1997 5.7 Gi fuel system

[saf]

Hello everyone.
Can somebody explain (or point me to the appropriate information source) how the fuel injection system works on the 5.7 Gi engines? I have 1997 Pursuit 2460 that had the original engine replaced by previous owner. The original engine was 5.7GIPLKDCE, i.e. fuel injected. The replacement engine is carbureted. To make things worse, the carburetor was later replaced by Edelbrock 1409. I am hating this carb, it made cold starts after long (over a week) periods of sitting at the dock a real pain. So, instead of buying a new carb I am contemplating going back to fuel injection. Naturally, I am trying to understand the original setup first. In particular, I have two questions:
1. I do not see any oxygen sensors in 5.7GIPLKDCE diagrams (even though there appears to be a knock sensor). Is this correct?
2. What is the deal with the fuel reservoir? I get it that it was used for fuel return from high pressure fuel pump. What's the deal with hoses connecting it to thermostat housing and risers? Does it have water circulating through it somehow? There also appears to be a float inside the reservoir, how does this work?

 

[alldodge]

The 1409 is one of the better carbs and easy to adjust. The trouble starting after long periods of sitting comes from the carb fuel evaporating out of the bowl. Would need to crank for a short period just to get the fuel back in the carb, unless you have an electric pump.

The original motor had 2 fuel pumps, one low pressure and one high pressure. The HP pump was located in a reservoir which the LP pump kept it full (like a carb fuel bowl). The HP pump takes fuel from the reservoir and increases pressure to 50-60 psi.

The motor does not show an O2 sensor. Has only normally found sensors

Here is the motor
https://www.marinepartseurope.com/en/e-volvo-penta-901-5.7GIPLKECE.aspx

 

[saf]

The 1409 is one of the better carbs and easy to adjust. The trouble starting after long periods of sitting comes from the carb fuel evaporating out of the bowl. Would need to crank for a short period just to get the fuel back in the carb, unless you have an electric pump.

The original motor had 2 fuel pumps, one low pressure and one high pressure. The HP pump was located in a reservoir which the LP pump kept it full (like a carb fuel bowl). The HP pump takes fuel from the reservoir and increases pressure to 50-60 psi.

The motor does not show an O2 sensor. Has only normally found sensors

Here is the motor
https://www.marinepartseurope.com/en/e-volvo-penta-901-5.7GIPLKECE.aspx

Thanks alldodge,
You are exactly right, the carb is easy to adjust indeed, and the problem lies with fuel evaporating from the bowls. However, I do have electric LP pump (I am guessing the legacy from the original setup), so, it takes some time for it to kick in. Also, when fuel evaporates from the bowls it tends to leave some residue behind (I think) because I had to blow the idle circuit twice last season to get the idle back to normal. Replaced the fuel filter twice (thinking the filter might be bad) - no difference. Furthermore, the fast idle setting is missing on 1409. I guess they expect the operator to increase idle manually on cold starts. I find it very difficult to get working smoothly.
Anyway, going back to my original questions. The fact that O2 sensor is missing, I guess, means that it was using preset fuel curves. Is that right? Can I get this curves somehow to tune the new EFI system?
On the fuel reservoir question I am puzzled by hoses connecting it to thermostat housing and to oil cooler (see the diagram). What is this all about?

 

[alldodge]

The issue with the LP pump not working during cranking is most likely the PO didn't install the circuit to turn it ON during cranking, or the diode blew

The ECM was preprogramed by VP, and they determined the curve through testing prior to selling the motor. Merc, VP and others all do it this way for standard production non-racing motors. They tune them a bit fat to help the motor last. The curve can be changed but would need some software to do so. The easiest way to go back to the Gi is buy a already tuned one from a place like OBD Diagnostics

I don't see the diagram

 

[alldodge]

There is a line going from reservoir to intake and that is there so if the valve in the reservoir does not shut off the fuel once its full, the excess goes into the intake as a safety measure

 

[alldodge]

Another thing your going to need is the fuel injection (FI) harness (unless its still there). The FI harness plugs into the motor harness

 

[Lou C]

