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2007 DF175
Note before reading I have never had this problem before in 10 years. I have had the vapor lock problem known to Suzuki’s where after a long run on a hot day when re-starting and advancing the throttle the engine shuts off. Resolved by pumping the bulb and re-start. Good to go. This is something that happened to me twice last summer and has never happened prior.
Last summer one morning after about a 2 mile run and fishing the first spot of the day, I was idling to the next spot when the motor shut off. Not a very hot day (July morning in Canada) Now I have had the vapor lock problems before that typically occurs after making a long run on a hot day where after shut down and fishing a spot then re-start the engine and at throttle advance the motor shuts off. This has always been solved with pumping the bulb until hard and then re-start and no problems after that. I was thinking this was the issue but it was not. After pumping the bulb and hearing the fuel surging through the low pressure lines to the fuel vapor separator (FVS) I turned the key and waiting for the fuel rail to pressurize. But the electric pump sounded as though it was cavitating (not pulling any fuel) and not building any pressure in the high pressure system. The engine would not start. No matter how many times I turned the key on and listened to the electric pump run (to prime the fuel rail) it made the same cavitating sound (not pulling any fuel). Definitely not the normal sound from the pump building pressure that I have come to know over the last 10 years. I had to be towed in and the exact issue and sound was duplicated by the mechanic at the local repair shop. The low pressure fuel pump pressure was good and again the electric pump was running but not appearing to be pushing any fuel at least that’s the way it sounded. The tech took the FVS apart and thought that during disassembly the seal at the top of the electric pump may not have been seated correctly. He was not sure if this happened during disassembly of the FVS or not? Nothing else was out of place so he re-positioned the pump and put it back together. After re-assembly when turning on the key the electric pump sounded normal (building pressure to the high pressure system and fuel rail) and the engine started right up. Didn’t have any more problems the rest of the trip.
Headed back to Canada in August for a week trip and on day 4 of the trip after putting on 60 miles a day, again I was idling from one spot to another when the engine died. The electric fuel pump made the exact same noise (sound as if not building any pressure) and the engine would not start. I had enough tools on board to take the FVS apart and everything looked to be in place. I ensured the electric pump outlet was seated properly and put it all back together. Still would not start and was making the same cavitating noise (not pulling any fuel) when selecting the key to the run position. So I was towed to a resort in the area so I could call the repair station to come and get me. It took an hour to tow me to the resort and as I was being towed I kept trying to start the engine with the same results. After being untied and I dropped the trolling motor in I thought maybe I will try one more time. This time the electric pump sounded normal and the engine fired right up. Engine ran fine the rest of the trip.
I didn’t use the boat the remainder of the season and decided I would trouble shoot the problem this spring. Seeing as there is not issue now and I cannot duplicate the problem, I decided to shot gun some parts at it. I broke down what I thought might be the likely cause into two categories, low pressure fuel system and high pressure fuel system.
As I thought about the LP fuel system and what could be the cause of the HP pump not being able to pull fuel and deliver it to the HP system, I came up with the following thoughts: possibly air being sucked into low press supply lines, intermittent clogged LP filter, bad check valve in bulb, anti-siphon valve, and or clogged vent to tank. I replaced the fuel supply line from the bulb to the inlet of the LP filter the LP fuel filter, the bulb as well as the line to the fuel fitting on the hull. I checked the fuel supply line connections at the tank and at the fitting on the inside of the hull. I verified the vent is clear and anti-siphon valve is good. But really cannot logically see why anything on the low pressure fuel system would have anything to do with this issue? Unless the problem was fuel starvation between the tank and FVS inlet, but when the problem was duplicable I could squeeze the bulb and could hear to the fuel being pushed through the LP lines into the FVS and the bulb would get hard. If the FVS is full of fuel the HP electric pump should be able to deliver it to the HP lines and fuel rail, should it not?
As far as the high pressure side, I thought it could be the HP pump intermittently internally bypassing, HP Filter or HP pump screen, needle/float issue preventing a full FVS bowl (HP pump starvation). Or most likely vapor lock is occurring in the HP fuel system that creates a situation where the HP pump cannot pull or push fuel through the FVS or the HP supply lines.
So to illuminate most of the problems I replaced the FVS assembly and the HP fuel filter. I know it’s extreme but when you break down in Canada 20-30 miles from the dock I’m willing to spend a little extra now.
With all that said, am I missing something or in the event that it happens again what would you look at next? Hard to trouble shoot something that’s not broken now.
From what I understand the high press fuel pump supplies fuel to the fuel rail but also via a “Y” fitting also routs HP fuel through a fuel cooler then back to the FVS.
Couple thoughts/questions I have after this are:
Could I have a clogged fuel cooler that is preventing cooling water to pass through the cooler and hot fuel in the HP system is causing a vapor lock?
Could the fuel passage in the fuel cooler be clogged not allowing the fuel in the HP system to circulate and not cool? I’m assuming it’s a counter flow heat exchanger?
Does it sound logical that a vapor pocket in the HP loop would cause this condition?
If it happens again on the water, what could I do to burp (bleed) the vapor lock condition? Last time disassembling the FVS did not work. As you might recall in my second failure, after taking the FVS apart inspecting and re-assembling it had the same failed condition (audible sound of HP pump not pulling fuel and would not start) then about an hour later it started.
Am I overlooking something in the low pressure system?
Open to any comments or suggestions.
