Loss of power on VP 5.7GI

[Berkley1]

I have a 2002 VP 5.7 GI it starts runs great for about 1hr or two then it starts having power issues where the engine drops RPM's last time out it died completely once it cools down it runs fine any suggestions on where to start would be helpful.

 

[Fun Times]

Thinking as a starting point, possibly a fuel tank venting issue going on time wise or maybe the ignition coil is getting a bit too hot for its age or most probable being a fuel injected engine is the water flow cooling portion of the fuel pump assembly has become blocked with debris allowing the fuel to get a bit too hot...See water hoses 10 and 11 to 33 for location,

For fuel tank venting issue thoughts, have a quick look at the following thread, https://forums.iboats.com/threads/2...s-n-0w354897-mysterious-loss-of-power.774745/

 

[Berkley1]

Thinking as a starting point, possibly a fuel tank venting issue going on time wise or maybe the ignition coil is getting a bit too hot for its age or most probable being a fuel injected engine is the water flow cooling portion of the fuel pump assembly has become blocked with debris allowing the fuel to get a bit too hot...See water hoses 10 and 11 to 33 for location,

For fuel tank venting issue thoughts, have a quick look at the following thread, https://forums.iboats.com/threads/2...s-n-0w354897-mysterious-loss-of-power.774745/

Awesome never thought about the cooling hoses will check this out for sure Thank you for the quick response most helpful

 

[ESGWheel]

As with any troubleshooting it all about a process of elimination and logically following the symptoms and test results. There is a ton of good stuff on the forum about these pumps having issues.

One of the easy tests you can do to determine if indeed fuel starved (due to any reason like pump overheating or gas tank not venting like FunTimes suggests) is to monitor the fuel pressure while underway. While you can check it at the dock while running at idle, your issue comes post running about, so need to test then.

Get yourself a fuel pressure gauge link. Not that expensive and can have it quickly fm Amazon or go to your local auto parts store. Set this up on the high-pressure side in such a way as can be readily observed when having issues. Make sure its secured (zip ties) and out of the way of spinning and hot parts. While at the dock and before starting engine, turn the key to ON (which will kick on the pump) and observe / check that there are no leaks and you have pressure. Start engine and while at idle, same check. Record pressure. Go have some fun but not too far out . When issue occurs, what is the pressure? Note: if stalls before can be read, no issue, turn key ON and look. Best if have another person on board to check the gauge.

Note: I do not know if your engine is TBI or MPI so others will have to say what the pressure spec is.

Now if the engine stalls and have low pressure, do these things with engine and key off: (1) Loosen the gas cap slowly, do you hear a hissing sound? (2) physically touch the fuel pumps all over including the electrical connectors. Are they too hot to touch for more than 10 seconds?

If hear hissing sound at cap > venting is the issue. See this link on how the combo vent caps work which you may have.

If pump is hot, cooling water issue or more likely the pump is craped up with paint. Other issues can also cause it to be hot and stop pumping like lack of fuel (fuel also cools these pumps and if something is blocking fuel delivery, it will heat up). See this link on the paint issue these pumps had and how to fix.

Caution when removing the fuel gauge it will leak a little gas, so be prepared for that (it’s just a few millimeters).

Post results or questions. Here is what I do know: this is 100% fixable. And as a bonus it will not only be fun to solve but also save you some hard-earned cash

 

[Berkley1]

As with any troubleshooting it all about a process of elimination and logically following the symptoms and test results. There is a ton of good stuff on the forum about these pumps having issues.

One of the easy tests you can do to determine if indeed fuel starved (due to any reason like pump overheating or gas tank not venting like FunTimes suggests) is to monitor the fuel pressure while underway. While you can check it at the dock while running at idle, your issue comes post running about, so need to test then.

Get yourself a fuel pressure gauge link. Not that expensive and can have it quickly fm Amazon or go to your local auto parts store. Set this up on the high-pressure side in such a way as can be readily observed when having issues. Make sure its secured (zip ties) and out of the way of spinning and hot parts. While at the dock and before starting engine, turn the key to ON (which will kick on the pump) and observe / check that there are no leaks and you have pressure. Start engine and while at idle, same check. Record pressure. Go have some fun but not too far out . When issue occurs, what is the pressure? Note: if stalls before can be read, no issue, turn key ON and look. Best if have another person on board to check the gauge.

