Tuthill diesel pump problems

[jcummins]

Had this pump for about 1 1/2 years, pumping from truck aux tank to mower, gator, tractor. Hasn't really pumped that much either. Worked great....until today. Runs, just stopped pumping. I'd use maybe a week ago, worked fine.

Took it apart limitedly, don't see issues. Checked the drawing line...no cracks etc. Tried to pull diesel from mower to gator, when I immersed the hose deeper into diesel. Testing suction directly at the pump with my finger, there simply isn't any.

Here's the pump and the inside...little white plastic pieces easyily pull out, don't look damaged. Didn't take it apart any further. To me the inside looks fine. Somebody tell me what's wrong and how to fix.

 

[Wyobuckaroo]

Hmmmmm..... If you run the pump and there is no suction, I got to think it is an air leak somewhere....

Can you immerse the suction end in a 5 gallon container of fuel... Wrap a rag around the opening and add a little compressed air to the container so it can get fuel to the pump.... If it pumps OK then shut off pump... Try to restart the pump... If it quits pumping on it's own, or won't restart pumping, I suspect air leak on the suction.... If there isn't a check on the discharge, plug the suction end of the hose, immerse the suction in fuel and again, wrap a rag around the discharge and put compressed air backwards through the pump to see if there are bubbles...

Are those pump veins spring loaded to seal against the pump body wall ?? If so, are they keeping the veins tight there... ??

Bound to be something simple, just not easy to diagnose.....

Good luck...

 

[nc redneck]

Try priming it.

 

[jcummins]

Try priming it.

I thought about doing that, but this pump is self priming...and I always flush the pump before pulling from the aux tank to avoid the diesel mess....but I will try that. If it has lost its self priming capabilities....I'll need to change my setup somehow.

 

[Lothar Schmitz]

The 5 blades seem to be made of Nylon and may have absorbed Diesel over time and swolen slightly. If so they will seal better inside the rotor slots and a higher vacuum will be created underneath the blades stopping the blades from maintining contact with the pump body bore. If that is the case the pump will not self prime anymore or even stop pumping altogether even when primed. To overcome this problem the 5 blades should have some grooves on their leading face connecting the cavity underneath the blades with the pumping chamber to allow Diesel to flow freely underneath the blades and thus preventing a vacuum.
A less likely cause could be if the pump is running too slow.

 

[jcummins]

I agree the blades are of nylon. They move freely in the slots, centrifugal force pushes them out, there are no springs etc. They don't seem swollen. The grooves you mention are built into the blades. To me...everything 'looks' normal.

BUT...I did what redneck said, I primed it (messy) and got it to pump. The way I use this pump, I simply push the inlet hose into the aux tank, and the pump self primes. I lose the prime after every use. SOO....I'm thinking I need to change my setup and discontinue coming from the truck. I've seen setups on this forum using the same pump I have using those blue barrels. That way I won't lose the prime after each use.

Is it normal after a low usage of this pump for 1 1/2 years to do this?

 

[Gary Fowler]

I would look at the little white plastic vanes. If those are really free enough to slide out. In the photo, 3 of them should be out next to the pump side wall but are still in the impeller part. Remove them and check for any little pieces of grit that may be producing some friction. If the impeller is turning, and those vanes are moving, it should pump.

 

[Gary Fowler]

It also looks like your rubber O-ring is bad. Replace that also. I would think that they make a repair kit for those pumps to include the vanes and O-rings.

 

[Lothar Schmitz]

I agree the blades are of nylon. They move freely in the slots, centrifugal force pushes them out, there are no springs etc. They don't seem swollen. The grooves you mention are built into the blades. To me...everything 'looks' normal.

BUT...I did what redneck said, I primed it (messy) and got it to pump. The way I use this pump, I simply push the inlet hose into the aux tank, and the pump self primes. I lose the prime after every use. SOO....I'm thinking I need to change my setup and discontinue coming from the truck. I've seen setups on this forum using the same pump I have using those blue barrels. That way I won't lose the prime after each use.

Is it normal after a low usage of this pump for 1 1/2 years to do this?

From what you say there is no doubt that there is an air leak. This is not likely to be in the suction pipework because you would have noticed it. The blade tips have hardly worn looking at the photo, so there is no problem. My guess is the blades have worn lengthwise and this will reduce the required vacuum at the suction side and stop the pump from priming. If this is the case, then a new set of blades would solve your problem for another 1 1/2 years. Very little extra blade clearance will loose you your vacuum. If there are some abrasive impurities in the Diesel I would consider fitting an inlet filter. If a check valve in your inlet pipework would not interfere with your mode of operation I would fit one; that would keep your pump flooded. Ask the manufacturer what the axial blade clearance in a new pump is and then measure your blades and compare. Every thousands of an inch counts.
It is not the 1 1/2 year usage that matters, rather how many hours the pump has run. From my experience this type of pump will see some priming loss after 1000 hours running on low viscosity liquids containing no abrasive particles.

 

[nc redneck]

I have the same pump with less than 4 hours of use. I dont think it can self prime at much over 6 to 12 inches. First start up they probably have 90 weight gear oil in it and it self primes. After that you are on your own. It is a cheap $ 100.00 dollar pump. If you can get supply to gravity feed into it, it will work well and probably for a long time.
Thanks
Scott