Fuel pump goes into high speed chatter when hot

[tome36]

Hello guys, was hoping someone has ran into this before. When the max gets up to temp and the fuel pump is hot as well, it starts hyper cycling and doesn't supply enough fuel to carbs to keep idling. This happens with fuel cap off and I checked filter is clear. Only happens when fuel pump is hot to the touch. Any ideas?

 

[tome36]

Forgot to add, the fast cycling sounds nothing like the normal quick cycle filling the carbs, it like a high speed chatter.

 

[Donny Daughtry]

Stock fuel pump with the mitsubishi stamp on the bottom?
Is it running constantly?

 

[sdt354]

The heat makes me think it's an internal electrical problem. Does it stop cycling and shut off, or keep running? Plenty of threads on it. I'd replace it, cheap enough on E-bay.
Steve

 

[tome36]

Yes, and yes. Just found in she shop manual how to ohm it out to verify it is in limits. It's factory 2001 with 26,000 miles on it so will replace it anyway before this long trip I have planned. Thanks for the response.

 

[Donny Daughtry]

Yes, and yes. Just found in she shop manual how to ohm it out to verify it is in limits. It's factory 2001 with 26,000 miles on it so will replace it anyway before this long trip I have planned. Thanks for the response.

It should shut off momentarily after filling the fuel bowls-as you ride it would then run again to keep supplying gas.
Running constantly means that the 2 rubber diaphragms have possibly flipped over and can be repaired by taking the 8 phillips screws out and turning the :clapping:diaphragms over and putting them back in their original position. There are threads on this and there is also low cost replacements on Ebay for around $17.00.

 

[Damon]

One other thing to check is the rear cylinder heat shield installed?

 

[Bill Seward]

My fuel pump lasted 130,000 miles before it failed. I replaced it with a twenty dollar EBay pump, and all is well. The new pump is a lot louder than the original. You will definitely hear it clicking..