7.4 GI, strange issue

[alindquist]

1999 7.4GI
Serial 4110176452
gipwtr

So I take the boat out on Friday (1999 Cobalt 232) and everything starts out just fine. Run for about 15-20 minutes and everything is going great. All of the sudden the engine dies at about 3300RPM's. This has happened to me before and the last time replacing the high pressure fuel pump fixed it. I thought minor set back, I got it started back up and idle over the the beach and replaced the high pressure fuel pump with a new one. Boat starts up, runs great for another 15-20 and then it happens again. Exact same scenario. It seems it's not the fuel pump. I haven't started digging into it yet but it was kind of weird. Thinking back the last time this happened there was a hesitation and a little surging going on before it died. This time it was like someone just turned off the engine. I'm starting to think it could be a corroded ground or something electrical. Anybody have any ideas?
Thanks,
Aaron

 

[bnicov]

Re: 7.4 GI, strange issue

Check &/OR replace the fuel filter and the water separator filter (if you have one).

 

[alindquist]

Re: 7.4 GI, strange issue

I was planning on doing that. Anything other ideas guys?

 

[alindquist]

Re: 7.4 GI, strange issue

Well I changed the filter and now the boat is having a hard time starting and idling. I might have guessed wrong and need a low pressure pump. I got one on order so I guess well see. If it fixes it I'll post back. If anybody has any other ideas I'm all ears.

 

[cobalt252]

Re: 7.4 GI, strange issue

What brand, type of fuel (E10, E15?) did you use with the last fill up? Before that?

 

[alindquist]

Re: 7.4 GI, strange issue

Unfortunately it's 89oct. E10... Have to run it since that is all that's available...

 

[QC]

Re: 7.4 GI, strange issue

What brand, type of fuel (E10, E15?) did you use with the last fill up? Before that?

Why is that relevant?

 

[cobalt252]

Re: 7.4 GI, strange issue

Why is that relevant?

Folowing is a release by Volvo Penta of the Americas:

Volvo Penta of the Americas
1300 Volvo Penta Drive
Chesapeake, Virginia23320-9810
Ethanol Blended Gasoline
Gas Engines
Distribution: M Date: 09-2009 Binder: C
Service Bulletin
Group Number Version
18-8 7 02
VPA 18-8-702 Sept. 2009

Ethanol Blended Gasoline and your Volvo Penta engine
Ethanol Blended Gasoline (E10)
Gasoline is distributed throughout the world that contains ethanol. Volvo Penta gasoline engines may be operated using gasoline blended with a maximum of 10% ethanol and that meets the minimum octane specification (see operator?s manual). Gasoline blended with 10% ethanol is referred to as E10.

Do not use ethanol blends greater than 10%, especially E85 (85% ethanol, flex fuel). Volvo Penta engines are not designed to run on high percentages of ethanol. Loss of performance, increased fuel consumption and decreased mileage/range will occur.

NOTICE! Engine damage may occur; damage caused by fuel with too much ethanol is not covered by warranty. Ethanol has several characteristics that can create problems in marine fuel systems. It acts as a solvent and it attracts and holds water, in a much higher percentage than earlier fuels.

NOTICE! Fuel system or engine damage caused by contamination from water, varnish, foreign particles, sludge, or gums entering or forming in the fuel system is not
covered by the warranty.

Water, varnish, foreign particles, sludge, and gums are created or freed by the ethanol and can enter or form in the fuel system. These contaminants can clog fuel filters and damage fuel system components: pumps, injectors, carburetors. The contaminants must be prevented from entering the engine's fuel system.

Recommendations for E10 fuel

1. Add a second water separating fuel filter between the fuel tank and the engine.
Volvo Penta gasoline engines (except 3.0GL) are equipped with a water separating fuel filter.
A second filter adds extra protection from water and contaminants in the gasoline. The filter must be approved for gasoline inboard applications (USCG, EU 94/25/EC) and installed in accordance with boat building standards (ABYC, EU 94/25/EC). The filter must have a minimum rating of 50 gallons (189L) per hour.

2. Water separating fuel filters should be checked frequently for water and contaminants
in accordance with the filter manufacturer?s recommendations. Check and/or replace the filters if engine performance is poor. Carry spare filters and needed tools and supplies to change filters while boating.

3. Use a fuel stabilizer such as STA-BIL?, if the vessel?s fuel will not be used within 30 days. Marine fuel stabilizer provides the best results. Add the stabilizer according to the stabilizer manufacturer's instructions. This will help prevent the formation of fuel contaminants.

NOTICE! If the boat will not be used for two months or longer, the fuel system must be properly prepared for this storage period. See your dealer for details.

Fuel Additives
Avoid any fuel additives and fuel system treatments that contain ethanol or are alcohol-based.

Fiberglass Fuel Tanks
WARNING! Fuel leak, explosion/fire may result from continued use of ethanol fuels in polyester resin fiberglass fuel tanks.

Some older boats (mid-80?s and earlier) may have polyester resin fiberglass fuel tanks. Ethanol can dissolve the resin in the tank walls, forming contaminants in the fuel and eventually fuel leakage. Volvo Penta does not recommend the use of ethanol blended fuels in fuel tanks constructed of polyester resin fiberglass.​

 

[QC]

Re: 7.4 GI, strange issue

Yeah, and Merc has something similar and they even warn of vapor lock under high ambient conditions, but I don't believe any of that would result in the engine dying under load. Restart problems yes, but not sure about simply shutting off while cruising as OP's first post suggests . . .

 

[cobalt252]

Re: 7.4 GI, strange issue

... Restart problems yes, but not sure about simply shutting off while cruising as OP's first post suggests . . .

Ethanol is a STRONG polar solvent

" ... Water, varnish, foreign particles, sludge, and gums are created or freed by the ethanol and can enter or form in the fuel system. These contaminants can clog fuel filters and damage fuel system components: pumps, injectors, carburetors. The contaminants must be prevented from entering the engine's fuel system."

 

[Tail_Gunner]

Re: 7.4 GI, strange issue

Try to make it simple...Start your boat get it hot and when it idles rough take a light (neon or led) and illuminate the fuel injectors. Notice the spray pattern it should be a robust conical shape and no drips. If not have your injectors cleaned and not with a solvent....Starting there is last chain of events in the fuel supply next is the TB...Fuel pressure regulator.....IAC valve can be a problem very unlikely.....then the pumps and then the tank itself. There is a lot of truth in the e-10 gas it is bad for marine application you may have to clean the enitre system. Little note here TBI is mid 80's tech finding a old GM tech fimilar with it can make things very easy.. that is cleaning up the TB if you know them they are very simple

As to electrical contatcs cleaning them up with WD 40 followed by some steel wool....flushed with a contact cleaner is not a bad ideal. Actually its just routine maintance...I assume you engine alram system is working and your not hearing any audible whistle...You may want to check to see if the alrm itself is working....I blew one of those guys once and 3200 is about then cut off point but that would not kill and egine that i am aware of...Bad grounds can create some funky stuff on a GI been there done that aka motor turned over but not much fuel pumped... turned out a injector wasnt grounded and having them cleaned showed they were 20% under max flow rate