SCLakes.com

SCLakes.com

Bringing fishermen togeather since 1998!
It is currently Wed Dec 19, 2018 9:57 am
Sponsors
       

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 5 posts ] 
Author Message
PostPosted: Wed May 29, 2013 6:59 pm 
Offline
Jr Member
Jr Member

Joined: Wed May 29, 2013 6:41 pm
Posts: 2
Hello, I recently did a complete rebuild (pistons, ring, bored cylinders .20 over, upper/lower bearings, voltage regulator/ primer/plugs/wires/impeller/new carb kits/thermostates/you name it I replaced it with new) on a 1987 OMC 140 HP outboard. I pulled the VRO pump and replaced with two new fuel pumps that are used on engines up to 115 hp. I teed off the pulse line to run both fuel pumps, teed off the fuel from the boat so each pump had a line going to it, then I ran both outlet lines from the pumps into a tee to consolodate to one line that runs to the large tee that feeds the carbs. The motor starts and idles beautifully, but will not get on plane or run high rpms without pushing in the primer button. Oh yeah, I also replaced all fuel lines from the tank to the carbs, new primer bulb, new fuel filters. I am assuming the issue has to be before the carbs as I rebuilt them, all jets are clean (soaked in Evinrude engine tuner for 24 hours and blown out with air, visually inspected), needles hold under pressure and floats are set in accordance with specs, plus the motor runs right when you push in the primer so I'm thinking it isn't the carbs. The only solution I can think is maybe the fuel pumps running in parallel aren't pushing enough fuel, do you think if I run them is series it would help. Any ideas or help would be greatly appreciated!!!!!!!!! Oh, yeah I know I have to mix my fuel now, since I pulled the VRO pump, it is currently 23:1 for break in, then I will go to 50:1 XD30 oil only. I pulled the VRO pump because I turned wrench at a marina for 3 years and 95% of the engines I rebuilt were because OMC's VRO pumps are overpriced garbage, same reason I had to rebuilt my new boats motor, got a good deal though, will mix gas till the day I die. Thank you again for any help!!!!!!!!!!!


Top
 Profile  
 
PostPosted: Wed May 29, 2013 9:30 pm 
Offline
Site Admin
Site Admin
User avatar

Joined: Tue Dec 06, 2005 3:05 pm
Posts: 4707
Location: Lake Murray SC
Not enough fuel pressure. Pushing the choke is adding more fuel. Get the vro pump reinstalled and just plug off the oil side.

_________________
One tequila, two tequila, three tequila, floor.....


Top
 Profile  
 
PostPosted: Thu May 30, 2013 7:49 am 
Offline
Technical Moderator
Technical Moderator
User avatar

Joined: Fri Dec 09, 2005 1:51 pm
Posts: 2043
Location: On the way to Tallahassee FL
If you had looked at the fuel flow diagram you would have realized that you don't feed the fuel pumps the way you are doing it. You need to feed one pump with the supply line then from the outlet of one pump go to the inlet of the other pump, then from the outlet of the last pump into the fuel tree. Not two separate feeds. Three years of turning wrenches huh? That's a ton of expierience.
BTW how may of the so called VRO failures did you see complete motor lock down? One bad cylinder does not indicate a VRO failure, if you know how they operate maybe you would re-think your statement. Shake and bake.

_________________
I'm not fluent in Idiot could you please speak slowly?


Top
 Profile  
 
PostPosted: Fri May 31, 2013 11:08 am 
Offline
Jr Member
Jr Member

Joined: Wed May 29, 2013 6:41 pm
Posts: 2
Thanks for the responses, I didn't want to use the VRO pump as based on evinrudes test it wasn't drawing enough oil, I know they can last years as a fuel pump, but I have also seen one only last 3 weeks after I capped off the oil, I plan on fishing the Great Lakes and figured with everything else I replaced on the motor there was no reason to worry about the fuel pump going out on me.

Three years of turning wrenches huh? That's a ton of expierience. -I never claimed to be an expert, if I had all the answers I wouldn't be on here asking questions, if it hurts you to answer people why are you a moderator?

If you had looked at the fuel flow diagram you would have realized that you don't feed the fuel pumps the way you are doing it.----I don't work as a mechanic anymore, so I don't have access to the tech pubs, but really all you did was confirm my statement "The only solution I can think is maybe the fuel pumps running in parallel aren't pushing enough fuel, do you think if I run them is series it would help.", so I don't really think I was out in left field.

BTW how may of the so called VRO failures did you see complete motor lock down? One bad cylinder does not indicate a VRO failure, if you know how they operate maybe you would re-think your statement. -----I have not seen one motor in complete lock down....I have rebuilt more than 20 motors that after conducting a cylinder leak down test did not have enough compression, then after pulling the heads observed cylinder scoring, then based on evinrudes test procedure of marking a clear hose in 1/4" incriments and based on time should move a certain distance concluded had bad VRO pumps. We always mixed the gas after a rebuild and tested the VRO pumps and let the customers know the status of it so they could decide if they wanted a new VRO pump or fuel pump (it was a requirement to get one or the other). I kinda have a rough idea of how a pulse driven diaphram could draw oil and fuel and mix them, and when the diaphram gets weak and no longer draws enough oil could cause the cylinders to be shy of lubricate and score them like the cylinders we had to bore out. Even an idiot mechanic like me understands that if you don't have enough oil you are going to smoke your engine. I feel confident in saying that it doesn't matter if 1,2,3 or all cylinders are scored, if the VRO pump isn't drawing enough oil it's the culprit. I am an Evinrude fan, I own 5 motors, mix the gas and they last forever, maybe they could have taken a lesson from Merc and used a worm gear that doesn't fail and then the world would have nothing bad to say about the company. 400 bucks to replace a VRO pump is crazy. I stick to my guns that the VRO pump is overpriced garbage.


Top
 Profile  
 
PostPosted: Mon Jun 03, 2013 12:53 pm 
Offline
Technical Moderator
Technical Moderator
User avatar

Joined: Fri Dec 09, 2005 1:51 pm
Posts: 2043
Location: On the way to Tallahassee FL
So can you tell me where Merc's no oil alarm is? Oh wait they don't have one! When the nylon gear on the oil pump fails yep you guessed it instant lock down. Motor is toast. At least Yamaha had a better idea than Merc even though it was a copy and uses a brass gear/drive system for their motors. If you had a clue you'd know that carbon is the worst enemy for a motor and routine maintenance is a key. Come back when you have a few more years under your belt and some better ideas on how outboard motors supply oil to them.

It doesn't hurt me at all to answer questions, been doing if for a long time. But screwing my customers isn't in my dictionary. 20 rebuilds too! You have the makings of a super tech! Too bad you couldn't figure out how to feed the fuel system properly.

Shake n bake

_________________
I'm not fluent in Idiot could you please speak slowly?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 6 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:


All content is copyright © SCLakes.com and its original authors. Forum powered by phpBB.