Engine starts and stops after emergency shutoff got hit

viper1216

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Do your gauges work when the switch is connected again?

Yep, Gauges are working fine. Fuel pump is mechanical not electric. I haven't replaced the pump yet, just the filter that goes in the bowl in the bottom of the pump.
 

viper1216

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Found the issue...the TKS module on the carb is not working. Instead of opening, it's staying closed and plugging the fuel supply to the carb.
 
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viper1216

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Ok, so the next question is, where the hell do I find this thing? I've been googling it and searching for 30 minutes. Found a bunch of stuff about the TKS system sucking....which is reassuring....but can't find the part number for this thing.
 

alldodge

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Here is your main parts catalog
http://www.mercruiserparts.com/3-0l-gm-181-i-l4-1a020544-up

Here is the TKS carb and item 1 is the module
http://www.mercruiserparts.com/bam/subassembly/30908/13603/70

That said the TKS module is only used during warm up time. Once the engine has warmed up it TKS module closes down the enrichment port. So even if the module stayed closed it would still run by giving it throttle. I would still check your fuel pressure

Also check the clear tube going from the fuel pump to the carb for fuel. Then check your engine oil level, if the pump is leaking it can be dumping fuel in the motor and raising the oil level
 

viper1216

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Thanks for the info AllDodge. How would I check the fuel pressure on a mechanical setup? I have a fuel pressure tester from my years as an auto tech, but none of the attachments allow me hook it inline aside from if I cut the hose in half, which I would rather not do. I did pull the fuel line off at the carb and hold it in a container and crank. Lots of fuel coming out and filled the container pretty quickly. The reason I am leaning towards the TKS, is that I removed it from the carb, and then held my finger over the hole where it installs. Cranked the boat and it started right up and stayed at idle for a good 30 seconds before I shut it down. Oil level is good and oil is clear and new.
 

viper1216

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So I ohmed out the sensor. Spec is 35-45 Ohms at 70 degrees I'm getting 39 Ohms and it's 78 degrees. So within spec there. Apparently from what I read there is an inline fuse that I will check for as well and also make sure it's getting power to the sensor itself.
 

viper1216

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Ok, so upon further evaluation, I don't think it's the TKS...passed the ohm test and just checked and it is getting 12v with at least 4psi of oil pressure per the manual. The engine will continue to run at idle if I keep spraying Carb cleaner every 2 seconds or so. So back to square one here. Since it's running on carb cleaner, it's making me think it's definitely a fuel issue. I just don't know where else to look. The only thing unchanged at this point in supply is the water separator and the pump. Since this is a low pressure system, can I just cut the fuel line in half and so I can use my tester, then just put some high pressure clamps on it? With a mechanical pump, it should only be pushing about 7 lbs I'm thinking so clamps should be ok.
 

viper1216

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**update** just for the hell of it, I pulled the line off from the tank and ran it to a gas can. Boat starts and idles, and will rev up a little...maybe 1200 or so. Any higher and it dies. But it will idle. Put hose back on tank and it won't idle. I am about to replace the Racor water separator/filter. It's the last filter in that system unless there is one in the tank. Not sure when it was changed last as I bought the boat in March and it recommends annually so it's due anyway. Any other thoughts on what else I can check?
 

alldodge

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The fuel pressure should be between 4 to 7 psi. To test you need to remove the line going to the carb and attach one end of a Tee fitting. Install a fitting in the carb inlet and attach to the other end of the Tee. The attach the gauge.

Since it runs better on a gas can then the tank, but still not good, IMO its either a restriction in the line, dirty fuel filter, dirty carb, weak fuel pump, antisiphon valve, or combination. Need to see what your pump is outputting first.
 

viper1216

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Fuel pressure is 6 psi and stays there regardless of throttle position. Replaced the fuel water separator filter. Engine will start and idle at about 1500 or so but any advancement of the throttle results in a stall.
 

viper1216

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Tried again and still having idle issues as well...sometimes it idles, sometimes it won't. But I can never advance the throttle or it stalls immediately
 

alldodge

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It has to be the carb unless you have a vacuum leak around the carb or intake

Needs cleaned/rebuilt
 

viper1216

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Thanks. Just an update. I took the top of the Carb off this morning and cleaned out the needle valve connected to the float. Put it all back together and seems to still be having an issue. One thing...and I'm sure unrelated but I will mention it. It started and idled for about 5 minutes...enough to get up to temp. But still if giving gas it dies. While it was idling, I went to the side of the engine where the oil switch is and wiggled the single wire. The idle increased a bit. I was able to then throttle up a few times, but when I let it back down to idle it died. I know I read somewhere that the oil switch can kill the engine, but I believe that was on electric pump, and I have mechanical. There is a T assemble that connects to the engine block and there are 2 oil sensors that go off either side of it. I am able to move this T around.
 

alldodge

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A long shot but how about disconnecting the wires on your shift interrupter. This shouldn't be causing the issue, but its just a thought
 

viper1216

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So rebuilt the carb and all is well. I'm wondering with the abrubt shut down if some gunk broke free in the carb and clogged something up.
 

alldodge

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In your original post you were at idle, a dirty carb can cause the motor to just stop, so its possiable
 
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