RE Fuel problem

[dbickford]

Well guys I have taken everything from your posts and still have come up short! I replaced the electric pump with a new 130 GPH pump from Jegs along with the matching filter, lowered the fuel selector,pump and filter so that gravity feed from the tanks would feed the pump. I set the regulator for 6 to 7 pounds to feed the 770 holley carb and still the pump ran dry when I opened the boat up! After this I tried to run the tanks seperatly strait through the pump with the same results:mad: I tried popping the top on each tank to see if the tanks needed venting! still the same results the pump holds pressure untill I get the boat up on plane then it looses pressure:mad: Last but not least I pulled the tanks out and they still had some crap in them but for the most part they were clean and the pick ups were not clogged in any way! I am at my wits end with this thing I think its posessed:reddevil: The boat is probanly pushing 70MPH which I would have never though it would go that fast! I just can't keep the fuel flowing to the carb. Anyone with any more thoughts? :mad::mad::mad::nonod:

[sunapeeboater]

Where is the pressure reading of the pump coming from suction side or discharge side?

[dbickford]

Its on the fuel rail going into the carb!

[dbickford]

Sorry I could have been more specific! the meter is on the fuel rail and on the discharge side. Sunapee boater thanks for the reply I just had to mention I have a brother that lives up there near you, he has a trailer set up near Wiers beach!:smiletest:

[Fonz69]

what type of carb are you using?

Was it checked after the stuff in the tanks was fixed?

the regulator is a return type right?

when you go full throttle how long does it last?

[sunapeeboater]

Thing that leads me away from the carb is the pressure is being lost before fuel gets to the carb. If the carb where plugged the pressure would increase. Still seems to me that there is a plug in a line before the fuel gage or a cracked pick up tube.

I love it over at wiers. My best freind lives right up the street out on govorners Island. You brother live there or just go in the summer?

[Duane HTP]

Take some type of fuel cell or small tank and install it directly before the fuel pump. If it still does the same thing, you have problems in the fuel pump, lines, filter, carb or something forward of the pump. If this solves the problem, you have trouble somewhere in the lines from the tank to the pump, pickups, venting problems of something behind the pump. If it runs okay with the test tank installed, unhook it at the pump and hook it to the fuel line that comes out of your tank. If it runs good then, it's in the tanks or pickups. If it doesn't run good like that, it's in the lines between the tank and the pump. I know it's a lot of trouble, but you've already had a lot of it. You just have to isolate one thing at a time.

[stvhelm]

Check the hose barb on the fuel tank. many boats have a check valve in this fitting to meet coast guard requirements. not much fuel can pass with a ball and spring in that thing.

[SS-201]

Go with a fuel return system fuel will flow constantly.

[dbickford]

Fonz69 the carb is a 770 holley brand new and yes both bowls were checked and cleaned! once I plane out the boat and throttle up it will run wide open for maybe 20 seconds. I'm not sure what you mean by return regulator but I will check into it! :rolleyes:Sunapeeboater I have replaced both pick ups which come out of the top of the tanks, I'm thinking like you that I'm not getting enough flow from the tanks to the pump! My brother has a summer trailer on the lake, he did live in Salem he moved to a town north of there I can't remember the name of it but he told me he was about 50 miles from the NH speedway! I'm a big time biker also and brother told me when ever I want too I can use the trailer for the wiers beach rally; Would love to make that one time, I heard it was a good time! Guys when I first put this motor in the boat it ran fine for the first two times I took it out! I've got both tanks cut out of the boat and both of them are clean; I think my next move is to try and get the in-tank pumps and sending units installed in both tanks or have the outflow nipple welded on the bottom of the tanks! Either way I'm thinking there's not enough flow from the tanks to keep up with the pump! Thanks again for the replies.:thumbsup:

[Duane HTP]

If you will hook up a test tank like I recommended, you will know if that is the problem real quick. You need to FIND the problem before you start spending money for "try it" parts. What size, (id), are the pick ups and lines from the tank? Welding the outlets in the bottom of the tanks is a dangerous way to go and aginst USCG regulations. Duane HTP

[dbickford]

Thanks DuaneHTP I didn't know that I guess if the external tank works I will go for the pumps in the tanks as I have allready spent a fortune on this problem alone!:mad:

[Fearless]

is it possible you're vapor locking it? where are the fuel lines running? next to anything hot? is the pickup in the tank near the rear? have you thought about using a baffled tank that sloshes less? are fuel cells a possibility?

[dbickford]

Fearless the pick ups are at the top of the rear of the tanks, and theres no way the fuel is boiling as the lines are no where near anything hot! after cutting the tanks from the boat I checked the tanks for baffels and they are in there! At the moment the tanks are out of the boat and I have flushed both of them and are being dried out!;) I am leaning towards the in-tank pumps as I believe the flow is not keeping up with the pump!:reddevil:Thanks for the reply and keep your fingers crossed!;)

[Fonz69]

return regulator is one that sends the fuel the carb does not need back to the fuel tanks and lets the fuel pump see fresh cool fuel at all times instead of the pump just spinning the unused fuel and heating up

Did you check the floats for proper height when in the boat?

