johnson outboard cranking problem

danny2313

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Jul 14, 2008
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i have a 1988 johnson 175 vro 6 cyl, mounted on a 20 stratos center console. the engine cranks fine at first, then when i kill it for more than a minute, it will not crank back in just the neutral idle position. i have to choke it and put it in fast idle. it has a new primer bulb, with new lines. the filter/seperator is new also. also i am only able to get 30 mph out of it. does this sound about right? i thought it was slow. i have a little mist of water coming out of the exhaust ports below the cowling. i had one high temp thermostat replaced with new gaskets about a month ago. any help?
 

HighTrim

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Jun 21, 2007
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10,486
Re: johnson outboard cranking problem

Welcome to iboats.

Regarding the speed, is this GPS speed or speedo? What RPM are you achieving at WOT (wide open throttle)?

Regarding the other issue at hand, when were the carbs last bathed/rebuilt?
 

danny2313

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Re: johnson outboard cranking problem

that is gps speed. my rpm guage bounces, but it think it is around 3800. the carbs were rebuilt about a month ago.
 

F_R

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Re: johnson outboard cranking problem

3800 rpm stinks. Either you have bad tach or a bad motor (not running on all 6)
 

danny2313

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Re: johnson outboard cranking problem

what should the rpms be. i will check it this evening. the motor runs smooth and sounds strong.
 

tashasdaddy

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Re: johnson outboard cranking problem

you should be 5,000-6,000. you either have a sick motor, water logged boat, or a really wrong size prop.
 

clemsonfor

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Re: johnson outboard cranking problem

if the carbs are not working right, ie. pluggerd high speed jets youll loose 1 or 2 cyls it can still run smooth with missies. Id check carbs sounds like they may be leaking back into the cyls and flooding it causing the high idle to be needed. id start with a carb (3 of them at least on my 15 gt (1991 )) rebuild!

-nate

ps i think you should se at least 45 mph.
 

danny2313

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Re: johnson outboard cranking problem

thanks. it will probably be friday before i can check the rpms in the water. i will gather some more info and update you on monday.
 

danny2313

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Re: johnson outboard cranking problem

okay, i made it home early enough and checked the prop size. it is a 14.5 x 19. i was looking at the fuel pump to see how many wires it had going to it for someone elses question. when i had the carbs rebuilt, we also had an alarm problem. all they could find was the fuel/oil injection pump was causing the alarm. when it is unplugged it does not sound. when plugged up the alarm sounds. even when the motor is off. when i went to look and see how many wires went to it, i found it unplugged. my fuel pump and oil injection pump are tied together in one unit. the more i look and ya'll talk the clearer this is becoming. could it be i have a problem with the fuel pump causing the alarm, with the wiring harness unplugged it is not getting enough fuel to run at max power? all the alarms started when were at the coast in may. i drove 300 miles home and got out and turned the key on and the alarm came on. one or two times at the lake last weekend, the boat was sluggish taking off but it cleared up quickly. before you ask i have been mixing the oil and gas since the system has been unplugged. does it sound like i need a new pump? okay i am editing this because i am the type of person who cannot sleep until i find out what the problem is. i went and explores some more and found two wires coming from my oil resevoir into th motor housing to a female plug. thats it. i cannot find anywhere to plug it in. heres my new theory. this is the oil level wires and with out being plugged in the system is reading a low level, thus causing the before mentioned alarm. i this was plugged into something i think the alarm would possibly clear. but where the heck do you plug it in. i searched until the giant airliner sized mosquitos texas is famous for started taking me away. if the alrarm does clear that solves one problem, but do you think it will solve the running and cranking problem? i do not have a manual, but am looking hard for one.
 
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danny2313

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Re: johnson outboard cranking problem

i talked to a man who had the same problem with the alarm on his oil resv. level. he just unplugged it and keeps the resv full. he only had one wire, and mine has two coming from the resv. what couldcause the alarm when the fuel/oil pump is plugged in besides the level in the resv?
 

danny2313

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Jul 14, 2008
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Re: johnson outboard cranking problem

okay, i have been reading some of the old discussions, and have decided to replace my vro oil/ fuel pump. i have seen the part number 438559 mentioned several times. one was for a 90 hp, the others did not say a hp. does anyone know if this will work on a 175 1988 model?
 

boatmonkey82

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Jul 21, 2008
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Re: johnson outboard cranking problem

sounds like you lost half of your fire , unplug all of the plug wires on one side and try to start on the hose . if it starts then plug the sid eback up and do the next , if it now wont start then you may have a bad power pack
 

danny2313

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Re: johnson outboard cranking problem

boatmonkey may be on to something here. before i read his reply, i talked to a man at work who work for a dealer during this motor's heyday. he said to take the wires off the plug and put a bolt in them and see if i get a strong spark at least 1/2 inch from ground. on one side i did and the other side i got weak fire, barely 1/4 inch. this falls inline with what boatmonkey said, except i am putting a rebuild kit in the fuel pump so i cant crank it. does it sound like a power pack on one side is bad? thanks boatmonkey for the lead.
 

danny2313

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Re: johnson outboard cranking problem

i just checked the compression on the motor and i have 5 that are 90 psi and 1 that is between 85 and 86. how does this sound?
 

wilde1j

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Re: johnson outboard cranking problem

I don't think compression's your problem. Those numbers are a little on the low side, but the motor should run OK, maybe a little down on power.

You need to get an OEM shop manual and start checking things in a logical manner.b If your motor has two power packs, that could hurt one bank. BTW, you should be getting ~ 5800 RPM @ WOT.

You haven't described the alarm sound, so we have no idea whether it's hot horn, low oil, etc. Tell exactly what the alarm sounds like.

Have you tried pulling plug wires while running to see if you get no or little RPM drop and exactly which cylinders? Tell us what you find. Also, have you tried activating the choke while @ WOT and/or squeezing the primer bulb while @ WOT and tell us the result?
 

danny2313

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Re: johnson outboard cranking problem

i now have an oem shop manual. its not real clear on what it is telling. the alarm is a constant alarm as i stated before. it only comes on when the vro plug is plugged in. even if the boat is sitting in the shop the alarm comes on when the vro is plugged in and the key is on, as i stated before.
 

wilde1j

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Re: johnson outboard cranking problem

Steady on is hot horn, so somethings screwed up in the horn circuit. The sensor has a tan wire that the sensor sends to ground when hot is detected. Sensor should be near the top, aft section of the PH and it has a knife disconnect. Discount it ... does the horn still sound. If it does, problem is in the wiring. If it doesn't, bad sensor ... replace it. BTW, this probably has nothing to do with the running problem. You need to focus on one problem at a time and not get multiple problems confused.

The running issue is entirely a separate matter.
 

clemsonfor

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Re: johnson outboard cranking problem

could be a power pack and could be another thing? concentrate on the running or the horn like previously suggested.
 

danny2313

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Re: johnson outboard cranking problem

i know that this is not the test yall would probably suggest, but i swapped sides with the power packs and the poor fire changed sides also. i have ordered a new pack and we will se if thats makes all the difference. thanks to everyon for your assistance.
 
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