1996 DT150s BASS random Overheat Alarm

[rexran]

Honestly I’m getting tired of chasing the over heating issue.

There's not much help out there for these 'zukes.

My boat's in good shape. Trailer, tires ok. No motor problems as yet. I'd like a proper prop, a newish graph for the front, and blacklights for my Clearlake night bite.

[Delta Bass Fool]

Well a lot has happened since my last post to update. Me and the other half separated shortly after all this on July 4th 2019. Have not been on the boat much since then. Maybe 5 times in the last couple of years. Yesterday I started the engine for the first time in probably 6 months and discovered something disturbing and not sure how to proceed for diagnostic purposes.

I primed the fuel line and started cranking the engine over and raw fuel started coming out of the prop exhaust port. Makes me think I have a problem with an injector. There have been times where I smell raw fuel while out on the water.

Does this sound like malfunctioning fuel injectors?

[billnorman1]

Sorry about your relationship. About your motor, I looked it up and it should have 3 carburetors not fuel injection ( I could be wrong). Anyhow you probably have a stuck float or piece of trash in a needle valve. Your fuel is probably no good after sitting all this time. If you never changed your impeller, this would be the time to do so after you get it runnig right.

https://www.brownspoint.com/store/pc...%20(87-97).pdf

[Delta Bass Fool]

Thank you Bill, 1996 EFI DT150S it is definitely fuel and oil injected. Think I need to pull the injectors and have them tested. Just hoping someone might have the knowledge before I go down that road.

[billnorman1]

These puppies have a needle and seat, might be your issue: They can also be disassembled and repaired if done carefully.

What is VST on Suzuki outboard?














VST stands for Vapor Separator Tank, FSM stands for Fuel Supply Module. These contain the high pressure fuel pump that builds your engines fuel pressure.

[Delta Bass Fool]

These puppies have a needle and seat, might be your issue: They can also be disassembled and repaired if done carefully.

What is VST on Suzuki outboard?














VST stands for Vapor Separator Tank, FSM stands for Fuel Supply Module. These contain the high pressure fuel pump that builds your engines fuel pressure.

I missed this reply somehow. I still need to get the fuel flooding figured out.

want to do another compression test as well so I know if raw fuel has washed a cylinder and caused scoring on the piston and rings.

[billnorman1]

If you scroll down to figure 16 you will find the carburetors used on a 1996DT Suzyuki. I'm pretty sure you're oil injected, but not fuel injected.

https://www.brownspoint.com/pdf/DT150%20(87-97).pdf

[Delta Bass Fool]

Negative on the carburetors. It has both of the low psi fuel pumps, the high psi fuel pump, fuel strainer bowl, high psi fuel filter, fuel pressure regulator and you can see the injectors behind the fuel rail. It is actually the DT150S bass motor and 12x NGK spark plugs.

Maybe I need to post some pics for you? I get lazy when it comes to messing with this because I have to remove the 2 cycle oil reservoir with out making a mess :/ just to access anything fuel related.

[Delta Bass Fool]

This is exactly how my engine looks behind the oil reservoir.

20240116_105340.jpg20240116_105349.jpg

[billnorman1]

Well that's interesting. If you have raw fuel coming out of the gearcase, any fuel line leak on the motor or anything past the quick disconnect will run out of the gear housing. To get into a cylinder you (should) have to electrically trigger it.

It seems (to me) a hose leak would not get into the L/U. What do you think about bad fuel getting into your injectors and locking them open. Also, what is the cold start mechanism to enrich the mixture? Lengthening the pulse or a cold start injector?

So you have one of the Super Six 12 plug motors?

I'm not an expert, I just try to get by by myself. I've only owned 3 Suzy's, a 65, a 175DF and a 200DF.

Be a shame if your fuel lines have deteriorated or been eaten by a varmint.

I just read many of your previous posts. You appear competent mechanically and electrically, I can see you have dedicated time and effort in a scientific manner trying to get your motor back to factory specifications. My posts were a shot in the dark, and I referenced the I P B of Brown's Point marina, from whom I've bought parts in the past.

Keep posting maybe I will learn something (seriously).

[Delta Bass Fool]

Ok the flooding hapens when I turn the key on and start cranking the engine. You made me think of a way to test something though. There are many problems compounding atm imo.

I always have to pump the primer bulb prior to starting it each time after sitting for months at a time.

Thinking I do need to get pretty methodical in diagnosing this thing. I'm going to pump the primer bulb till just about firm. I think it will allow me to pump on the primer bulb continously not allowing the bulb to reach full psi. The manual mentioned a way to test the bulb with a vaccuum pump like those used for bleeding brakes etc.

Anyway after I pump it up good and enough I'll see if there is any gas prior to turning the key over to know if the fuel flooding only happens after the motor is starting.

Mechanic at a boat salvage around the corner said to check the low psi pump diaphrams, the needle and seat in the vapor separator as you previously suggested or the injectors and possibly the fuel pressure regulator.

Think I'll start with checking after priming real good prior to turning the key on. And move forward from there. Will be updating with my findings.

