M35 Fuel Pump

[SturmTyger380]

I was parts picking the other day but not for the M35. The guy had a M35 fuel pump laying on a shelf among some other parts. I asked him if the pump was good. It looks almost new with some shelf wear on it. He said take it and try it and if it works then pay me. We are good friends so I brought the pump home.

So I tested it outside the tank by quickly touching the power lead to the positive cable of this 24 volt battery lash up I keep to test stuff. I had the negative clamped to the ground point.

The pump sounded like a blender and made a rattle noise. I took the power off. Is this pump bad or is there a better way to test it?

Alan

 

[gimpyrobb]

Its hard to say with out being there. If its dry, I could see it being a bit noisy, but sounding like a blender- I dunno. Maybe try spraying it with some wd40 and trying again.

Noise is not good.

 

[welldigger]

Stick it in a bucket full of diesel. Any pump with an impeller will make some god awful noises when dry.

 

[rosco]

You have the motor part driving the pump part with a magnetic coupler. Because the motor runs, does not mean its pumping. So test it in fuel with a hose on it. Its worth the time. BE CAREFUL.

 

[clinto]

Make sure to point it where it's okay for lots of fuel to go.

Don't ask me how I figured this out.

 

[welldigger]

If its making a marble in a blender sound then that tells me the impeller is turning. I would be more concerned with the amp draw of the motor.

 

[JasonS]

Stick it in a bucket full of diesel. Any pump with an impeller will make some god awful noises when dry.

None of the new ones that I have purchased from ebay made anything but a whirring sound.

 

[welldigger]

None of the new ones that I have purchased from ebay made anything but a whirring sound.

Ok, maybe not every pump that uses an impeller. But its not uncommon for a dry pump with a floating impeller to make racket. When its dry the impeller will slap around in the housing. When there is fuel present in the housing it lubricates and stabilizes the impeller. I wouldn't be surprised if it quiets down after pumping some liquid.

 

[doghead]

No need to use fuel for testing.

Water would be fine.

 

[Floridianson]

No need to use fuel for testing.

Water would be fine.

I would use your Whale oil.

 

[doghead]

I've been thinning it with baby seal bone marrow, in this cold weather.

So far, so good!

 

[SturmTyger380]

Okay will do with some diesel. Maybe this weekend as we are getting ready for another dive in the temperature.

The M35 had a 10 am slow blow fuse in the line going to the current pump in the tank. The fuse was blown. A 10 amp seems high for a pump.

Alan

 

[gimpyrobb]

Yes, I wouldn't go over 7amp slow blow fuse.

 

[JCKnife]

Why fool with a questionable fuel pump when like-new ones can still be had for $50?

 

[SturmTyger380]

Good question. I got the friend discount but if there's a chance it is unreliable. Well.....

 

[SturmTyger380]

Well a bit of good news. Once it got above 30F outside we took the fuel pump assembly out of the tank. Found the hose disconnected at the top end. The pump looks brand new. We tested it and it ran fine so we put a new clamp on the hose. Once back in the tank we put a 7 amp slow blow fuse in. The M35 runs great and now has more power.

Alan

 

[olbucksnort]

If your doing the whirling sound check with Bad Hearing then what?
I installed a second tank on my Bobber and thought I herd the "Whirling" sound.
Now with full tank of Fuel I can't hear a thing. The #1 tank being transferred to doesn't show it's being filled.
There is 25.8 vdc going to the plug and the pump checks for good working ground but,
I'm wondering how many Ohm's the pump should show ?
Well " If something can go wrong it usually will"
So I'll drive around till something shakes loose (in the fuel pump pickup).
Glad to see everyone again next week at the Aberdeen Rally.

 

[olbucksnort]

Ahh Yea. No Pumpy da' Fuel. pulled the little block off plug behind the fuel output block. Na-da-ting.
Oh Kay time to find a replacement Pump or.... Wait for Murphy's Law to fade out.
I might try and prime the line w/ Trany Fluid just to see if that encourages it.
More than likely start hunting for a cheep replacement .

 

[gimpyrobb]

I have in-tank pumps, PM if interested. $50 plus the ride.

 

[rustystud]

Ahh Yea. No Pumpy da' Fuel. pulled the little block off plug behind the fuel output block. Na-da-ting.
Oh Kay time to find a replacement Pump or.... Wait for Murphy's Law to fade out.
I might try and prime the line w/ Trany Fluid just to see if that encourages it.
More than likely start hunting for a cheep replacement .

The fuel pumps do not need priming ! Take it out and look at it. It might just be a bad fuel hose. If it is get a "full immersion" diesel rated hose. Anything else will rot and you'll have the same problem again real soon.