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snivesatgt
01-03-2009, 01:08 PM
here are the symptoms on my 1988 Prostar 190.

The boat runs great for 2-3 hours of either skiing or wakeboarding. Doesn't have much issue starting (sometimes give it a little throttle when starting to get it some extra fuel) or running.

About 2-3 hours into the day (usually about 6 sets or so) the engine starts stalling and dying at speed. Often times when this occurs - it can then idle ok back to the dock but we often cut the day short (turning it off after this often makes us wait until it cools back off).

We have an electronic ignition with a new skidim coil on it. It has the Edelbrock carb with a metal and wood spacer. The fuel filters have been regularly replaced, and the fuel pump is about a year old.

From the feel of it, I want to think that it's a fuel issue - but I'm out of ideas. I was thinking that the fuel was vaporizing in the carb before it could reach the cylinders, but I really don't know if this is happening.

Right now there are technically 3 filters for fuel (thinking of getting rid of one). There is one right at the tank (the style that has the glass tube in it). there is the water/air seperator filter, and then there is the one in the fuel pump itself.

Does anybody have ideas - and how I would go about testing that part/theory (rather than just replacing everything - since that hasnt' been much luck for me).

Searching the site (which has helped quite a bit before) hasn't given me any great ideas on this issue (this time).

Thanks,
Ben

Cloaked
01-03-2009, 01:22 PM
How thick are the spacers?

I have experienced the vaporization with the 4160 carb and added the 1" plate. Took care of the problem.
(http://skidim.com/prodinfo.asp?number=R062075)


However a dying or stall is more likely to be a fuel starvation issue as you suspect. I'd remove the filter at the tank (and the anti-siphon valve at the tank) if it is eqiupied with one.

JimN
01-03-2009, 02:08 PM
here are the symptoms on my 1988 Prostar 190.

The boat runs great for 2-3 hours of either skiing or wakeboarding. Doesn't have much issue starting (sometimes give it a little throttle when starting to get it some extra fuel) or running.

About 2-3 hours into the day (usually about 6 sets or so) the engine starts stalling and dying at speed. Often times when this occurs - it can then idle ok back to the dock but we often cut the day short (turning it off after this often makes us wait until it cools back off).

We have an electronic ignition with a new skidim coil on it. It has the Edelbrock carb with a metal and wood spacer. The fuel filters have been regularly replaced, and the fuel pump is about a year old.

From the feel of it, I want to think that it's a fuel issue - but I'm out of ideas. I was thinking that the fuel was vaporizing in the carb before it could reach the cylinders, but I really don't know if this is happening.

Right now there are technically 3 filters for fuel (thinking of getting rid of one). There is one right at the tank (the style that has the glass tube in it). there is the water/air seperator filter, and then there is the one in the fuel pump itself.

Does anybody have ideas - and how I would go about testing that part/theory (rather than just replacing everything - since that hasnt' been much luck for me).

Searching the site (which has helped quite a bit before) hasn't given me any great ideas on this issue (this time).

Thanks,
Ben

Are the filters changed at one time, or is at least one of them much older? Get rid of the oldest one first. The first one (closest to the tank) needs to have the largest openings, then another at the carb that's maybe 50 microns. This will catch anything down to the size of water molecules.

Make sure the fuel line isn't being compressed, kinked, hasn't delaminated or is clogged. If necessary, when the motor starts to run weak, connect a fuel tank from an outboard and see if it runs. If not, it's caused by the fuel pump or something after it.

You may want to do a compression/cylinder and vacuum leakdown test.

As mentioned, the spacer may fix it but I would do the three tests just to have a baseline for the motor.

snivesatgt
01-03-2009, 05:29 PM
as always, thanks for the quick responses.

It actually has the built in spacer and than a 1 inch I added later on, which the problem persisted.

The odd part is that it only occurs when it gets hot after about 2-3 hours.

I'll try the recomendations and see what data I come up with.

Thanks,
Ben

JimN
01-03-2009, 06:27 PM
How much fuel is usually in the tank on a regular basis? If you don't fill it, you may have a weak fuel pump diaphragm and after the decrease in fuel level, the pump isn't able to overcome the added vacuum needed to pull the fuel out of the tank.

snivesatgt
01-04-2009, 01:54 PM
It always happens when it's greater than 1/2 tank, but definitely could be something that has to do with the pump.

the pump is about 1.5 years old - but we ski year round.

Thx,
Ben

Cloaked
01-04-2009, 02:55 PM
It always happens when it's greater than 1/2 tank, but definitely could be something that has to do with the pump.

the pump is about 1.5 years old - but we ski year round.

Thx,
BenMaybe, but even at year-round use, it should last a long time (as I have experienced the use of mechanical pumps).

Something is restricting the fuel at one point or another, unless another issue arises in the distribution of ignition from heat or wear failure.

I keep going back to the thoughts of my problem several years ago.

A filter may be collapsing, coil going bad, vapor-lock, electric fuel pump going south, low fuel level for an out-of-whack pick-up..........$hit-O-dear.... Just thinking outloud...

JimN
01-04-2009, 05:15 PM
It's a mechanical fuel pump and those last for decades. They're not sensitive to running out of gas, either. Check the whole fuel line, filter(s), anti-siphon valve, fuel pickup in the tank, look into the tank to make sure there's no debris being sucked up and if you find a slimy clear ooze, you'll need to clean the tank completely.