Fuel issues - 97 175 OP 60 degree Looper

[Maichip]

My Looper is on the fritz.

On the above noted motor I have recently rebuilt all six carburetors with OEM rebuild kits, replaced the plugs and decarbed the motor. The motor has run extremely well for the last 50 hours or so since the carb rebuild. Monday I took the boat out and a new problem popped up.

While running the motor from the dock, I went about 1/2 a mile when the motor began to surge. The motor eventually dropped rpm's until it died. I pumped the bulb and it started right back up. The motor ran for another 1/4 mile or so and did the same thing. I checked all fuel line connections, all were tight. I had my wife drive while I pumped the bulb and it ran fine. I stopped pumping and once again the motor died. This time I removed the engine cover and listened while I pumped the bulb. I could hear the fuel pump reservoir fill up when I pumped the bulb. I was able to get the boat back to the dock and on the trailer. I put the boat back in the shed as I was a little pizzed at the time.

My synopsis is obviously a fuel delivery issue. I will check the fuel delivery to the pump by using a separate fuel line leading into a separate fuel tank.

Here is my question: I suspect that there is an issue with the fuel pump. There is no fuel pump rebuild kit for this motor. What is the repair? Replacing the fuel pump seems a little excessive and expensive. Has anyone had a similar experience and if so, what was the repair.

Thanks in advance for your help.

 

[hidef]

Re: Fuel issues - 97 175 OP 60 degree Looper

Your fuel pump is dead unfortunately. You can get a fuel pump rebuild kit from Maxrules http://www.maxrules.com/fixomcvro.html however I don't recommend it. It is just for the fuel side only as you cannot repair/rebuild the oil side. Your pump has to be darn near perfect to repair if there is a problem in the middle section of the pump the rebuild kit won't help.

 

[Maichip]

Re: Fuel issues - 97 175 OP 60 degree Looper

hidef,

That is exactly what I was afraid of.

Thanks for the advice. I am going to go and burn this motor now.......

 

[boobie]

Re: Fuel issues - 97 175 OP 60 degree Looper

If it was my mtr I'd rebuild the fuel side of the pump, disconnect the oiling side of it and run 50:1 premix.

 

[Chris1956]

Re: Fuel issues - 97 175 OP 60 degree Looper

If it were my motor I would verify the pump is bad before I did anything. That motor has a vapor seperator, which is the first place the gasoline goes to on the motor. The attached vapor pump and the separator cover gasket need to be working and sealing properly. I would check/replace those first....

 

[multimech]

Re: Fuel issues - 97 175 OP 60 degree Looper

The pump is very specific to that engine. The reasons for the pump failing is usually the diaphragm is damaged, usually do to age or ethanol fuels.

You can get a rebuild kit for the diaphragm. It will work if the pump is not warped or has any cracks in it.

I agree that if you rebuild it, close off the oil line and put oil in the fuel.

You can also buy a fuel only pump for it for about $50.00 less than the $400.00 you would pay for a new pump, full whack retail obviously.

 

[multimech]

Re: Fuel issues - 97 175 OP 60 degree Looper

Forgot to add it is a very simple test of the pump. Get a vacuum pump and put it on the fuel inlet, put your finger over the fuel outlet. Pump it to 15 hg and hold your finger firm on the outlet. remove the pump and then remove your finger. If it clicks when you remove the pump, the diaphragm is bad. If it holds pressure until you remove your finger, it is good. Do the same test with a pressure pump, same pressure, 15 psi and same finger test.

 

[Maichip]

Re: Fuel issues - 97 175 OP 60 degree Looper

I am going to tear it apart tomorrow. I'll have a look see and try to figure out what is going on with it.

I appreciate your comments. I really do not think the pump is cracked or warped. I am hoping it is just a diaphragm or something simple.

PS... its a good thing I came to my senses before I burned the motor down to the ground. It could still happen... We'll see!

 

[Chris1956]

Re: Fuel issues - 97 175 OP 60 degree Looper

So you are not going to check the vapor pump and vapor seperator first? That makes no sense, as the parts to repair them are real cheap, in comparison to the cost to repair the OMS Pump.

 

[Maichip]

Re: Fuel issues - 97 175 OP 60 degree Looper

Chris,

I am going to check the vapor pump first as you suggested. I'll have a look at it this evening.

 

[Maichip]

Re: Fuel issues - 97 175 OP 60 degree Looper

Well it appears that I have more than one issue with the fuel pump. First issue appears to be the diaphragm on the vapor pump assembly. Although I am not sure that this was the reason for the motor failure, I am going to replace it. Second, it appears that I was not the first person to get into the fuel pump. There is no gasket in the vapor separator assembly. This could have easily caused a problem. Not really sure why it manifested itself now but I have ordered a new one. I also found that the top cover to the primer solenoid has multiple cracks. In fact it looks so bad that if I take it apart, the top cover may just fall apart. I don't think this was the reason for the motor failure but might as well replace it as I have the fuel/VRO pump assembly off.

