Hard starting when warm

F

FB400

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Joined
Mar 2, 2004
RO Number
12883
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28
I have 2005 Rinker Fiesta Vee with Volvo Penta 5.7OSXi. This boat is 8cyl fuel injected

The boat was out of the water for 3 seasons. It was run each year but not for a long time. I kept stabilized gas in the boat and the tank was completely emptied 1.5 years ago. Since then fresh stablized gas in the tank

Problem:
I launched boat in late April. A couple weeks ago It started having an issue with hard starting after it has been run and is warm. when cold the boat starts perfectly and idles well. no issues whatsoever

After running up to temperature and having been off for a period of time (20.30 60 minutes or more) it won't start. If I give it wide open throttle and crank for several seconds it will start and really this is the only way I can get it started. After running for a few seconds at high rpm to burn off the extra gas it will idle smoothly and all is fine.

I changed the plugs just last weekend. properly gapped at 0.60. Not helping at all.

I also added fuel injector cleaner and have run the boat for probably 3 hours with this in the gas. This isn't helping either

Any ideas what would be cause and possible fixes?

Thanks
FB
 
Not sure how your fuel injection system is configured but sounds to me that the choke is closing too much for a warm engine.
 
This is a fuel injected engine, so no choke is involved.

The Volvo fuel injection computer has a special mode to turn off all the injectors when starting with the throttle full open. This is what you are using to start a warm engine.

I have exactly the same problem as you do and use the same method you do. My guess is that the injectors leak a bit when a warm engine is shut down, which makes the mixture too rich on the next start attempt.

Mike
 
What you describe, Mike, is exactly what a choke closing on a warm engine does. How you guys are overcoming it is the same as a 'flooded' engine.
 
Sounds to me you have to replace your fuel pump. It cost $800 for fuel pump another $300 to put it on.
 
With a carbed engine I make sure to let it idle for a minute or more to burn up the excess gas before shuting down the engine. I wonder if this woukd help with your situation.

Doubt it but would be worth a quick try.
 
If it has an electric fuel pump vapor lock should not be a problem. try letting the pump run a bit with the key on see if you can hear it.
 
My SeaRay 290da had Mercruiser 5.0's, fuel injected, electric fuel pumps and the Mercruiser "cool fuel" system. Still, every spring when the warm weather set in and I still had "winter blend" fuel in the tanks I was guaranteed a vapor lock situation once or twice. Run the boat 30min / hr stop anchor for awhile and it would not start. To get it to start I would pour cold fresh water over the fuel pump and lines and it would start. Also check all your fuel line fittings, at the tank, pump etc and make sure they are tight. A loose fitting would just aggravate the issue by letting air in the system.
 
Some of these engines are Throttle Body Injected and some are Multi-Port Injected, but I believe both have the feature that shuts injectors off when cranking if the throttle is open. You know, push the button to disengage gear then push throttle toward Full. To me, drippy injector(s), especially after storage, is a good possibility. And likely to reduce or go away as the boat's used through the season. Maybe some fuel system cleaner to speed up the process.
I also believe the GM engines of similar ages use similar fuel and control systems. I hear reference to "MEFI" as Marine Electronic Fuel Injection, followed by a number representing the generation of the technology, like "MEFI3". Our '96 wasn't Cool Fuel. It has a Mechanical, engine mounted, low pressure pump that fills a VST, Vapor Separator Tank. VST has a carburetor-like float, a very fine filter, and the high pressure electric pump that feed the two-injector TBI system.
Two hot-start problems. First, after shutting down hot, would not start without a 30-minute or longer cool down. Mechanic diagnosed/replaced high pressure pump. Didn't really help. I didn't carry extra fresh water, rather an extra bilge blower, and cooling the system would let it start. VST and block-mounted pump were close enough that the blower hit both of them. I got tired of this and replaced the low-pressure pump, that engine-mounted one, and it now starts nearly every time.
Second problem, sometimes still doesn't start a few minutes after hot shut down. Open the throttle and it starts every time. I suspect drippy injectors. After 1300+ hours I don't blame them.
 
I boat on a lake so had plenty of cold freshwater - haha. I re-read this and the fact that it will start by holding the throttle open kinda rules out vapor lock. Seems like more what j-d is saying, basically a flooding condition. If an engine is vapor locked, it just isn't going to start period until the fuel that has vaporized in the lines cools / condenses back to a liquid - the fuel pump just can't pump air!
 
Like j-d ,it sounds to me also like possible leaky injectors from a little grit blocking the seal .
If it's an MPI, you might put a fuel pressure gauge on the rail to see if pressure drops when the engine has been run but is turned off.
These gassers aren't direct injection into the cylinders, so you might be able to smell excess gas at the throttle body from pooled-fuel fumes in the staging area of the intake.
 
Old fuel has a lower vapor pressure, boils at a much lower temperature in the fuel rails. Does this engine use a return line back to the tank?
If so you may try cycling the key on for about 10 seconds, without cranking, then back off. Do this for about 5 cycles to purge vapor from the fuel rails. Then try a normal start sequence.
 
No return line back to fuel tanks on this type of Volvo engine.

My theory has always been the high-pressure fuel remaining the injector rails after shut-down gets heated by the warm engine, expands slightly and causes the injectors to leak a little into the manifold. This causes a rich mixture on the next start. But if the engine sits long enough the excess fuel evaporates, so the problem only occurs when trying to start a warm engine.

My procedure is if a warm engine does not start immediately I abort the start attempt, go to fuel throttle (which shuts down the injectors) and attempt another start. The engines almost always start after just a few seconds of cranking.

Mike
 
It would be interesting to measure the fuel pressure on the high pressure side and see how the pressure changes when the engine is shut down.
 
I bought a Harbor Freight gauge to do just that. Didn't come with the needed fittings so I got some at the auto supply. Put it together and leaked at the fittings like crazy. Thought I'd blow the boat up. So at least in my case I still don't know...
 
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