Engine Start Problems

Well it is all about helping. And more heads are better than 1. Just trying explain my opinion.
 
Flytrade said:
As per your suggestions above, I had the IAC and fuel pressure tested, and they are normal.
We could not duplicate the condition at my dock - I suspect the engines need to be run at normal speed and temp for a while.
I did take the boat our for a run, but turned on the blower for about 5 minutes before shutting down the engines. This seemed to solve the problem.
I was also told the problem could be with the fuel blend. It seems the blend is changed depending on use for summer or winter. I could have a winter blend - which is more volatile - but it could be causing a vapor lock because I live in Florida and we are having a warm winter.
In any case, I would like to thank everyone for your help.
Click to expand...

This is actually pointing more towards vapor lock. your engines should be new enough that the low pressure pumps are already installed to help "overcome" this. I am in Bradenton as well. I know all too well the virtues and drawbacks of warm weather vs. cooler temps North of here.
 
370Dancer said:
This is actually pointing more towards vapor lock. your engines should be new enough that the low pressure pumps are already installed to help "overcome" this. I am in Bradenton as well. I know all too well the virtues and drawbacks of warm weather vs. cooler temps North of here.
Click to expand...
Thank you for your response, but now there is even more to the story. I brought my boat up to Tampa yesterday, and when idling into the marina the port engine quit. It would start immediately, but after several seconds it would again quit. However, if I ran the blower then the engine would start and continue to run. I am anticipating an uneventful trip home today, but would like to get this issue resolved, especially since it only happens on the port engine.
My current thinking is that I should exchange the idle air control valves between the two engines. If the problem then goes to the starboard engine that means the idle air control valve is the problem. Unfortunately I have no idea what the idle air control valve looks like, or where it’s located on the engine. If someone could help me find this valve with a description of where it is on the engine, and possibly some photos, and any particular work that’s needed to disassemble, I would appreciate it.
 
Another point I should’ve added to my previous post is that advancing the throttle, as mentioned above on starting the engine, does not seem to work. I have tried various throttle positions, including advancing to full throttle and then back to idle, but nothing seems to work except using the blower. Again, I would like to thank everyone for their input. It would be nice for all of us to solve this problem.
 
Right on top of the engine.
20200306_070501.jpg
 
Re; the blower. There is a thread on here about when to run ER blowers. Of course there are several opinions. Your symptoms seem to indicate that running the blowers lowers the ER temp enough to prevent the stalling. Your problem could be vapor lock which is caused by high ER temps. Myself I run my blowers 100% of the time my engines are running. In a gas powered boat I think it's the prudent thing to. Engines run more efficiently when the combustion air is cooler.
 
Craig said:
Right on top of the engine.
View attachment 80553
Click to expand...
I will certainly change out the IAC’s to see if that is the problem. However, since the blower keeps the ER cooler, which seems to solve the problem, that would indicate whatever is being cooled is not attached to the engine, since it then has more cooling air blowing around it. If that is the case, what could it be that’s getting hot?
 
This is strange one. Blower thing is puzzling.
 
Craig said:
Right on top of the engine.
View attachment 80553
Click to expand...
Thank you for the photo of the IAC valve. I have tried to change out the two I have, but I'm unable to disconnect the electrical wires. The wires go into a plastic cap, which fits over the plastic electrical connector connected to the IAC. I imagine the connector must be held securely in place because of all the vibration, but I have not been able to figure out how to disconnect. Any thoughts would be helpful.
 
I have had the same issue - but only when the water temp is pretty warm (i'm in GA). Bought a brand new 310 SLX and the starboard issue had all sorts of issues just like this late last summer 2019. I went to the top at SeaRay, had Mercury engineers fly down - all inconclusive. basically said, "let's see what happens next summer." I know that's not much help, but you're not alone... My boat does this with 30 hours on it!
 
Flytrade,

I had a similar (read almost identical) on my 98' 330. After a bit of trouble shooting, I came to the conclusion noted above about vapor lock. My solution was a multi-step approach.

First, I checked my impellers, they were in horrendous shape. Replaced and back flushed the trans cooler. Lots of rubber pieces washed out. Slightly better flow from the exhaust, but still not where it should be. Problem reoccurred after first couple days out.

Next, read up on barnacle and tiger mussel growth on the inside of the cooling system. Read up, and ended up buying Barnacle Buster to flush the system. It's not cheap, but as soon as it had run through the blue solution turned almost black. Ran it through a cycle until risers got too hot to touch comfortably and left it sit in the engine for 4 to 5 hours. Re-hooked up the lines to the exhaust and through hull and started the boat. "Black gunk" came out of the exhaust that should have been clean water. After a minute or so of running it turned clear again. Did the same thing to starboard the following day. Same results. The engines are now running significantly cooler (and quieter) due to additional water running through.

I can run for multiple hours at the 3k RPM range, pull over, open engine hatch, and get down on the engines without it being too hot to touch. Engine bay is also significantly cooler.

If vapor lock issue persists, I would check the cooling system.

Nic
 
Simpsonn8908 said:
Flytrade,

I had a similar (read almost identical) on my 98' 330. After a bit of trouble shooting, I came to the conclusion noted above about vapor lock. My solution was a multi-step approach.

First, I checked my impellers, they were in horrendous shape. Replaced and back flushed the trans cooler. Lots of rubber pieces washed out. Slightly better flow from the exhaust, but still not where it should be. Problem reoccurred after first couple days out.

Next, read up on barnacle and tiger mussel growth on the inside of the cooling system. Read up, and ended up buying Barnacle Buster to flush the system. It's not cheap, but as soon as it had run through the blue solution turned almost black. Ran it through a cycle until risers got too hot to touch comfortably and left it sit in the engine for 4 to 5 hours. Re-hooked up the lines to the exhaust and through hull and started the boat. "Black gunk" came out of the exhaust that should have been clean water. After a minute or so of running it turned clear again. Did the same thing to starboard the following day. Same results. The engines are now running significantly cooler (and quieter) due to additional water running through.

I can run for multiple hours at the 3k RPM range, pull over, open engine hatch, and get down on the engines without it being too hot to touch. Engine bay is also significantly cooler.

If vapor lock issue persists, I would check the cooling system.

Nic
Click to expand...
I did not take you advise on flushing the engines because both have always (I have had the boat about 10 months now) run at 160 degrees.
However, I did switch out the IAC valves and took off the cover to the flame arrester on the port engine, and that seems to have made a difference. I'll have to wait to get the boat out for more testing, but at least I'm hopeful.
And again, thanks to all that have responded.
 
Flytrade said:
I did not take you advise on flushing the engines because both have always (I have had the boat about 10 months now) run at 160 degrees.
However, I did switch out the IAC valves and took off the cover to the flame arrester on the port engine, and that seems to have made a difference. I'll have to wait to get the boat out for more testing, but at least I'm hopeful.
And again, thanks to all that have responded.
Click to expand...

Good luck!

For what it’s worth, mine we’re also running along at 160 range without ever over heating. It was only after the engines sat for a bit that I would have any problems.

Keep us updated on progress!
 
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