5.7L Mercruiser Hard To Start When Warm

[torrin]

Hey guys, i just got my boat running again and she runs beautifully, but the only thing is that she starts instantly when she is cold (off the trailer) but once the boat gets up to temperature, and we shut it off, say to switch skiiers, or go for a swim etc..., the duration of the boat being off doesn't seem to affect this problem but it takes a good 7-10 seconds of turning the key to get her to start. But she always starts, every time after 7-10 seconds. I have read about a bunch of problems that this could be, vapour lock or the carb leaking after shut-down etc... Does anyone have any suggestions of what I could do? Any signs i should look for while out on the lake next time? Another solution to getting it to start, is to turn her over for a few seconds, then stop for a second, and then she starts up a bit faster.

Any input is appreciated!


Engine serial: 0L006680, 5.7L Mercruiser 350 Competition Ski
Boat: 1998 Tige PRE2002WT
Carb: Ill get that next time im on the lake, otherwise it is the stock carb and some of you guys will already know the model

 

[airchair]

Re: 5.7L Mercruiser Hard To Start When Warm

I have a tige also with the 98 350 in it also mine vapor locks alot. i had brought it in and the found that the tach was shorted out in the dash, from what i was told each gauge has its own dash modual in it.

 

[franktrav]

Re: 5.7L Mercruiser Hard To Start When Warm

check the choke for proper operation....should be all the way open on a fully warmed engine
also ,most carbed engines require a little bit of throttle to start,,,if youre not doing that already

 

[Trooper583]

Re: 5.7L Mercruiser Hard To Start When Warm

I had the same problem on my 4.3. Sounds like you need to have your carb rebuilt. It is most likely flooding when you shut down. A temporary remedy is to use your throttle only function to roll it to WOT then start it. When it fires up roll back to neutral. It will start much faster this way until you can get the rebuild.

 

[anymanusa]

Re: 5.7L Mercruiser Hard To Start When Warm

cold carbed engines should require fuel to start. YOurs doesn't, but it starts right away, and then is difficult to start when warm, making me think that you have a leaky carb.

 

[torrin]

Re: 5.7L Mercruiser Hard To Start When Warm

thanks guys, i will definitely look at rebuilding this carb, how much does that usually cost? and is there a kit you can get?

Also, a little confusion, can someone explain how starting it with WOT will temporary fix the situation because wouldn't that pump more gas into the carb when the problem already is most likely a leaky carb, meaning to much gas in the carb as is?

 

[Trooper583]

Re: 5.7L Mercruiser Hard To Start When Warm

Yes, to rebuild the carb you can buy a kit. You'll need to know exactly what kind of carb you have. There should be a number stamped somewhere on it that will allow your parts guy to match up the correct kit. The cost is case by case. The kit for my Weber 4 barrel was $80.00.

As for your other question, it sounds like your carb is flooding when you sit still...so that hard to start symptom would suggest that you have to turn the engine over until the carb can clear itself and then start up. When mine did this, I would turn it over and over and then engine would sort of "stumble" to a start. When you roll the throttle to wide open and turn the key, this opens up your carb and clears it out, also allowing more air to get through your intake thus it will start much faster. So really you are dumping all that excess fuel out instead of adding more.

 

[WILSONS88]

Re: 5.7L Mercruiser Hard To Start When Warm

My 5.7L 4bbl does the same. Rebuilt the carb twice, it was leaking fuel after shut off out of the right venturi (facing the front of the motor). Had to adjust the float a few times. It quit leaking for the most part. But it still is hard to start it after warm up. The WOT at start up when warm does work well. Have new carb just haven't installed it to see if that fixes the issue.