'85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

[FBPirate95]

I took my "new to me" boat out today for the first time. I have had other issues(mainly due to my new boater ignorance) since I purchased it, but was able to get everything running in my driveway this weekend. Today I took it took it to the boat ramp for the first time. I fired it up, then it died on me. I repeated this several times. From me and my father's deduction, it seemed like the boat would start and burn the gas primed to it, then died. Almost as if the fuel pump isn't pumping, or a filter is partially plugged. We checked the hose from the tank, and had no issue there. It seems like it is isolated to the pumping ability itself.

One thought I have had is that I may have gotten trash in a filter or the carbs from this weekend when I ran it. I did get the gas tank real low. However, I cannot see an inline filter prior to the fuel pump.

Does anyone have a suggestion on how I should attack this? I'm betting the end game is pulling the pump and carbs off to clean. I just want to make sure I'm not missing anything simple.

 

[tashasdaddy]

Re: '85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

do you have any idea what your idle rpms are when on muffs? you are either idling too low, or you are on the right track. can't remember are you premixing fuel.

 

[FBPirate95]

Re: '85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

I haven't really run it enough to notice what the idle rpm's are. This problem is occuring with the warm up lever in the full up position. I don't pre-mix, although I've been debating eliminating the VRO. Do you think its most likely trash in the pump/carbs or can a fuel pump just fail all of a sudden? I've also noted the pump is the 3 wire variety, what are the purpose of the wires? I assumed the pump worked off vacuum from the motor, but for all I know with the wiring it could be electric.

 

[tashasdaddy]

Re: '85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

they wires are senders, nothing to do with function. yes a pump can fail that quickly. if it were mine, being an 1985 i would premix, those pumps are known for the oil side failure. does it start right back up, or do you have to repump the primer bulb. have you tried, pushing in on the key, to activate the electric primer to keep it running?

VRO conversion w/ pump still working

if the fuel side on your Pump is still working it is very simple. unplug the 2 line harness going to the oil tank, unplug the 3 or 4 wire harness, going to the Vro pump. cut and cap the oil line going into the motor. add oil to fuel tank, mix well, then remove fuel line at top carb, catching gas in a container, pump the fuel line bulb until you get premixed gas to the carb. you can tell as it will change color. put line back on carb, and go boating.

 

[FBPirate95]

Re: '85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

I did push in the key and the motor would surge as it got a shot of gas, but then it would shut down. I could restart it with out priming the bulb at least a couple of times as long as I pushed in the key first. The bulb would get some softness to it, and I'd give it a squeeze.

I personally believe this problem has to do with the fuel pump. I think there would be slim chances that trash got into both carbs equally. Also I would think if the needles were plugged in the carbs, it wouldn't ever fire off to begin with. It sounds great for the 2 seconds it does run, with no bucking or shuttering.

If this fuel pump is shot, would I be better to try and get a fuel pump rebuild kit, or go ahead and switch the fuel pump out with a non VRO system. (if there is one that would fit it)

I also have the potential in purchasing an 80's model 115 for a very low price. They bought it cheap planning to use it but they needed a long shaft, not short shaft. Currently it doesn't run and one of them thinks its a blown head. However it has good compression. My thought is that the power pack is bad. Either way, is the lower unit interchangable with the 90hp? Are there enough compatible parts to make it worthwhile to have as spares? (Granted if its just the power pack and I could get it to run, I would swap it out with the 90)

 

[joho5]

Re: '85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

my 89 70hp vro did the same exact thing...it would run crappy and when I would prime it, it would surge back up.

After checking everything (fuel lines, gas tank, filter, carbs 3 times), I decided it was a faulty pump.

I then proceeded to buy a regular premix pump. The one that goes on the 83 70hp, it would be 90 in your case, but actually I think its the same pump on the two.

now it runs, idles, like a dream.

my pump was bad...I still have the vro and I pulled it apart and nothing looks bad on it, but when I switched it out, it fixed everything.

 

[ezeke]

Re: '85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

If your mid section is the same length as the parts motor's, the gearcases will swap - the driveshaft length is the reason.

Fuel pumps simply lifts fuel from the tank to the bowls on the bottom of the carburetors and fills them. Squeezing the primer bulb does the same thing.

When you push in the key, the primer solenoid (which is just a valve), allows fuel to bypass the carburetor and be injected directly into the intake manifold. That is what you are running on.

When the motor is functioning properly the engine pulls fuel from the float bowls, mixing with air, through the carburetors. Your carburetors are not working; if the bowls were full the engine would not cut off in seconds.

 

[FBPirate95]

Re: '85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

I guess my first approach will be to check the carbs out and make sure the jets aren't plugged. Any advice on troubleshooting this is much appreciated.

 

[ezeke]

Re: '85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

Couple of videos that might help:
http://www.youtube.com/watch?v=o5cxBMDezuU
http://www.youtube.com/watch?v=kZI-e2Rl0XM&feature=related


Notes: Don't use rags use compressed air instead.

 

[FBPirate95]

Re: '85 Johnson 90Hp VRO- Starts, runs for 2 seconds...shuts off

Is there any way to check the fuel pump as well?