Fuel delivery issues

[duppie03]

Since having Ethonol fuel destroy my fiberglass fuel tank I have been running external tanks. I'm running a 1991 Johnson 150, and the tanks work great while cruising however when Im at WOT the tanks can't keep up, and either the motor dies or one of my buddies has to pump the bulb to keep us going.

Anyone have any suggestions, or know of any modifications I can make so the tanks can keep up? The tanks are just temporary till February when the floor is being cut out and new tank is installed.

Thanks for your help with this.

Aaron

 

[bktheking]

Re: Fuel delivery issues

The tanks should work fine, there is no pump in them so i'm not sure what you mean. Are you opening the vent on the tanks? If you are, you might be looking at more of a pump issue than a tank issue.

External tanks should have a vent in the cap, you need to open it. The issue would not exist with the built in tank, they are self venting with a seperate line usually.

 

[bankerjohn]

Re: Fuel delivery issues

I assume you're running new portable tanks with new hoses and primer bulbs?

Have you checked the filter in your fuel pump?

BTW, it's always a good idea to list the model number of your motor when you post a question.

Welcome to iBoats!

 

[duppie03]

Re: Fuel delivery issues

Thanks for the response.

Sorry my motor is a 1991 Johnson GT150 V6.

Yes I am running new lines and primer bulb, and the motor ran fine with the original tank. I also checked to make sure the vent on the tank was open.

Is there a possibility that I am sucking air at one of the connectors, and that's causing my problem? I've never had an issue with portable tanks before.

Thanks for all the help.

Aaron

 

[bktheking]

Re: Fuel delivery issues

Pretty easy to tell, if you pumped the primer bulb it would puke fuel everywhere if it weren't a sealed connection.

 

[bktheking]

Re: Fuel delivery issues

This thing has a VRO2 pump and an inline fuel filter, when was the last time the filter was changed?

 

[duppie03]

Re: Fuel delivery issues

I don't know when it was last changed, but I will check that out this weekend, when I go to work on it.

 

[bktheking]

Re: Fuel delivery issues

No problem, if the filters even a little plugged up they will starve the motor of fuel at top end.

 

[rolmops]

Re: Fuel delivery issues

If all else fails,you can try a different hose.
Tempo used to have 2 sizes of fuel supply hose and the large one was specially made for large engines with high fuel consumption.I use a large one on my big old mercury and ever since I started using it, all the top end trouble stopped.

 

[CharlieB]

Re: Fuel delivery issues

Aftermarket fuel fittings and primer bulbs are always suspect on most engines over 115.

Most of us here highly recommend Factory primers and fittings to solve WOT leaning problems.

If the primer bulb outlet fitting or the quick connect on the line to the motor are restrictive, then squeezing the primer bulb (pressurizing those fittings) reduces the suction demand on the fuel pump, and allows the greater fuel flow.

As a test, disconnect the fuel line from the fuel pump and route it into a suitable container, crank the motor for 15 seconds measuring the volume of fuel delivered and observe the strength of the fuel pulse/flow.

Replace the primer line with straight hose from the tank to the carbs. Start and run the motor at a fast idle to be sure all air is bled out of your temporary fuel supply line.

Again, test fuel delivery after the fuel pump to make a visual comparison of fuel delivery pulse, flow, and volume.

If noticable greater then go get that Factory fuel primer and fittings.

 

[emdsapmgr]

Re: Fuel delivery issues

Are you running a 3/8" fuel line on the new tanks? All V6 and high hp V4's need the 3/8" fuel line from the tank. Best to run the black rubber (factory type) hose-I've seen internal malfunctions/delaminations/restrictions on the silver/grey 3/8" hoses that some aftermarket companies use. In case the tank vent is not working properly, unscrew the cap slightly to improve venting and see if that makes a difference at WOT.

 

[kenmyfam]

Re: Fuel delivery issues

Agree with the bigger bore fuel lines being needed.

 

[duppie03]

Re: Fuel delivery issues

I am usinr the 3/8 line, however I got a universal bulb because that was all they had. Saturday I will head to the lake and put OEM bulb on and try cracking the fuel cap.

Thank you everyone for your help.

Aaron

 

[emdsapmgr]

Re: Fuel delivery issues

Hopefully, you got a new hose bulb which has the 3/8" hose barb fittings. If it is the one with 5/16" fittings, it is the wrong one.

 

[kenmyfam]

Re: Fuel delivery issues

The cheap and cheerful universal bulbs seem to work better when they are vertical.
And of course the arrow is in the correct direction.