Engine starts and dies.

[Fatih]

Hi, I am writing from Qatar. My engine is inboard Volvo penta 5.0 OSi-F in my boat. We changed long block with new one last September 2020. Engine was working properly until beginning of March 21. Now Engine is starting at first attempt but dies in seconds. My technician checked all sensors, relays, harness and petrol pump. All is fine. If we add petrol directly Engine works well until we stopped fueling directly. We are thinking some thing tells to pump or Engine stop. But big question is what? Your support highly appreciated.

 

[dypcdiver]

Check your alternator, that is what supplies power to the petrol pumps after you release the starter.

 

[Fatih]

Thanks. Alternator is new also. However we have checked it and cables are fine.

 

[alldodge]

What is the fuel pressure at the rail?
It should be 50 to 60 psi

 

[Fatih]

What is the fuel pressure at the rail?
It should be 50 to 60 psi

 

[Fatih]

I'll ask to my technician to measure. Thanks your interest

 

[Backyardmech]

I know on the older model volvo pentas the fuel pump swich is operated by oil pressure after the engine is running. Either low oil pressure or a bad switch is a possibility.

 

[Fatih]

We measured it is 55 psi.

 

[alldodge]

This motor doesn't use the ALT or the oil pressure switch to keep pump ON

We measured it is 55 psi.

Was that while running (pour gas down throttle body), or just with key ON?

 

[Bt Doctur]

poss a bad diode ,

 

[Bt Doctur]

 

[Bt Doctur]

The alt powers the fuel pump on a volvo

 

[alldodge]

Its an OSi which is same wiring as GXi
The ALT powers the ignition, he has spark but is not getting fuel. The fuel pump is running just need to know if it stays running when gas is being poured in, or does it shout OFF.

This drawing is from a Gi but the wiring for the fuel pump and ignition is the same

 

[alldodge]

Here is the GXi

 

[Fatih]

Thanks a lot. I'll share these info and diagrams with my technician.

 

[Fatih]

This motor doesn't use the ALT or the oil pressure switch to keep pump ON



Was that while running (pour gas down throttle body), or just with key ON?

When pour gas down to throttle body engine is working well until we stop pouring.

 

[alldodge]

When pour gas down to throttle body engine is working well until we stop pouring.

OK, and does the pressure stay at 55 psi when pouring gas?

 

[Fatih]

OK, and does the pressure stay at 55 psi when pouring gas?

Yes.

 

[alldodge]

OK, then need to start looking on the electrical side. The injectors are not being turned on/off (
Can you scan the the motor for codes?

Can make up a scanner with a 12V resistor LED or use a digital multimeter that has a tone function if (Big IF) you have a MEFI ECM which looks like the one in the pic

 

[Fatih]

My technician is working on.