84'Johnson 90HP V4 not drawing fuel ??

[stevetedder]

Title says it all, motor starts to die out, hit the primer bulb a couple of times and it revs back up. Checked the draw lines in tank for air leak, tightened clamps around filters and checked diaphram in VRO fuel pump. Any other thoughts? something simple Im overlooking? Any thoughts are appreciated. Also the VRO has been bypassed for premix, could a person just add a electric fuel pump to keep a few pounds of pressure to the system?

 

[DJ]

Re: 84'Johnson 90HP V4 not drawing fuel ??

Electric fuel pumps are a bad idea for this application.

You are losing your prime, so to speak. You have an air leak-somewhere.

 

[emdsapmgr]

Re: 84'Johnson 90HP V4 not drawing fuel ??

Try constantly priming the fuel hose bulb while at full throttle. This will force extra fuel into the carb bowls around the fuel pump. If the engine runs fine when you constantly prime that bulb, you probably have a weak fuel pump.

 

[Will Bark]

Re: 84'Johnson 90HP V4 not drawing fuel ??

Or you could have a stopped up vent at the tank.

 

[stevetedder]

Re: 84'Johnson 90HP V4 not drawing fuel ??

All great thoughts! I spent ALL day on it today. I took the VRO/Fuel pump apart and cleaned it again, Can see no holes in diaphram, could hear a little suction when pressing on it, check valve seems to be working on it replaced all the zip tie hose clamps with real ones. I also sprayed the carbs down in and out with carb cleaner. Adjusted the linkage so that the carb butterflies open up more, lithium grease in about a dozen spots, tightened and blue thread locked the hand loose nut on top of the starter(was about to lose that one ), and cleaned the spark plugs. Seems to be running ok on muffs but this has also been the case before.(Sorry guess I should have mentioned the problem was semi sporadic earlier)

Ive got to get the pictures of this boat uploaded. New 3/4 instead of 5/8 deck (lots of routing involved), carpet, paint job and Bimini top this past winter.I took some pics along the way, just haven't got them off my phone yet.

 

[DargelJohn]

Re: 84'Johnson 90HP V4 not drawing fuel ??

Couple more suggestion, With the engine off, pump the primr bulb til it is hard and look for leaks in the system. Also try cracking open the gas cap when it acts up next time and see if it makes a difference; that would be a clogged vent.

 

[stevetedder]

Re: 84'Johnson 90HP V4 not drawing fuel ??

I had tried taking off the gas cap as one of first things as the symptoms resembled vapor lock, but pressurizing the system to look for the leak did not occur to me, I tend to think of the more complicated solutions 1st for some reason and forget about the basics sometimes. Thanks!

 

[stevetedder]

Re: 84'Johnson 90HP V4 not drawing fuel ??

OK interesting discovery, unplug the top fuel line from the VRO (where the mixed fuel is supposed to come out to go to the carb's and then I start the motor with enough fuel in the filter to run a few minutes and nothing, no fuel coming out the top of the VR0. Am I wrong or is this a definite sign that the Fuel pump inside the VRO is not pumping?

 

[stevetedder]

Re: 84'Johnson 90HP V4 not drawing fuel ??

removed off topic post, getting late here zzzzzzzzzzzzzzzzzzzzzzzz

 

[stevetedder]

Re: 84'Johnson 90HP V4 not drawing fuel ??

OK replace the VRO with a regular fuel pump and now its running great, thanks to all who replied.