Converted to electric fuel pump problems

[big_b]

I have converted my 1977 deck boat with a AQ130D motor to an electric fuel pump due to my mechanical one breaking.

I have it all hooked up and it starts but if I give it any throttle it will die due to no fuel getting to the carbs .. If I goose the throttle fuel comes out very well out of both carbs and it will run well for a little while then it will die down and barely idle...

It was running great before my mechanical fuel pump went bad...

I bought the low pressure pump 3-5.5 PSI .... I thought maybe it was not giving the boat enough fuel so I bough the high pressure one and tried it tonight ...

It starves for fuel when going from idle ..

DOes the carb need adjusted after the change to a electric fuel pump ?


I am lost on this one !

 

[boat127]

Re: Converted to electric fuel pump problems

is it a marine rated pump? how many fuel filters do you have installed. any loose hose clamps or fuel connections will suck air and cause starvation for fuel

 

[cooter2506]

Re: Converted to electric fuel pump problems

What was the problem with the old mechanical pump? Same issue?

 

[big_b]

Re: Converted to electric fuel pump problems

The old mech fuel pumps' arm fell out and broke due to the screw vibrating out ... It was running great before that..

I did notice the check valve on the tank was preventing fuel from going through a little .. so I removed that and placed a "nipple" on it without a check valve ..

The fuel pump I have is a low pressure Cater fuel pump marine rated.. I bypassed the filters and ran directly to the carbs .. it idles fine .. when I rev it up to say 2500 RPM and hold it there it will slow down then come back up ..

IF I do a high rev say 4000 .. it will run great then when it omes down to idle it will drop to like around 300-400 RPM then die or sometimes come back up but the idle never sits still ... Nothing has changed on boat except for the fuel pump ...

It is really hard to bring it from idle to say 1500-2000 RPM .. you can hear the air sucking and no fuel being delivered .. If I goose the throttle some the fuel will come out of both carbs nicely .... at idle the carbs shoot fuel out with throttle just off idle too ...


I am confused .. I did just order a used replacement mech fuel pump on ebay but I want to figure out the electric one..

Also I have replaced all fittings and hoses ..

SHould I use any sealent on the fittings ? THe fuel pump manual said not to but it seems like I should..

 

[big_b]

Re: Converted to electric fuel pump problems

Any ideas ?

Is the pick up tube in the tank come out with the fuel valve on the tank ?


Thanks,

 

[big_b]

Re: Converted to electric fuel pump problems

I also have the electric pump placed right at the location of the old mechanical pump.. I wonder if I move it close to the tank or even mount on the tank if it would help..


I guess electric pumps push better than pull ?

 

[bruceb58]

Re: Converted to electric fuel pump problems

If you are using an electric fuel pump, you also need to wire it up so that it only comes on when you have oil pressure or when you are cranking. Have you done that? Removing the anti-siphon valve from the tank is also a safety no-no.

You should just replace your mechanical fuel pump.

 

[big_b]

Re: Converted to electric fuel pump problems

I ordered a mechanical used pump off ebay so that will be my backup plan I guess....

I removed the check valve (has a ball in it) just to see if that was preventing fuel from moving from the tank ...

I have a oil pressure switch already wired up and all that works ...

I called the Carter tech support and they said I need to mount the fule pump using 18 inches or less of line from the tank .. I have 3 feet so it was not able to pull that much fuel.. They push better than pull ...

They said I should mount to tank and try again ..


The advantage of the electric pump is that it is cheaper to replace if it fails...


So you saying the mechanical pump would be mroe reliable ?

 

[Fishermark]

Re: Converted to electric fuel pump problems

I called the Carter tech support and they said I need to mount the fule pump using 18 inches or less of line from the tank .. I have 3 feet so it was not able to pull that much fuel.. They push better than pull ...

They said I should mount to tank and try again ..

Here's what the Coast Guard regs say regarding the placement of the pump:

Each fuel pump must be on the engine it serves or within 12 inches of the engine, unless it is a fuel pump used to transfer fuel between tanks.

