Volvo Penta 8.1 Hard/wont start

[Jskhome62]

Hello all. Only posting as a new topic bc after searching for a bit couldnt find anything in the list of engine problems that seemed to relate. If there’s a posting, feel free to point me there. Always appreciate the help from the forum.

Port engine on my vp 8.1 Gil-c gas engines has always been a bit slow to catch. Turns over fine. Sometimes I can get it to start by pushing the throttles (transmission disengaged) full forward or reverse and letting it sit for a bit. Lately it won’t start unless I break the fuel filter loose and dump it - or at least that’s the trick I’m currently using. So I was thinking maybe a batch of bad gas or gas with some water in it. Happens hot or cold so I don’t think it’s a vapor lock thing. I also recently changed the oil and fuel filters and after the change it fired right up.

Took the boat out yesterday and same thing - no start. Dumped the fuel filter and it started up. Ran for about 5 hours continuous at everything from idle to 3600 rpm and no issues. When I got back to the slip and tied up, after having the engines off for about 5-10 minutes I tried starting them up again right away just as a test. Not only did the port engine not start but I didn’t get the 2 beeps when I turned the key. I didn’t try the fuel filter trick but did pull the gas cap of the tank to see if I had any pressure issues - nothing. I do recall early on when this problem first started I pulled the cap and got a lot of suction.

Once in a blue moon I’ll have similar starting issues starboard but can usually get it to go with the throttle cycle. The only time it didn’t start, I found the fuel filter loose - but this was after a change and once tightened started right away.

Any suggestions on where to start looking for the issue would be most welcome. Clearly seems to be fuel supply related. Know the fuel pumps on these engines have an ‘inside paint’ issue but would think that would keep the engine from running at all.

[pepmyster]

Hi, Same boat and engines but 2004. Have you, cleaned the flame arrestors, clean throttle plates, replace the plugs? I did all that when I bought our boat. Also ,the IAC are very well known problem for these engines (and also not expensive).

[bud37]

My advice , try to get a mechanic to connect up to the ecu's and run a diagnostic recording to watch things like fuel pressure, tps. iac, voltage stability etc. Really just guessing otherwise. Before that though be sure all the filters are clean and check the anti siphon valves and have a good look at your fuel lines for any damage or kinks etc.

Does this happen no matter how much fuel is in the tanks ?

I do agree based on your findings so far that it seems to be fuel related for one reason or another.

[Viper]

I agree with recommendations noted above. What stands out to me more than anything is your comment about putting her in full throttle to help with starting. That is normal procedure to clear a flooded engine condition. Based on that, I'm wondering if you have one or more injectors that are leaking. Also wondering how old your fuel is and whether there is water in it. Did you check the contents when you dumped the filter? Is this the same boat that sat at the dock for a while before you bought it, same one with concerning oil analysis numbers?

[MirrorFinishPolishin]

Maybe I missed this in your original post, but have you tried checking fuel pressure? If so, what exactly does it do when the key is on? A good way to check it is to have another person watch and video with a phone, or setup a phone and video what it is doing while you turn the key on at the helm. The reason I say that is sometime fuel pressure could go up to 50 and then drop to 10, 0 or whatever before you even make it back there to look at the gauge. It would be good to know exactly what it is doing to troubleshoot further.

Sometimes the connectors on the high pressure pumps will be weird where you disconnect and reconnect (even though they look fantastic) and the high pressure pump starts working perfect for months again. Of course sometimes the high pressure pump could just be going out too.

[Jskhome62]

Thanks all for the quick responses. Always appreciate those taking the time to do so.


Pepmyster. Been through all of that except the plugs. Trying to do the easy stuff first but will put on the list. As for the IAC, not having any idle issues once they start- engines run at a steady 800 rpm hot or cold. You think the IAC could be part of the starting problem?

Bud37 - all the filters are new and doesn’t seem to be fuel tank level dependent. All the lines and fittings also seem good - at least nothing obvious. I haven’t gone back to the anti siphons (yet) as they’re kind of hard to get to, but every time I’ve cracked the filter loose, it’s full of fuel. Would I expect that to be the case if the fuel was dumping back into the tank? And not sure why I hadn’t considered getting a reader on the ECM for a more detailed diagnostic (duh) but I did buy a set of fuel pressure gauges to get a little bit more info on my own.

Viper - not sure where I read about the throttle trick, but I thought that was for getting more fuel into the engine rather than getting too much out. The leaky fuel injector is an interesting thought. If they are leaking and flooding, wouldn’t I expect to smell excess fuel like a normally flooded engine? Not getting any fuel smell at all, so what else would I look/smell for that might point to the injectors? And yes, this is the same boat I posted about/solicited advice on when I first jointed the forum. Other than this recent issue and what I would call the normal nonsense and headaches of boat ownership (said with a smile on my face), none of the concerns I originally posted about have (yet) to manifest. The engines don’t burn any oil between changes (which I’m doing every 50 hours), the don’t run hot, stumble/stall/stutter, etc., etc., etc.. Overall I’ve been very happy with the boat, glad I threw a little caution to the wind and took the flyer. I’m even enjoying solving these (hopefully) little problems from time to time. It’s all been good.

Mirrorfinishpolishin - haven’t had a chance to do as you suggest just yet, but once the gauge set I ordered comes in that’s the plan.

Was hoping someone would have that definitive ‘oh yeah - that happened to me and here’s how I fixed it’ response but this appears its going to be more of a rabbit hole to find and fix. I’ll probably start with replacing the pump as I know there are lots of postings about these - especially around this model year (2003) - having issues. At least there seems to be consensus it’s a fuel delivery issue. I will post what I find and again thank you everyone for taking the time to lend me your thoughts on where to go next.

[MirrorFinishPolishin]

I really think you are going to find this is some type of fuel issue in some way. In my opinion the number ONE thing to check is see what fuel pressure is doing at key on especially since it is such an easy test to do. The IAC can cause the hard start issues that you are having as well though, but still goes back to fueling as a faulty IAC can cause the engine to become "flooded" when it doesn't start immediately especially after trying over and over again. If it is flooding at all you will want to do high throttle quickly to get through the flooding stages.

[Viper]

Source of the post.... Viper... I thought that was for getting more fuel into the engine rather than getting too much out. The leaky fuel injector is an interesting thought. If they are leaking and flooding, wouldn’t I expect to smell excess fuel like a normally flooded engine? Not getting any fuel smell at all...

I'll start by saying that there are several things that can contribute to hard starting, could be something simple or complicated with fuel delivery or ignition but there are a slue of other things that can be the cause as well like bad manifolds spraying water into one or more cylinders, low voltage, bad electrical connection, fuel pump, fuel regulator, failed sensor, the list goes on but we should take one thing at a time and eliminate it as a possibility. The wide open throttle just stood out so that indicates a possible flooding condition which can be caused by several things. For the record, when the ECM sees wide open throttle at power up, it will not fire the injectors as that is the procedure to clear a flooded condition. The full throttle also allows the most amount of air into the cylinders to help evaporate the flooded condition. It's also not uncommon for there not to be any excess fuel smell in a flooded condition, it doesn't take much to flood and there are too many variables, but it does cause hard starting.