1989 20hp Johnson, wont stay running

[garrybaer]

I recently purchased the boat,motor,trailer from an estate, that had been sitting for several years. purchased a new gas tank and fuel feed, and the 1989 johnson 20hp started up after a few pulls, but still wont stay running (a few caughs then dies). it has a engine-mounted primer (not a choke) so if you pump every 5-7 sec) it will stay running. clearly a fuel issue

I ordered a fuel_pump and carburetor rebuild kits, took a day to disassemble, clean out, rebuild both, blowout out all fuel passages with carburetor cleaner & air-hose (no obvious signs of fuel separation or any other problem). reassemble and Fired it back up, and same issue. ( Checked low-speed jet, and its at 2 full turns (4 1/2 turns) so that seems about right.

fuel line pumps up solid and stays that way, so no leaks. after babying it for 1minute, I Checked the plugs and they look ok (and dry).

Ive worked on small outboards before, but this one has me stumped. IMHO its clearly fuel-starved, but the rebuilds didnt show any obvious issue (before) and yet it still wont stay running (after rebuild), no change in symptoms..

Its gotta be something simple Im overlooking 0 any/all suggestions welcomed...

-Garry

 

[flyingscott]

What is.your.compression? Does.spark.jump.a 7/16" gap? Did you soak. the carb in.a.good cleaner?

 

[boobie]

Pull the fuel line off of the carb, start the motor up and see if your getting fuel out of the line.

 

[anthill]

I am a newbie, so use caution. I would replace the fuel line from the fuel pump to the carb with a clear hose and look for fuel flow and/or air bubbles. Bubbles are indication an air leak, hence loss of fuel flow. If no flow, failed hoses?

 

[garrybaer]

thanks for the suggestions, my responses below:
- flyingscott: have not done a compression check, will pick up a gauge and do that. spark plugs are gaped right, spark seems good (turned over with plugs out) I did NOT soak it, but did blow out all the ports with cleaner and 80psi airhose.and everything seemed clear. There was also NO sign (reside) of fuel separation anywhere in the carb.

- bobbie: I did pull the pump->carb line and turn it over (before& after FP rebuild) both tests yielded good volume of gas flow.

- anthill: no obvious air bubbles in test (above) into a glass jar. both the flow volume and solid-stream-flow seem ok

I called the the son-in-law for more intel, in the offchance he might be able to shed some light. THe guy seemed pretty handy with engines, and said he had it idling (in a water barrel) last fall, just to make sure it ran, but couldn't remember how long it ran for (IMHO could be a "false positive" datapoint that it actually stayed running).

FYI - I have the low-speed idle screw set to 2 full turns out from seated (4 -1/2 turns)..
over the years I've rebuild ~5 small motor carburetors, so I've seen the insides when fuel turned to varnish/or separated. I followed the same cleanup/rebuild, but the symptoms suggest that I must have missed something. I'm not against pulling it apart again, and may do that (just to eliminate the possibility I missed something) if the compression checks out OK

 

[RaisedByWolves]

Is your float height correct?

Also, did you happen to spray your float needle with carb cleaner?

The rubber tipped needles will swell up if sprayed with cc and get trashed.

 

[garrybaer]

today's update

-flyingscott: I checked compression and both cylinders are within spec.

-raisedbyWolves: good thought. I did did spray the carb with CC, but both the new-old needle & seat were brass (no rubber present). RE: floats - I pulled the carb off today to double-checked both HI & LOW float settings, and all on spec. removed both jets & blew out with air-hose (again). reassembled carb & started, same symptom. double-checked fuel flow from pump, plenty of gas volume coming out of feeder hose to carb, (hand pull-start, plug wires off). Its clearly getting fuel TO the carb,....

symptom - 2 pumps of the on-motor primer to start, after a few seconds when the motor sputters and starts to die, do 1 pump on on-motor primer will keep it running. when motor sputters... Im able to keep it running for 1minute, which points to classic fuel starvation (E.G. carburetor)

This is the third time Ive had the carb. off & apart, so clearly Im missing something.... The carb is not that complicated.
Maybe I should throw in the towel take it to a marina, --- but all the older guys are retired, and the kids only seem to know Fuel-Injection LOL

(feeling frustrated...)

 

[54bobby]

reed valves?

 

[Willyclay]

...purchased a new gas tank and fuel feed,

Any "new" tank made since 01/01/2012 must be self-vented per the EPA and some forum members have reported similar motor problems with them. Good luck!

 

[RaisedByWolves]

Can someone define “self venting”?

 

[garrybaer]

update 2: brought the tank&line (for the 6hp) back, to eliminate 1 more thing (nojoy);

-54bobby: good though, will check those tomorrow.

tomorrow Im going to pull the carb and check the reed valves. While the carb is off (again) might as well replace all the inside fuel hoses, to eliminate that. If the reed valves are ok, then might be time to throw in the towel and take it to a marina... (god forbid, that will kill the rest of the summer :-( )

 

[opinionated-guy]

Sorry to bring this back from the dead a year later, but did you ever get it sorted? I'm having identical issue right now.

 

[GA_Boater]

Sorry to bring this back from the dead a year later, but did you ever get it sorted? I'm having identical issue right now.

Start a new thread. He left.

Closed.