1973 50 hp evinrude (50373r) bogs down past half throttle

[jake83]

Started it up same ol song and dance. The fuel pump rebuild kit was the wrong one but wow I didn't realize the diaphragm would be so soft. Mine doesn't feel like that at all. So that and the fact that motor won't run long, and I've replaced almost everything else, tells me it GOT to be the fuel pump. I'll pick up the right rebuild kit on Monday and post results. Even if it ends up being the fuel pump, something simple and cheap, many of the items I have replaced were on their last leg so as long as that fixes it I'm still in good shape. Time to go drink beer and complain the rest of the weekend that napa sold me the wrong kit....even though the bag says replaces 393103 which is evinrude part number and I bought the Sierra version. Oh these beers are gonna taste good

 

[oldboat1]

Hope I'm wrong, but I think you will have difficulty finding a diaphragm to fit that pump. It (the pump) is obsolete, and the replacement has a slightly different configuration. Your kit will fit the replacement pump (0438559), but not the original one.

this kit looks like it might work with the original pump (diaphragm shape, at least), but guessing: http://www.iboats.com/mall/partfind...gd_poid=109273&gd_row=65&session_id=766647558

You might want to just go ahead and get the newer version of the pump (probably around $90). The price isn't really all that bad, as pumps go -- or might look for a used one, and rebuild it with your kit.

 

[jake83]

I hope you're wrong too. Lol. I will bring the Sierra kit with me to the evinrude shop and check the new one against it. Just sucks because everything lines up but the top hole is just a little short. If I have to I will get the while new pump. We shall see.

 

[oldboat1]

Yeah, sorry. Hope the shop can help. Couple more beers.

 

[jake83]

Working on that now

 

[jake83]

Got the right rebuild kit and put it in. Put new plugs in too. Calls for champion ul77v, which is a surface gap plug,but trying to find those locally not happening. I could get ql77jc4 or l77jc4 but not around here. Got some Ngk b7hs gapped to .030. Compression still good at 160 on top and 165 on the bottom. Still can't get it to run longer than about a minute. Doesn't matter if at idle or if I hold the throttle down a little (or a lot) Reprime and it will do it again. Shorting bottom plug still kills motor. Hmmm.

I never had issues with the motor dying until I pulled the intake and swapped the reed boxes. Guess I'll swap them back and see what happens

 

[oldboat1]

Hey -- glad you got a local fuel pump fix! (didn't help much there. sorry -- in fact, apparently gave you a link for a kit similar to one you have. Didn't think of checking Bill K.'s site at maxrules -- and does appear he has a kit for the old pump. Might be good for future reference.)

not a lawyerly question (don't know the answer in advance): Are the upper and lower carbs jetted differently? Should they be? In any case, right jets in place?

Similarly, don't know what the proper fuel line assembly is at carbs, might be worth rechecking -- also clamping (Maybe an air leak.)

Shoot....

 

[jake83]

Flipped reed valves back. No help there. Ran it in the dark and I am intermittently getting an arc from the boot the the plug base. (That's when it stutters, who would have thought) so that's one problem, gonna have to figure that out. It doesn't do it always, but I did get witness it die due to it shorting out.

Still only can run till bowls are empty. Must have an air leak somewhere best I can figure. I did get it to run on only the top cylinder for the first time tonight so there's that.

 

[ronward]

Just read through you're entire post, couldn't sleep tonight. #108 said "still only can run till bowls are empty." That sounds like a primer bulb issue maybe. You finally got it to run on the top cylinder so maybe you fixed the problem, but you'll never know that if you're not keeping fuel to it.

 

[jake83]

That is one heck of a read and appreciate your interest.

Brand new primer bulb. It gets real hard. The first time I got it hard it leaked at the inlet hose to fuel pump and under the screen cover. Probably because i cut the lines to the pump to bring it to napa in a rush, thinking i would replace all fuel lines while I was at it. Didnt realize that the main line had a spring to keep it fromm kinking till new line kinked. Took quite a bit of effort to attach that cut end to fuel pump inlet. Also i am sizing the lines by the size of the brass nipples since everything was all one size so maybe somebody could tell me which lines should be what size, I can only find part numbers. (Kind of tempted to just get a whole new fuel pump and all new evinrude fuel lines at this point though) tightened that up and no more leak. But I can keep pressure on the bulb once tight and it will collapse ever so slowly soooooo, gotta be a leak right.

