2007 175 intermittant shut off at idle (Not vapor lock)

[MuskyTime]

2007 175 Suzuki

When idling from one fishing spot to another the engine shut off, no sputtering or indication that it was about to quit just a sudden stoppage. I thought it was vapor lock just like many times before but she would not start after pumping the bulb. When turning on the key to the run poss to prime the fuel rail I could audibly notice that rather than the normal sound of the pump running and building pressure it sounded almost as if the pump was cavitating. More of a higher pitched cavitation noise. Motor turned over fine just but acted as if it wasn’t getting any fuel and would not start. I was towed in and at first the marina could not find anything obvious after checking fuel filters and verifying no water in the fuel. It could be duplicated 100% of the time as the motor would crank but no start. They removed the fuel vapor separator and disassembled. Upon disassembly they found the fuel pump cocked slightly and they thought maybe the supply output tube wasn’t properly seated. But they were not sure if this was the actual condition or if it moved during disassembly. After reassembly and install the motor started and worked great for the next few days until my week-long trip was over.

I returned to the water last week for another week-long trip and on day 3 the exact same problem occurred again. Same sudden shut off in idle and same cavitation sound coming from the pump when first selecting the ignition switch to run poss. So I took the fuel vapor separator apart and upon disassembly it did not appear to me that the pump supply tube was cocked in any way and nothing was out of order as far as I could tell. I reassembled and reinstalled the fuel vapor separator but still would not start and still would make cavitation noise upon ignition switch to start poss. I got towed to a resort and once tied up to the dock I thought I would give it one last try. This time the pump sounded normal and it started right up. I didn’t have any more problems with it for the remaining days of the trip. NOTE: Prior to removing the fuel vapor separator I removed just the output line on the top of the fuel vapor separator and turned the key to the run position and the pump ran and made the cavitation noise and no fuel came out of the output port.

Not knowing much about the fuel system and not wanting this to happen again 30 miles from home, I need to start launching parts at it. Looking for any suggestions as to what could be causing this issue? Because it’s not hard failed now I have nothing to trouble shoot.

My first thought is that the pump is by-passing internally and not priming or supplying fuel pressure at start or idle when in the failed condition. Possibly the pump is starting to go? Or is there a check valve in the system that is intermittently preventing good fuel pressure to be delivered to the fuel rail during start and idle?

Any thoughts?

Thanks! Ed

[Moonlighter]

I am not sure this will be the problem, but it could be a factor. In any case, its a cheap easy thing to do and if it doesnt solve the problem, nothing is lost.

Anti-syphon valve on your fuel tank could be failing. Causing restricted fuel flow at times. We had an issue on my mates Striper where his DF300 started to stall out when we had been running along and came back to idle. Could only get it started again by pumping the hell out of the primer bulb. Did some research on google and found many examples of similar failures.

In any case, these valves are not a requirement on outboard powered boats.

We simply took the fuel lines off, unscrewed the valve from the tank (its part of the barb fitting on the fuel tank), took it to the workbench, and used a punch to punch out the tiny ball, seal and spring inside there so it was now a completely open/empty barb fitting. Reinstalled it on the tank with some gasket goo to seal it up. Reconnected fuel hoses.

(The alternative of course is simply to throw the old fitting away and put a simple barb fitting back there instead. Saves punching the inside parts out of the old valve.)

Problem solved.

Hope this helps.

[Harper]

You might also check the condition of your battery and cables/terminals. Might be just enough juice from the motor's alternator above idle to prevent any problems, but less voltage at idle, and coupled with battery or cabling issues, could cause the ECM to shut it down, followed by hard starting.

[MuskyTime]

Moonlighter and Harper thanks for the reply's.

My condition is (I think) related to the electric pump located within the fuel vapor separator housing. When in the failed condition when you turn the ignition key to run, the pump runs for a few seconds and shuts off to prime the fuel rail like normal only the sound coming from the pump is a very different noise. The noise is more of a cavitating or churning noise. When in the normal condition the pump is very quiet and you can actually hear the pitch change in the pump as it builds pressure. So as I listen to it, when in the failed condition it almost sounds like the pump is either by-passing internally or trying to pump air.

I know the obvious part to replace would be the pump. But I guess I'm wondering if there is something else in the system that could be failing that intermittently is either allowing air to be introduced up stream of the pump or not allowing the pump to build pressure to the fuel rail.

Just trying to gather as much input as possible before I start shot gunning parts.

Electrical system is fine. Pumping the bulb until the cows come home had no effect during the failed condition.

The only thing that I hate about owning a Suzuki is that the Suzuki dealers never work on the motors (because they don't break down) and are clueless when it comes to knowing how to fix issues. More knowledge on this site than the combined knowledge of the dealers in my state!

[artdf175]

is there a possibility that you have a loose connection in the fuel line
allowing air to get sucked in?
start by watching the in-line fuel filter pre low pressure pump and see if there is any air in the filter .. should be none..
seems to me that some of the places the fuel hose connects to are less that perfect .. I think in a couple of places I have cut 1/2 inch off to get better fit..
Just an idea

Art
one other thought.. is the fuel float in the high pressure pump adjusted correctly? the usual problem is just the opposite of yours, where fuel dumps via the overflow hose into the crankcase and mixing with oil.
could yours be closing off not allowing fuel to fill up the VST?