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Author Topic:   1986 70 HP Evinrude Fuel Starvation

grosseile88 posted 07-03-2014 02:41 PM ET (US)
As of yesterday, my [1986] 70-HP Evinrude has started to starve itself of fuel at high speeds. Today, I replaced in-line fuel filter on engine and remote fuel-water filter. All fuel fittings, primer bulb, and fuel lines from the tank to the carburetors were replaced last year with ethanol resistant lines. I can get it to maintain speed if I squeeze bulb and force fuel into carbs. Bulb feels pretty firm as I perform this procedure. Any thoughts on what could be causing this? Do I have a fuel pump that is dying a slow death?
Thanks for any thoughts on the matter!
jimh posted 07-03-2014 04:00 PM ET (US)
If the fuel lift pump on the 1986 Evinrude 70-HP engine is original, it is now 28-years old. A c.1986 fuel pump may not have been manufactured for use with our modern blended fuels that contain 10-percent ethanol (or more in some circumstances). Based on your narrative of running problems with the engine, a failed fuel pump is a very likely cause. Given the age of the fuel pump, its possible risk of damage if exposed to ethanol-gasoline blended fuels, and the symptoms, replacement of the fuel pump is likely to be the remedy to this problem.
tedious posted 07-03-2014 05:01 PM ET (US)
Sure sounds like the fuel pump is not working well enough to keep the carbs fed at full throttle. It could certainly be the pump itself. Is this a "VRO" motor? I think the cutover was in 86 but I don't know for sure. If so, the VRO motors were supposed to be ethanol-resistant.
But either way, before you replace the pump, check the vacuum line that powers it - goes from the crankcase to the pump. If that is cracked or otherwise leaking it could be the culprit, and all it takes to fix is a short piece of 1/4" fuel line.
Tim
grosseile88 posted 07-03-2014 05:04 PM ET (US)
Thanks for the input! Pretty sure the pump is original, engine was originally a VRO set up but that was disabled by previous owner long ago. If I am not mistaken it appears to be be original VRO fuel pump with the oil inlet portion capped off.
I will start there!
Thanks!
tedious posted 07-03-2014 05:11 PM ET (US)
Since it was a VRO but you're not using it, if you end up wanting to replace the pump, get the non-VRO version. It costs way, way less. I can probably dig up the part number if you get to that point.
Tim
crabby posted 07-05-2014 09:27 AM ET (US)
You might try just rebuilding the pump, very easy to do.
grosseile88 posted 07-05-2014 04:24 PM ET (US)
Any idea were the vacuum lint to the fuel pump hides? I can find the fuel hose that feeds the pump from the bottom and the fuel hose that feeds the carbs that exits the top but cant see the vacuum hose? Yes if you can dig up the non VRO pump # that would be great. The VRO pumps seem to run around $450!!!!
Thanks again for the input!
grosseile88 posted 07-07-2014 07:41 PM ET (US)

Removed fuel pump from engine today. All fuel lines and pulse line look great, no kinks, holes etc.. I knew all fuel lines were replaced last year, looks like pulse line was too. I am going to go with the rebuild kits instead of trying to retro fit a standard pump to the engine. I assume I should get kit #435921 to replace the air motor diaphragm side of pump and #436095 to replace the fuel side???? I could not find one kit to do the whole job. Any input would be great before I order the kits.
Thanks!
Sean
tedious posted 07-07-2014 08:15 PM ET (US)
Sean, for reference the non-VRO pump appears to be part number 0438557 and it goes for $109. Its the pump for a 1996 65 horse.
Tim
jimh posted 07-07-2014 08:56 PM ET (US)
You can locate parts, part numbers, and prices on SHOP.EVINRUDE.COM.
tedious posted 07-08-2014 09:18 AM ET (US)
For reference, the price I quoted was from marineengine.com. The new, non-VRO pump appears to cost less than the combined cost of the rebuild kits for the VRO pump.
Tim
grosseile88 posted 07-09-2014 09:25 AM ET (US)

I took apart the pump last night, the diaphragm and seals actually look to be in good shape. No noticeable holes, tears or warping. However I am guessing rubber may not be as pliable as new diaphragm given their age.
One thing I did notice is when disassembling the fuel side of the pump, the plunger that is connected to the fuel diaphragm and goes into the oil portion of the pump was pretty well stuck in that side of the pump. I found on another site that this is often the culprit because it caused the fuel side to stop cycling properly on VRO pumps that are now running premix. Kind of makes sense because this would restrict the movement of the fuel diaphragm. So I am going to disconnect the plunger when I rebuild pump. Before I do, does this make sense?
I am going to pull off the pulse fitting too and make sure it is not gummed up.
Thanks for the input!
jimh posted 07-09-2014 10:40 AM ET (US)
I think you are describing "the plunger" as acting as a damper on the movement of the rubber diaphragm, due to "the plunger" being stuck. If that is the case, I suspect that freeing up "the plunger" or even removing it entirely will stop the damper effect. This may result in more fuel being delivered.
I think "the plunger" is shown in the illustration in
http://continuouswave.com/whaler/reference/VRO.html
where it is identified as "Oil Pump Piston." Is that what you meant?
grosseile88 posted 07-09-2014 12:40 PM ET (US)

Jim
You are correct "oil pump piston" is what I was referring to, plunger is the only term that I could come up with before my morning coffee. I am going to remove it since it no longer serves any purpose and see how she runs. The oil pump piston on my fuel pump definitely does not move freely. I will report back, hopefully this will fix the problem. Who knows, maybe I will gain 10 knots in top speed after all said and done!
grosseile88 posted 07-24-2014 09:07 AM ET (US)

Removed the oil pump piston on existing VRO pump and pump still did not function. Replaced pump with Sierra 18-7353 and she runs like a champ. Over and out!

