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2000 omc 130 v4 fuel issue

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Backchannelmako

Member
I am working on a 2000 oceanpro 130 Johnson with plastic carbs. and it has a fuel issue. The motor will run with the primer solenoid engaged when it is not engine will slowly die and rev up when primer solenoid is engaged again. Checked ignition, compression and went through carbs. I checked fuel pump diaphragm looks good and swapped out another VRO fuel pump and same thing. I'm thinking carbs are warped and not making a seal to the throttle body. What's the best way to check this? Spray fogging oil around carbs while cranking? Think it might be something else?
 
Throttle bodies.
They have plates OR Welch plugs in the sides. Behind those plates are very tiny holes.
If you skip cleaning the throttle bodies on ANY ENGINE with plastic carbs, then you have only done half the job,
because the idle fuel circuits have been skipped.
 
Thanks for the info. Haven't done a lot with plastic carbs. Just take the throttle body off the engine and shoot compressed air through the holes under the plates on sides of throttle bodies?
 
You could clear them that way.
While TB is off, examine very carefully the throttle, bore right adjacent to the butterfly. Look carefully on the side that the round welch plug is on.
You will see a number of very tiny holes coming thru the side of the TB.
Those are the holes that can clog.

An alternative method that may or may not work is to take a can of spray carb cleaner with the straw, and insert the straw into the brass idle air
bleed jet on the face of each carb. While running, shoot carb cleaner directly into the idle air bleed jet.
That introduces carb cleaner directly into the idle fuel passages and might clean those tiny holes. Use the entire can on four carbs.

If that is not the problem, examine very carefully the tiny brass tube that extends down from the plastic carb body into the bowl.
That is the idle fuel pickup tube. It is tapered at the top. If those tubes are narrowed down with gas residue, idle fuel will be less than it should be.

Normally, when the idle circuits are clogged, the engine will mis-fire....lean sneeze. Is it doing that?
 
Ok, so basically it is clogged to the point of running out of gas at idle speeds.

Check what I suggested....TBs and idle pickup tubes.
With primer activated, you are supplying gas at the intake, bypassing the carbs, and giving it enough juice to keep running.
 
I'm cleaning the throttle body right now. The holes don't looks as bad as I thought they would but acouple are noticeabley dirty to the ***** eye. Also pilot screws have some junk on them
 
When throttle bodies come off, you must pay attention to the link and sync...particularly the sync of the two sides' butterflies opening and fully closed settings.
I hope this is your problem.....i

Also, use a fine welding torch tip cleaner to get into those holes. The smallest one is very tiny especially on the V6 carbs.
If this doesn't do it, consider the idle pickup tubes. I generally suck on those to judge if they flow air evenly.
You can feel the air on your tongue and tell fairly well if they are open.
Remember, they taper smaller at the top.

You have to ask yourself why the engine is not able to pull gas from the bowls....figure that out, and you will solve the problem.

Double check the integrity of the round center portion of the bowl gasket. If it doesn't seal, the carb won't flow gas.
 
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Put the throttle body back on . Did a link and sync and it runs like new! Thanks for the help. I feel dumb not realizing the idle circuit is inside the throttle body knowing the pilot screw goes into it, but you learn something new everyday.
Thanks for the help I really appreciate it.
 
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