***UPDATE*** 1987 175 HP outboard Evinrude surging still

[rolander]

Ok so I think I am figuring out my surging problem. When it Surges it surges to more power. Meaning it picks up power when it surges. I have Ohmed the coils, changed plugs, decarboned the motor with the sea foam and a gallon of gas trick. Compression on the engine is 95-100 PSI on all 6 cylinders. It doesn't feel like it's missing at all. I am not getting the RPM out of this motor. I run less then 5K full throttle.

Now a different thing I noticed . Exactly like when the surging happens.yesterday, when I push the choke on the key, It revs up and starts performing for a bit.

this is on the IO to OB conversion boat, I ran a 140 on there with no issues, this 175 acts like it is either dropping a cylinder and picking it back up, or is running out of fuel.

Also when I punch it to take off out of the hole, it revs to beat hell for a second or so, then bogs down and starts taking off slower. Like the bowls of the carbs empty down and then runs out of fuel.

Any ideas?

 

[mrcj001]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

Sounds like a carburator issue.

 

[rolander]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

I am starting to think the same thing on the carbs.

another thing I forgot to mention, while running full throttle, I had my bro in law try pumping the fuel bubble to see if the performance would change, It did not. He said he could feel fuel running through it and when he squeezed it, the bubble squeezed down but would not return back. It stayed sucked in until I backed off the throttle.

 

[Sir Robin]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

dbl post

 

[Sir Robin]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

Sounds like you found it to me, bulb not returning....... substantial fuel use diffrences between V-4 & V-6. I have a check valve at tank and it will sometimes stick half way, although I am not sure if it is stuck half open ,,,,,or half closed.................

 

[Sir Robin]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

You didn't say if you are using vro or premix. I had the plastic relax on the vro AND the carb bowls alowing air in and disrupting the flow of fuel on the high end. New pump (450.00 )surfacing the bowls, new needle & seats and paying attention to the gaskets so they would seal worked for me. The bowl gaskets want to suck into the bowl if just left on their own


hope it helps

 

[rolander]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

I was running the VRO I disconnected it because it was over oiling, and went to premix now. No differencd in the way it runs going VRO VS premix.

 

[rolander]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

Sounds like you found it to me, bulb not returning....... substantial fuel use diffrences between V-4 & V-6. I have a check valve at tank and it will sometimes stick half way, although I am not sure if it is stuck half open ,,,,,or half closed.................

The bulb stays open while running, it's when my bro in law went to pump it while running WOT is when it didn't return.

My tank also has a check valve, lets fuel come out but nothing back in.

 

[emdsapmgr]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

The bulb should not go flat while running. That's a fuel delivery problem You could have a problem with ball valves in the fuel primer bulb on the hose or the anti-siphon valve at the tank. You did not mention a warning horn in the control box from the vacuum switch on the side of the engine. Is that switch still connected and working?

 

[ezeke]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

The bulb stays open while running, it's when my bro in law went to pump it while running WOT is when it didn't return.

My tank also has a check valve, lets fuel come out but nothing back in.

The check valve on most built-in tanks is USCG required anti-siphon valve. The function is to prevent fuel from being siphoned out of the tank in case of a fuel leak in the fuel system, not to keep fuel from flowing into the tank.

Because of the design, they are easily fouled and sometimes stick, preventing the free flow of fuel to the engine.

 

[d.boat]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

I was running the VRO I disconnected it because it was over oiling, and went to premix now. No differencd in the way it runs going VRO VS premix.

I could be wrong, but to my understanding of the system, that would lead me to look for the problem before the fuel pump as opposed to the pump itself or the carbs. If it was over oiling, there probably was an air leak or something reducing the amount of fuel going into the pump. The pump is just a little machine which does nothing but pump fuel and oil as a ratio of the pulse its getting from the pulse fitting to the crankcase. On the fuel side, some of what it was pumping was air instead of fuel. It was putting in as much oil as should have been required give the pulse, but the amount of fuel didn't match it, was less, therefore over oiling.

If you haven't seen this, it's a great over view of the system:

http://continuouswave.com/whaler/reference/VRO.html

I'm thinking that whatever is causing that is either intermittent or at a low enough level so it causes a surge (upward you say) when more adequate gas is delivered from time to time.

Therefore, I'd guess it's not a pump failure at all and I'd re-attach and re-prime the oil side and figure out what the real problem is on the fuel side. Start at the pickup inside the tanks, the anti siphon valves at the tanks, trace fuel lines all the way to the pump, check primer bulb, fuel filters, all connections, make sure there's no restrictions or air leaks. It could be a bunch of little things and just re-habbing the whole system solves it, or it could be something obvious.

To do a quick and dirty test of the fuel system up to the engine, connect a temporary "known good" portable tank. If it works better, you have some good clues!