Also I'm pretty sure it's not the original pump because there are three mounting holes on air silencer and only bottom two line up, coupled with part numbers lining up. I ended up with sierra 18-7821 instead od 18-7820. Only problem is the white plug that protrudes out the back of pump once primed didn't fit. Didn't come with new o rings either, just the pinwheel looking gasket. I removed the two orings thinking it was a change but feel like I should put them back on. Looks like I should have gotten 18-7800 now that I am looking for myself instead of listening to napa. Crap. All gaskets fit well at least, so maybe just remove new gasket under screen cover and put o rings back on.

 

[jake83]

Also the plug that was arcing out had a black insulator. Real black. And I didn't run it all that long. Looked to be covered in soot. I noticed boots are getting hard to remove. I saw some blackness on the outside of the ceramic before and now realize what it is from. Maybe I need to throw the gapless ul77v champions in? I will have to order them but am willing to if that's the reason. At least I'm making progress. Both cylinders sound like crap when run by themselves bow, but they both are working. THIS MOTOR WILL NOT WHOOP ME! ..........maybe. lol

 

[AlTn]

primer bulb becomes soft with engine running....yes, get the champion plugs...replace both plug boots and terminal ends < they pull off, then cut ~ 1/4" off each lead and reattach terminal ends and boots..rubbing alcohol is a lubricant that will evaporate if you need one >

 

[jake83]

They are brand new wires, came with the coils. I will pull the boot back and look, maybe I did something wrong. Which champions, the surface gap ones or standard?

 

[jake83]

Bought a set of each type of Champions and a new boot with spring just in case. I will update and let y'all know what happens

 

[oldboat1]

seems to be a little deja vu here -- similar issue in another thread (arcing to plug base, '70s motor.) Solution there appeared to be plug gap (.030, rather than .040) -- OMC instructions apparently changed, like with recommendations on later motors re. oil ratios (from 100:1 back to 50:1). So with a standard plug, .030 gap should be right. Not sure if surface gap plugs would affect the arcing or operation. I think the UL77V is a standard plug, btw, not a surface gap(?)

would want to be using solid core wires rather than carbon suppression type. Presumably, also would want to be sure you are running the right coils (think this is the one in the Sierra line: http://www.iboats.com/mall/partfind...139=50&gd_search_14140=2&session_id=459379491 ). There is also a ground strap or two on the powerhead -- worth checking the condition. Beyond that, think reattaching spring clips is a good idea, like AITn says. Make sure the spike is in solid contact with the wire core.

 

[jake83]

No Title

Ul77v is definately surface gap, but I also picked up ql77jc4 which I will gap to .030 if I use them. Seems ul77v are better at idle and ql77jc4 for more WOT, at least that is my understanding. I am reattaching the springs now springs now. Coils and wires are straight from the evinrude dealer. Is there any particular trick to making sure they stab through the wire correctly, or is it just a "feel" kind of thing?

 

[oldboat1]

yup -- surface gap (thx for the pic). I use a pliers to pinch the spike through -- probably lots of ways. Good to expose the butt end of the wire a little too, and fit the connector up flush -- get contact there too. Little stuff....

 

[jake83]

That's how I did it, but I think the spike might be slipping past the wire. What a stupid design. Crimps are so much easier. Oh well. I redid both but I suspect I screwed something up, gonna mess with them a little more when I get the chance, but I feel like those are a big part of my problem.

 

[oldboat1]

You probably hit it -- pretty hard to miss the core if you push on through somewhere near the center.

 

[jake83]

Got it to bog down when grounding out top plug. Figured time to try in water. I left it on the trailer and put it in gear. Advanced the throttle and it started to push, but not very strong, just like when it was bogging down trying to get up on plane. So I put it in neutral, but it stayed in gear. Finally got it back in neutral but then had no reverse. Then it started to Rev up and down in 2 second increments and wouldn't steady out. Also there was quite a bit of oil sheen in the water. Took it right back out of the water.

When I put the foot back on I put it in forward and tried to spin prop. No go. In neutral it spun free and in reverse it wouldn't spin either. After this time in water, forward stops the prop, neutral spins free and reverse kind of clicks but still spins free. I must have screwed something up, so seems I am going backwards instead of forward as far as my repairs are concerned. Guess I am not as smart as I had thought. Also there is a hole in the foot with oil leaking from it. I parked it in a buddy's driveway and he was supposed to have his mechanic buddy look at it. That never happened, maybe next weekend but I doubt it. Hard to rely on free help but I am out of money and patience so I guess I'm out 2000 bucks. This really sucks. I may have a 90 hp that I can borrow to put on the boat until i can get my motor fixed but we shall see how that pans out. I appreciate all the help I have received on here, but I fear this boat may get the best of me. At least for now it is not in my driveway taunting me. Maybe I will come back to it but right now I am feeling quite defeated. Anybody on here in northwest Florida?