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50 HP '87 Evinrude fuel problem

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BenC

New member
Guys,

To start with my problem (from 6 seconds onwards): https://youtu.be/YbdG-p2ooUw

Background...

I've been working on my 2nd hand bought 1987 Evinrude 50HP (E50BELCUD).

On the first test run idle was fine but the engine died immediatly on throttle.

I replaced the VRO pump with a generic fuel pump: OEM replacement Part # 433386
Vendor states this would be the correct replacement part. (https://www.allesmarine.nl/omc-benzine-pomp-of-voor-ombouwen-vro-naar-normaa.html)
Looking at the part number it seems like this is for a 20-30hp engine. But I'm still confident about good advice from the vendor.

I've also replaced the carb float chamber incl high speed jets which were very bad. (new jets are full open)

With these replacements I was positive about a good running engine but on test it only runs 10Km/h on full throttle and is halting.
Here's how it sounds: https://youtu.be/YbdG-p2ooUw

Fuel line, jets etc are all clean.

Looks like a fuel issue but I have no idea what it can be.

Any thoughts?
 
yes ,I'd think a fuel issue. late in your video looks like your pumping primer bulb, if so probably not fuel pump. when carbs were off, were floats adjusted?
so new float chamber with 50D jets?
 
Three inspections / tests to do.---Compression , what are the values.----Test for spark jumping a gap of 3/8" on both leads.----Check the flywheel key.
 
scalhoun506 said:
yes ,I'd think a fuel issue. late in your video looks like your pumping primer bulb, if so probably not fuel pump. when carbs were off, were floats adjusted?
so new float chamber with 50D jets?
Click to expand...


The tank and primer bulb are new and tried a different one as well with the same result.

The new chambers came with jets already installed. I have not adjusted them. One is fully in. One is just a mm out like the image (blue marking reflects how far the nozzle is out.)

330503.jpg

Not sure is they are 50D jets or different. (i'd rather not remove them as these are easy to break)

I checked the floats and needle and they looked fine. The floats can not be adjusted I think?

Any way to test to confirm they are working properly?
 
floats should be adjusted, with float installed, turn carb body upside down, float should be level with carb body. many threads about this on this forum maybe pics too
 
fdrgator said:
High speed jets (orifice plugs) should be screwed all the way in, not "adjusted"
Click to expand...

Would it explain my problems from the video if the jets installed are 38D (30-40hp) jets instead of 50D (50hp) jets?

I'd assume it would make a bit difference but not as much as what i'm experiencing.

If not I'll try adjusting the floats first.

Thanks!
 
I wish I could but I don't have any equipment to do this myself.

Hoping any expertise here can help me out before spending money for inspections.
 
You spent $ on a fuel pump already.----Many auto parts places will rent / loan you a compression tester.----Spark checker can be made with some wire and a piece of cardboard / wood / glue.-----Key can be checked with a screwdriver.---Today is a good day to learn some basics !
 
Thanks Guys.

I'll give it a try.
I'll adjust the floats first, screw in the jets all the way and then do the checks and post numerical results from post 3.
 
First checks showed the floats are perfectly level with carb body.
Fuel intake works fine (tested by blowing in the fuel intake and lowering float)

Noticed one of the two jets is 44D (0.044"), the other one is a 50D (0.050")

Would this make much difference or explain my problem? Or would this just result in minor issues then I'm having?

(still need to do compression test..)
 
Last edited:
Ok. I finally had some time to continue with this monster...

Checked compression. 124 PSI 1st cylinder, 128 2nd cylinder.
Spark check; about 0.35" gap for both.
Replaced high speed jets. Both clean and 50D jets.
Cleaned rest of the carbs and replaced seals to air intake.

All looks fine but still having the same issues on a test run.

No idea where to look next... Any last ideas before I buy another one? :(
 
if you can, with a helper driving, observe the linkages at the carbs, are they moving? is the linkages that moves the armature plate (the stuff under the flywheel) moving along with engine RPM's?
also maybe air leaks on suction side of fuel system. does pumping primer bulb while running change anything?
may need to do a visual check of stuff under flywheel
just a few ideas!
 
Hi,you say carbs were "very bad", what kind of bad? What kind of fuel tank are you using? Is it an "built-in" tank? I am worried about crap involved back in the fuel system. If problem is suspect, you can check operation by removing engine end coupling and see if it will siphon out on its own after priming with the squeeze bulb. The fuel pump will not work properly, if at all, if there are restrictions and/or vacuum leaks "upstream". The siphon method is a simple way to test the source and supply line. No need to be concerned there if it will siphon. Good luck, K.I.S........keep it simple.
 
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