df90 wont start possibly fuel issue HELP

[acsoherron]

This may get a little long winded but i will try to put in all that i have found and tried. So i was on the ICW this weekend, ran 15 miles up, caught some black drum and some croakers to use for bull reds. fishedsthere for about 2 hrs. Cranked up to head to the jetties, boat ran smooth as normal, no skipping, no missing... seemed flawless. Halfway back at around 35 mph and 5700 rpms the boat just knocked off, bulb was soft and would not harden up. Cranked and cranked without it hitting a lick. trolled back and luckily found a willing fisherman to tow me in. got home after loading the boat up and it fired right up, for about a minute it ran perfectly at idle, then knocked off. cranked and cranked and would not start. Next morning, same thing. found a pin hole in the fuel line at the small filter on the engine. i do not have an external filter. replacred that hose and the bulb gets hard and plenty of fuel pressure at the top of the fuel rail. YES!!! PROLEM SOLVED!!! well of course it wasnt that easy. checked oil, good... checked compression, good... Checked spark from each plug wire, good... replaced positive and negative cable lugs and cleaned battery posts. 13 volts at battery and 11.6 when cranking, so thats good...cranked it up after sitting a few hours, purrs like a kitten for about a minute... then knocks off and refuses to crank. i hear the high pressure pump running prior to cranking each time, and i have fire at each cylinder, so my only guess is the fuel rail just clogged at the top. pulled the fuel rail and gas just pours out of each injector hole. cleaned each injector and replaced, again got it primed and plenty of fuel pressure. Boat cranks for about a minute then knocks off and will not run again until i let it sit for a few hours. Im pulling my hair out here, any help would be appreciated.

[acsoherron]

Forgot to mention, i never got an alarm or any lights flashing on the tach, motor has about 700 hrs per the tach prior to starting... and all the testing i have done was after the boat refuses to crank, so i am not testing while the boat is running fine, but after it knocks off. i have fire, and i have fuel pressure. i have power to the high pressure pump and coils, and since fixing the hole in the fuel line the bulb has stayed firm throughout all my testing. i know my testing has been fairly simple and im sure it can get more complex, but i am about to the end of my knowledge of these things so im turning to you guys.

[Moonlighter]

Fair chance the VST is full of dirt/contaminants and needs to be cleaned out. I gather there is a small fine screen filter in there as well that needs to be cleaned or replaced. Replace all filters on the engine as well.

If you intend to do this yourself you may want to get a service manual.

It is VITAL that whatever this problem turns out to be, that you fit a good quality water separating fuel filter between the tank and the engine, usually fitted before the primer bulb.

Absolutely essential that efi engines have such a filter to protect from dirty or contaminated fuel. I am amazed that whoever fitted the engine didnt install one at that time!!

RACOR make a suitable filter with a clear bowl that can be readily inspected for water etc and can be easily drained.

[acsoherron]

Good to know about the water separator, engine was a repower from my old 2 stroke 88 johnson spl (bulletproof but thirsty). Had a local shop put it on and wire it up. i have replaced the sole inline filter that i have and it seemed clean but replaced it anyway. i had it put on 2 yrs ago. question about the VST though, i am getting solid pressure to the injectors which is past the VST, so wouldnt that mean that ts flowing through the VST without obstruction? Also the engine has ALWAYS been ran on non-ethanol since i have owned it

[acsoherron]

when i say plenty of pressure i may be wrong, as it just pours out the fuel rail, but not at close to 40psi... there is not valve that i have seen to put a guage on to check it. i will pull the VST and filter this weekend and clean it all up and replace the filter. if there ares igns of corrosion on the pump ill go ahead and replace it too. im not sure on the float assembly, never messed with one

[acsoherron]

when i put in the water separator do i need to put it between the tank and the bulb or between the bulb and the engine?

[jHydroman]

Mine are between the tank and the bulb.

Jim

[acsoherron]

Thanks Jim. How would i test the pressure without a valve present to put the guage on? i plan on taking the intake off this weekend and cleaning up the VST and replacing the high pressure filter, but wanted to check the output once i finish. Would like to know what it is at this point as well

[acsoherron]

Also Moonlighter, i am sure with your experiences and knowledge of these engines there was a reason that was your first diagnosis. i am trying to learn as much about his issue as i can while im working on it in case i have future problems. How exactly did you come to that possible diagnosis first? Granted, i did check everything from the tank to the pre-filter first. I have not checked to see if my injectors were firing electronically, but that would not likely be intermittent. Definitely made more sense for it to be a fuel issue. i kind of thought that once i cut the engine off and let it sit, the pressure was being taken off the filter, allowing fuel through until the trash gets pumped back into the filter by the HP pump... made sense in my little mind anyhow

[Moonlighter]

Just the symptoms, plus the lack of a filter. Same logic that you came up with. Might or might not be the cause...

filter goes between tank and bulb.

[acsoherron]

thanks moonlighter, i don't have supreme confidence in my mechanics on these 4 strokes yet, but a, somewhat mechanically competent. It's nice to have you guys input. thanks again. ill let you know how the cleaning goes

[Murray]

thanks moonlighter, i don't have supreme confidence in my mechanics on these 4 strokes yet, but a, somewhat mechanically competent. It's nice to have you guys input. thanks again. ill let you know how the cleaning goes

I would suggest you get a genuine Suzuki Service Manual, with the manual and this forum it will give you the confidence to tackle most maintenance/repairs.

I found mine on the internet for $10US, unfortunately I don’t remember the website.

https://www.selffixer.com/outboard.motors/suzuki/

[jHydroman]

I believe there is a port with a plug on the high pressure manifold that feeds the injectors. My service manual is in my boat, I will check it tomorrow when I go to my shop where my boat is stored.
Jim

[Murray]

Try searching “self fix it dot com” all one word. They might have a service manual for your engine

[acsoherron]

Got it all apart took the vst apart and looked like brand new inside, filter screen was in perfect shape, cleaned it all with carb cleaner and put the vst back together temporarily while waiting on new hp pump and filter to arrive... I was kinda hoping it was really dirty in there but it wasn't. Can the pump be working weakly and not be able to keep up while the engine is running? I don't know where else to look, hopefully the new pump and filter fix it