Sounds like your just using up the fuel in the bowls when you hit the gas and it lasts for 20 seconds untill the fuel is all gone from them.

If you have the tanks out now anyway just do as Duane sugggested and strap a 5 gallon gas can in the back and stick a hose in it and see if the problem goes away. If that works then your problem is forward of the tanks

[Duane HTP]

Those intank pumps don't seem to last very long in a boat. I'd repair the problem before spending that much. PUT A TEST TANK IN AND RUN IT WHILE THE OTHER TANKS ARE OUT. WE WILL FIND THE PROBLEM! Duane HTP

[dbickford]

Yes we checked the floats and they are fine! the only problem with a can in the boat is that the pump is more for pushing rather than pulling but I'm at the end of my rope and willing to try anything at this point! Believe me guys this has been an ongoing thing for about two months and I'm about to wear out the trailer putting the boat in and out of the water! (Just Kidding) but its a good thing I live in Florida where I'm not far from water! again thanks to all for the replies!:thumbsup:

[Duane HTP]

One other remote possibility is that the needle and seats in the carburetor are not of the right size. Don't flow enough. Or the pull down tangs are not on the float properly and not letting the floats drop enough. But you need to isolate wheather the problem is before or after the pump next. If the above were the problems, it would not have run right the first time.

[sunapeeboater]

One other remote possibility is that the needle and seats in the carburetor are not of the right size. Don't flow enough. Or the pull down tangs are not on the float properly and not letting the floats drop enough. But you need to isolate wheather the problem is before or after the pump next. If the above were the problems, it would not have run right the first time.
If this were the case wouldnt he see high pressure on the fuel pump? I still think it is between the tanks and the pump. Its getting starved. fuel pressure drops. Says problem most likely is before the pump.

[Duane HTP]

That's what it sounds like. That's why I'm trying to get him to test it with another tank and sullpy line.

No, that would not cause much difference in fuel pressure if any. The relief spring in the pump is made to regulate what ever is put in front of it.

Duane HTP

[sunapeeboater]

That's what it sounds like. That's why I'm trying to get him to test it with another tank and sullpy line.

No, that would not cause much difference in fuel pressure if any. The relief spring in the pump is made to regulate what ever is put in front of it.

Duane HTP

What does this pump bypass within itself like a positive displacement pump does?
Ya I have to agree with you though either way. just the fact that the pressure drops tells you something in the suction side from the tank

[Propster]

See if you can remove the pick up tube from the tank.

Mine had a screen on the end of the tube and it was plugged up. Just a small pinhole in the gunk in the screen allowed the engine to idle, then it died when I got on plane. Also, replace the fuel line between the tank and the pump. If the fuel line deteriorates, it can act like a check valve and prevent fuel from getting to the pump.

[Duane HTP]

See if you can remove the pick up tube from the tank.

Read post # 10.

[SS-201]

You still need a return fuel system. It not only returns the fuel but it allows the need for fuel is supplied ex. if at any time the fuel demand is needed it will supply it. Go to a search and type in return fuel system.

[stvhelm]

Well guys I have taken everything from your posts and still have come up short! I replaced the electric pump with a new 130 GPH pump from Jegs along with the matching filter, lowered the fuel selector,pump and filter so that gravity feed from the tanks would feed the pump. I set the regulator for 6 to 7 pounds to feed the 770 holley carb and still the pump ran dry when I opened the boat up! After this I tried to run the tanks seperatly strait through the pump with the same results:mad: I tried popping the top on each tank to see if the tanks needed venting! still the same results the pump holds pressure untill I get the boat up on plane then it looses pressure:mad: Last but not least I pulled the tanks out and they still had some crap in them but for the most part they were clean and the pick ups were not clogged in any way! I am at my wits end with this thing I think its posessed:reddevil: The boat is probanly pushing 70MPH which I would have never though it would go that fast! I just can't keep the fuel flowing to the carb. Anyone with any more thoughts? :mad::mad::mad::nonod:

if youre pulling off the top of your tank there is no way youre going to gravity feed your pump. my guess is if you do not find a restriction in the line between the pump and the tanks pickup tube then there must be a air leak somewhere and the pump is loosing its prime. this often happens with bad a water seperator filter. if the rubber seal is not sealed it will leak air and the pump will get enough air to loose prime. recheck and seal up all the thread hose fittings between the pump and the pickup in the tank and double check the elbow and fitting on the tank to make sure there is no ball and spring in it.
I would do like other said. remove the line off the tank and just shove it in a gas can to rule out the motor

[Duane HTP]

if youre pulling off the top of your tank there is no way youre going to gravity feed your pump.

This would be true if the fuel pump is higher than the bottom of the tank or there was not a long enough pick up going down into the tank.

But, if the pump is below the tank or the fuel level, the siphon effect will gravity feed the pump, (unless you have an air leak). Very good point made about the air leak in the seperator! Duane HTP


I would do like other said. remove the line off the tank and just shove it in a gas can to rule out the motor