Fuel Pump Issue (Urgent help!)

Simple test.....have him check the fuel pressure at the carb. That way you know in a minute if it is the fuel pump.

Leaking fuel out the carb is a major problem. No way should you have to keep the throttles wide open to re-start it. That is a carb problem.

Yes I am a Holley fan but the change over does require a few things to make it work. At a minimum you need to install a throttle control plate and possibly a converter to go from a square bore Holley carb to a spread bore manifold (if the carb is not a spread bore to begin with). Additionally you have to install a fuel rail to feed the Holley and tie it into the existing fuel line. If the Holley carb has a electric choke then that needs to be wired in as well. All in all it is worth the effort. Starts every time with no hassle or leaks.
 
PlayDate said:
Simple test.....have him check the fuel pressure at the carb. That way you know in a minute if it is the fuel pump.

Leaking fuel out the carb is a major problem. No way should you have to keep the throttles wide open to re-start it. That is a carb problem.

Yes I am a Holley fan but the change over does require a few things to make it work. At a minimum you need to install a throttle control plate and possibly a converter to go from a square bore Holley carb to a spread bore manifold (if the carb is not a spread bore to begin with). Additionally you have to install a fuel rail to feed the Holley and tie it into the existing fuel line. If the Holley carb has a electric choke then that needs to be wired in as well. All in all it is worth the effort. Starts every time with no hassle or leaks.
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Thanks for the info. Reason I am thinking it’s a fuel pump problem is because of this thread:
http://www.clubsearay.com/index.php?threads/engine-flooding-after-shutting-off-engine.31404/
 
That thread was about a mechanical fuel pump whose diaphragm had failed. The vent line from the fuel pump housing which normally holds air was full of fuel and it was dumping the excess into the carb. A mechanical pump only works while the engine is running and bleeds off very quickly when it isn't. Do you have fuel in the vent line?
 
PlayDate said:
That thread was about a mechanical fuel pump whose diaphragm had failed. The vent line from the fuel pump housing which normally holds air was full of fuel and it was dumping the excess into the carb. A mechanical pump only works while the engine is running and bleeds off very quickly when it isn't. Do you have fuel in the vent line?
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It’s hard to tell if there is fuel in it. It is literally always a yellow colour. I think that is where the gas could be leaking out of though?

Last night I drove the boat to the marina and then sat for 5 minutes and it restarted up fine… I hope they can replicate the problem and figure it out.
 
These are the notes i passed on to the mechanic:

The engine usually starts up fine on the first attempt with a bit of throttle. The engine is flooding on restarts after it is driven and sits for a while (30 min - 1 hour). On restarts, I have to put it in neutral and wide-open throttle in order to get it to try and start (it does not always start when I do this).

I have had fuel leak out beside the carb on the engine block and there is a strong smell of gas. Is the fuel coming from the yellow vent line?

Once the boat sits long enough and I can get it restarted, I need to take off fast or else it will bog down and not restart.

When I brought the boat back to the marina after the carb rebuild and tune-up, the needle valves/float were readjusted, but it is still flooding.

When I dropped off the boat last night, I restarted the engine multiple times and it was fine, but I only let the boat sit there for 10 minutes or so.
 
What you are describing is a classic issue on vintage carb Sea Rays. The original carbs leak down after running for a while (and getting hot)........then they become flooded and are difficult to restart.

They will restart properly all day starting and stopping it at a marina.

The "yellow" line is easy to check ......just pull it off at the fuel pump and see if any gas comes out.

My money is still on the carbs. While others defend them.....the original carbs were junk and required no end of monkey business to start a hot engine. My guess is that when those carbs get hot the tolerances change and they leak down which is why rebuilding them doesn't usually solve the problem for long. Holley's just don't have this problem by design.
 
I may have missed something, so apologies in advance if I'm covering the same territory...

Fuel should never be found outside the carb. If it is, then you have a leak. If the carb is leaking then perhaps the fuel bowl is empty when you try to restart, which leads to my next question - How do you know the problem is a "flooded" engine?

An engine hard to start/not starting after it has reached operating temperature and then shut down for a long enough period is a classic sign of vapor lock, which is when the heat causes the fuel in the line to evaporate, and the pump doesn't like pumping vapor. An easy way to check this is to remove the spark arrestor / filter to peer into the carb. Before starting but after a long enough time to cause the problem, pump the gas. If you see gas spray from the accelerator pump, you have gas available in the carb. If you don't see it, then either the gas has left the scene (possibly vaporized), or the accelerator circuit is clogged up.
 
PlayDate said:
What you are describing is a classic issue on vintage carb Sea Rays. The original carbs leak down after running for a while (and getting hot)........then they become flooded and are difficult to restart.

They will restart properly all day starting and stopping it at a marina.

The "yellow" line is easy to check ......just pull it off at the fuel pump and see if any gas comes out.