Have you made sure that:
The choke fully or nearly fully closes with a cold engine
The choke pull off pulls the choke plate open a fraction of an inch after started
The electric heated choke fully opens after a few minutes

Marine carbs do not have automatic fast idle cams as you’d have in automotive applications, for safety reasons.
Fast idle must be set by the operator by either pulling the remote control out and advancing the throttle to fast idle position (1/3 forward or so) or pushing the button in the center of the control; it depends on the control you have.
If you’re not doing this you will always have trouble with cold starts. A carbed engine must have fast idle when it’s on choke to keep running. EFI does not have this same requirement.
I have a 32 year old boat with a Rochester Quadrajet; cold starting goes like this: I pump the throttle 3 times, pull out the control lever and advance the throttle 1/3. Crank it over it will start on the first or second crank over. Adjust fast idle to 1500 rpm and allow to warm up. Even after it sits for 6 months it will usually start on the 3rd crank over.
EFI is nice when it’s fairly new and all components are working as designed. However in a marine environment there are wiring and terminal issues that reduce reliability. Then there is the trend by both Merc and Volvo to make certain components no longer available like ignition modules and engine ECMs. For these reasons I greatly prefer carbs on older boats that can be 100% supported in the aftermarket. Learn how the carb works, thousands of old boats and classic cars do just fine with them. Edelbrock or Holley take your choice.

 

[saf]

Have you made sure that:
The choke fully or nearly fully closes with a cold engine
The choke pull off pulls the choke plate open a fraction of an inch after started
The electric heated choke fully opens after a few minutes

Marine carbs do not have automatic fast idle cams as you’d have in automotive applications, for safety reasons.
Fast idle must be set by the operator by either pulling the remote control out and advancing the throttle to fast idle position (1/3 forward or so) or pushing the button in the center of the control; it depends on the control you have.
If you’re not doing this you will always have trouble with cold starts. A carbed engine must have fast idle when it’s on choke to keep running. EFI does not have this same requirement.
I have a 32 year old boat with a Rochester Quadrajet; cold starting goes like this: I pump the throttle 3 times, pull out the control lever and advance the throttle 1/3. Crank it over it will start on the first or second crank over. Adjust fast idle to 1500 rpm and allow to warm up. Even after it sits for 6 months it will usually start on the 3rd crank over.
EFI is nice when it’s fairly new and all components are working as designed. However in a marine environment there are wiring and terminal issues that reduce reliability. Then there is the trend by both Merc and Volvo to make certain components no longer available like ignition modules and engine ECMs. For these reasons I greatly prefer carbs on older boats that can be 100% supported in the aftermarket. Learn how the carb works, thousands of old boats and classic cars do just fine with them. Edelbrock or Holley take your choice.

Thanks Lou, this is great advice. I've been toying with the idea of putting in Holly Sniper Marine EFI - looks like one can get it for not much more than a good carb. You a remaking a good argument though...

 

[Lou C]

Thanks Lou, this is great advice. I've been toying with the idea of putting in Holly Sniper Marine EFI - looks like one can get it for not much more than a good carb. You a remaking a good argument though...

Read on the Holley forums you will see that these can be troublesome too. Learn, know and love your carb. Some of us grew up with cars that had carbs and learned how to deal with them in all kinds of weather.
Every 6 years or so I take my Quadrajet apart clean it out and re assemble with a $55 rebuild kit. The mechanical fuel pump lasted 30 years replaced with new for $85. Carbs win out for low cost of repair and aftermarket availability of parts. Whats the OE cost of those troublesome Volvo low/high pressure fuel pumps? $1000? And the vapor assembly is NLA. No thanks I will never own one. Learn the carb!

Carbs can be bought new on sale (either Edelbrock or Holley) for around $500, a low pressure electric pump is about $100, or so depending on what you buy. The theoretical advantages of EFI are there, no denying it but in the real world practical concerns dictate that carbs are much less expensive to keep going. Yes they require some user knowledge, like starting a lawn mower or a 2 stroke weed wacker. Given both Merc's and Volvo's bad habits of discontinuing mission critical parts, I am not a fan of EFI for boats. The healthy demand for carbs in the classic car and muscle car hobbies have made it good for old boat owners, this keeps the supply of parts full. In fact I can get nearly every part I might need for a 32 year old Quadrajet and these have not been made since 1990. Why? Because nearly every GM standard V8 and high performance car came with them, from 1966 to 1986 or so, plenty of demand still for the parts. And even if this were not the case, I could have changed to a Holley or Edelbrock as well, starting out brand new.
Here's my most recent Quadrajet rebuild....

