Engine model number is 5.0 FI PHUSCE
Temperature, oil pressure is all normal
The Problem:
- engine will not restart after running for an hour or more.
- I was initially working under the assumption that it was a vapour lock problem - I found a few problems that could have contributed to a vapour lock condition,(piece of rubber in the check valve from the fuel cooler allowing hot water to back flow heating up the fuel cooling tank) but after the last no start - I pulled a sparkplug and they are soaked in fuel.
- if I attempt to restart immediately after shutting if off - the engine usually restarts.
- If I wait for 10 - 15 minutes then during the first restart attempt, the engine almost starts and from then on it is flooded and won't start until it cools off. I just learned about the 'flood clear' procedure so I have not had an opportunity to see if this helps
- this condition cannot be recreated by simply idling at the dock - even after 30 minutes of idling it starts fine - the condition occurs after the boat is run for an hour or more and then sits for 15 minutes.
- engine has about 350 hours on it
- other than this issue - runs ok - WOT of 4600 rpm - same as when the boat was new
- engine was overheated about 15 years ago - this flooding has been a problem for the past 10 years (I have just been living with the problem -just never had an opportunity to work on it).
What has been done:
- there is a possibility that I might have 'cupped' or stretched valves becuase of the overheating years ago but compression seems ok - see below.
- performed a vacuum test - 15 in Hg at idle (600rpm - 19 inches at 1500 rpm and above - the only thing out of the normal was on the rapid throttle increase/decrease test - my vacuum gauge actual went into the pressure zone to 1-2 PSI - supposedly this indicates worn rings - none of the other vacuum conditions were out of the ordinary.
- following were the compression test results - engine was warm - but not hot:
Cylinder # Compression (PSI)
1 130
2 128
3 130
4 134
5 130
6 128
7 125
8 125
Max/Min % range: 7.2%
- no codes during KOEO test - one continuous code 53 - overvoltage from TPS. Changed TPS and code did not return after one run - but the same flooding condition occurred again. My $30 meter kept getting shut off during the KOER test so I was not able to pick up any codes from that test.
- changed CTS just incase it was faulty - I did a resistance check on the old one at home and it followed the temp/resistance according to specifications - I doubt this was causing the problem - I have not run the boat long enough to see if this correct the condition.
- changed sparkplugs yesterday, All of the old plugs (10+ years old)were in great condition - normal wear - no carbon build up.
- Fuel pressure in the HP fuel rail is 34 psi and constant - upon shutdown of the engine it slowly decreases to 28 psi over a 15 minute period and then stays steady for 30 minutes - I did not leave the gauge on past 30 minutes.
- I checked to see if there is a cracked diaphragm in the HP fuel regulator vacuum - there is no fuel in the vacuum line back to the manifold.
- Had a good spark on the plug I pulled for inspection when I determined the engine was flooded.
The only thing I have found out of the ordinary is the vacuum guage readings during rapid throttle increase/decrease. I am not sure if this is a fautly reading or truly a piston ring problem. I do not have any other symptoms of worn rings - blue exahust, oil consumpton, fouled plugs, loss of power.
Questions/Comments:
1) I did all of the vacuum tests at the dock - should these test have been done with the engine under load?
2)There are two temperature sensors on this engine - I changed the CTS (the one to the right of the distributor when looking at the front of the motor) does the other sensor (to the left of the distributor) have anything to do with the operation of the engine or is it just the sender unit for the gauge?
Any other suggestions would be greatly appreciated - I really do not want to get into a major overhaul of a motor that runs great 99% of the time - but that is the direction my mechanic is pushing me.
Temperature, oil pressure is all normal
The Problem:
- engine will not restart after running for an hour or more.
- I was initially working under the assumption that it was a vapour lock problem - I found a few problems that could have contributed to a vapour lock condition,(piece of rubber in the check valve from the fuel cooler allowing hot water to back flow heating up the fuel cooling tank) but after the last no start - I pulled a sparkplug and they are soaked in fuel.
- if I attempt to restart immediately after shutting if off - the engine usually restarts.
- If I wait for 10 - 15 minutes then during the first restart attempt, the engine almost starts and from then on it is flooded and won't start until it cools off. I just learned about the 'flood clear' procedure so I have not had an opportunity to see if this helps
- this condition cannot be recreated by simply idling at the dock - even after 30 minutes of idling it starts fine - the condition occurs after the boat is run for an hour or more and then sits for 15 minutes.
- engine has about 350 hours on it
- other than this issue - runs ok - WOT of 4600 rpm - same as when the boat was new
- engine was overheated about 15 years ago - this flooding has been a problem for the past 10 years (I have just been living with the problem -just never had an opportunity to work on it).
What has been done:
- there is a possibility that I might have 'cupped' or stretched valves becuase of the overheating years ago but compression seems ok - see below.
- performed a vacuum test - 15 in Hg at idle (600rpm - 19 inches at 1500 rpm and above - the only thing out of the normal was on the rapid throttle increase/decrease test - my vacuum gauge actual went into the pressure zone to 1-2 PSI - supposedly this indicates worn rings - none of the other vacuum conditions were out of the ordinary.
- following were the compression test results - engine was warm - but not hot:
Cylinder # Compression (PSI)
1 130
2 128
3 130
4 134
5 130
6 128
7 125
8 125
Max/Min % range: 7.2%
- no codes during KOEO test - one continuous code 53 - overvoltage from TPS. Changed TPS and code did not return after one run - but the same flooding condition occurred again. My $30 meter kept getting shut off during the KOER test so I was not able to pick up any codes from that test.
- changed CTS just incase it was faulty - I did a resistance check on the old one at home and it followed the temp/resistance according to specifications - I doubt this was causing the problem - I have not run the boat long enough to see if this correct the condition.
- changed sparkplugs yesterday, All of the old plugs (10+ years old)were in great condition - normal wear - no carbon build up.
- Fuel pressure in the HP fuel rail is 34 psi and constant - upon shutdown of the engine it slowly decreases to 28 psi over a 15 minute period and then stays steady for 30 minutes - I did not leave the gauge on past 30 minutes.
- I checked to see if there is a cracked diaphragm in the HP fuel regulator vacuum - there is no fuel in the vacuum line back to the manifold.
- Had a good spark on the plug I pulled for inspection when I determined the engine was flooded.
The only thing I have found out of the ordinary is the vacuum guage readings during rapid throttle increase/decrease. I am not sure if this is a fautly reading or truly a piston ring problem. I do not have any other symptoms of worn rings - blue exahust, oil consumpton, fouled plugs, loss of power.
Questions/Comments:
1) I did all of the vacuum tests at the dock - should these test have been done with the engine under load?
2)There are two temperature sensors on this engine - I changed the CTS (the one to the right of the distributor when looking at the front of the motor) does the other sensor (to the left of the distributor) have anything to do with the operation of the engine or is it just the sender unit for the gauge?
Any other suggestions would be greatly appreciated - I really do not want to get into a major overhaul of a motor that runs great 99% of the time - but that is the direction my mechanic is pushing me.