My money is still on the carbs. While others defend them.....the original carbs were junk and required no end of monkey business to start a hot engine. My guess is that when those carbs get hot the tolerances change and they leak down which is why rebuilding them doesn't usually solve the problem for long. Holley's just don't have this problem by design.
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So i should not get a new OEM carb if that is what they recommend, but instead ask for a Holley and the below items? The marina is a reputable one, but I feel like they do more work on newer boats and may not want to do the below... I am definitely one of the older boats in the shop...

- Install a throttle control plate and possibly a converter to go from a square bore Holley carb to a spread bore manifold (if the carb is not a spread bore to begin with).
- Install a fuel rail to feed the Holley and tie it into the existing fuel line.
- If the Holley carb has a electric choke then that needs to be wired in
 
BarryCF said:
I may have missed something, so apologies in advance if I'm covering the same territory...

Fuel should never be found outside the carb. If it is, then you have a leak. If the carb is leaking then perhaps the fuel bowl is empty when you try to restart, which leads to my next question - How do you know the problem is a "flooded" engine?

An engine hard to start/not starting after it has reached operating temperature and then shut down for a long enough period is a classic sign of vapor lock, which is when the heat causes the fuel in the line to evaporate, and the pump doesn't like pumping vapor. An easy way to check this is to remove the spark arrestor / filter to peer into the carb. Before starting but after a long enough time to cause the problem, pump the gas. If you see gas spray from the accelerator pump, you have gas available in the carb. If you don't see it, then either the gas has left the scene (possibly vaporized), or the accelerator circuit is clogged up.
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I am pretty sure the mechanic checked that when I brought it back. He got it up to operating temp and then was peering down the carb. He said he adjusted the needle seat, but i had the same issue eventually. I am not knowledgeable enough to know what to look for to be honest.
 
There are only two things that would cause fuel to get outside the carb... either the fuel pump is putting out too much pressure (which is VERY rare, but does happen), or the carb has a problem either with leaks or the float mechanism.

It's an easy test to check the pressure out of the fuel pump and unless that shows an issue, this is a CARB problem. Whoever rebuilt that probably didn't do a good job, but I wouldn't be surprised if that's the case, especially after reading that paragraph of "diagnosis and recommendations" listed earlier. I'd also suspect their compression measurements and want to have that test redone by someone competent to verify those numbers.

Holley carbs are great, but they have their foibles just like Rochesters. A good rebuilt Rochester would be fine on that engine as would a new replacement. A new replacement shouldn't cost anywhere near $1500 but less than 1/3 of that.
 
There are some important differences between a Holley Marine and Holley Automotive carburetor.
The first and most important is the fuel bowl vent tube - the Marine is shaped like a "J" so should the float/needle valve fail the overflow fuel is directed into the engine; the automotive is straight up and fuel will flow all over the carb.
The second is in the marine version there is an interface on the side for that mechanical fuel pump dump hose to interface so should the fuel pump diaphram fail the fuel is directed into the engine.
At one point I heard Holley had the throttle shafts O-Ring'd to prevent any fuel leakage around the throttle shafts but I think they dropped that early on due to cost.
There are other differences such as different calibrations on the economizer valve, and different cams on the acceleration pump. Carbs for OEM Mercruiser applications had specific fuel jet sizes and air bleed sizes.
 
ttmott said:
There are some important differences between a Holley Marine and Holley Automotive carburetor.
The first and most important is the fuel bowl vent tube - the Marine is shaped like a "J" so should the float/needle valve fail the overflow fuel is directed into the engine; the automotive is straight up and fuel will flow all over the carb.
The second is in the marine version there is an interface on the side for that mechanical fuel pump dump hose to interface so should the fuel pump diaphram fail the fuel is directed into the engine.
At one point I heard Holley had the throttle shafts O-Ring'd to prevent any fuel leakage around the throttle shafts but I think they dropped that early on due to cost.
There are other differences such as different calibrations on the economizer valve, and different cams on the acceleration pump. Carbs for OEM Mercruiser applications had specific fuel jet sizes and air bleed sizes.
Click to expand...

All basically true. The most important aspect on the Holley are the jet sizes for the primary and secondary metering blocks. Different acceleration pump cams really don’t have a profound effect on a boat.

Same goes for the power valve which I believe you refer to as an economizer valve.

Boats are always under load so they are actually easier to sort out than a race car.

Reading plugs used to be a dark science for tuning the jets. Today though that is easily accomplished with air fuel sensor.

Out of the box….a marine Holley will be on the rich side of the equation especially on a stock engine.
 
PlayDate said:
All basically true. The most important aspect on the Holley are the jet sizes for the primary and secondary metering blocks. Different acceleration pump cams really don’t have a profound effect on a boat.

Same goes for the power valve which I believe you refer to as an economizer valve.

Boats are always under load so they are actually easier to sort out than a race car.

Reading plugs used to be a dark science for tuning the jets. Today though that is easily accomplished with air fuel sensor.