Read more: http://cfr.vlex.com/vid/183-566-fuel-pumps-placement-19764357#ixzz0osPnmqzT

 

[big_b]

Re: Converted to electric fuel pump problems

Why do the sale the low pressure fuel pumps then? I understand about the uscg regs but that is near impossible when you have to mount fuel filters and such.


I guess I can mount it next to the fuel filter about a foot from the motor and run 6 inches of line to tank and try.


Should i be able to pull tge valve off the tank and the pickup line come out with it? The valve just screws on

 

[bruceb58]

Re: Converted to electric fuel pump problems

Is this a marine fuel pump?

 

[big_b]

Re: Converted to electric fuel pump problems

Yes, it is a marine approved pump made by Carter.

I bought it from Marine Engineering.com

 

[big_b]

Re: Converted to electric fuel pump problems

I moved the pump closer to the tank and the throttle response is much better but after a "high" the idle drops way low and dies alot of the time..

I cannot find anywhere that that is leaking air in the fuel line ..

Should I look at the pickup in the tank ?
Or does it still sound like it has a fuel starvation problem ?

I am using 5/16" fuel line ... Is that enough for this motor ?

It is hard to believe the mechanical pump would be able to pull that much more fuel than this electric..


WOuld the carbs need adjusted at all after switching to a electric fuel pump ?

THanks

 

[big_b]

Re: Converted to electric fuel pump problems

I opened up the carb screws and it runs alot better. It still idles rough below 1000 rpm. I think have the screws opened to much because it is blowing a nice puff of grey smoke. It's done that before when flooded it.

So maybe it has to much fuel pressure ?

 

[lime4x4]

Re: Converted to electric fuel pump problems

most carbs feed pipes are 3/8. That might be your problem. When i installed my electric pump they had 2 models 5/16 or 3/8. I used 3/8th cause that was the line size from the gas tank and carb

 

[big_b]

Re: Converted to electric fuel pump problems

I think I am getting somewhere ...

I reset the carbs to about 2 turns out from fully screwed in..

It no longer smokes and has good throttle response now .. There is a very little bit of hesitation now and sometimes after I do a high rev and drop to idle quicly it will idle down but not die and usually return to about 1,100 RPM idle and hold steady...


Sounds like I just need to adjust the carbs some more now ... Any tips on how to do that ?

Think I had to add more fuel to the carbs because the electric pump had more pressure that the mechanical ?


I also have it running through my water spe/fuel filter and oil cutoff switch ...

seems to be doing alot better ... I am just glad the smoke went away !


You guys think I am heading in the correct direction ? It stills idles a little (very little) rough and sounds a little different than it used to

Iam thinkning maybe I need to change my plugs too by now ... I am sure me playing around with them I have fouled them up some .. (they are black)


Thanks !

 

[PiratePast40]

Re: Converted to electric fuel pump problems

It's going to idle a little higher without any back pressure.

I turn the idle mixture screws in a quarter turn at a time until it begins to stumble and then back off. Or, turn them out until it doesn't improve the smoothness. Then play with the idle speed screws until they're at the same setting. One will lead until you get them set the same. Blip the throttle once in awhile to get the linkage to settle in.

Sounds like you're doing great.

 

[big_b]

Re: Converted to electric fuel pump problems

Thanks for the advice .. SHe is running really well now and is dropping and holding steady at 1,100 RPM and running smooth after high revs ..

I am going to take it to Brookville Lake in the next day or two and hopefully make it back to the ramp under it's own power this time...

Just in-case I did buy 2 deep cycle optima marine batteries for my trolling motor.. It's only a 30lb thrust Minn Kota but it moves the boat about 1.5 MPH on full speed against the wind .. so it will get me somewher if I need it


I may look into re-building the motor next year ... I think it has some life left in her still yet though ..

 

[bruceb58]

Re: Converted to electric fuel pump problems

What carbs do you have on that engine? Are you sure you are adjusting idle mixture screws because that should gave zero affect other than idle.