1986 Evinrude 70 hp fuel problem ?

[finish line 88]

Starts great, idles great runs great at 1/3 throttle. Try to run @ WOT it falls off after a few seconds of running. Pull the throttle back to idle wait a few seconds and it will rev up again and do the same thing. It never quits running or stalls.
Powerhead is new and it has a VRO fuel pump that is new but the oil side is not hooked up. I have only run 10 to 12 gallon of pre mix fuel to break it in. Hard to think it could be a fuel pump. Just replaced the bulb and fuel line with new 5/16" fuel line.
Any help would be great ! Thanks

 

[Daviet]

Re: 1986 Evinrude 70 hp fuel problem ?

Have you checked the high speed orifices in the carbs? If you have a restricted or plugged orifice it will not allow fuel into the high speed circut of the carb.

 

[finish line 88]

Re: 1986 Evinrude 70 hp fuel problem ?

No I have not checked that. Plan to pull boat today and start to check things out. I also was told since I am not using the oil side of the VRO pump to disconnect the plug to it and make sure the oil line is plugged. Thanks

 

[finish line 88]

Re: 1986 Evinrude 70 hp fuel problem ?

Found that the oil line had not been plugged. Capped it off but have not done a test run. Found another problem. Turn the key switch and the motor will not crank. New battery and it is good and well charged. Solenoid does not seem to be working so I change it but still does not crank. Jumpered the solenoid and it fired off. I took the spare from a running motor so I must have another problem than the solenoid. NEED HELP

 

[SideW@ys]

Re: 1986 Evinrude 70 hp fuel problem ?

I had a similar problem and found that my floats in the carburator were not aligned properly. They were not allowing enough gas into the carb bowls and that same thing happened. It could also be a restriction in the gass lines somewhere. Try squeezing your primer bulb when you run full throttle and see if that helps. It also could be a clogged jet but if you can get up to speed and then it falls off that indicates to me that you are running out of fuel and then when you slow down you are able to build up the reserve

 

[finish line 88]

Re: 1986 Evinrude 70 hp fuel problem ?

Thanks for the reply. Seems I have a few different things going on a one time. Just tested the solenoid and found that it tested bad. Do you think the open oil line on the VRO pump would show up as a vacuum leak and starve the engine for fuel ? I tried squeezing the bulb but it was firm, It did help though

 

[emdsapmgr]

Re: 1986 Evinrude 70 hp fuel problem ?

Next time you go out boating, when you go to WOT, have someone constantly prime the fuel hose bulb. This will force extra fuel into the carb bowls. If the engine runs normally (at WOT), then you have a fuel delivery problem-probably a weak fuel pump. Strong enough to run it a low speeds, but not strong enough to run Wot. If the starter cranks by jumping the solenoid, possible the solenoid is bad-or that you have blown the small 20 amp fuse in the wiring harness under the cowling.

 

[finish line 88]

Re: 1986 Evinrude 70 hp fuel problem ?

Thanks for the reply. Can I install the standard fuel pump and remove the VRO pump ? I am using premixed fuel any how and the VRO is a lot of $. I checked the fuse and it checked OK. Ordering a new solenoid today.

 

[finish line 88]

Re: 1986 Evinrude 70 hp fuel problem ?

OK now I installed the new solenoid and the problem is still there. Found the problem though. Jumped a ground from the ground on the solenoid to the neg battery lead on the motor and it cranks great. Now to get to the fuel problem Thanks for all the replys.

 

[obxleadlineman]

Re: 1986 Evinrude 70 hp fuel problem ?

Check your fuel lines on the engine, after mine was rebuilt found a kinked hose on the supply side of the pump, when i replaced it, corrected the fuel starving problems. Thought my problem was fuel pump, changed out VRO pump from a spare motor, was not the problem. make sure all you fuel lines are in good shape

 

[finish line 88]

Re: 1986 Evinrude 70 hp fuel problem ?

The supply side fuel line has a spring inside the hose and it is on the bottom of the fuel pump. Not much room there to make a 90 degree bend. Tried to run boat today and it is getting worse. Misses and acts like it is not getting fuel. Got it back on the trailer and going to start all over. Test fuel pump,check fuel lines and pull high speed jets before I disassemble carbs.

 

[finish line 88]

Re: 1986 Evinrude 70 hp fuel problem ?

Here is the update if anyone is interested. I removed the VRO fuel pump and installed the standard fuel pump. IT RUNS GREAT !!!!!