Thanks,
Ed
Note before reading I have never had this problem before in 10 years. I have had the vapor lock problem known to Suzuki’s where after a long run on a hot day when re-starting and advancing the throttle the engine shuts off. Resolved by pumping the bulb and re-start. Good to go. This is something that happened to me twice last summer and has never happened prior.
Last summer one morning after about a 2 mile run and fishing the first spot of the day, I was idling to the next spot when the motor shut off. Not a very hot day (July morning in Canada) Now I have had the vapor lock problems before that typically occurs after making a long run on a hot day where after shut down and fishing a spot then re-start the engine and at throttle advance the motor shuts off. This has always been solved with pumping the bulb until hard and then re-start and no problems after that. I was thinking this was the issue but it was not. After pumping the bulb and hearing the fuel surging through the low pressure lines to the fuel vapor separator (FVS) I turned the key and waiting for the fuel rail to pressurize. But the electric pump sounded as though it was cavitating (not pulling any fuel) and not building any pressure in the high pressure system. The engine would not start. No matter how many times I turned the key on and listened to the electric pump run (to prime the fuel rail) it made the same cavitating sound (not pulling any fuel). Definitely not the normal sound from the pump building pressure that I have come to know over the last 10 years. I had to be towed in and the exact issue and sound was duplicated by the mechanic at the local repair shop. The low pressure fuel pump pressure was good and again the electric pump was running but not appearing to be pushing any fuel at least that’s the way it sounded. The tech took the FVS apart and thought that during disassembly the seal at the top of the electric pump may not have been seated correctly. He was not sure if this happened during disassembly of the FVS or not? Nothing else was out of place so he re-positioned the pump and put it back together. After re-assembly when turning on the key the electric pump sounded normal (building pressure to the high pressure system and fuel rail) and the engine started right up. Didn’t have any more problems the rest of the trip.
Headed back to Canada in August for a week trip and on day 4 of the trip after putting on 60 miles a day, again I was idling from one spot to another when the engine died. The electric fuel pump made the exact same noise (sound as if not building any pressure) and the engine would not start. I had enough tools on board to take the FVS apart and everything looked to be in place. I ensured the electric pump outlet was seated properly and put it all back together. Still would not start and was making the same cavitating noise (not pulling any fuel) when selecting the key to the run position. So I was towed to a resort in the area so I could call the repair station to come and get me. It took an hour to tow me to the resort and as I was being towed I kept trying to start the engine with the same results. After being untied and I dropped the trolling motor in I thought maybe I will try one more time. This time the electric pump sounded normal and the engine fired right up. Engine ran fine the rest of the trip.
I didn’t use the boat the remainder of the season and decided I would trouble shoot the problem this spring. Seeing as there is not issue now and I cannot duplicate the problem, I decided to shot gun some parts at it. I broke down what I thought might be the likely cause into two categories, low pressure fuel system and high pressure fuel system.
As I thought about the LP fuel system and what could be the cause of the HP pump not being able to pull fuel and deliver it to the HP system, I came up with the following thoughts: possibly air being sucked into low press supply lines, intermittent clogged LP filter, bad check valve in bulb, anti-siphon valve, and or clogged vent to tank. I replaced the fuel supply line from the bulb to the inlet of the LP filter the LP fuel filter, the bulb as well as the line to the fuel fitting on the hull. I checked the fuel supply line connections at the tank and at the fitting on the inside of the hull. I verified the vent is clear and anti-siphon valve is good. But really cannot logically see why anything on the low pressure fuel system would have anything to do with this issue? Unless the problem was fuel starvation between the tank and FVS inlet, but when the problem was duplicable I could squeeze the bulb and could hear to the fuel being pushed through the LP lines into the FVS and the bulb would get hard. If the FVS is full of fuel the HP electric pump should be able to deliver it to the HP lines and fuel rail, should it not?
As far as the high pressure side, I thought it could be the HP pump intermittently internally bypassing, HP Filter or HP pump screen, needle/float issue preventing a full FVS bowl (HP pump starvation). Or most likely vapor lock is occurring in the HP fuel system that creates a situation where the HP pump cannot pull or push fuel through the FVS or the HP supply lines.
So to illuminate most of the problems I replaced the FVS assembly and the HP fuel filter. I know it’s extreme but when you break down in Canada 20-30 miles from the dock I’m willing to spend a little extra now.
With all that said, am I missing something or in the event that it happens again what would you look at next? Hard to trouble shoot something that’s not broken now.
From what I understand the high press fuel pump supplies fuel to the fuel rail but also via a “Y” fitting also routs HP fuel through a fuel cooler then back to the FVS.
Couple thoughts/questions I have after this are:
Could I have a clogged fuel cooler that is preventing cooling water to pass through the cooler and hot fuel in the HP system is causing a vapor lock?
Could the fuel passage in the fuel cooler be clogged not allowing the fuel in the HP system to circulate and not cool? I’m assuming it’s a counter flow heat exchanger?
Does it sound logical that a vapor pocket in the HP loop would cause this condition?
If it happens again on the water, what could I do to burp (bleed) the vapor lock condition? Last time disassembling the FVS did not work. As you might recall in my second failure, after taking the FVS apart inspecting and re-assembling it had the same failed condition (audible sound of HP pump not pulling fuel and would not start) then about an hour later it started.
Am I overlooking something in the low pressure system?
Open to any comments or suggestions.
Thanks,
Ed
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