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Author	Topic: 1986 70 HP Evinrude Fuel Starvation
grosseile88	posted 07-03-2014 02:41 PM ET (US) As of yesterday, my [1986] 70-HP Evinrude has started to starve itself of fuel at high speeds. Today, I replaced in-line fuel filter on engine and remote fuel-water filter. All fuel fittings, primer bulb, and fuel lines from the tank to the carburetors were replaced last year with ethanol resistant lines. I can get it to maintain speed if I squeeze bulb and force fuel into carbs. Bulb feels pretty firm as I perform this procedure. Any thoughts on what could be causing this? Do I have a fuel pump that is dying a slow death? Thanks for any thoughts on the matter!
jimh	posted 07-03-2014 04:00 PM ET (US) If the fuel lift pump on the 1986 Evinrude 70-HP engine is original, it is now 28-years old. A c.1986 fuel pump may not have been manufactured for use with our modern blended fuels that contain 10-percent ethanol (or more in some circumstances). Based on your narrative of running problems with the engine, a failed fuel pump is a very likely cause. Given the age of the fuel pump, its possible risk of damage if exposed to ethanol-gasoline blended fuels, and the symptoms, replacement of the fuel pump is likely to be the remedy to this problem.
tedious	posted 07-03-2014 05:01 PM ET (US) Sure sounds like the fuel pump is not working well enough to keep the carbs fed at full throttle. It could certainly be the pump itself. Is this a "VRO" motor? I think the cutover was in 86 but I don't know for sure. If so, the VRO motors were supposed to be ethanol-resistant. But either way, before you replace the pump, check the vacuum line that powers it - goes from the crankcase to the pump. If that is cracked or otherwise leaking it could be the culprit, and all it takes to fix is a short piece of 1/4" fuel line. Tim
grosseile88	posted 07-03-2014 05:04 PM ET (US) Thanks for the input! Pretty sure the pump is original, engine was originally a VRO set up but that was disabled by previous owner long ago. If I am not mistaken it appears to be be original VRO fuel pump with the oil inlet portion capped off. I will start there! Thanks!
tedious	posted 07-03-2014 05:11 PM ET (US) Since it was a VRO but you're not using it, if you end up wanting to replace the pump, get the non-VRO version. It costs way, way less. I can probably dig up the part number if you get to that point. Tim
crabby	posted 07-05-2014 09:27 AM ET (US) You might try just rebuilding the pump, very easy to do.
grosseile88	posted 07-05-2014 04:24 PM ET (US) Any idea were the vacuum lint to the fuel pump hides? I can find the fuel hose that feeds the pump from the bottom and the fuel hose that feeds the carbs that exits the top but cant see the vacuum hose? Yes if you can dig up the non VRO pump # that would be great. The VRO pumps seem to run around $450!!!! Thanks again for the input!
grosseile88	posted 07-07-2014 07:41 PM ET (US) Removed fuel pump from engine today. All fuel lines and pulse line look great, no kinks, holes etc.. I knew all fuel lines were replaced last year, looks like pulse line was too. I am going to go with the rebuild kits instead of trying to retro fit a standard pump to the engine. I assume I should get kit #435921 to replace the air motor diaphragm side of pump and #436095 to replace the fuel side???? I could not find one kit to do the whole job. Any input would be great before I order the kits. Thanks! Sean
tedious	posted 07-07-2014 08:15 PM ET (US) Sean, for reference the non-VRO pump appears to be part number 0438557 and it goes for $109. Its the pump for a 1996 65 horse. Tim
jimh	posted 07-07-2014 08:56 PM ET (US) You can locate parts, part numbers, and prices on SHOP.EVINRUDE.COM.
tedious	posted 07-08-2014 09:18 AM ET (US) For reference, the price I quoted was from marineengine.com. The new, non-VRO pump appears to cost less than the combined cost of the rebuild kits for the VRO pump. Tim
grosseile88	posted 07-09-2014 09:25 AM ET (US) I took apart the pump last night, the diaphragm and seals actually look to be in good shape. No noticeable holes, tears or warping. However I am guessing rubber may not be as pliable as new diaphragm given their age. One thing I did notice is when disassembling the fuel side of the pump, the plunger that is connected to the fuel diaphragm and goes into the oil portion of the pump was pretty well stuck in that side of the pump. I found on another site that this is often the culprit because it caused the fuel side to stop cycling properly on VRO pumps that are now running premix. Kind of makes sense because this would restrict the movement of the fuel diaphragm. So I am going to disconnect the plunger when I rebuild pump. Before I do, does this make sense? I am going to pull off the pulse fitting too and make sure it is not gummed up. Thanks for the input!
jimh	posted 07-09-2014 10:40 AM ET (US) I think you are describing "the plunger" as acting as a damper on the movement of the rubber diaphragm, due to "the plunger" being stuck. If that is the case, I suspect that freeing up "the plunger" or even removing it entirely will stop the damper effect. This may result in more fuel being delivered. I think "the plunger" is shown in the illustration in http://continuouswave.com/whaler/reference/VRO.html where it is identified as "Oil Pump Piston." Is that what you meant?
grosseile88	posted 07-09-2014 12:40 PM ET (US) Jim You are correct "oil pump piston" is what I was referring to, plunger is the only term that I could come up with before my morning coffee. I am going to remove it since it no longer serves any purpose and see how she runs. The oil pump piston on my fuel pump definitely does not move freely. I will report back, hopefully this will fix the problem. Who knows, maybe I will gain 10 knots in top speed after all said and done!
grosseile88	posted 07-24-2014 09:07 AM ET (US) Removed the oil pump piston on existing VRO pump and pump still did not function. Replaced pump with Sierra 18-7353 and she runs like a champ. Over and out!