Takes a couple of turn overs before starting

[bharris6]

Have an 07 sante with a 330 excalibur and sometimes it will crank right up and sometimes ill push the start button and the motor will turn over but it wont start, sometimes ill have to do this 4 or 5 times before it starts. Once it starts the boat runs great. Ive search on here for similar problems but cant seem to find any quite like this. Could this be a potential bad fuel pump or just a clogged fuel filter?

[AirTool]

Possibly a stubborn fuel pump relay (one of two).

[bharris6]

Where would that be located?

[Mamigacz]

When you first turn the key to the run position (not start), the computor sends a signal to the fuel pump relay for approximately 5 seconds. This is the fuel priming function which makes starting faster. When the engine is turning over, the crank sensor tells the computor to signal the relay and send current to the fuel pumps. When you turn the key on (not start) do you hear the fuel pumps run for 5 seconds? If you hear the fuel pumps turn on the relay is not bad.

Gm usually uses two circuits for getting power to the fuel pump. The first is the signal from the computor that powers the relay. The other is the oil pressure switch. Even if your relay fails the oil pressure switch will still send current to the fuel pump. Unfortunately, the engine will lag in starting until the oil pressure builds up enough to close the oil pressure switch.

I know there is a low pressure fuel pump and a high pressure fuel pump. However, I'm not sure if one relay powers both pumps. Maybe someone else can clarify.

[DanielC]

One relay controlled both pumps on a GT-40, and I am pretty sure one relay controls on 10 or so year old GM engines. I am not sure on the latest throttle by wire engines.

[bharris6]

I know after I push the start button to turn on the electronics I here it prime and usually wait about 10 seconds to try to start her up.

[Mamigacz]

I know after I push the start button to turn on the electronics I here it prime and usually wait about 10 seconds to try to start her up.

I think that rules out the faulty relay. I would check fuel pressure next.

[AirTool]

When you first turn the key to the run position (not start), the computor sends a signal to the fuel pump relay for approximately 5 seconds. This is the fuel priming function which makes starting faster. When the engine is turning over, the crank sensor tells the computor to signal the relay and send current to the fuel pumps. When you turn the key on (not start) do you hear the fuel pumps run for 5 seconds? If you hear the fuel pumps turn on the relay is not bad.

Gm usually uses two circuits for getting power to the fuel pump. The first is the signal from the computor that powers the relay. The other is the oil pressure switch. Even if your relay fails the oil pressure switch will still send current to the fuel pump. Unfortunately, the engine will lag in starting until the oil pressure builds up enough to close the oil pressure switch.

I know there is a low pressure fuel pump and a high pressure fuel pump. However, I'm not sure if one relay powers both pumps. Maybe someone else can clarify.

This is the case for auto engines and the duration is 2 seconds.

I'm pretty sure...but not 100% that marine engine pumps do not come on until you press start. I've said before and will say again...one day I will confirm this.

On 5.7 Excalibur engines, there are two fuel pump relays

On the 6.0, I have heard there is only one relay...not 100% sure on this.

[Mamigacz]

Does anyone have any experience with a nonworking low pressure fuel pump? I'm curious what kind of symptoms happen when the low pressure pump does not supply fuel to the high pressure pump?

[mf01]

I had a low pressure fuel pump go out last year. I didn't have much trouble starting it when cold. When hot it had trouble starting. Eventually it got worse. I noticed it over 1.5 years. Finally on a hot summer day, it wouldn't start. Got it back home, checked the fuel pressure and it was low. The next morning it was cold, fuel pressure was up and it started fine.

[Mamigacz]

Here is what I would do:

-Check the fuel pressure. Note whether its low or out of spec.
-Verify if the low pressure pump is working or not.
-If the low pressure pump is not working, check to see if there is power to it when the engine is running.
-If there is not power to to the pump, check to see of the relay or fuse is faulty (if it has its own dedicated relay). It might be easiest to replace. However there are ways to check it.
-If there is power to the pump, and the pump is not working, it needs to be replaced.

If you don't know how to do any of these checks, respond back and I can give you proceedures. I don't own a boat like this, so I don't know where the low pressure fuel pump is located or the relay. Someone else might help you out with the locations.

[bharris6]

I will check these next weekend. If the boat runs fine when turned on, can the low fuel pump still be bad?

[mf01]

It could be going bad, but won't work if it is bad.

[Mamigacz]

bharris6: Just curious, did you figure out your problem?