I've never replaced the high psi fuel filter either so it might be time for one of those as well.

[Delta Bass Fool]

Ok did a little digging today.

Primer bulb is bad. I had to smack it a few times after removing the engine side hose. Pumped it while connected and it would not pressurize but the engine started and ran until it ran out of fuel. Put $20 of super unleaded in it and that is when I discovered that i needed to smack the primer bulb to get it to prime

I was able to pump the primer bulb afterwards to to point where I could not prime it any more. Tight bulb.

Then I started and ran it again untill it idled down and noticed no pee from the tell tell pee hole. Poked the hole with some mig welding wire to make sure it was not clogged up. Started it again and after it idled down it started peeing but with a week streem. This tells me the water pump inpeller is fouled up and needs inspecting. Eventually it stopped peeing again :/

I also checked the compression in all cylinders while cold and they all are at 100 to 105 psi. So nothing irregular there. I did not think to re-check the compression after getting it up to temps.

More to come... .. .

[Delta Bass Fool]

In this Video I ramble on a bit and repeat my drunken self while trying to coherently explain how this fuel injection system works on this dt150s. I struggled through it but you can clearly see how it is a fuel injected unit ;)

[Tim Kelly]

Are those orange fuel hoses actually fuel hoses? Never seen fuel hoses that are orange like that, only rubber hoses, which wouldn't be fuel rated.

[Delta Bass Fool]

I honestly don’t know. I did not install those orange/red hoses so I have no idea. They could be breaking down inside for all I know.

I have been thinking up a way to check the low psi pumps with out opening them up to inspect the diaphragms as that likely can tear them up in the process of opening them for inspection.

In theory when I crank the motor over to inspect low psi fuel pump flow rates the 2 cycle oil will still be getting injected into the crank as well as the fuel vapor separator.

Once I disconnect the low psi fuel line from the input to the Fuel vapor separator I’ll have to disconnect the high psi pump to prevent it from pumping raw fuel into the injection system. This will or should cause oil to start accumulating into the FVS during engine cranking. This will throw off the oil mixture ratios. Perhaps I should disconnect the oil line to the FVS at the same time and monitor oil flow coming from the oil pump to the FVS.

Now I’m thinking I need to get a hand held push button starter jumper out so I can watch what is going on at the port side of the engine while cranking it over.

Heck the FVS will more than likely have to come apart or be inspected as well. So I’m probably worrying too much about stuff that is not a big deal anyway so long as I don’t damage any part of the auto oil injection system in the process.

I should mix the raw fuel in the tank to 50:1 prior to staring the remainder of diagnostics as this is the only way to ensure the cylinders will be fed a fuel/oil mixture once I go to run the engine again.

I placed an order for the lower unit water pump impeller last night and will pull the lower unit soon in preparation for the new impeller. I just don’t like having any more stuff accumulating in my already jam packed and cramped garage. That is how things get lost and or damaged.

[Delta Bass Fool]

I also need to come up with some type of 2 cycle oil intravenous system to feed the engine oil while I have the oil reservoir off during fuel system diagnostics. Nothing easy about messing with this thing. Perhaps I’ll weld up a bracket that I can bolt the reservoir to that will allow me to sit it on the back deck of the boat so that it is elevated above the oil injection pump and gravity will keep oil flowing properly. I don’t want to starve the crank of oil.

”Hmm” I wonder if those open spouts near the fuel injectors is for oil injection. Probably not. Time to burry my head in the service manual again.

Also yesterday I observed some white stuff in the exhaust mixed into the water while running the engine and was not sure if this was oil or fuel. It did not smell like raw fuel or perhaps my sinuses are not working good enough atm to detect the presence of raw fuel mixed in the water but it did not hit me like that usual raw fuel smell while running. Perhaps it was 2 cycle oil coming from the crank. IDK... .. .

Hoping I find the issue and this is not an intermittent gotcha type thing that only happens when the right circumstance occurs. Honestly I’m just a cheap ass that should be paying a pro to do all this because sometimes I feel like I’m getting in over my head. As long as I don’t make any dire mistakes and take my time I should be ok. I hope so anyway.

Oh yeah I need to get another primer bulb and some more fuel line.

[Delta Bass Fool]

Sorry guys I keep referring the VST as a FVS.

VST = “ Vapor Sererator Tank “ and I was referring to it as a FVS “ Fuel Vapor Separator “ my bad.

[Delta Bass Fool]

Just had another thought. I may need to contact Mercury about this one. I’m not sure but I might have mixed regular mercury quick silver 2 cycle oil with synthetic mercury quick silver 2 cycle oil.

I don’t think it is a problem but it might be possible for the two different oils to coagulate if they are not compatible with each other. So I’ll also try to remember to put in a call to mercury tech support this next week.

[Delta Bass Fool]

Pic of the engine port side with the 2 cycle oil reservoir attached. The fuel systems sit behind this and it makes it impossible to do anything to the fuel supply systems behind it with out having to remove it.

20240119_124935.jpg

[Tim Kelly]

Just pre mix the fuel, shouldn't need to worry about the oil then?