5.0Gi feps engine flooding problem

[Wmsproul]

2001 FourWinns Horizon 200, VP SternDrive 5.0Gifeps SX-M 1.60

Recently replaced;
TPS
cap
rotor
plugs
serp belt
serviced fuel pump using Mancave Mech's instructions and oring kit
fuel filter
injectors serviced/cleaned
regulator diaphragm replaced
throttle body cleaned, gaskets replaced

Boat idles fine at 650rpms on muffs in driveway, will idle and move around at low throttle in water, upon reaching end of 5mph will get up on step easily and do fine at WOT, but upon adjusting throttle even a little engine floods. When i remove the spark arrestor and open butterfly valves i see a lot of fuel and fuel vapors escaping. Once they all clear out i can repeat the process. If i stay at rpms under 2k and don't touch the throttle it seems like it will run all day at that speed, until i adjust it again. moving around at anything under 1k rpms it doesn't stall out.

Cheked the Map sensor with a brake bleeder vacuum pump with the key on, it gives an initial read out of 3.5v at 0"Hg
2.75v at 5"Hg, 2.0v at 10"Hg, 1.25v at 15"Hg and .75v at 20Hg.

Any help would be greatly appreciated.

Matt S.

 

[alldodge]

Check fuel pressure just to see if there is an issue

Where did you send the injectors to for flow testing?

 

[Wmsproul]

Would i check at the shrader valve ports on the pump?

I had them done at a local shop in the Scaramento,Ca area.

Also i used a normal GM 305 TPS sensor to replace the VP one, is there an issue with that?

 

[alldodge]

Yes check pressure at shrader ports

Unless the CA shop indicates it does marine injectors I would be suspect. Did they provide a test sheet?

Don't know about the TPS, would need to know the part number

Could also use the serial number of your motor

 

[Wmsproul]

Ok I took pics of the engine serial# and the spec sheet from the injectors service people. Which did know they were from a boat and said they had serviced them before.

Aldo I checked the map sensor while running at idle and its putting out 2.0~v, less than 1.7v at around 1300rpms. Can anyone verify if it’s running ok or it’s a little off at those readings?

Both TPS sensors read the same throughout the range of movement(0.6 at rest and 5.16v at full throttle) so I put the stock VP back in.

By the wiring on the third pic are the injectors wired correctly? The left one is pink/white and brown/orange, and the right injector is pink/white and brown/blue?

 

[alldodge]

Note the pressure the injectors were tested at it list (20 psi). Your injectors run at 31 to 27 (30 psi). There is also no metion of rpm, so they are an automotive shop and if they were doing my car I think i might even have a problem of how it was tested.

Unable to find the injectors or TB, all out of production (typical VP)

Injector wiring is of no issue, it uses power in and negative out, either way is correct

 

[Wmsproul]

I am going to pick up the gauge attachment needed tomorrow to test the fuel pressure

 

[Wmsproul]

Ok so I tested the high pressure side of the pump at idle and it was consistent at just under 30psi. Ran it on muffs till the temp reached normal operating temp and started to cool back off a little. Also replaced the iac with a new one, replaced the spark plug wires and swapped the injectors wires so the tan/blue and pink/white is on the left side facing aft on the throttle body. Taking it out tomorrow afternoon for another test run.

 

[Wmsproul]

Okay, so after more testing today i have some answers. Left the fuel pressure tester connected to the high side and at anything above 3k rpms the fuel pump pressure dropped to an erratic 10-14 psi then cut out completely. Turn off key, let it sit for a second, restart it and pressure went back up to 30 psi until I went over 3k rpms process repeats as many times as I want.

Maybe a new pump is in order??

 

[alldodge]

Well its either the regulator, pump or a restriction in the line to the pump.

Remove fuel filter and dump contents into a clear container to see if there is anything but clean gas

Check low pressure side of the pump, should be 6 to 8 psi. If low pressure reduces

Get a gas can and place the gas line in the can and the other end connected to the fuel filter.

If fuel pressure still drops then low pressure pump is the issue

If low pressure stays up but high goes low, the need to check the regulator but issue is reg is part of the throttle body. Or its the hp pump

muc thoughts

 

[Wmsproul]

Well I checked the fuel line going from tank to the pump all is clear and in good condition. However there was a tie rap on the fuel maybe partially blocking it?? Indention left in the hose when removed.

The anti syphon valve is free of debris

Also the pick up in the tank looks free of debris(see pic)

There is what looks like a valve connected to a line going from the throttle body under the tps to the top of the fuel pump tank(vst). Should this valve be open in both directions like it is? And what is it for/called?

Going to check the LP fuel pump pressure tomorrow.

 

[alldodge]

There is what looks like a valve connected to a line going from the throttle body under the tps to the top of the fuel pump tank(vst). Should this valve be open in both directions like it is? And what is it for/called?

That is used if the VST starts to overflow. The VST is a tank and is filled like a carb bowl with a float and needle seat valve. If something gets in the seat and starts to overflow the tank, the excess gas is dumped in the TB

 

[muc]

There is what looks like a valve connected to a line going from the throttle body under the tps to the top of the fuel pump tank(vst). Should this valve be open in both directions like it is? And what is it for/called?

That's a "pulse limiter" basically just a small screen inside. Purpose is to keep any backfires from igniting the vapor. This part of the system isn't there so much to handle overflow due to a stuck float (although it will do that) it's main job is to allow the safe removal of any gas vapors.

There are a number of things that could cause your problem ----- like do you have good cooling water flow through the VST? is the cooling water check valve working?

I highly recommend you find a copy of the EFI Diagnostic workshop manual. This was one of Volvo's better manuals and will walk you through all the different systems that might be causing you issue.

 

[Wmsproul]

Is that supposed to be a one way check valve?

 

[Wmsproul]

I will check the cooling passages and make sure they are clear, but how would that relate to either or both of the pumps dropping pressure??

 

[muc]

The one for gas vapors ---- no ---- I don't think so. But not 100% sure. Why? does it only flow one way?
The one for cooling water ---- yes ---- very sure on this one.
Sorry I forgot to give you the part number for the manual. #7797354
You can search for it online --- maybe find it free? But I will warn you that most manuals get updated after the first printing and we techs find things that are wrong in them. The factory sends out corrections to us and changes the new ones they print. Unfortunately most of the free online manuals I have looked at (not many because I can access the newest ones through dealer software) are the early version and will have some things wrong.

If you would have bought this manual earlier, it probably would have paid for it's self many times over.

 

[Wmsproul]

Ok so the check valve for gas vapors does flow both directions.

Ask where is the water cooling check valve you are referring to?

 

[muc]

I will check the cooling passages and make sure they are clear, but how would that relate to either or both of the pumps dropping pressure??

When the pumps and fuel get too hot. You can sometimes have symptoms like your describing.
Wouldn't be the first thing I would test. But I just threw it out there as an example of how this system, while it's pretty simple can have a number of problems. And if you don't fully understand how it works ---- can spend a lot of time and money replacing/repairing things that were working just fine and in doing so, you have a good chance of adding more problems on top of what you started with.

But your on the right track now. You have identified a problem with fuel pressure and need to correct that problem. Only then will you know if that's the only problem with your engine.

 

[muc]

Ok so the check valve for gas vapors does flow both directions.

Ask where is the water cooling check valve you are referring to?

Follow the 2 small cooling hoses and find it.
While your there ---- blow through them and make sure water will flow like it's designed to.

 

[Wmsproul]

This kink was in the cooling hose coming from the pump outlet on top and going to the port exhaust riser.