bad fuel pump?

[rkilpa]

1997 Volvo Penta 4.3GL PLKD. Engine started and ran for a few seconds. Will crank but will not start. Will start with starter fluid directly in the carb but dies immediately when fluid burns off so fuel delivery is the problem, right? I dont have my computer. Im on my phone. Where do I start?

 

[Silly Seville]

Re: bad fuel pump?

I am not familiar with your Volvo setup, but I'm assuming you have an electric fuel pump? Check it for operation. It would be an ignition relay controlled device that also requires a signal from an oil pressure switch to remain on after start-up. Check wiring to pump. Check relays and fuses. Check oil pressure switch/sending unit. If it's a mechanical pump, you may have a broken actuator rod or the camshaft lobe is worn down to a nubbin'. Check your water separator, is it full of H2O? Check fuel filters. Check fuel supply line for kinks. Check fuel line venting or return hose for obstruction/kinks. These are my first guesses off the top of my head, and in no particular order. And I have to ask, do you have sufficient fuel on board?

 

[Silly Seville]

Re: bad fuel pump?

edit double post

 

[tpenfield]

Re: bad fuel pump?

You are on the right track looking at the fuel. In addition to the pump, check the filter for water, etc. If it is an older filter, then maybe just replace it.

 

[rkilpa]

Re: bad fuel pump?

The fuel filter/water separator had fuel in it, but the level was an inch below the intake tube from the electric pump. I added fuel to the filter and added fuel directly into the carburetor and the engine started and continued to run. I assume the pump couldn?t prime before, but once it did everything worked.

What could cause the fuel level in the filter/water separator to go down so much? The engine sat for about a month since I last started it, but I?ve gone a lot longer between starts before. Is this a symptom of a failing component?

 

[Silly Seville]

Re: bad fuel pump?

I'm just taking a shot in the dark here, but it is possible with changes in barometric pressure (atmospheric) and fuel system venting to cause a virtual climate for evaporation of fuel from the filter/separator. You may also already be aware that some electric fuel pumps are not dry priming, thus if fuel is not present, flow will not start. Is your fuel supply line from the tank higher than your pump, and did you have a measurable quantity of fuel in tank?

 

[Don S]

Re: bad fuel pump?

It sounds to me like you have carb problems. If the fuel bowl drains out after a few days, you need to find out why, because it shouldn't.
The fuel pump should be running when you crank the engine with the starter, and should fill the carb, but it will take a bit of cranking to fill then start. Get the carb fixed, and you will probably fix your low fuel filter at the same time.

 

[NetDoc]

Re: bad fuel pump?

A typical 2 bbl Carb can evaporate about an ounce or an ounce and a half of fuel a day. Larger bowled carbs can evaporate even more. That's why its important to run that blower for five minutes before you try and start that engine. So, having to crank a lot if the engine has been sitting for a week or more is appropriate. My guess is that you have a bad fuel pump or a leak between the fuel pump and the gas tank. Let us know what it turns out to be.

 

[Don S]

Re: bad fuel pump?

A typical 2 bbl Carb can evaporate about an ounce or an ounce and a half of fuel a day.

How can that happen? Since the bowl is not open to the atmosphere, how can it evaporate out of the fuel bowl?

 

[NetDoc]

Re: bad fuel pump?

How can that happen? Since the bowl is not open to the atmosphere, how can it evaporate out of the fuel bowl?

Its not a perfectly closed system as there are all sorts of openings in a carburetor. Sure, they vent into the body (venturis) to keep the boat safe while underway, but what happens when the engine is not running? The vapor will find a way out! Fuel has a relentless vapor pressure that increases with temperature. IOW, the further south you live, the quicker it evaporates. Also, fuel changes about 1% in volume for every 15F change of temperature resulting in a very slight pumping effect. Here in the hot south, its not that unusual for a carb to completely dry up. I'm sure you don't have that problem in Washington. Still, its best to vent the engine compartment COMPLETELY before you start that puppy up!

 

[Don S]

Re: bad fuel pump?

OK, what ever you say ....... :facepalm:

To the original poster, I still think you have a leaky carb, since it's a 98 engine, and has probably been working fine for a number of years, I guess it's completely possible that the hot California weather has suddenly started evaporating your gas out of the carb.. Probably those extra evaporation chemicals used in the gas down there :facepalm:

 

[NetDoc]

Re: bad fuel pump?

I guess it's completely possible that the hot California weather has suddenly started evaporating your gas out of the carb..

Oy Don,

Condescension doesn't suit you. In fact, California was one of the first places to mandate Low RVP Gasoline. Evaporating gasoline is a real problem on boats as it's heavier than air and will accumulate in bilges. You can deny it all you want, but carb bowl evaporation starts when an engine is turned off. I know of some boaters here in Florida who have even installed a bypass switch to fill their carbs first, before they start to crank the engine.

However, as quick as this happens I think he has problems elsewhere. I certainly don't think he has a leaky carb since he has not complained about a strong smell of gasoline after he turns the engine off. As I stated at the beginning, its more likely a fuel delivery problem and very possibly a leak in the fuel line before the fuel separator. I think it was you who shared a link with a wonderfully logical method to diagnosing that kind of issue in another thread.

 

[rkilpa]

Re: bad fuel pump?

I think I just ran out of gas...

I pulled the boat from the garage to the driveway to run it on muffs to warm up the oil for an oil change. The incline of the driveway had the boat tilted bow downward. I know I had a little gas left from the previous outing but the gauge read empty with the bow tilted down.

I'm guessing that the fuel pickup is near the back of the gas tank and when the fuel in the line couldn't fill the filter/water separator it sucked the level in the filter down below the electric pump pickup and starved the engine.

Only after I put about 5 gallons of gas in the tank and filled the filter and the carburetor with gas would it run in the bow down position.

If only all repairs could be this simple...

 

[Maclin]

Re: bad fuel pump?

Sounds like it was a short between the seat and the ignition switch