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1990 Johnson 88SPL bogs down at 1/4 throttle when cold

Bonstrosity

New member
I have a 1990 Johnson 88SPL (J88mslesa) that is having some trouble. The engine fires up and idles without much if any trouble. It needs the key bumped a few times with the throttle advanced a little bit but fires up right away. However if the engine is cold it bogs down and dies if you try to put it into gear and throttle up. In gear idling is not a problem. If you bump the key to give it some more gas while it is bogging it will gain power and run as you would expect. Once the motor is warmed up, it does not have this issue.

Work done on the motor:
Recent power head replacement - Compression is 110psi across all 4 cylinders
Water pump rebuild
Carbs cleaned multiple times, dipped in solvent and all passages/jets cleared with a wire - plastic bowls replaced with metal
New Coils, plugs, wires (New plugs after initial break in)
Carbs linked and synced per the manual
Rollers on throttle cams replaced as they had deteriorated and fell apart.
New Carb gaskets - assumed a possible vacuum leak.

Any suggestions would be greatly appreciated.
 
Last edited:
lotta looks but no answers...a question....is the bulb pumped hard before start?..what is your start procedure?..i ran a 88 from 1994 to 2011...
 
Yes, to start I pump the bulb till hard, place the throttle forward 1/4 of the way maybe a little less. I then turn the key one click and push it in and crank the engine. It will be fine in neutral and will start and rev. Once I try to go into gear and rev it the engine will stall or bog down.

Forgot to add rebuilt the fuel pump too.
 
have you checked spark with a spark gap tester?spark should jump 7/16 inch with a good pop..i would also put an inductive timing light on each plug wire to double check its running on all 4 at failure point..what spark plugs are in it?
 
The usual causes of having a engine bog down (die out) when throttle is applied is:

High speed jets clogged or too small. (Unlikely... the size doesn't change with temperature... BUT...!). Parts Book states the 4 high speed jets as part #325019... Inside Diameter .056... jet imprinted as 56C . High altitude would require a size change.

Timer base under flywheel sticking when advancing. (Temperature could affect that).

Throttle butterflies opening too soon. (butterflies must start to open and close at the same time... Butterflies should just start to open when scribe on metal cam is dead center with the throttle roller, not before or after).

Idle timing set wrong. (Whatever the degree setting is for your engine's Idle Timing Setting, check it... especially if it's been reset by someone else!)
 
Thanks for the replies, I'll start looking into this stuff. I called the shop that did the link and sync and now they are saying they did it by ear when it was warmed up and didn't notice any of these symptoms. With what Joe said it seems to happen right at the point the butterflies start to open. So I'll look into the last 2 issues about opening at the same and correct time.
 
I will have to order a spark tester to try that out.

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

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

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

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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Update: after having our second child and getting settled I had some time to look at this.

1. The mark on the cam was no where near center when opening the butterflies. Essentially the timing was advancing too far before they'd open. Once that was set correctly it helped considerably. Spark was good when tested, strong pop.

2. I ran out of time but I still need to adjust the idle timing. It idles high but will need to tackle that another day.

Thank you very much for the help it was way more than the shop who was paid to do this.
 
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