2002 SX150TXRA Hard starting after running for a while

[jb1]

2002 Saltwater OX66 150HP, new electric HP fuel pump motor, new primer bulb, new spark plugs. Motor is in good shape garage kept. Recreational fishing use only. Just happened this weekend. 1st time for this. After a total engine run time of 45 minutes total, with 3 stop and starts over a 3 hour period on the 4th start engine was hard to start. Cranked for 2 - 3 minutes before it would run, once running ran fine. It would try to start but not run. Did this again so after getting it started I made the run to the launch. Got it home and it fired right up. Seems to be related to the engine getting warm.

Any suggestions

Thanks

 

[Tucker99]

Re: 2002 SX150TXRA Hard starting after running for a while

Unfortunately you have to wait until the condition rears it's head to check things out. The first thing I'd is check the the HP fuel pressure using the shrader valve on the VST. If it's low, its a sure sign that your LP fuel pumps are bad, believe you have 2. Are they original? Why would you have to replace the HP fuel pump already? Need to keep your post at the top, keep us current with developments.

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

Thanks for the suggestions.

I was by myself and ran out of hands to check the HP fuel pressure on the fuel rail. Yes I have 2 LP fuel pumps, they are original and never have been changed, 2002 motor.

On the original HP pump change not sure if the connection from the positive or negative post opened up to the stator wire connections or if it was the commutator / brushes were acting up (still had brush length, not worn down) on the HP fuel pump but it would randomly stop pumping. So changed the pump 2 years ago and never had another problem. Pulled the original electric pump apart and cleaned the commutator with emory cloth and it spun fine. Did want to take a chance and be stuck again so bit the bullet and installed a new one, you know what that feel like. Not a cheap little DC pump though.

Wondering what cycles the electric fuel pump when the engine is not demanding full fuel flow from the pump? Maybe that's what acted up???? I know there is a little pressure regulator mounted on top of the VST. Have not researched it yet.

i am not a bad mechanic just not familiar with this engine. I have a Yamaha manual though and I will eventually figure it out just trying to save some time if someone has had a similar issue.

Thanks

Unfortunately you have to wait until the condition rears it's head to check things out. The first thing I'd is check the the HP fuel pressure using the shrader valve on the VST. If it's low, its a sure sign that your LP fuel pumps are bad, believe you have 2. Are they original? Why would you have to replace the HP fuel pump already? Need to keep your post at the top, keep us current with developments.

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

On the LP fuel pumps do i just change the diaphram or other parts.

Thanks for the suggestions.

I was by myself and ran out of hands to check the HP fuel pressure on the fuel rail. Yes I have 2 LP fuel pumps, they are original and never have been changed, 2002 motor.

On the original HP pump change not sure if the connection from the positive or negative post opened up to the stator wire connections or if it was the commutator / brushes were acting up (still had brush length, not worn down) on the HP fuel pump but it would randomly stop pumping. So changed the pump 2 years ago and never had another problem. Pulled the original electric pump apart and cleaned the commutator with emory cloth and it spun fine. Did want to take a chance and be stuck again so bit the bullet and installed a new one, you know what that feel like. Not a cheap little DC pump though.

Wondering what cycles the electric fuel pump when the engine is not demanding full fuel flow from the pump? Maybe that's what acted up???? I know there is a little pressure regulator mounted on top of the VST. Have not researched it yet.

i am not a bad mechanic just not familiar with this engine. I have a Yamaha manual though and I will eventually figure it out just trying to save some time if someone has had a similar issue.

Thanks

 

[Tucker99]

Re: 2002 SX150TXRA Hard starting after running for a while

Change the entire pump, about $42 each if I recall correctly.

 

[99yam40]

Re: 2002 SX150TXRA Hard starting after running for a while

Wondering what cycles the electric fuel pump when the engine is not demanding full fuel flow from the pump? Maybe that's what acted up???? I know there is a little pressure regulator mounted on top of the VST. Have not researched it yet.
Thanks

Pump should not shut down while motor is running, otherwise there would not be any pressure on the rail.If ECU does not see motor is turning then it will turn off pump.
on some motors they run power through a resistor to slow down pump at lower RPM and full 12v at high RPM.

Monitoring fuel pressures is the best way to troubleshoot.

 

[Tucker99]

Re: 2002 SX150TXRA Hard starting after running for a while

Pump should not shut down while motor is running, otherwise there would not be any pressure on the rail.If ECU does not see motor is turning then it will turn off pump.
on some motors they run power through a resistor to slow down pump at lower RPM and full 12v at high RPM.

Monitoring fuel pressures is the best way to troubleshoot.

X2 with yam40. The pressure is constant at 35-38 PSI. That pressure regulator maintains that pressure in the rail. Gotta get back to basics and like he said check the pressure and check the LP pumps for leaking. Guys replace that HP pump and the drop of a hat and I'm willing to bet it's not always the problem. Never heard of anybody taking one apart and rebuilding it.

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

Update Forum.

