20v motor dies

[tigeky]

Would it be worth it to mount a fan facing the fuel pump that could be switched on 5-10 minutes before starting. Could the fan cool the pump enough to make a difference.

[dod1655]

Would it be worth it to mount a fan facing the fuel pump that could be switched on 5-10 minutes before starting. Could the fan cool the pump enough to make a difference.

I have been on vacation and just got home today. I spoke with Harvey at Tige' and he told me of a problem in Florida identical to mine. I spoke with the service dept there and the problem was the hose on top of the crankcase (crankshaft? Sorry not good with mechanical things) that is L shaped was collapsing because of a corroded spring inside. This caused the fuel to percolate creating vapor lock. He said they've had three boats with this problem, one with only 60 hours. I'm taking our boat in today and will let you know if this is the problem. Thanks again for all your replies.

[dod1655]

I have been on vacation and just got home today. I spoke with Harvey at Tige' and he told me of a problem in Florida identical to mine. I spoke with the service dept there and the problem was the hose on top of the crankcase (crankshaft? Sorry not good with mechanical things) that is L shaped was collapsing because of a corroded spring inside. This caused the fuel to percolate creating vapor lock. He said they've had three boats with this problem, one with only 60 hours. I'm taking our boat in today and will let you know if this is the problem. Thanks again for all your replies.

Replacing the L shaped hose as suggested did not fix the problem. The problem still persists. If we wakeboard for 30 min then swim for 30 min, the boat will start up and run for about 100 yards then die and won't start for 30 min. I spoke with Harvey at Tige' and he told me to bring the boat to Abilene and Tige' will fix the problem. It's a long drive but after 3 summers and 4 boat dealers with no resolution, I'm ready to take it to the experts. I will post the resolution once the problem is solved.

[jsz]

I have a merc 350 with the same problem. The mechanics pinned it down to a "starving for fuel" problem since it ran fine at all other times. I was told the anti-siphon valve was making the pump work "too hard" to suck fuel and causing symptoms of vapor lock.

A new A.S. valve was put in but next trip it did the same thing. I finally replaced the fuel pump and it has been fine since. The old pump was making noise like it was running but it would never actually prime the system.

[SPBFAN]

Usually a vapor lock condition is created by a weak fuel pump. Get your hands on an scope and a low amp probe. Check to make sure that the pump is working to specs. You can see a pattern on the scope and catch any glitch in the pump very easily. Most likely it is a problem with the low pressure pump.

[jsz]

When I had the boat at the shop, it was hooked up to a fuel pressure gauge. The mechanic even showed me how much pressure it was putting out and all seemed ok. However... it was with the motor running which I believe reads the pressure from the low pressure pump that is in the tank. My problem was the high pressure pump that primes the system before starting.

For "starting" problems I would look at the high presuure pump.
For "running" problems, look at the low pressure pump.

[SPBFAN]

When I had the boat at the shop, it was hooked up to a fuel pressure gauge. The mechanic even showed me how much pressure it was putting out and all seemed ok. However... it was with the motor running which I believe reads the pressure from the low pressure pump that is in the tank. My problem was the high pressure pump that primes the system before starting.

For "starting" problems I would look at the high presuure pump.
For "running" problems, look at the low pressure pump.

Just a little confused here. The low pressure pump does only one thing. It supplies the high pressure pump. If you are looking at fuel pressure at the fuel rail with or with out the engine running you are only looking at pressure from the High pressure pump.

[SPBFAN]

You really need to get a low amp prob and a scope. Then hook it up the the fuel pump wiring and see what the low and high pressure pumps are doing. That would be the next step.

[jsz]

Just a little confused here. The low pressure pump does only one thing. It supplies the high pressure pump. If you are looking at fuel pressure at the fuel rail with or with out the engine running you are only looking at pressure from the High pressure pump.

Now I don't understand. Are you saying that the 2 pumps are running all the time? I agree that the low pres pump feeds the high pres initially, but I thought the high pressure pump only runs when the ignition is first turned on to prime the fuel rails. That is what we hear for 1-2 seconds after turning the key. Once the high pres pump shuts off and the motor is started, it is my understanding that only the low pres pump keeps running.

[chpthril]

Now I don't understand. Are you saying that the 2 pumps are running all the time? I agree that the low pres pump feeds the high pres initially, but I thought the high pressure pump only runs when the ignition is first turned on to prime the fuel rails. That is what we hear for 1-2 seconds after turning the key. Once the high pres pump shuts off and the motor is started, it is my understanding that only the low pres pump keeps running.

Both keep running. Most electric pumps do not like to suck fuel, they like to create pressure and push the fuel. For this reason, there is a low pressure feeder pump to supply the hi-pressure.

The ECM controls the High pressure, if not both. When the key is turned on, the ECM energizes the fuel pump relay for a few seconds to prime the system. If the ECM doesnt see ignition reference (the engine cranking over) it knows that no fuel is needed, so it shuts off the pump. As soon as the ECM sees the engine cranking, it re-energizes the relay and the pump(s) run. This is why you hear the pump run and shut off when the key is turned to the "on" position.

[jsz]

Thanks a lot... Just when I thought I understood things you had to confuse me with the facts.

Just kidding, that is a good explination.

[dod1655]

Replacing the L shaped hose as suggested did not fix the problem. The problem still persists. If we wakeboard for 30 min then swim for 30 min, the boat will start up and run for about 100 yards then die and won't start for 30 min. I spoke with Harvey at Tige' and he told me to bring the boat to Abilene and Tige' will fix the problem. It's a long drive but after 3 summers and 4 boat dealers with no resolution, I'm ready to take it to the experts. I will post the resolution once the problem is solved.

We got the boat back on the water last week after leaving it at Tige' in Abilene and the problem with vapor lock has been resolved. Harvey said there was a water hose with a tube inside that was supposed to help force the water thru but the tube was inserted backwards, impeding the water flow. Once this problem was corrected, the boat ran fine with no more vapor lock. Woohoo! Finally!

I must say that Tige' and Harvey Smith really stand behind their customers. Thanks Harvey!!