It is also possible that the fuel side of the pump is failing - that's rebuildable.


Or could be something completely different, but that's how I'd approach it.

 

[Sir Robin]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

I could be wrong, but to my understanding of the system, that would lead me to look for the problem before the fuel pump as opposed to the pump itself or the carbs. If it was over oiling, there probably was an air leak or something reducing the amount of fuel going into the pump. The pump is just a little machine which does nothing but pump fuel and oil as a ratio of the pulse its getting from the pulse fitting to the crankcase. On the fuel side, some of what it was pumping was air instead of fuel. It was putting in as much oil as should have been required give the pulse, but the amount of fuel didn't match it, was less, therefore over oiling.

If you haven't seen this, it's a great over view of the system:

http://continuouswave.com/whaler/reference/VRO.html

I'm thinking that whatever is causing that is either intermittent or at a low enough level so it causes a surge (upward you say) when more adequate gas is delivered from time to time.

Therefore, I'd guess it's not a pump failure at all and I'd re-attach and re-prime the oil side and figure out what the real problem is on the fuel side. Start at the pickup inside the tanks, the anti siphon valves at the tanks, trace fuel lines all the way to the pump, check primer bulb, fuel filters, all connections, make sure there's no restrictions or air leaks. It could be a bunch of little things and just re-habbing the whole system solves it, or it could be something obvious.

To do a quick and dirty test of the fuel system up to the engine, connect a temporary "known good" portable tank. If it works better, you have some good clues!

It is also possible that the fuel side of the pump is failing - that's rebuildable.


Or could be something completely different, but that's how I'd approach it.

This is where i would re submit the bit about mt NEW ( bummer ) pump.
The plastic relaxes then LEAKS.... even if premixing, the old pump will let air entrain ...........Examine the pump mating surfaces closely. Usually, if it is dry it is ok, if wet,,,,it leaks, and if fuel can get out, air can get in

 

[d.boat]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

This is where i would re submit the bit about mt NEW ( bummer ) pump.
The plastic relaxes then LEAKS.... even if premixing, the old pump will let air entrain ...........Examine the pump mating surfaces closely. Usually, if it is dry it is ok, if wet,,,,it leaks, and if fuel can get out, air can get in

Where on the VRO/OMS pump was it leaking? There is no mating surface to the engine, just hose connections.

 

[rolander]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

Thank you for all the replies everyone, I will be checking alot of these ideas this weekend, along with pulling the carbs off and cleaning and checking those, trying to run a serperate fuel tank closer to the engine, and checking out the VRO pump closer. I will check all fuel lines to the engine.

I also noticed that little fuel shut off on the side of the motor leaks out of the shrader valve. I can't remember what it's called, it's that red lever. on the right side of the motor. I believe it deals with the choke. I noticed that when the boat sputters it spews a little bit of fuel out of that shrader valve. I will also be replacing that or buying parts to rebuild it.

 

[Sir Robin]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

see continues wave pic, the fuel side that is repairable has 6 screws that hold the 2 halfs of the chamber togeather. This is where fuel leaking was happening, as the plastic warped and the gasket would no longer seal. I would have gone premix had the pump been good but for only 75$ more, no mixing was my choice. The original oms pump went 15 years without problems, a no brainer to me

 

[Sir Robin]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

A thought.....
My outboard go to said that the '' little red leaver'' can sometimes crack and also said it was not real easy to see, so close inspection is the key. if it leaks around the plastic, and not from the valve that is a replaceable part.
I was hoping that was my bogg problem, but alass.... Pump & needle & seats and link & sync
I can not stress enough that the plastic that is used for timing, carbs,pumps ect. relaxes. EVERY fastener in plastic was loose along with the MAIN JETS One even fell out into my hand???? I understand that the drain screw has been elongated to stop this...........

 

[emdsapmgr]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

That red lever on the side of the fuel primer solenoid has two positions. Make sure it is in the correct position. When you are normally running the engine, the red lever must be parallel to the length of the solenoid.

 

[jonesg]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

I see multiple problems,
if the vro was over-oiling there is an air leak in the fuel side somewhere.
Going to pre-mix doesn't fix the air leak.

Hopefully you upgraded the fuel lines for the 175.
The bulb stays flat after being squeezed because the fuel line is too small.
Just a guess but it sounds logical so...

 

[rolander]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

Right, but where do you find a 7/16 fuel bulb? Every marine store around here sells the small lines ones?

 

[emdsapmgr]

Re: 1987 175 HP outboard Evinrude surging still

Re: 1987 175 HP outboard Evinrude surging still

A 3/8" fuel line and a 3/8" hose bulb is fine for that V6 engine. See your local Bombardier dealer and get a factory hose and bulb.