Changed both lp fuel pumps today. Took old pumps apart and both diaphrams looked okay. Ran motor with ears and it ran fine and started fine. Well have to run it in the water to really find out.

I did pull the old HP pump apart, wanted see how it worked. Amazing design with the fuel circulating around the brushes of a 12vdc motor. Guess when you are over rich and there is no air, you don't get a boom.

Will keep everyone updated as I make the run in the boat. Thanks for all the help

JB

X2 with yam40. The pressure is constant at 35-38 PSI. That pressure regulator maintains that pressure in the rail. Gotta get back to basics and like he said check the pressure and check the LP pumps for leaking. Guys replace that HP pump and the drop of a hat and I'm willing to bet it's not always the problem. Never heard of anybody taking one apart and rebuilding it.

 

[Tucker99]

Re: 2002 SX150TXRA Hard starting after running for a while

Wait a second. Gas flowing around the brushes?? How can that be?? Isn't there spark between the brushes and commutator??

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

I know it does not sound right but it's true.

Not if there is no air. Got to have fuel, air (O2) and an ignition source for an explosion or burn. No air. Check it out yourself, look into the immersed (or in tank) electric fuel pumps. The pump impeller is attached to the armature and it pushes the fuel up through the stator around the armature and brushes.

Check out the video: http://www.youtube.com/watch?v=QbzEeWy1b3o A little long but a good video.

The Yamaha pump looks a little different on the electrical connection end, but works the same way. The pump is totally immersed in gas within that tank (VST). It's the same type of cylindrical immersed pump that is in the fuel tank in MOST cars today.

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

Still having the issue after changing both lp pumps and fuel check valve. Also changed both stats and rubber gromet on water valve. Motor runs fine when it is cold and not warmed up. Ran for about 10 or 12 miles. Then shut down and fished for 20 minutes, motor stared fine then as I was going to get on plan motor died. Cranked and cranked an it would not run. Did not have pressure gauge at the time to check the rail pressure.

Got it home while it was still warm. Fuel pressure on the rail was low ~5psi. Let everything cool down and ran pump without engine running. Pump now showed 36psi. Engine started and ran fine. Seems to be when the engine (block) get's to operating temperature electric pump starts acting up. Anyone heard of a pump operating incorrectly once it gets to operating temperature?

Also is there anything in the ecu that will shut the fuel injectors down for any reason? Such as engine temperature. If it senses too warm and engine block will it shut down the fuel?

Thanks.

I know it does not sound right but it's true.

Not if there is no air. Got to have fuel, air (O2) and an ignition source for an explosion or burn. No air. Check it out yourself, look into the immersed (or in tank) electric fuel pumps. The pump impeller is attached to the armature and it pushes the fuel up through the stator around the armature and brushes.

Check out the video: http://www.youtube.com/watch?v=QbzEeWy1b3o A little long but a good video.

The Yamaha pump looks a little different on the electrical connection end, but works the same way. The pump is totally immersed in gas within that tank (VST). It's the same type of cylindrical immersed pump that is in the fuel tank in MOST cars today.

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

Alright you Yamaha expert mechanics, got one for you guys. Found that I had crushed the vacuum tee connection for the vacuum line that goes to the pressure regulator on the VST. Mashed it between the block and the bottom bolt washer of the HP fuel pump VST housing. What happens if the vacuum line to the regulator is open to atmosphere? Also can the pump over heat and not work (low fuel pressure)? Can the vacuum line not connected cause the pump to run too much and overheat? Just throwing things out there.

When the engine is not running and you turn the key on but do not start the engine the electric pump runs for several seconds then shuts off. What tells it to shut off?

Reconnected the vacuum line and ran the engine for over 14 miles and shut it down. This time no problems. Engine did not miss a beat. Now I am really confused.

Problem does seem to be temperature related though.

Help.

Please

Still having the issue after changing both lp pumps and fuel check valve. Also changed both stats and rubber gromet on water valve. Motor runs fine when it is cold and not warmed up. Ran for about 10 or 12 miles. Then shut down and fished for 20 minutes, motor stared fine then as I was going to get on plan motor died. Cranked and cranked an it would not run. Did not have pressure gauge at the time to check the rail pressure.

Got it home while it was still warm. Fuel pressure on the rail was low ~5psi. Let everything cool down and ran pump without engine running. Pump now showed 36psi. Engine started and ran fine. Seems to be when the engine (block) get's to operating temperature electric pump starts acting up. Anyone heard of a pump operating incorrectly once it gets to operating temperature?

Also is there anything in the ecu that will shut the fuel injectors down for any reason? Such as engine temperature. If it senses too warm and engine block will it shut down the fuel?

Thanks.

 

[Tucker99]

Re: 2002 SX150TXRA Hard starting after running for a while

JB sounds like you found the problem, pinched vacuum line. That is a good ending. Gonna go out after work and check mine and make sure I didn't make the same mistake. Sounds easy to do.

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

What is still puzzling me though is when it was not connected (had not found it yet) when I would turn the key to the first position the pump would run but the engine would not start. VST housing was quite warm, is it maybe with the pump reaching an elevated temperature it will not build enough pressure to all the injectors to spray? Seem kind of reaching here.

