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Discussion Starter · #1 · (Edited)
Repowered by boat back in the spring going from a 99 130 Johnson to a 96 175 Evenrude.

I am having fuel pressure issues. Once the primer bulb is pumped up, it loses fuel pressure when under power, and shuts down. I can pump it up to full pressure, remove the fuel line and you cannot feel any suction while the engine is running. The motor will run fine if someone is constantly squeezing the primer bulb while running at medium to high speed.

History: the prior owner of this motor used the VRO. When I mounted it on my boat, I unplugged and blocked the hose to the VRO and used pre-mixed fuel like I did with my previous motor.

The first couple of times I had it out, no problems, motor ran great.

Then about the 4th time having it out, I started having fuel pressure issues. The only difference between times: 1/4 tank of fuel vs. full tank of fuel when the problems started.

Since then, I have replaced the fuel line and primer bulb(new), replaced all of the clamps on the fuel lines from the main inlet to the fuel rails. I pulled the fuel bracket on Saturday and inspected everything. Fuel filter was clean, the vapor float assist looked good.

Would the lack of suction be caused by a bad diaphragm in the pump assist or do I need to be looking somewhere else?

Two other things to mention: sometimes the voltage gauge shows it charging, sometimes it don't. Also, RPM's are not showing on the tach.

Looking for any help or feedback!!!

dale
 

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I had an issue like that with a 135merc black max and I was at Norris lake years ago_On the third day toward evening it would hardly run at wide open.The next morning I took it out and got it on plane only to have it slowdown to the point I had to pump the primer bulb with in gear at idle and steer it back to dock. Long story shorter the fuel pump membrane was stretched do to the alcohol in the fuel and after a trip to the merc dealer east of town and about $35 for a pump rebuild kit and 25min work it ran great.
 

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"One More Time"
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Sure sounds like the onboard fuel pump...should be easy enough for you to rebuild. However, other things to check would be a plugged up vent line off the fuel tank (Do you hear air escaping the vent as you fill the tank? Then your vent is probably OK), a sticking anti-siphon valve at the fuel tank (it is a fitting on the fuel line just outside the tank...could have a sticking ball in there), or a clogged up screen at the bottom of the pickup tube in the fuel tank (I had one once where the motor would prime and run well at idle, but a faster fuel draw would pull a feather over the pickup tube screen and starve the engine of fuel).

RPMs not reading on the tach (plus the not charging) is a dead giveaway of a bad voltage regulator/rectifier. You can replace that as well. It would be best if you had a service manual of the engine to review.
 

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There should be a shrader valve by the elect pump on the port side of your motor. A test gauge would be needed if the pump is running. A week press could be many things but the filter could be @ fault. You should build 40-50 psi and hold it by just putting key in run position. Pump should cycle and stop intill cranked. I have an o3 but I would think they are close. Johnny?????
 

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Discussion Starter · #5 · (Edited)
Sure sounds like the onboard fuel pump...should be easy enough for you to rebuild. However, other things to check would be a plugged up vent line off the fuel tank (Do you hear air escaping the vent as you fill the tank? Then your vent is probably OK), a sticking anti-siphon valve at the fuel tank (it is a fitting on the fuel line just outside the tank...could have a sticking ball in there), or a clogged up screen at the bottom of the pickup tube in the fuel tank (I had one once where the motor would prime and run well at idle, but a faster fuel draw would pull a feather over the pickup tube screen and starve the engine of fuel).

RPMs not reading on the tach (plus the not charging) is a dead giveaway of a bad voltage regulator/rectifier. You can replace that as well. It would be best if you had a service manual of the engine to review.
Workdog: the pick up screen is new with a new ascending unit 2 years ago, I will have to check next time I fuel it to see if air is escaping.

As a test, I removed the fuel line and used a gas can with pre-mix. Pumped up the fuel and when the engine was running, put my thumb on the end of the hose and there wasn't any suction coming from the motor.

I do have a Seloc manual and its been helpful. It always nice to get the extra feedback and advise.

I ordered a new diaphragm and gasket kit today for the main vapor pump assist and vapor sep.

Thanks for the feedback.

dale
 

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Discussion Starter · #6 ·
There should be a shrader valve by the elect pump on the port side of your motor. A test gauge would be needed if the pump is running. A week press could be many things but the filter could be @ fault. You should build 40-50 psi and hold it by just putting key in run position. Pump should cycle and stop intill cranked. I have an o3 but I would think they are close. Johnny?????
Jig: are you running a fuel injected system?

dale
 

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Ya! But your going to tell me its carbed? I hav a Fitch 225. "The Bomb."
 
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