Wont start after engine warm

84 Ski Nautique

Starts fine initially. Runs great. Idles fine. But when i turn the engine off, it will not start again.
(of course this happens out on the water and far from the boat ramp)

Carb is getting plenty of fuel.

Im thinking ignition problems...

Anyone have this happen before or know a solution?

I have another post just like this... I had an 84 as well.. great boat!   Mine I have to pump pump pump pump while turning over, then she fires.

So when I shut it off, I should see fuel dump in the carb from the front of the carb body? Or?

Ok, so I checked, no dribble. But I was able to repeat this process like clock work. After she is warm. Say 150-160. (idle to 2k in my driveway)

I shut it off.
Pump 3 times
Starts right up every time.

When it was cold, it started almost 3/4 of a turn and it started.

So im thinking its a holley adjustment no? I dont think its timing related if I can pump three times and it starts.

But if i dont pump, it will not start until I start pumping the throttle..

Now.. what could this cause be?    sorry for the double post, but Im going to update my other posting as well.

Thanks all!

rpg168 wrote: I have seen no extra fuel coming out of the carb after the engine stops. Im pretty sure the carb is not needing a rebuild. It was installed new about 3 years ago (Edelbrock 750cfm). I keep hearing that "vapor lock" is the culprit, but I am not convinced due to the fact that after some time, the additional fuel which "flooded" the engine must eventually evaporate and a new start attempt should be a success. Yesterday, I let the engine cool for over an hour, after she did not want to start, and I never even got a cylinder fire. My next guess would be an overheated ignition coil. The coil heats up excessively and just doesnt want to work anymore until it is "cool" again. Is this scenario even valid or not? Would an electric fuel pump replacement of the mechanical fuel pump be a good idea? Of course i would install this away from the engine to reduce the heat on the pump. Thanks for all the advice so far!! much appreciated

You must tell us more.
The 750 carb sounds like a "back yard abortion" job. Sorry but you DON'T need that size carb!! WHY?

Vapor lock? not likely!!

Electric fuel pump? who's telling you this? Don't!! the OEM mechanical is great. Have you even checked the supplied pressure to the carb from the existing?

Ignition problem - Yes but you need to do more testing. What's up with the ignition system? has a EI conversion been done? Has the ballast resistor been by-passed? does the EI/conversion call for it?

Andy,
You must give us more info. you haven't filled out much of your profile which does give us some understanding of what your background is! Pictures??? Did you purchase a "hack job"??

8122pbrainard wrote: tommer12 wrote: Ok, so I checked, no dribble. But I was able to repeat this process like clock work. After she is warm. Say 150-160. (idle to 2k in my driveway) I shut it off. Pump 3 times Starts right up every time. When it was cold, it started almost 3/4 of a turn and it started. So im thinking its a holley adjustment no? I dont think its timing related if I can pump three times and it starts. But if i dont pump, it will not start until I start pumping the throttle.. Now.. what could this cause be?    sorry for the double post, but Im going to update my other posting as well. Thanks all! Have you checked the choke?

Choke plate is wide open when warm. (top plate right?!)

rpg168 wrote: the edelbrock has run flawlessly and really allows that big block to stretch its legs. Its alot of carb for a 350, but not a 454. Why is vapor lock not likely? I have heard this culprit from quite a few mechanics that i've explained the symptoms to. Electric fuel pump....well, you always have constant fuel pressure, if the pump is submerged in fuel it stays cooler and you have gas the instant you turn the key on. Simple. Easy to troubleshoot. I have replaced the mechanical for an electric on my 3/4 ton pickup. I guess that would be a "backyard abortion"? Ignition system: Not sure why i'd even think this would be the case except that im getting no spark once the engine is heated up. That tells me that the ignition system (coil, distributor, wires, spark plugs) have an issue somewhere. Im not sure that knowing much about my background would help in making my boat start up after its warmed. I guess this might help others to know for sure if im a guy that likes to get ripped off by "hack jobs". Im pretty proud of my boat and have had many great comments about her. ---------- Is there another poster that would like to comment on the "starting after warmed"? thanks

Andy,
Sorry but you did not state what size engine you're running the 750 on in your first post so I incorrectly assumed it was a small block. The small block is more common in our boats. Hopefully the 750 is a marine. We have seen plenty of "back yard" mechanics go after their engines and it typically starts with a larger carb hence the "hack job" comment. Many even have bought these "hack job" boats with problems created by the PO and didn't realize what they have gotten into. You need to fill us in.

Under dog house (engine enclosure) temps in a boat do not get as high as a car so vapor lock is unlikely. Are the mechanics telling you it may be vapor lock, are they marine? What's the fuel pump putting out? Have you put a pressure gauge inline to check it?

Consistent fuel pressure with an electric? Same is true with a mechanical!!

It wasn't until your last post where you state you do not have spark when warm. Sorry I've commented on the fuel problem but do understand you did talk fuel from the beginning. Get the spark back and then go after the fuel. Ohm out the primary coil on the coil when hot. Don't just start throwing parts at it without testing first. You are simply guessing at the problem.

Talked to my speed shop guy and he thinks for sure its a boiling gas problem. To solve this, add in a phenolic spacer between the carb and the manifold. This will keep the fuel from getting too hot.   Im going to install one hopefully tomorrow or Thursday and see how it goes.   It basically gasket, metal, gasket, metal, gasket sequence between the carb and manifold.   

It is a stock 351, but we put new GT40 heads on last year.    I can idle steady at 500/600/700 on my trailer no issue.   I have not checked vacuum, but if it was an issue, vacuum should be bouncing my RPMs around at idle, which its .not.

I'll check the vacuum though to make sure Im peaked. I did adjust the mixture screws slightly and noticed if I turned a little each one way (cant remember which, I think in) it would start to sputter, so set it back to where it was. Idle was on the trailer at about 600 rpms steady

My holley must be older, I cant figure out where the vacuum connection is. I had a newer holley on my 84 and it had a separate plug to simply attach the vacuum gauge. This holley, I can figure out where you plug it in. Any tips?
Thanks!!