Electric fuel pump, Relay or anti siphon?

[kneedragger]

Ok,

I have a 94 4.3 L Alpha one Mercruiser with an electric fuel pump, and a four barrel carb. It has a fuel water seperator mounted about even with crankshaft pulley on the motor(down low), just up stream from the pump.

After sitting for more than 12 hours or after a small trip on the trailer, it is very hard to start. Even if I pump the throttle mentioned in the starting proceedure. The motor turns over fine, and I can hear the fuel pump running after it has been turned over a couple of revolutions. The fuel pump will not "run" when the key is first turned to the ignition position, it has to turn over a couple of revolutions , before kicking on, is it supposed to run when the ignition is on?

It will start and run for a short period of time if pour a little gas in the throught of the carb, but it not stay running. I have removed the hard line from the carb, and noticed that when the fuel pump is "running", it is not pumping fuel.(I know I am being very careful with the flamable conditions)

What I have discovered is, that if I remove my hard fuel line from the carb, and connect a hose, with a funnel, and pour a little fuel into the line and "prime the pump" from the top down, and then reconnect the hard line, it will run fine, and idle fine all day long as if nothing is wrong. Once it has its "morning coffee", it does fine.

I have read this thread http://forums.iboats.com/showthread.php?t=315482&highlight=electric+fuel+pump

and I know my oil pressure switch is working because my oil pressure guage is operating fine. Is there a possibility that a wire is

Could it be my fuel ant-sipon plunger on my tank? Is my fuel pump bad?

Thanks so much in advance!!

 

[180shabah]

Re: Electric fuel pump, Relay or anti siphon?

You have one, two or all three of the followng:

1. Weber carb is "draining" into the intake manifold, leaving the fuel bowls empty.
2. AS valve is obstructed and not closing fully
3. you fuel pump is giving you advance notice, that it is dying.

If you go up to the adults only section - you can get the REAL mrec manual for your engine. There is also a fuel system tutorial there that will be helpful.
If you need the weber carb suppliment PM me with your email - I'll send it to you.

There is no "fix" for the weber draining issue - but there is a work around we can discuss after you verify your AS valve and pump are opperating properly.

 

[Don S]

Re: Electric fuel pump, Relay or anti siphon?

and I know my oil pressure switch is working because my oil pressure guage is operating fine.

Your gauge has nothing to do with the oil pressure switch that controls the fuel pump.
If you have the wire off the starter solenoid that goes the the oil pressure switch, the pump will not run till you get the engine started.

 

[kneedragger]

Re: Electric fuel pump, Relay or anti siphon?

If you have the wire off the starter solenoid that goes the the oil pressure switch, the pump will not run till you get the engine started.

Don s Thanks for the post. One question. When is the pump supposed to run at start up? After a couple of revolutions trying to start, or immediately after the key is turned "on" to the ignition position?

From your statement above it is after a couple of revolutions, Correct?

 

[kneedragger]

Re: Electric fuel pump, Relay or anti siphon?

There is no "fix" for the weber draining issue - but there is a work around we can discuss after you verify your AS valve and pump are opperating properly.

180 Shabah,

Thanks for the response, the Weber Draining issue on my four barrel is something I had not heard of, and is new to me. I will research in Adults only heading as mentioned.

One question. The AS valve is very straight forward. However, is there a test I can perform on my pump to determine if is bad, not performing the way it should? BTW I do have the complete Mercuiser manual from a PDF online.

Once again, once I prime the hard line in the morning, I have no trouble the rest of the day with starts and stops. Even 3 to 5 hours between starts.

Thanks again for the help.

 

[180shabah]

Re: Electric fuel pump, Relay or anti siphon?

The fuel system tests in adults only are a great start, bu they won't tell you if fuel is draining backwards through your pump while not running or if the pump runs every time power is applied to it.

I tested my pump three time, the first two it was perfect. Third test happened two days later and it would not run - replaced it and the AS valve (redicualous amount gunk in it) and added a momentary switch to fill the carb in the morning, I have been starting on the first try ever since.

 

[bruceb58]

Re: Electric fuel pump, Relay or anti siphon?

Have someone pump the throttle and see if you are getting two healthy squirts of fuel into the carb. I had a similar problem with a Weber that needed to be cleaned out.

 

[kneedragger]

Re: Electric fuel pump, Relay or anti siphon?

Have someone pump the throttle and see if you are getting two healthy squirts of fuel into the carb. I had a similar problem with a Weber that needed to be cleaned out.

Bruce,

First thing in the morning, I am not getting any fuel to the carb. I have disconnected the hard line at the carb, and I am not getting any flow.

Thanks for the post though!!

 

[kneedragger]

Re: Electric fuel pump, Relay or anti siphon?

The fuel system tests in adults only are a great start, bu they won't tell you if fuel is draining backwards through your pump while not running or if the pump runs every time power is applied to it.

.

I have read that thread, and it seems to me that I could have the same issues that you had. I guess an electric pump could be only performing a little. I sort of thought it was all or nothing, since it is mechanical pump operating electrically.

BTW, How is the Holley 4 barrel float bowl drain preventable? However, I think I have more of a supply problem.

Thanks for the help to all!!

Scott

 

[kneedragger]

Re: Electric fuel pump, Relay or anti siphon?

I hate threads with out closure. So, here goes. I wound up replacing my fuel pump, and it worked great afterwards.

Still just a little hard to start, when cold, but it made a huge difference.

 

[Don S]

Re: Electric fuel pump, Relay or anti siphon?

Thanks for posting the outcome. Glad it works for you.

 

[Bondo]

Re: Electric fuel pump, Relay or anti siphon?

I hate threads with out closure.

Ayuh,... Ditto,... Thanks for this 1,+ the other up-dates...

 

[21Rinker]

Re: Electric fuel pump, Relay or anti siphon?

Your gauge has nothing to do with the oil pressure switch that controls the fuel pump.
If you have the wire off the starter solenoid that goes the the oil pressure switch, the pump will not run till you get the engine started.

Don S,

I am having the same problem as Kneedragger. My boat will not start on a cold start unless I spray Ether down the carb. once running, everything is fine. I do have this wire from the solenoid and checked to see if I have power at the fuel pump when cranking. I do have power. However, per your quote above, how does the pump prime then? I thought my pump was bad because no fuel comes out during cranking, only when running. Any help appreciated.

Thanks

 

[bruceb58]

Re: Electric fuel pump, Relay or anti siphon?

You should start your own post.