Does the intake manifold suck?

[offshore100]

I've been given a cute little 1962 Evinrude "Fisherman," 5.5 hp, in remarkably good shape. It's got decent compression, 90/95psi., decent spark, the carb was gummed up so I cleaned it and put new gaskets in it, so I thought I was in business. Put a new fuel pump on it too, and new plugs, J6C's.

But here's the problem: after repeated pulling efforts, she just doesn't want to start. I checked the plugs and they seemed way too dry. I noticed when choking, it didn't seem to be pulling up fuel from the bowl like she should, so I put a couple of fingers over the carb mouth in addition to choke and fuel was pulled up. She fired off a little but still didn't want to start. Sprayed WD40 into carb throat, fired off a little but......
Took the carb off and apart and it all looked perfect.
OK, now (sorry for the long post), I put my thumb over the hole in the intake manifold where the carb bolts on and had a mate pull.......not much suction.
Took the plugs out, put my thumb over each of those hoes and had him pull....plenty of compression.


Question: how much suction should I feel from that hole where the carb bolts on? I would have guessed a fair bit, and it was very little; orders of magnitude less than the compression in the cylinders.

Any ideas????
Thanks much.


ps, I took off the manifold too and the reed valves look fine.

 

[Geauxfish]

Re: Does the intake manifold suck?

What about covering the exhaust to create more backpressure? We would do that on deuce and a half's in order to get them turned over in cold weather.

 

[mikesea]

Re: Does the intake manifold suck?

I bet your carb still has issues,how well a job did you do on the carb,Im thinking it needs to be soaked,the passages are tiny and fuel should be sucked up when choaked,are you sure the tube from the bowl to the throat is clean,use a spray clreaner and a tip cleaner if need be to insure the choke will work

 

[offshore100]

Re: Does the intake manifold suck?

That's what I would have thought too, Mike, first thing i checked....clean as a whistle. So to my original question, how much suction should one feel from the hole where the carb bolts on? a little, or a fair bit?

 

[F_R]

Re: Does the intake manifold suck?

Very little at cranking speed. Now back to the real problem: Did you check the high speed orfice jet? It is in the very bottom of the carburetor bowl, deep in the hole behind the hex head plug. I'll just betcha that it is dirty or gummed. It has to be absolutely shiny clean. Anything less will cause the grief you are experiencing.

 

[offshore100]

Re: Does the intake manifold suck?

Thank you for your response, F R, but this little motor doesn't even have a high speed orifice, it has a high speed needle valve down there, which is very clean, and initially adjusted out about one turn....
But i heard what you said re. the manifold suction.

 

[CATransplant]

Re: Does the intake manifold suck?

Check the needle and seat again, along with the float level.

 

[offshore100]

Re: Does the intake manifold suck?

OK guys, I'll go back into the carb, especially down low, and re-clean.
I'm still perplexed as to why the engine didn't fire easily with WD40 being sprayed through the carb throat. That "starting fluid" trick always works for my other engines.

 

[F_R]

Re: Does the intake manifold suck?

Sorry about the confusion. Adjustable HS jet on the 5.5 Guess I'm getting punchy.

 

[Xcusme]

Re: Does the intake manifold suck?

OK guys, I'll go back into the carb, especially down low, and re-clean.
I'm still perplexed as to why the engine didn't fire easily with WD40 being sprayed through the carb throat. That "starting fluid" trick always works for my other engines.

The old propellent in WD40 was much more volatile, propane I believe. EPA bs made them change it....

 

[mikesea]

Re: Does the intake manifold suck?

if you want to test it ,use a spray bottle with gas oil mix,if you have good comp,the reeds are ok ,your prob.is the carb.

 

[offshore100]

Re: Does the intake manifold suck?

Exactly what I was thinking, Mike, based on what Xcuseme said. Will keep you posted. Thanks.

 

[wilde1j]

Re: Does the intake manifold suck?

Have you tried opening the HS needle more than one turn. May not be open enough to start or run. BTW, there's no 'magic' number of turns ... it's just where the motor will run right.

 

[Chinewalker]

Re: Does the intake manifold suck?

When you had the carb apart, was the gasket that sits between the main jet standpipe and the bowl present? It's a thick cork gasket, about the diameter of a dime, with a 1/4-inch diameter hole in the middle. These deteriorate over time and are often forgotten when rebuilds are done...
- Scott

 

[Scaaty]

Re: Does the intake manifold suck?

There (I think on the Rude too) is no HS jet knob..fixed. I have a 61
Ignore this..I was wrong..there IS a HS adjustabe jet..just looked ..I was thinking some other motor!
Anyway..
5.5 Johnny, and that SOB just WILL NOT START cold. The front cover was tossed long ago, and there is a big hole where the idle speed rod comes out on the airbox. I simply gave up and had a small squirt bottle of gas mix, and would shoot a little in there..purred, ran fine rest of the day. This motor is in my stash, and used very little if at all (I have others to put on rowboats). I raised the float level for more gas, seemed much better, and sold it.
Guy could NOT get it started..I took it back. It was laying on its back on the way home. Stuck it in the barrel, fired right up second pull on choke. Let it sit for a few weeks (upright), and back to no start unless I shoot some gas in there.
Its back in my shop right now. I've had the carb off twice before, and dammnit, I'm gonna figure it out yet. Have a slightly weak top spark, so I will start there. On the carb, well, it being clean, I don't have an answer, just a post to let ya know you are not alone, as I was thinking worn reeds too...

 

[Scaaty]

Re: Does the intake manifold suck?

When you had the carb apart, was the gasket that sits between the main jet standpipe and the bowl present? It's a thick cork gasket, about the diameter of a dime, with a 1/4-inch diameter hole in the middle. These deteriorate over time and are often forgotten when rebuilds are done...
- Scott

Scott, would this not cause a flooding out problem instead? If memory serves, I worked on a 2hp rude with a bad cork, and it flooded out..(and I can't remember what the innards look like on the 5.5)

 

[offshore100]

Re: Does the intake manifold suck?

When you had the carb apart, was the gasket that sits between the main jet standpipe and the bowl present? It's a thick cork gasket, about the diameter of a dime, with a 1/4-inch diameter hole in the middle. These deteriorate over time and are often forgotten when rebuilds are done...
- Scott

yep, China, the high speed pickup cork gasket was in pretty bad shape. I replaced it with a wee bit thicker alcohol-resistant brown rubber one. Bowl to carb still screws up nice and tight.
I'm guessing, without the gasket, it would be richer.....? just took it apart, fuel would go up that high in the bowl I reckon.