High fuel pressure on 04 Mercruiser 350 5.7

[Justin Snow]

Hello.. I’m currently in the middle of an engine rebuild on an 04 mercruiser 350 5.7 and when we dropped the engine in and started it up I t was smoking black pretty bad and running poorly... especially after throttling up. We pulled and cleaned the injectors and hooked up a computer that told us the fuel pressure is around 67 psi which seems a bit high.. I’m trying to find a way to dial it back with out having to replace the fuel pump. Has anyone dealt with an issuer like this? the out drive is a Bravo 3. Any advice is greatly appreciated. Thanks in advance

 

[Bt Doctur]

get the right pump, no more than 42-43 psi

 

[alldodge]

Serial number please?

Have you check with a gauge?

 

[Justin Snow]

I don’t have access to a gauge at this time. I’m gonna try and pull the screen out near the fuel pump. I’ll get back to you with the serial number

 

[Justin Snow]

OW6500 is what I can make out on my phone

 

[Scott Danforth]

Get a mechanical gauge and check fuel pressure

 

[alldodge]

Agree your high, 43 psi at 1800 rpm

Should have a bravo drive and the regulator is item 10. This pump does not have a screen which will restrict the fuel flow like the Gen 2 cool fuel. The screen it does have is more for filtration stopping larger particles

https://www.mercruiserparts.com/bam/subassembly/31751/12840/70

 

[Justin Snow]

Agree your high, 43 psi at 1800 rpm

Should have a bravo drive and the regulator is item 10. This pump does not have a screen which will restrict the fuel flow like the Gen 2 cool fuel. The screen it does have is more for filtration stopping larger particles

https://www.mercruiserparts.com/bam/subassembly/31751/12840/70

So that link you sent was very helpful. Turns out I actually have an alpha fuel supply module connected to a bravo 3 out drive.. so my fuel pump may have that screen after all. Has anyone else had similar experiences dealing with the Alpha Fuel Module putting out too much fuel pressure?

 

[alldodge]

The screen, the regulator or another restriction in the return line can increase the pressure. The pressure your showing, it would be the screen as the first look.

After removing the Reg, if you have a compressor and air regulator it can be tested after removal

 

[Justin Snow]

So I pulled the screen (what a pain in the butt!), cleaned it and put it back together and she started up nice and ran a lot cleaner. Then she died when I went to reconnect the PCV valve and wouldn’t restart. I got ahold of a pressure gage and tested at the rail and the pressure came down to 41-44 psi which is great!! But I can’t get her restarted?! Help!!! Lol I’m going crazy

 

[alldodge]

Are you getting any codes?

When cranking can you see at least 300 rpm on the tach?

Have you checked fuses on the motor?

 

[Justin Snow]

No codes. The tac is a little jankey. No movement when starting. It’s frozen on 800 until she runs for a while. I’ll look at the fuses today