1991 Johnson 90 hp idle problems

My cousin recently aquired a boat with a 1991 Johnson V4 90 hp. He ran it a bit and it smoked really bad, used a lot of oil and wouldn't idle. It also leaked fuel/oil inside the engine cover and down into the splashwell. I found that when squeeezing the ball, fuel leaked out the VRO pump. I also found several inlet fuel leaks. To get the boat ready for spring fishing, I completed the following work:

check compression ? 120 psi left bank; 125 psi right bank
new VRO fuel/oil pump
new fuel hoses, evinrude/johnson squeeze ball, oil hoses and clamps
new fuel filter
rebuild carburetors
new spark plugs
new water pump/housing kit
new thermostats, poppet grommets, gaskets, and hose clamps
new propshaft seals, bearing housing o-ring and gear lube
new shift and throttle cables; adjust and synchronize shift, throttle and ignition linkage

Motors a bit cold blooded, but overall runs well. it won't fire right up after sitting more than about 3 minutes. Have to give it high idle to start. I thought it was flooding so adjusted the floats 1/8" lower. It would not even run so I raised float level 1/8" and it again ran fine except for hot start idle problem. Floats are set with toe just a tad higher than the needle/seat end. After running several hours and about 20 gallons of gas it won't idle at all. It will fire right up with the high idle lever raised, but dies before we can get it in gear. Pumping the ball doesn't help. Fuel filter looks good. The two time I had the carbs apart they were squeaky clean inside.

Is it possible to have a blown head gasket with good compression? I'm curious if water in the cylinders keeps it from idling. I'd appreciate any ideas.

Re: 1991 Johnson 90 hp idle problems

Anyone?

Re: 1991 Johnson 90 hp idle problems

Hey do you have a push key choke on the ignition switch? your compression seems good as long as the numbers are close within 5. Have you checked to see if you have spark? just some Ideas to check. I've always started with the small stuff first.
Good luck, warm weathers coming!

Re: 1991 Johnson 90 hp idle problems

Yes it does have a push key choke. The boat does run well at upper RPMs. I take the boat out and can run miles flawlessly at cruising speeds just idles really poorly and dies. To get into gear I have to rev it way up then slam it into gear quickly before it dies (sometimes take 3-5 tries) Once boat seems to clear itself out (smokey and poorly running) it runs perfect at upper RPMs, then I stop to fish and 10-15 minutes later it starts poorly and very difficult idle all over again. Last trip out I really couldn't get it to idle at all.

Thanks for any help!

Re: 1991 Johnson 90 hp idle problems

CenterConsolefisher said:

Yes it does have a push key choke. The boat does run well at upper RPMs. I take the boat out and can run miles flawlessly at cruising speeds just idles really poorly and dies. To get into gear I have to rev it way up then slam it into gear quickly before it dies (sometimes take 3-5 tries) Once boat seems to clear itself out (smokey and poorly running) it runs perfect at upper RPMs, then I stop to fish and 10-15 minutes later it starts poorly and very difficult idle all over again. Last trip out I really couldn't get it to idle at all.

Thanks for any help!

Click to expand...

try adding seafoam to your fuel it will clean any carbon buildup on the pistons. you may have a air leak somewhere.
I have no Idea of why it shifts hard unless your linkage is incorrect??
I'm no pro at this but I have a evinrude 88spl and have been doing a little to it here and there first thing I did is I bought a Repair manuel.
maybe some others will join in. you may want to do a search on hard shift on this form.
I'll keep in touch.

Re: 1991 Johnson 90 hp idle problems

check this http://forums.iboats.com/johnson-ev...-90-horse-evinrude-slams-out-gear-590323.html

Re: 1991 Johnson 90 hp idle problems

DOES THIS MOTOR HAVE PLASTIC FLOAT BOWLS>IF SO CHECK THIS........1989 90hp johnson.....My last 3-5 fishing trips my motor was getting hard to start,it would not idle very well,but would run good at speed.Then I notice what looked like a gas leak from around the float bowl..I had rebuilt these's carb.s about a year ago,so I thought maybe the screws were loose,so I pulled the carbs off and all was tight,that when I seen where these plastic float bowls would warp and had to be replace at over 110.00 each...after a little thinking I decided to sand the bowl level..I used 600wet-dry paper,layed the paper on a hard smooth surface and with the water running starting sanding slowly,after about 10 min.s of sanding,I place the bowl on a piece of glass and it was so flat and level I could not even slide a piece of papaer under the bowl,I checked all the way around an it was 100% flat...put it all back together fill the carbs up with gas and NO LEAKS at all.I let it set for 2 day and still a perfect seal.I hook up the muffs and the motor started on first try and idels very smooth.Took it to the lake today and same thing,started 1st try and idels very good,it has never startd this easy before I guess it has always had a very small leak or had been sucking in air and just got worst....this fix cost me nothing ,already had the sand paper,took me about 2-3 hours to compete the repairs..I guess time will tell if this fix is good,but so far it looks good...

Re: 1991 Johnson 90 hp idle problems

Anyone else got any ideas, still awful idle.

Re: 1991 Johnson 90 hp idle problems

check the fuel lines aren't sucking air and ensure the tank's vent is open, is the manual choke shut?

Re: 1991 Johnson 90 hp idle problems

When that engine idles, the carb butterflys are completely closed. Idle fuel is introduced into the carb thru special dedicated idle fuel passages. If you crack the throttle, even just a little, fuel is drawn into the engine from other mid-high speed jets. Possible it will run just great at top end, but idle poorly. It's possible these small idle passages have some leftover-dried fuel inside, causing a restriction and poor idle. Only way to cure this is to disassemble the carbs and clean out the idle passages with a special fuel cleaner, like a Gumout product. Once you get the idle passages cleaned, I would not be suprised that it starts much easier.

Re: 1991 Johnson 90 hp idle problems

Thank you for all the replies, I think I have found and fixed the issue...........the Anti-syphon valve. I replaced this and went to a local lake and it runs and idles like it has never before.

Re: 1991 Johnson 90 hp idle problems

Awesome! Glad it was nothing major. Have a great summer!