I did change out the Iac valve and the idle seems too low. I think around 500-600 rpms. Where can I get the information for adjusting the IAC properly. I've adjusted it one time while in fixed mode but maybe I didn't do it correctly. Thanks

[artdf175]

the service manual -- if you are working on your engine I can only recommend having one
there are some online but having the book to look at has been a big plus

[redlowrey]

Didn’t you have hesitation problems after you changed the ecu a while back.

[Bcribb]

Yes its always has a little hesitation problem since I changed out the high pressure fuel pump. Today I put a pressure gauge on the fuel line going to the injector rail. When I turn the key on the gauge reads 20 lbs. When I start the engine the pressure drops to about 15 lbs. When I shut the engine off the pressure eventually drops to zero. Should the pressure drop? I thought it was supposed to stay at around 20 lbs or more..

[Murray]

My service manual (2009 DF90A) specifications is 36.3psi with the key on( not running) residual pressure after 5 minutes should be 28.4psi or more.

[Bcribb]

I cranked it up again. It does drop to 20 when running and falls back to zero when the engine is off for a few minutes. I noticed when I gave it gas it was running rough and the gauge was fluctuating really bad. After a few minutes it starts to clear up. So what i'm reading in your post is the pressure shouldn't drop to zero when the engine is off for a couple of minutes.I'm wondering if I should try another fuel pump and replace the pressure regulator in the vst tank? I'm trying to figure this out before I take it to a repair shop.

[Murray]

My manual gives no specifications when running so I don’t know if 20psi is valid when running. As per manual it should hold pressure(28.4psi) for 5 minutes not drop to 0 within a couple of minutes. If you had an external leak in the system you would see and smell fuel. The test procedure for checking the fuel pressure regulator is a hand pump to a air pressure gauge which is then attached to the fuel pressure regulator. The regulator should not let air pass until pressure reaches between 34.1-38.4psi. If the fuel pressure regulator was shot and allowing fuel to pass at 20psi that would explain your low fuel pressure. I don’t have enough knowledge to explain why it bleeds down to 0psi so fast, in my mind there must be an internal pressure leak in the VST?? If you Google s e l f f i x e r dot c o m(all one word) they have a Suzuki service manual for your engine in PDF format. I purchased my service manual from them a few years back and didn’t pickup any viruses. $8.95 can’t go wrong. If it is your fuel pump that would be your 3rd pump since new? No pump will last forever but potentially 3 pumps since 2007 seems excessive. I’m spitballing here but what if your fuel pressure regulator has been deteriorating for some time causing your fuel pump to work harder than it was designed to. Just some random thoughts from a guy who knows enough to be dangerous.

[Bcribb]

Thanks Murray. I think i'm going to replace the fuel pressure regulator. Hopefully the attachment screw won't be to awful hard to get out. I'll order the regulator first so I can still fish till the part comes in.. Thanks and i'll let you know my results..

[Murray]

4AECEEDF-44DB-4DF9-9F5B-2D36C69249F7.png
A screen shot of the test procedure for the pressure regulator. For some strange reason it’s always blurry,

[Bcribb]

Sorry it took so long to respond back. I replaced the fuel pressure regulator and that didn't help. I took my boat to a dealer and they checked everything they knew to check and didn't figure out anything. Said the grommet that the HP fuel pump fits into could be worn or leaking causing low fuel pressure. I replaced the grommet and also checked the pump when it was out. The pump would only go to 25 lbs. I didn't know what it was supposed to be so I had a spare pump and checked it and got 40 lbs.The connector on my pump was hard to get off. When I got it off and looked at it the terminals they were a little nasty looking. I cleaned the connectors up and re-tested the pump.The pressure was 40 lbs. I double checked both pumps again and got the same pressure.That seemed strange to me how it went from 25 lbs to 40 lbs. Anyway I reinstalled the vst tank and checked the pressure at the fuel rail and it was around 25 lbs when running. The mechanic at the shop said it should run around 35 lbs.. Today i'm going to put a pressure gauge at the exit point of the vst tank and one at the fuel rail to see if there is a drop in pressure. If the pressure is low at both points i'm going to remove the vst tank again and re-test the pump. I have a new pump ordered and when it comes in I want to check the pressure on that pump so I can get an Idea what these pumps pressure up to. One question I have is that when the engine is running should the voltage to the hp pump be 12 volts constant. I'll check that today also just to see what its reading. I really think the hesitation i'm getting when throttling up is due to a fuel problem.. Any ideas on any of this stuff I just wrote. I'm not giving up on this thing until I get it resolved.It would be nice to have spare parts to try swapping out but that's a little expensive.. Thanks for all your help and anyone else's..

[Bcribb]

Update on my 2006 DF 150. Installed a new HP fuel pump , new vst tank seal and the rubber seal that the fuel pump discharges through. I checked the fuel pump pressure before installing it and it pumped up to 80 lbs dead headed. I installed the vst tank back on the engine and primed everything up before starting. The fuel pressure is now running around 38 lbs. The engine is running good with no hesitation.Apparently these engines need more than 23-28 lbs of fuel pressure and good electrical connections to the HP fuel pump to perform correctly.. Thanks for all the help on this forum. I hope my information helps someone else.