Educate me on the PCM Fuel System

[Shooter]

2003 PCM Excalibur 330

I pulled the boat from storage and it won’t start. I'm now positive the engine is not getting fuel. Thanks to an earlier thread, I believe my fuel pump has gone out and desperately need some input.

I have two hoses that go from the fuel tank. I believe one hose runs to the high pressure fuel pump and the other runs to the low pressure fuel pump. Why are there two fuel pumps and which one should go on when the ignition is turned on? Is there a fuse or breaker for the pumps? I don’t have a volt meter and think I should check that first.

I'm guessing I need to change the low pressure pump. Is it as simple as swapping them out? Do I need to worry about priming the pump during install? Anything else I need to know.

I would normally have the dealer fix this, but funds are a bit tight and I'm may be forced to do this repair myself. It doesn’t look that hard, but I'm afraid of making a costly mistake.

Thanks in advanced!

http://planetnautique.com/vb3/showth...winter-storage

[Shooter]

Here is how a decided it was a fuel pump issue:

When you turn on the key, does the fuel pump pressure up? Check the shrader valve at the top of the fuel pump (looks like a tire valve) and see if there is pressure in the line while ignition is on. If you are not getting gas squirting out, your fuel pump is not powering up or quit working. Disconnect the fuel pump wires and test with a voltage meter to make sure that the pump is receiving power. If it is, it’s the pump, if its not, it’s a relay or ECM. I just replaced a 15.00 relay in mine, that cost me a half a day out on the lake. Hope this helps.

I do not have pressure at the shrader valve. I disconnected the fuel hose from the low pressure pump like mrbobolina suggested, but I'm not getting fuel. I also can’t hear the FCC cycle when the ignition is on.

[core-rider]

If you can't hear the fuel pump cycle when turning on the ignition then you need to get a voltage meter and make sure you even get power to the pumps. Don't waste a bunch of money replacing parts only to find out a breaker was tripped, relay is bad, or some other dumb thing.

Now to answer your original questions...
The first picture you attached is the low-pressure pump. The larger hose with the hose clamp at the bottom of the pic is the fuel supply from the tank. The smaller braided hose at the top of the pic is the supply line going from the low-pressure pump to the FCC. In your picture of the FCC, the hose you have removed is the line coming from the low-pressure pump to the FCC. The large hose with the hose clamp is the fuel return line going back to the tank. The 2 lines on top of the FCC leading to the fuel rails on top of the engine are the supply and return lines to the engine. The larger line being the supply and the smaller being the return.

The low-pressure pump pulls fuel from the tank and feeds it to the FCC. This is because high volume/high-pressure pumps do not pull well and since there is no good way for gravity the feed the FCC given it's mounting location the low-pressure pump is the best alternative. Once the fuel is in the FCC the high-pressure pump boosts the volume and pressure to adequate amounts to feed the engine. Any remaining fuel is returned through the fuel pressure regulator and back the the FCC where it will either go back the the tank via the return line or be recirculated back through the engine again.

You will have an electrical connection at both pumps. I don't know for certain, but I would assume you should have 12 VDC at those connections when the ignition is first turned on and the pumps cycle. Now also assuming you have proper voltage at the pumps, then I could assume your pump may be bad. The louder of the two pumps should be the one in the FCC (high-pressure pump). This would be the one you would hear where the ignition is cycled. I doubt both your pumps have gone bad at the same time, but I have seen stranger things happen.

[Shooter]

Great info Core! I should have picked up a tester before posting, but I thought they were expensive (only cost me 4 bucks). It looks like I'm not getting power. I guess I need to figure out if it’s the ECM, Relay or breaker. I assume the breaker would be under the helm (all of those look good). Still working on it.

[Shooter]

Where is the relay for the pumps located?

[Shooter]

It looks like there are three relays arranged like a triangle located on the top forward driver side of the engine. From what I can tell the ignition is left, starter is right and fuel pump is the forward relay. I tested all three relays on the starter line and each worked. It does not appear the Pump relay is getting power. What next?

[gmdattilo]

See the attached, it should help

I think that this drawing from a model year 2005 MEFI manual but it should give you a pretty good idea of how the relays and fuel pumps are wired.

When you first cycle the ignition on the pumps will only have power for about 2 seconds. This is the computer's attempt to prime the pumps. The pumps won't start running again until the computer sees pulses comming from the distributor (or crank sensor if you have DIS).

You can jump out the fuel pump relay to force the fuel pumps to run. Unplug the fuel pump relay and put a jumper wire in from terminal 30 to terminal 87. This should cause the pumps to run continously.

Before you do any of that make sure you check your circuit breaker and all 3 fuses at the engine. You can unplug the MEFI system relay and check for voltage at pin 30 (to ground) of the connector. If you dont have about 12.5V you need to look at the circuit breaker or the supply circuit from the battery.

[Shooter]

Thanks for the diagram. I see there is a "Fuel pump relay fuse 20A" just prior to the relay. Anyone know where that fuse is located and what it looks like?

[gmdattilo]

Fuses

All three fuses will be in one little holder that looks like an electrical connector with a cap on it. There will be wires coming in one side of the fuse holder. There is a weather proof cap that pulls off and there should be 3 fuses inside. It should be somewhere close to the relays and MEFI module.

[teamseal]

Hmm!!!! Not reading anywhere that you checked the Emergency cut off switch. The laynard that is supposed to be in place completing the circut for the pumps and ignition.
Did this get checked?

[Shooter]

The cut off laynard is in place and it looks like it is working. When I remove the laynard the gauges go dead.

[Shooter]

Booya!!! 20A fuse was blown. $2.00 part and I'm ready to ride. I knew it had to be something simple; I'm embarrassed I didn’t know those fuses were there. At least I'm much more educated incase I have fuel related issues in the future. Sooo happy, you guys rock!

[Shooter]

One last thing. Should I be concerned that this fuse blew in the first place? I notice the do not run over 1200 RPM warning light will not go out . All the temps look good though.

[core-rider]

One last thing. Should I be concerned that this fuse blew in the first place? I notice the do not run over 1200 RPM warning light will not go out . All the temps look good though.

That has to do with the v-drive fluid. Check the fluid level. That sensor works off pressure. If the pressure is too low the light will not go out. Glad to hear the fix was easy and didn't cost too much money. Diagnostics pays off... It's a lost art to some technicians.

[PHB]

Shooter, anymore problems from that fuse. Mine blew last year and now blows every time I try to start the boat this year. Any suggestions? Thanks.