Out of the box….a marine Holley will be on the rich side of the equation especially on a stock engine.
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I'm comparing the marine version to the road version that Holley produces with specifics on the Mercruiser OEM applications.
I agree the differences in the power valve (Holley calls it an "Economizer Valve"), the accelerator pump cam, and the air bleeds are incidental, but they are in fact different. If you bought an OEM carb from Mercury the calibrations are unique compared to one out of the box, obviously. As you say the jetting will be the most unique. We can talk all day long on jetting and how to get it right but the truth is 99.9% of those replacing the carbs including almost all shops do nothing to install the correct jetting.
As an edit almost all of the SBC based Mercruiser engines I've seen have 2bbl carbs - so only a single metering block. Correct me if I'm in error but all non FI BBC engines have 4bbl carbs.
 
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"all non FI BBC engines have 4bbl carbs."

You are correct. None of my Mercruiser manuals show a 2bbl on a BBC
 
muskokamarc said:
I am pretty sure the mechanic checked that when I brought it back. He got it up to operating temp and then was peering down the carb. He said he adjusted the needle seat, but i had the same issue eventually. I am not knowledgeable enough to know what to look for to be honest.
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Can't be done with the engine running. You have to check as I stated it, with engine off. It's easy to see. Either a stream of fuel squirts out when the throttle is operated or it doesn't. If it doesn't there is either a bad accel pump (diaphragm, clogged port) or there is no gas present indicating you have vapor lock or an issue in the carb causing the gas to leak out.

Your scenario fits this very closely.
 
BarryCF said:
Can't be done with the engine running. You have to check as I stated it, with engine off. It's easy to see. Either a stream of fuel squirts out when the throttle is operated or it doesn't. If it doesn't there is either a bad accel pump (diaphragm, clogged port) or there is no gas present indicating you have vapor lock or an issue in the carb causing the gas to leak out.

Your scenario fits this very closely.
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Sorry i should have specified, he would shut the boat off and peer down the carb.

If it is vapor lock, what is the resolution?
 
muskokamarc said:
Sorry i should have specified, he would shut the boat off and peer down the carb.

If it is vapor lock, what is the resolution?
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Vapor lock is rather rare on boats because they typically operate at lower temperatures. It's caused by heat, causing the fuel to "boil". Most mechanical pumps will not pump very well when liquid is not present. If that is the problem then you need to look at the routing of the fuel line and make sure it's not routed close to the hotter parts of the engine. On a car it would help to replace the mechanical pump with an electric, located further from the engine. The pump can then push the liquid and vapor through without an issue. You may already have an electric pump, which makes it less likely to be a case of vapor lock.

It seems related to heat soaking. When you shut the engine down heat begins to spread throughout. I've seen ignition components that fail when they get hot, gas evaporate from the fuel bowl in the carb, etc.

You can't shut the engine down and look as it is something that happens over time. That's why it fits your scenario - starts fine if you shut it off and then restart, but not 20-30 minutes later. Then fine again when it's been cold for quite some time. At least that's what I think you have said.

Earlier you seemed to think it was a "flooded" engine. Why did you think this? Could you smell gas? On cars that's a sign of flooding. On boats we hope the blower is getting any vapor out of the engine compartment.
 
BarryCF said:
Vapor lock is rather rare on boats because they typically operate at lower temperatures. It's caused by heat, causing the fuel to "boil". Most mechanical pumps will not pump very well when liquid is not present. If that is the problem then you need to look at the routing of the fuel line and make sure it's not routed close to the hotter parts of the engine. On a car it would help to replace the mechanical pump with an electric, located further from the engine. The pump can then push the liquid and vapor through without an issue. You may already have an electric pump, which makes it less likely to be a case of vapor lock.

It seems related to heat soaking. When you shut the engine down heat begins to spread throughout. I've seen ignition components that fail when they get hot, gas evaporate from the fuel bowl in the carb, etc.

You can't shut the engine down and look as it is something that happens over time. That's why it fits your scenario - starts fine if you shut it off and then restart, but not 20-30 minutes later. Then fine again when it's been cold for quite some time. At least that's what I think you have said.

Earlier you seemed to think it was a "flooded" engine. Why did you think this? Could you smell gas? On cars that's a sign of flooding. On boats we hope the blower is getting any vapor out of the engine compartment.
Click to expand...
I have seen gas once or twice now outside the carb when the engine was flooded. I am quite certain that when the non-start occurs, the engine is very hot.

The reason why i think it is a flooded engine is because I can get the boat started (roughly) when i put it in neutral and wide open throttle start it.
 
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muskokamarc said:
I have seen gas once or twice now outside the carb when the engine was flooded. I am quite certain that when the non-start occurs, the engine is very hot.

The reason why i think it is a flooded engine is because I can get the boat started (roughly) when i put it in neutral and wide open throttle start it.
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I may have missed the starting with wide open throttle, a classic way to clear a flooded engine. It runs rough for a few moments because of the raw gas present. It would help if we knew how, from where, the gas outside is coming from. That should never happen with a boat engine, any gas delivery issue should just dump down the carb. Is your fuel pump mechanical or electrical? Also, if you wait until the engine is cold does it start normally?
 
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