83 johnson gt150 compression test results, and need advice please

[motodave]

Ok, the short re-cap so far: on my last lake test after rebuilding carbs I discovered that I had rotten fuel in at least one of my tanks. Up until the point I switched fuel tanks (ok fuel to rotten) the motor ran decent in neutral and once up on plane, but it still had a dead spot around 2000 rpm, the motor would die and didn't want to idle while in gear. As some of you suggested I tore down the carbs again, taking my time and removing every jet to inspect, I could not find a blockage in any of them, all 3 carbs were really clean despite the rotten fuel. Cleaned again, double checked everything and replaced gaskets again. (Note - I did remove and replace the small metal plugs in the carb body). Since then Ive also rebuilt the fuel pumps and replaced every gas line on the motor - I am going to run it on an auxiliary tank until I have time to remove the tanks and clean them up right.

I did a 'cold' compression test (with carbs removed) the results:
starboard side: 100, 101, 100
port side: 97, 99, 98
I am planning on testing compression again once I can run the engine.

I am also planning on checking the timing and also check spark before I run the engine again. I have read several stickys on checking the timing and they seem to differ just a little, was wondering if someone could walk me through it, anything to watch out for? I do not have a timing light but will buy one if theyre not too high.

Also, the only part of the fuel system I haven't touched is the primer solenoid (besides replacing the fuel lines). Is it common for these to need a rebuild? Has anyone done this lately? Any suggestions or other procedures I need to do before running? Thanks all you guys, sorry for the rambling!

 

[robert graham]

Compression tests numbers are good....Rotten(old/deteriorated) fuel should be replaced with fresh....

 

[emdsapmgr]

When you pulled the internal plugs out of the carbs, and re-installed them-did you re-seal those plugs with the proper sealant? There is a product called Gasoila which must be used to reseal those plugs before they are hammered home, or they can leak. (they are not supposed to leak.) You replaced all the fuel lines on the engine. Did you replace them all with regular bulk hose, cut to fit- or did you purchase original factory hoses that come pre-formed to flow through the hoses that have tight bends. (specifically, hose part numbers: 324078, 324866 322762) [Bulk hose will kink when bent in a tight radius.] The factory would have you set the max timing when the engine is running 5000 rpm's. That's to compensate for the normal timing creep from idle to WOT. You can't set it at idle according to the factory. If you have to set the max timing at idle, you can check out the Joe Reeves method, found in the "top secret files", the first post on the top of page 1. You don't set the idle timing by degrees, you set it to a specific rpm when idling, in the lake, and in forward gear (under load.) Set the idle to 650-700 rpm's. If the fuel primer is not working, you need to see if it's the solenoid or the valve seat components atop the solenoid, or leaky hoses, or cracked plastic tees. All parts are replaceable individually. I think you'd know if the choke was not working, as that engine is a bear to start when cold without a functioning choke. It is normal to have a small compression variance between heads, ( up to 5 lbs or so) due to the way the blocks are original machined at the factory.

 

[motodave]

Hey thanks for your reply, I had no idea those plugs needed a sealant, I've never heard of gasoila do you know where to find it? I haven't put the carbs back on yet so I guess I could order more if they sell separate. All I did was leak test it with isoprobic alcohol, like I used to with 4strokes after a valve job. I got the fuel line from a local dealer, not preformed but he understood which hoses would work, and I don't have any kinks, that brp lined hose is expensive! The primer is definitely working, Im just anal about leaving bad gas on anything at all, and it was leaking a bit, found a upgrade kit today. Thanks for the help, if anyone's interested I'll post a few pics

 

[emdsapmgr]

Any Evinrude dealer sells gasoila. Ask them for part number: 200763. Keep your eye on those 3 hoses inside the cowling-in case they develop a kink over time. Best not to let that engine run lean at high rpm's and that could happen when using bulk hose. Anytime OMC assigned a part number to a fuel hose, it was considered a "critical" hose and came from the factory heat-formed to flow fuel around tight bends.

 

[racerone]

Check for proper spark on all 6 leads.---Spark must jump a gap of 7/16" or more.-------Timing on these motors does not go out of adjustment , unless of course it has been tampered with.-----Did you look at the reed valves when carburetors were off ?

 

[motodave]

emdsapmgr - Thanks I will check with him for that sealant, might as well do it now while they are off. I will definitely keep a close eye on the hoses. racerone - Yes I think I will check the spark on all six before I worry about the timing, as I don't have access to a tank yet to run at 5000 rpm. I checked the reed valves, did not see any cracks or warping, so after the spark test I hope Im good to run some engine tuner through the engine (with auxiliary tank). Thanks again for all your help guys, I will post results on next steps.