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96 90hp 60 degree fuel issues

No RTV should be used in the fuel system components at all.....NEVER.
The pulse limiter passes air both ways.
If you have low crankcase compression in #4 crankcase, you will have weak Pulses that drive the VRO.
Are you sure that when running you do not have gasoline rain droplets coming out of #4? If so, the reed may be leaking,
causing the low crankcase compression.

I am NOT saying that this is your problem, but that it can contribute to low crankcase pulses.
 
racerone said:
My simple advice is often ignored , folks do not want to trouble shoot.---------Want the instant fix !-----------The pulse limiter is a protection device to prevent over pressure of the pump.--------------The pump would explode from a violent backfire in the crankcase if that were to happen.-----------------Post the results of a compression test first.
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starboard 120, 125. port top 115, 120
 
faztbullet said:
Just test the pump.....
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Gasket change on fuel seperator made no differance. Did the pump test and was led down the trail to intermediate housing trouble. Instead of taking off pump to do the part about covering and uncovering the fuel outlet we just opened the flow hose on the fuel pressure gauge between vapor seperator and carb. Is that an ok way to do it?
 
daselbee said:
No RTV should be used in the fuel system components at all.....NEVER.
The pulse limiter passes air both ways.
If you have low crankcase compression in #4 crankcase, you will have weak Pulses that drive the VRO.
Are you sure that when running you do not have gasoline rain droplets coming out of #4? If so, the reed may be leaking,
causing the low crankcase compression.

I am NOT saying that this is your problem, but that it can contribute to low crankcase pulses.
Click to expand...

Put vacume/pressure gauge on pulse fitting and got readings of about 10 inches and maybe 5-7 lbs..... ? Kinda hard to read with that needle bouncing back and forth
 
What is the deal with the red service valve on enricher? have seen fuel come out around it when engine cranks a couple of times. Also hose from pulse fitting seems pretty dry, no droplets. Still don;t know how strong the pulses are supposed to be. Can they be measured with guage? Have guage on carb feed and can pump to whatever pressure you want but bleeds down to nothing after a bit. Pinched off line back to tank, not going that way. Not flooded when engine is cranked so assume it's not going past needle & seat. See no external leaks anywhere........
 
ss396fish said:
Put vacume/pressure gauge on pulse fitting and got readings of about 10 inches and maybe 5
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I never put a gauge on the pulse fitting before, but I have done that on the intake manifold of a Suzuki 2 stroke. I know what you mean about the wild swinging of the gauge needle.
Regardless, I bet those numbers are just fine. Just a guess tho.
 
I know I've be asking alot of questions but what I'm dealing with in my dad is a guy in his career as a mechanic was never just a parts swapper until he lucked up and hit it. He was the guy who figured out what was wrong before he tried to fix it. Problem is we have never worked on anything quite like a vro pump. With all the time we got trying to understand this thing I could have probobly bought every part of the fuel system. Dad is 86 but still pretty damn sharp and he does'nt want to let this thing whip him. But I'm about ready for someone to tell me to just buy the pump......
 
I feel for ya. I've been having issues with my 98 150. The things I've replaced on this motor. VRO, carb rebuild kits, fuel manifold O rings, throttle body to manifold gaskets, vapor separator lid/gasket, fuel rail, on & on. Damn thing still doesn't run right. Wish I could tell you what the issue was/is. I've gotta take it all a part again to see if there might be a pinched gasket or something like that. Very frustrating I know.
 
Problem is we have never worked on anything quite like a vro pump.
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It doe not pump on the crankcase pulse like a diapram pump does, the pulses drive the air motor and it wll not discharge fuel until spring internally overcomes pressure then it squirts.
 
(What is the deal with the red service valve on enricher? have seen fuel come out around it when engine cranks a couple of times)

That is the primer solenoid. That red "switch" is for manually priming, if the electric doesn't work. I've had to replace mine. It wouldn't start without moving that red switch. There shouldn't be any fuel coming out of or around that primer solenoid. I'd say it needs to be replaced. They're around $150, give or take depending on where you purchase one from.
 
I forgot to mention, that there are two small hoses that come off the back of that solenoid & a large O ring where the solenoid goes into the fuel rail. Its possible one of the small hoses is loose or the O ring just needs replacing. Maybe not the whole solenoid. Check the hoses on the back of the primer, & the O ring.
 
