Engine Hard Starting when Hot

Dear Community,

I have a 2004 Volvo Penta 5.7 GI-E. I'm having trouble starting the engine when it's hot. It won't start unless I put it in neutral and give it full throttle. When it does start, it smells like gasoline, as if it's flooded.

The engine starts fine when cold. I've consulted the manual and it suggests two potential issues:

1. Fuel lines near hot surfaces: I've checked the fuel lines and they seem to be routed normally, similar to other engines I've seen.
2. Fuel tank vent: I've blown air through the vent and it's working correctly.

Does anyone have any other suggestions or troubleshooting tips for this issue? I'm running out of ideas and would appreciate any advice.

check the water cooling hoses for clogs at the cool fuel pump

Bt Doctur said:

check the water cooling hoses for clogs at the cool fuel pump

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Would that affect the engine temperature? Because currently it's operating under the normal temperature 160 Fº. Thanks

no ,but it could impact the fuel temerature

Bt Doctur said:

no ,but it could impact the fuel temerature

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ok, Thanks for the info; I didn't realize there was a water cooling hose in the fuel pump (learning every day).

I just removed the top hose and water was coming out from the pump and the hose.

I assume there is no clog

I am going to suggest your symptoms and direction of troubleshooting are at opposite ends of the spectrum. Let me explain.

• Troubleshooting: Fuel lines getting too hot, blocked tank vent, overheating fuel pump all would generally cause a lack of fuel. In the case of hot fuel, it can literally boil causing vapor lock. If the tank is not venting, then the pump will eventually not be able draw any more fuel.
• Symptoms: need to hold throttle wide open and strong smell of gas ‘like its flooded’ or too much fuel.

Going with the symptoms, it is flooded and not starving for fuel.
One possible cause is leaking injectors. But why does it start ok when cold? When shut down for the day the injectors are still leaking by and would cause flooding if you restarted. But you leave for the night or days and it gives the fuel time to evaporate, so starts as it should. Been running about, pulled up to a sandbar for some fun and that drip drip drip from the injectors is there when you start up flooding out the engine.

I do not know of a test for leaking injectors while still in the boat other than this: When first getting started for the day with a nice and cold motor that has sat for a day or more, prior to starting put your nose next to the spark arrestor and sniff (pull off that plastic shroud if you have one, get close and personal with the arrestor). Should not smell any fuel. Starts normally. Go have fun and prior to restarting that warm engine, sniff again. Strong smell of fuel > more than likely leaking injectors.

Also in some applications with a computer the fuel injectors are shut off if motor not running and WOT is applied

Bt Doctur said:

Also in some applications with a computer the fuel injectors are shut off if motor not running and WOT is applied

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I have heard this before and it certainly makes sense to program that way, but I have never seen it in official documentation. Intrigued I poured thru my VP EFI Diagnostic manual (7742218) looking for it. I did not find it but interestingly I did find a test for (still installed) leaking injectors. Not surprisingly it involves a pressure drop test on the fuel rail:

• Post installing a pressure gauge need to turn the key on as needed to bleed out any air and ensure no leaks (note: turning the key on (not start) will trigger the fuel pump to run for a couple of seconds). Then key on > get pressure > key off and wait 10 minutes. A drop of more than 2 PSI indicates amongst other things leaking injectors.

So back to the nose test as the simplest method.

BT Doc: I am curious, is there a listing somewhere for the EFI computers will shut off the injectors under a motor not running and a WOT? How could one know for sure if that is what their EFI will do? Thanks!

ESGWheel said:

BT Doc: I am curious, is there a listing somewhere for the EFI computers will shut off the injectors under a motor not running and a WOT? How could one know for sure if that is what their EFI will do? Thanks!

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Need to look in the MEFI manual
Not all MEFI's have clear flood mode but some do, as example MEFI-4 (VP type) has clear flood mode

Search "mefi clear flood mode", can find in PCM engines, VP 4B and off the top my head, MEFI-3 with Merc. Even cars have this. @Fun Times is more up on this then I

Thank you!

I'm ready to bet that you have a leaking injector. I also have a 2004 5.7Gi-D, and over the span of 6 years, that exact problem happened twice. Both times it was a leaking injector. Start by installing a fuel pressure gauge on the fuel line nipple. Pressure will go down when the engine is stopped. Next, you can pull the fuel injector rail out, put a paper towel under each injector, then turn on ignition without starting the engine, the fuel pump will prime and the bad injector will drip on the paper towel.

Hi everyone, I've completed the fuel injector cleaning and testing today. All injectors were run through a cleaning machine with a leak test function. While I found no leaks, the spray patterns were definitely dirty and poor. I've cleaned them thoroughly and will reinstall them shortly. Additionally, I serviced the fuel pump, removing the internal paint. I'll update you all after reassembly and testing. To be honest, I'm still not optimistic about finding the root cause since the leak test didn't reveal any obvious issues. Thanks for all your insights

Scuse my ignorance but does it have a separate cold start injector ?

gilsaraiva said:

ok, Thanks for the info; I didn't realize there was a water cooling hose in the fuel pump (learning every day).

I just removed the top hose and water was coming out from the pump and the hose.

I assume there is no clog

View attachment 402936
View attachment 402937

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Also make sure that water is exiting the fuel pump. If the fuel pumps water jackets are clogged there will be no water passing through the pump to cool it.

Mc Tool said:

Scuse my ignorance but does it have a separate cold start injector ?

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no it doesn't