 

[Scott06]

Thanks alldodge,
You are exactly right, the carb is easy to adjust indeed, and the problem lies with fuel evaporating from the bowls. However, I do have electric LP pump (I am guessing the legacy from the original setup), so, it takes some time for it to kick in. Also, when fuel evaporates from the bowls it tends to leave some residue behind (I think) because I had to blow the idle circuit twice last season to get the idle back to normal. Replaced the fuel filter twice (thinking the filter might be bad) - no difference. Furthermore, the fast idle setting is missing on 1409. I guess they expect the operator to increase idle manually on cold starts. I find it very difficult to get working smoothly.
Anyway, going back to my original questions. The fact that O2 sensor is missing, I guess, means that it was using preset fuel curves. Is that right? Can I get this curves somehow to tune the new EFI system?
On the fuel reservoir question I am puzzled by hoses connecting it to thermostat housing and to oil cooler (see the diagram). What is this all about?

in addition to Lou s comments about cold starts - its seems like your engine had fuel injection on it, then someone hit a roadblock parts or maintenance wise and swapped out for a carb? Must have been problematic enough to tear it out?

i have a1409 on my mercruiser 5.0 that works very well, although I do have to crank to refill the fuel bowl after a long time with out use. when you say you had to blow out the idle circuits several times it sounds like it didn’t get completely clean of dirty fuel is replugging the carb. I’d suggest trying to really clean and rebuild the carb again before giving up on it.

 

[Lou C]

Also, when using the carb instead of EFI I would have gotten rid of the fuel reservoir there is no need for it on a carbed engine and gotten a Carter low pressure fuel pump and make sure it is wired correctly so that you have power to the pump during cranking from the terminal on the starter solenoid and then when oil pressure builds the pump is powered off the oil pressure safety switch. It must be wired up the right way for safety (if the engine stalls then power to the pump is cut by the oil pressure safety switch so the engine doesn’t flood with gas). If this engine still has the fuel reservoir and Volvo low pressure pump from the EFI set up the conversion might not have been done right.

 

[Lou C]

I took a look at the diagrams, it appears for that year range the engines still could come with a mechanical fuel pump, I'd check yours to see if there is a block off plate that can be removed, (it depends on what engine block was used when they replaced the original) if so I'd use the mechanical pump since it is simpler (no wiring via the oil pressure switch) cheaper and likely will last longer based on my experience with them.
If you look at the parts breakdown for the fuel injected engine (which by the way is just a throttle body system not port injection) you can see many of the parts are obsolete or out of production.
The carb used is just a garden variety Holley marine carb. But no reason why you could not use your Edelbrock. Perhaps you had trouble with the idle passages because of the Volvo spec electric fuel pumps which were painted inside and the paint can break down and clog the fuel system. It was a recognized problem on these engines for some time. The mechanical pumps are not painted inside and you will not have this problem.

Volvo Penta Exploded view / schematic Fuel Pump and Filter 5.7GLPLKE, 5.7GLPLKR, 5.7GSPLKD, 5.7GSPLKE - MarinePartsEurope.com

Volvo Penta Exploded view / schematic Carburetor 5.7GLPLKA, 5.7GLPLKD, 5.7GLPLKE, 5.7GLPLKR - MarinePartsEurope.com 2bbl carb

Volvo Penta Exploded view / schematic Carburetor 5.7GSPLKD, 5.7GSPLKE - MarinePartsEurope.com 4bbl carb

the mechanical fuel pump is just a standard Carter marine fuel pump, no need to buy from Volvo they can be found on Summit Racing or Jegs, just make sure it has the nipple for the safety overflow as the carb should have. Volvo's price is probably 2x the normal price.