Logo
FULL SITE MENU

69 Johnson 4HP runs at full choke only

T

Tim K

Guest
"Hi all - I have a 1969 Johnso

"Hi all - I have a 1969 Johnson model 4W I am trying to get running. I picked it up via Craigslist and don't know it's history.

I installed new plugs and cleaned the carb - I did not install any new carb parts - and made sure the float was level. After reinstalling the carb, it would start and run for a few seconds before sputtering out. I found a loose hose clamp on the fuel pump inlet and replaced it. Now I can start it pretty easily at full choke (actually, very near full choke - full choke doesn't work well), but it dies at anything less. Any suggestions on my next step?"
 
"I tried cleaning the high spe

"I tried cleaning the high speed jet more thoroughly, but no joy. The carb is now disassembled and soaking, I'll through a carb kit on it after that. Thank you very much for your advice, I'll let you know how it goes."
 
so it only idles with full cho

so it only idles with full choke....do you have to run full choke at wot for it to stay running?
 
"David,

I ran it a bit belo

"David,

I ran it a bit below mid-throttle on full choke, hoping it would warm up quickly and run better. Did not try to idle it down.

Don't know why I said through instead of throw earlier... guess I'm getting old."
 
"first i would start it up, ge

"first i would start it up, get some carb cleaner and while its running (probably with some help) spray the carb cleaner around the carb to intake gasket....if it dies out it has an air leak if not you may still have a dirty carb.

by choking the motor you create more of a sucktion on the carb causing it to draw more gas.

how is the compression?

does the spark jump a 7/16 gap with a good blue spark?

does the primer bulb pump up hard?

it may not be the case with yours but water in the gas will cause similar symptoms....the runnin on choke."
 
"Go back to the carb diagram s

"Go back to the carb diagram supplied by VicS. Observe the thick cork gasket (#21) that installs on the bottom of the nozzle tube. If it is missing, therein lies your problem.

Your explanation still indicates a carburetor problem.

Are you located anywhere near the central west Florida area?"
 
"All,

I cleaned the carb an

"All,

I cleaned the carb and installed a kit, including gasket #21 and the carb to intake gasket. I have 90# in each cylinder, so I think compression is good. Now it runs a bit better, but not much. Full choke and low/no choke will kill it, but it runs just about anywhere in between. The primer bulb pumps up hard. I have a spark tester, but it's hard to pull the starter and keep an eye on that darned thing. It seems to have plenty of spark for mid-choke operation, though. Fresh, water-free gas.

I'm going back to try the gasket leak test David suggested. I think my inexperience is probably making me miss something that should be obvious, but I don't know what. Thanks for continuing to help.

Joe - I wish I was in sunny Florida (I visited Winterhaven about a year and a half ago) but I am in Oregon."
 
"Try looking at the fuel pump

"Try looking at the fuel pump next. Try pumping the primer bulb, engine warm and running, no choke, what happens? Temporarily install a piece of clear vynle fuel line available at hardware stores between the pump and carb, pumping the primer bulb you can clearly see the fuel fill the float bowl. With engine running and all lines tight there will be no air in this line."
 
"Al - That is a beautiful Idea

"Al - That is a beautiful Idea. I had to put this motor aside for a bit because I hadn't fixed it and other projects were pressing. I will try the clear tubing as soon as I can. If that (or earlier suggestions I might not have tried yet) doesn't help, I'll clean and rebuild the carb one more time. Thanks!"
 
"I assume that the thick gaske

"I assume that the thick gasket is between the pump and the powerhead? If not, therein lies your problem.

If the gasket is there, leave hoses connected to fuel pump but remove the two retaining screws to remove the fuel pump. Now put nuts on the ends of those two screws and tighten them so that the pump is sealed properly.

Pump the fuel primer bulb. If fuel leaks out the back of the pump at the center pressure/vacuum hole, the diaphragm is cracked, in which case, replace the fuel pump."
 
"A better recommended spark te

"A better recommended spark test is to use a tester whereas, on that model, you could set a 1/4" gap. The spark should jump that gap (with the s/plugs removed) atcranking speed with a strong blue lighting like flame..... a real SNAP!

(Spark Tester - Home Made)
(J. Reeves)

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:


..........X1..........X2

.................X..(grd)

..........X3..........X4

When time permits, visit my store at: http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"
 
Back
Top