Low fuel flow

[pjhmth]

Hi, recently changed my whole fuel line system. Had a heck of time starting it, until I continously depressed primer bulb.<br />Once started it runs fine but occasionally bogs out at high speed or quits all together at low speed. I replaced everything as original. Noticed when experiencing condition bulb is soft. What would be causing this? And if air in lines how would you go about purging. Engine is a 1987 Mariner 135 v-6

 

[kevlar3000]

Re: Low fuel flow

Did you clean or rebuild the carbs? Floats, ect... I just had air in my fuel line, v6 Merc. I had added an in line filter, I loosened my fuel line connection to the filter and pulled it almost, but not all the way off, I then pumped the bulb til a bit of fuel expelled itself and then attached everything again. Has been real good since.

 

[12Footer]

Re: Low fuel flow

Order a fuel pump rebuild kit, and rebuild it. The fact that you can manually pump fuel up and it runs better would indicate the carb(s) are not getting fuel. If possible, do a compression test too (no compression, no pump).<br />Hope you find the problem.

 

[pjhmth]

Re: Low fuel flow

Dear kevlar,12 footer:<br />All I did was replace fuel line and primer bulb. Prior to this motor did not experience this (though I do plan to rebuild fuel pump<br />in the near future) and did not starve for<br />lack of fuel. I have fuel line coming from tank going into a water seperator filter, then an inline filter, then the primer bulb. System has been like this for about 10 years with no issues. Also there is the factory installed inline filter under the motor cowl. Was wondering if two inline filters were perhaps restricting fuel flow.

 

[kevlar3000]

Re: Low fuel flow

I have two filters as well with no problems.<br />If all was normal before, I would have to think you have to have air coming in somewhere. There has also been the occasional bad primer pump sold too.<br /><br />It is frustrating when you are trying to help your engine and it messes up!!

 

[pjhmth]

Re: Low fuel flow

Kevlar,<br />Thanks for the tips. Just to clarify, I have a water seperator, an inline fuel filter, the primer bulb then the mariner inline fuel filter installed under the cowl. This has been the same setup for about 10 years and was working fine until I replaced all of the above. Now the primer bulb does not stay hard and the engine starves for fuel. I also think there is air in the lines (also gonna try putting the old primer bulb back in). Will the air eventually purge out on it's own?

 

[12Footer]

Re: Low fuel flow

Ok, we are on the same page now. As Kevlar3K says, the priomer ball is prime suspect. There are thousands of totally defective primer balls in blister packs at the boat store. I have run-into 2 personally. Also,check for minute air leaks at all the fuel line connections. A leak the size of a pin is enough to drive you buggy on the water.<br />Seeins how these are the only changes you made, that leaves only those two possabilities.<br />Let us know what u find.

 

[gfpk]

Re: Low fuel flow

If it is not the primer bulb, you may want to check your air vent to the gas tank.

 

[pjhmth]

Re: Low fuel flow

Thanks for your help guys. Just picked up fuel pump and rebuilt kit. Have to water test it now. Brought original bulb with me just in case and tightened up all fuel connections again.

 

[kevlar3000]

Re: Low fuel flow

Also make sure the cuts you made in your Fuel line are strait and really clean, a sloppy cut can lend to air problems. I hope it works!!

 

[pjhmth]

Re: Low fuel flow

Rebuilt fuel pump performs like brand new. Thanks!!

 

[GUMBY]

Re: Low fuel flow

pjhmth,<br /> Thats rather rude of you!!!