Suzuki DF 90 / 2005 Idle problem / Rancheriee ???

[ezrollin]

I'm re-posting because due to priorities I had to postpone working on my boat...now my priority is my boat It will crank and idle for a while but it dies it re-start or is hard to re-start. Today I checked the plugs for condition and gap,all look ok. I do have a CD repair manual and some experience on older outboards . What would be the order of checks in finding the problem,any useful input would be appreciated .Just found a trouble shooting chart on the CD,I will start running some test tomorrow and post my results,maybe be helpful to someone with like issues .

[rancherlee]

How long does it idle before it dies? Will it die if you give it just enough throttle to raise the RPMs a bit?

#1 new plugs, even if they look good
#2 sqeeze the primer ball to see if it will stay running if you keep pumping it, if it does the low pressure Mikuni fuel pump may be bad or the check valve in the primer ball itself is bad. Another sign of a bad low pressure pump is the gas in the oil pan.
#3 water in the high pressure pump unit, should be a drain screw you can access to drain the Vapor chamber that has a small tube attached. Usually this will cause high speed issues though
#4 Idle air control valve, known issue but it wouldn't idle at all without slightly advancing he throttle.
#5 weak coil, pretty rare by they do go bad and usually show up at first only when the engine warms up.
#6 dreaded mid section corrosion issue, 07' and older engines, a salt water use issue though.

[ezrollin]

Thank you for your input, I will go through your list tomorrow and see what I can find. I'm studying the CD manual and familiarizing myself with the motor... my intent is to able to do the maintenance and repairs.

[ezrollin]

Ok, I'm starting at ground zero. I cleaned one of the gas tanks inside and out,removed the fuel connection / pickup and blew it out,then put in some fresh fuel. Removed and replaced the fuel ball / hose, the original may have been ok but it was old.Tomorrow I will take a look at low pressure fuel pump,no water in engine oil,can I assume the pump is ok if it pump strong while turning the engine over ?

[rancherlee]

If the low pressure pump is pulsing fuel it should be OK, its just a basic vacuum diaphragm style pump used on many offroad toys. If the rubber diaphragm fails it allow the engine to pull fuel into the crankcase. If the check valve "flap" goes bad or gets a debris in it then it will quit pumping fuel to the high pressure vapor chamber. Another way to test is feed the engine with an external tank above the height of the engine which allows "gravity" to push the fuel to the high pressure vapor once the primer bulb is stiff.

[ezrollin]

Good tip on checking the low pressure fuel pump,I do feel it is a fuel related problem. This motor had sat up for while I was building my boat (yeah I know better) so I did have to replace the hp fuel pump and at the same time I replaced the low pressure filter an a thermostat that looked suspect. I also rigged up device to activate and pressurize the injectors so I could make sure they were operational. I'll check that low pressure fuel pump next and then check the idle speed / reset as soon I locate a tach induction pick up.

[ezrollin]

If the low pressure pump is pulsing fuel it should be OK, its just a basic vacuum diaphragm style pump used on many offroad toys. If the rubber diaphragm fails it allow the engine to pull fuel into the crankcase. If the check valve "flap" goes bad or gets a debris in it then it will quit pumping fuel to the high pressure vapor chamber. Another way to test is feed the engine with an external tank above the height of the engine which allows "gravity" to push the fuel to the high pressure vapor once the primer bulb is stiff.

My trouble shooting chart mentions a 44 pin test cord for checking values of sensors etc. Is this a an existing cord I can access or is it a cord you have to buy...in other words can I get to these terminals to make these test with a multi-meter ?

[rancherlee]

If the low pressure pump is pulsing fuel it should be OK, its just a basic vacuum diaphragm style pump used on many offroad toys. If the rubber diaphragm fails it allow the engine to pull fuel into the crankcase. If the check valve "flap" goes bad or gets a debris in it then it will quit pumping fuel to the high pressure vapor chamber. Another way to test is feed the engine with an external tank above the height of the engine which allows "gravity" to push the fuel to the high pressure vapor once the primer bulb is stiff.

My trouble shooting chart mentions a 44 pin test cord for checking values of sensors etc. Is this a an existing cord I can access or is it a cord you have to buy...in other words can I get to these terminals to make these test with a multi-meter ?

I have no clue on that, not too many sensors to test anyhow as these have very basic open loop fuel injection systems. For idle it's probably only referencing engine temperature and throttle position to determine fueling needs.