Wondering now if I have reduced the life of the pump by running it at elevated temperatures??

JB sounds like you found the problem, pinched vacuum line. That is a good ending. Gonna go out after work and check mine and make sure I didn't make the same mistake. Sounds easy to do.

 

[99yam40]

Re: 2002 SX150TXRA Hard starting after running for a while

Not sure if you would call that a vacuum line on a 2 stroke VST, maybe vent to intake. All depends on which side of throttle butterflies it connects to
Did you pinch it off to where the vapors could not be removed from the Vapor Separator Tank?

If the motor heated the VST up and could not get rid of vaporized fuel, it could cause some problems with the liquid fuel not filling up properly. And a HP motor running in just vapor could hurt it as the liquid also lubes and cools the electric motor.

The Ecu tells pump to run if motor is turning over or it turns off after a few seconds of key on of it does not see it turning

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

Thanks for the info, appreciate the response.

It is the hose that connects to the pressure regulator on the top of the VST. The other end of that hose eventually connects to a port on the intake manifold downstream of the intake butterfly valve on the other side of the block. If you follow the hose as it leaves the intake manifold port and go towards the VST, refer to the attached image. Hose 47 attaches to the intake port. It is right behind the lower VST mounting bolt and with those big ss washers you can smash it pretty easy. Where hose 49 attaches to tee part number 48, I smashed the portion of the tee that connect to hose 49. The hose that connects to the pressure regulator. From that tee the line splits to two check valves (look like checks) and then connects via two hoses to ports on top of the VST near the pressure regulator. The hoses labeled 46 in the image.


I think that the hose going to the regulator was just not connected and open to atmosphere, but not sure. So if the tee was open to atmosphere then there was no connection to the two other lines connected to the top of the VST. Meaning no engine vacuum was getting to the regulator or vent lines to the VST. Or just the tee connection to the regulator was smashed and it was smashed firm enough that the connection was good to the two vst lines but not the regulator line. Don't know how the vent lines work so can't go thru the ways that it could be not working. When i pulled all three bolts from the VST to the block, hose 49 was not connected to the tee and that end of the tee had been under the washer because it was deformed flat.

I think if I under stood how all three lines worked i would be able to piece together maybe what was happening.

Not sure if you would call that a vacuum line on a 2 stroke VST, maybe vent to intake. All depends on which side of throttle butterflies it connects to
Did you pinch it off to where the vapors could not be removed from the Vapor Separator Tank?

If the motor heated the VST up and could not get rid of vaporized fuel, it could cause some problems with the liquid fuel not filling up properly. And a HP motor running in just vapor could hurt it as the liquid also lubes and cools the electric motor.

The Ecu tells pump to run if motor is turning over or it turns off after a few seconds of key on of it does not see it turning

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

I have a Yamaha service manual on the OX66 150HP, not sure if it's the factory manual. Does anyone have a factory service manual and how many pages is it????? Don't see any description in the one I have on the functioning of the ECU, for example no description of shutting power off to electric fuel pump if it does not see the engine running. Where can I get the infor on the functioning of the ecu???


Thanks

Thanks for the info, appreciate the response.

It is the hose that connects to the pressure regulator on the top of the VST. The other end of that hose eventually connects to a port on the intake manifold downstream of the intake butterfly valve on the other side of the block. If you follow the hose as it leaves the intake manifold port and go towards the VST, refer to the attached image. Hose 47 attaches to the intake port. It is right behind the lower VST mounting bolt and with those big ss washers you can smash it pretty easy. Where hose 49 attaches to tee part number 48, I smashed the portion of the tee that connect to hose 49. The hose that connects to the pressure regulator. From that tee the line splits to two check valves (look like checks) and then connects via two hoses to ports on top of the VST near the pressure regulator. The hoses labeled 46 in the image.
View attachment 140513

I think that the hose going to the regulator was just not connected and open to atmosphere, but not sure. So if the tee was open to atmosphere then there was no connection to the two other lines connected to the top of the VST. Meaning no engine vacuum was getting to the regulator or vent lines to the VST. Or just the tee connection to the regulator was smashed and it was smashed firm enough that the connection was good to the two vst lines but not the regulator line. Don't know how the vent lines work so can't go thru the ways that it could be not working. When i pulled all three bolts from the VST to the block, hose 49 was not connected to the tee and that end of the tee had been under the washer because it was deformed flat.

I think if I under stood how all three lines worked i would be able to piece together maybe what was happening.

 

[Tucker99]

Re: 2002 SX150TXRA Hard starting after running for a while

I have the factory service manual that I would let you have for a very resonable price. Make me an offer.

 

[jb1]

Re: 2002 SX150TXRA Hard starting after running for a while

Be glad to, would like to make sure the one you have is different than the one I have. Don't need two of the same. I'll post a copy of a page and maybe you can do the same??? Do it later this evening.

Thanks

I have the factory service manual that I would let you have for a very resonable price. Make me an offer.