Optimax Primer bulb Sucks in

[Don1938]

I have a 1998 150HP Optimax that when I run over 2500rpms the fuel primer bulb sucks in and the engine dies. The fuel tank is a 40 gallon built in. the entire fuel line has been replaced,the vent line replaced,the primer bulb replaced twice.and the fuel pump rebulit.The fuel fifter has also been replaced .Any ideas?

 

[199675hpforce]

Re: Optimax Primer bulb Sucks in

If the bulb is getting tight then dieing wouldnt the tank be the problem? Some have a filter before it goes inline might be worth a look, also is it venting properly.

 

[hkeiner]

Re: Optimax Primer bulb Sucks in

If nothing else solves your problem, you may want to check if the anti-siphon valve (located on the assembly where the hose attaches to the tank) is stuck closed or if the pickup tube screen (located inside the tank) is plugged.

 

[Don1938]

Re: Optimax Primer bulb Sucks in

Thanks for the reply. The tank has no screen and the anti-siphon is good. I also hooked up a portable tank and had the same problem.:

 

[hkeiner]

Re: Optimax Primer bulb Sucks in

Seems like you have a challenging situation to troubleshoot. The symptoms do point to a restriction in the fuel line upstream of the fuel pump. You seem to have replaced/checked the usual suspects. To troubleshoot further, you can consider using a vacuum gauge to both confirm that there is a restriction and to locate where it is. The below linked Service Advisory provides some guidance on this.

 

[Silvertip]

Re: Optimax Primer bulb Sucks in

If the primer bulb is getting sucked flat, the issue is between the bulb and and fuel pickup in the tank. It cannot be any other place. 1) make sure the bulb is installed in the right direction (as in arrow toward the engine). 2) if the bulb was an aftermarket, pitch it and buy OEM. 3) For testing purposes, remove the anti-siphon valve and replace it with a simple barb fitting from the plumbing dept of any home improvement store such as Lowes or Home Depot. 4) Remove the dip tube and check the pickup for debris. It may be the tank has crud at the bottom that clogs the screen. HOWEVER, if the problem occurs on a portable tank as well, you may have fuel lines that are too small for the job. If you are using the same fuel line on the portable tank as on the built-in, then the bulb becomes suspect. You are overlooking something in the hose/bulb/tank system.

 

[Don1938]

Re: Optimax Primer bulb Sucks in

Went back to square one. Pulled pickup tube from tank and found tube to be 9.5" long and tank is 8". tube was cut at a 60 degree and that angle must have been against the bottom of the tank. Shortened tube and motor runs great. I think there was a problem with the portable tank i used in a prior test. Many thanks to everyone for their help.