Davem02 said:
(What is the deal with the red service valve on enricher? have seen fuel come out around it when engine cranks a couple of times)

That is the primer solenoid. That red "switch" is for manually priming, if the electric doesn't work. I've had to replace mine. It wouldn't start without moving that red switch. There shouldn't be any fuel coming out of or around that primer solenoid. I'd say it needs to be replaced. They're around $150, give or take depending on where you purchase one from.
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Is it possible thats where I'm losing fuel pressure? After all this I'm still only getting a max of maybe 2.5-3psi on the pulse and gets down to near nothing till it pulses again. Despite the occaisional leak it cranks and fast idles like it should.... Just looked at this sites parts list and oring 51 is not listed.
 
Error in the parts pages.-----------Look at other years / models to find o-ring part # for the primer.
 
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The primer cap, valve, etc. is repairable with a kit.
You don't have to buy the whole solenoid.

No that is not where you are losing fuel pressure. If you pump the primer bulb, any leaks will immediately show up.
If you were losing fuel pressure on the pressurized side of the fuel system, (VRO to carbs) you would see an obvious leak all the time.

I have set up fuel pressure tests / gauges on the output of these VROs and have ALWAYS observed large fluctuation from 3 to 0 like you are experiencing.
Is that the criteria you are using to determine the pressure is bad? I know what the books says, but I have never seen that in real life.

The pressure jumps to 3 when the pump unloads or clicks. Then as the carbs use the fuel, and the bowls are replenished, the pressure drops, until the next click.
Realize that the carb bowl can be perfectly full, and yet there might be 0 fuel pressure until the next click.

If your primer solenoid valve cap is leaking internally, in that fuel is shooting out those small hoses and into the intake manifold at all times, even when in the normal run position, then maybe you could blame low fuel pressure on the primer solenoid, but the engine would idle like crap due to the way rich fuel mix being supplied.

Engine running, primer solenoid manual lever in the normal run position, gently pull one of the two smaller hoses off the nipple it is attached to. There should be no fuel flow out of the primer solenoid cap nipple. The larger hose (still small) is the supply to the primer solenoid. If you pull that one off, fuel will shoot out of that hose under fuel pump pressure. Those nipples are VERY EASY to break. Be gentle, like you would with other nipples....:D
 
Yes that is the criteria I was assuming was causing my problems. That has'nt changed much from before the fuel pump rebuild till now. Dad 's thinking not enough crankcase pulse because he can use hand held vacume pump on pulse fitting to get the pressure to carbs on up there. Hard to test crankcase pulse when you don't know proper procedure or what the numbers are supposed to be. Also confused about reeds as we thought they just were to keep crankcase pulses out of carbs. Still seems to me if there were internal crankcase problems it would'nt run as good as it does when the bulb is pumped by hand. But I don't pretend to know that much about it...
 
Perhaps there are issues with sealing rings on the crankshaft itself.-----------These rings keep the 4 crankcases seperated.--------------Very important item for proper operation of any OMC / BRP outboard.
 
Racer...u wanna help? Get a looper up on a test stand, and put a vacuum/pressure gauge on the pulse port and see what you come up with.
I would do it, except I do not have a looper to run right now.
 
Going back to the fuel pump test procedure, manual made it sound like you do the test with the pump off and holding it your hands. We thought it might act differantly with air in it instead of gas so we left it on and did last step of uncovering fuel outlet by opening flow hose on pressure gauge on carb line. Did'nt that do the same thing? Wondering about books interpretation of "rapidly" Thinking about zipping it up, going to the water and seeing if we might have fixed it without realizing it... Can't help but be a bit nervous about if it's getting oil but we filled a clear hose with oil and it sucked it up.
 
ss396fish said:
Going back to the fuel pump test procedure, manual made it sound like you do the test with the pump off and holding it your hands. We thought it might act differantly with air in it instead of gas so we left it on and did last step of uncovering fuel outlet by opening flow hose on pressure gauge on carb line. Did'nt that do the same thing? Wondering about books interpretation of "rapidly" Thinking about zipping it up, going to the water and seeing if we might have fixed it without realizing it... Can't help but be a bit nervous about if it's getting oil but we filled a clear hose with oil and it sucked it up.
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....If it's getting oil if I have to pump bulb to get back to the ramp, can't hear pump click when it's running....
 
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