87 dt 40 starts but won't stay running

[majortwo]

ok guys heres my problem and i'll keep it as short as i can but still give as much info that i can. i took her out last weekend and it started and ran fine at first. headed out to the lake running almost wide open and then the motor died. started back up and got to where i was going. as i started to slow down the motor died again. after that i haven't been able to keep it running for more then 30 sec. i took the carb off and cleaned it. still nothing more then the 30 sec. even if i keep pumping the bulb. thinking it was a fuel problem. each cly has 110 lbs compession. ordered a new fuel pump just because i don't know where else to start. fresh gas and new plugs used. so what do you guys think? thanks...

well i got it fixed. turns out it was just the carb needed cleaning. i took it off and cleaned it but i must not have did as good of a job as i thought i did. took it off again and cleaned it. now she runs like a million bucks....

[Billcarpenter]

94 st 40 won't stay running

My dt 40 which is a 94 now starts hard but will only run for a couple of seconds, maybe 15? Carbs were done a year and a half ago and just can't figure this one out. I also had it to a mechanic who diagnosed it last year as bad gas. I now have 3 week old gas hi test with Stabil and shook the portable tank and loosened the vent cap. The primer bulb that is 2 yrs old did seem hard and I installed a fuel water separator last year but Yes, I have run it with this filter. Anybody have any ideas out there? Thanks in advance guys.

[Solarman]

dt40 running issues.

You should probably go through the carbs again.
And maybe the fuel pump.

[Billcarpenter]

So solarman, what did you use for the carbs? I thought the same thing and also thought maybe a float problem. I had the carb professionally tuned but it was like a year and a half ago and my situation is the first time this year so I have not been able to get out. Something that might have happened over the winter? I do fog the cylinders and all but I guess I will clean the carb and recheck the fuel pump. I did install a new fuel water separator and did not fill it with gas first but I did that the first time I installed it and it still started. Any help out there would be much appreciated. Thanks

[Solarman]

rebuilding your carb(s)

I had 4 carbs on each of my dt140's... If the boat sat for too long (6-8 mos). had to clean them all out. With two engines you get used to all the parts. Bought two 1 gal cans carb cleaner, with the baskets from the auto parts store. Put 2 carbs in each basket in pieces to soak for couple hours each time I rebuilt them. Have been doing this every year for the past 15+ yrs... ('94). It started bout the 2nd yr. We had them. Till about 3-4 yrs ago, when we had both engines rebuilt, one only lasted bout 6mos. Or 2 trips offshore (one threw a rod). So we invested in couple of used dt140 EFI's. And have gotten them back in shape, weren't running when I got them, had a few problems with sub-water pickup, and one magneto being destroyed by the flywheel magnets coming loose. But have now put about 15 good running hours on both, and given good seas this weekend, will go again.
So carbs, are a constant problem and have to be cleaned if not used regularly. That's why I picked up the EFI versions. Fuel injection is more forgiving running straight gas through the system.
The low & high pressure fuel pumps will continue being a problem. Those little plastic check-valves, not part of the rebuild kit, would have cost me almost $500, if I hadn't found several used ones I bought off some junked motors.
Hope they offer them for purchase in the future, or will have to make some myself?
Now you have my history on my motors...lol
Good luck on your motor(s).