I took the oil reservoir out and plan on disconnecting the VRO and mixing oil/fuel from here on out. I will replace the fuel lines and hand pump as I already have a new one in the garage. Kinda bummed over disconnecting the VRO as I like not having to hand mix the fuel/oil. I would rather mix fuel/oil than burn up the motor though.

I will post an update when the parts arrive and its all back together.

 

[Chris1956]

Re: Fuel issues - 97 175 OP 60 degree Looper

You did not describe any issue with the OMS pump, but plan on disconnecting it anyway? Why?

You will need a fuel pump anyway, so why disconnect the oil connection to the OMS pump?

 

[Maichip]

Re: Fuel issues - 97 175 OP 60 degree Looper

You did not describe any issue with the OMS pump, but plan on disconnecting it anyway? Why?

You will need a fuel pump anyway, so why disconnect the oil connection to the OMS pump?

Chris,

While I agree with you regarding disconnecting the VRO, at the same time, the motor is 15 years old. At this time the VRO works and I prefer to use it over mixing fuel/oil. The decision boils down to this: if the VRO fails, the motor burns up. I have got to believe that it would be easier to mix fuel/oil than replace the motor.

I am not replacing the fuel pump body. I am replacing the vapor pump assembly (not rebuilding it), replacing the gasket in the vapor separator and repairing the primer solenoid. There is no need to replace the entire fuel pump assembly in my opinion.

 

[Chris1956]

Re: Fuel issues - 97 175 OP 60 degree Looper

To premix or not to premix is a personal decision. On my '98 Johnny V6, I carry a gallon of 2 cycle oil (63 gal fuel tank) and count on the warning system to tell me when it is no longer working. I can then premix the fuel, on the spot.

 

[Faztbullet]

Re: Fuel issues - 97 175 OP 60 degree Looper

The vapor pump will not cause this problem......you have (a) airleak in vapor separator (b) defective air motor on VRO/OMS pump (cracked housing,diaphram)

 

[Maichip]

Re: Fuel issues - 97 175 OP 60 degree Looper

Well here we go again,

I replaced the vapor pump, vapor separator gasket and repaired the primer solenoid. The problem still exists. I went back and forth on disconnecting the VRO. When I test ran the motor I noticed the "No Oil" light came on. That pretty much settled it for me so I disconnected the VRO and mixed the fuel/oil.

Question: although I did not find any cracks in the fuel separator or VRO pump, would a crack in the VRO (OMS) cause this problem even after it has been disconnected.

I am feeling now like I should have just replaced the fuel pump system as hidef suggested. No offense meant to anyone here. It would have been expensive but if in the end, I have to replace it I may have just wasted dollars attempting to repair it.

Any help would be appreciated.

 

[hidef]

Re: Fuel issues - 97 175 OP 60 degree Looper

Use the flowchart to verify that it is dead. I have also included links to two fuel pumps one with VRO and one without. If you have built in tank I would keep the VRO. That engine has ran for 14 years there is no reason it wont run another 14 with a new pump.

http://www.maxrules.com/graphics/VROpics/VROflowchart.jpg

If you want to keep the VRO go with this one
http://www.marineengine.com/newparts/part_details.php?pnum=OMC5007420&ptype=&Engine=&Model=

If you don't want VRO and save a little money order this one
http://www.marineengine.com/newparts/part_search.php?part_num=5007422&submit2=Go

 

[Maichip]

Re: Fuel issues - 97 175 OP 60 degree Looper

Thanks hidef,

I ordered a new pump with VRO. I will re-install the oil reservoir and get it ready to install the new pump.

Thanks for everyone's help.

 

[hidef]

Re: Fuel issues - 97 175 OP 60 degree Looper

I went through this last year with a 1998 90 that belongs to my brother. We tried rebuilding the VRO pump but the issue was in the mid section. What really ticked us off was we had a brand new VRO2 pump from a 70 but we couldn't use it because the fuel outlet on that pump was fixed and wouldn't clear the vapor separator. He kept the oil injection it is easier with a built in tank. If you have the system check gauge hooked up I wouldn't worry about the VRO the alarm system works quite well.

 

[Maichip]

Re: Fuel issues - 97 175 OP 60 degree Looper

I tested the pump according to the schematic you attached and it appears that the diaphragm is bad. I am not going to mess with trying to rebuild it. I re-installed the oil reservoir and ran new fuel lines today. When the new pump arrives it is all ready to be installed.

Any ideas on where I can get spiral wrap or flexible rigging conduit. I'd like to cover the electrical and fuel lines for a little cleaner look.