Note: I do not know if your engine is TBI or MPI so others will have to say what the pressure spec is.

Now if the engine stalls and have low pressure, do these things with engine and key off: (1) Loosen the gas cap slowly, do you hear a hissing sound? (2) physically touch the fuel pumps all over including the electrical connectors. Are they too hot to touch for more than 10 seconds?

If hear hissing sound at cap > venting is the issue. See this link on how the combo vent caps work which you may have.

If pump is hot, cooling water issue or more likely the pump is craped up with paint. Other issues can also cause it to be hot and stop pumping like lack of fuel (fuel also cools these pumps and if something is blocking fuel delivery, it will heat up). See this link on the paint issue these pumps had and how to fix.

Caution when removing the fuel gauge it will leak a little gas, so be prepared for that (it’s just a few millimeters).

Post results or questions. Here is what I do know: this is 100% fixable. And as a bonus it will not only be fun to solve but also save you some hard-earned cash

Thanks for the response I will give it a shot.

 

[Berkley1]

Thanks for the response I will give it a shot.

So far I have checked the fuel tank vent all good, ran at slip for about an hour varying RPM's no issues fuel pump never got hot using thermal thermometer temps never above 125 deg at headers no loss of power, next I will replace anti syphon and blow out pick up tube any suggestion on where to look from here?

 

[ESGWheel]

Need to catch this having the issue. While good it did not at the dock (well, not really , your original description does sound like starving for fuel vs a distinct / abrupt cut back of RPMs due to the computer going into safe mode. So, I am back to installing the fuel pressure gauge and monitoring it per post 4. Said differently it needs to “fail” to see what is going on, else it’s a guessing game. No issue changing out the antisiphon but some words of caution: they can be difficult to get off and there is a risk of damaging the tank’s mount for the fuel pickup. Also, if going to use compressed air to blow back into the tank (1) have the gas cap off and (2) use very low air pressure, like 5# and only for short bursts.

Other’s may have different ideas or approaches.

 

[Berkley1]

Need to catch this having the issue. While good it did not at the dock (well, not really , your original description does sound like starving for fuel vs a distinct / abrupt cut back of RPMs due to the computer going into safe mode. So, I am back to installing the fuel pressure gauge and monitoring it per post 4. Said differently it needs to “fail” to see what is going on, else it’s a guessing game. No issue changing out the antisiphon but some words of caution: they can be difficult to get off and there is a risk of damaging the tank’s mount for the fuel pickup. Also, if going to use compressed air to blow back into the tank (1) have the gas cap off and (2) use very low air pressure, like 5# and only for short bursts.

Other’s may have different ideas or approaches.

Thanks you are right this is a guessing game I will take the boat out this weekend to run under load to see if I can recreate opening gas cap good idea also going to check plugs for condition.

 

[Berkley1]

Thanks you are right this is a guessing game I will take the boat out this weekend to run under load to see if I can recreate opening gas cap good idea also going to check plugs for condition.

Just an update found that there was water in the fuel cleaned up and running great

 

[ESGWheel]

This is great you found the root cause which based on the symptoms was unexpected. Would you please post what led you to suspect water in the gas and how you tested it to validate. This will help others with similar symptoms to hopefully get to a quicker resolution. Thanks!

 

[Berkley1]

This is great you found the root cause which based on the symptoms was unexpected. Would you please post what led you to suspect water in the gas and how you tested it to validate. This will help others with similar symptoms to hopefully get to a quicker resolution. Thanks!

Well here is the skinny what I thought was a fuel problem through further investigation I had to pull the exhaust manifold and riser for another issue when I did I found the cooling fitting to the fuel pump completely blocked with crud eliminating all flow to the fuel pump causing a fuel pump to overheat issue once I get everything back together I will update to let you know if that fixed the issue.