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

 

[sodamo]

Is there a relief valve? Remember reading some place the they sometimes cause a problem.

David Sent from my iPad Air using TractorByNet

 

[Redneck in training]

I also have the same or very similar pump. It primes easily 2.5 ft in diesel. The vanes are pushed out of the rotor by pressure in front of the vane through the groove. Therefore it is important to install the vanes in the rotor correctly. The groove has to be on high pressure side. Only thing I can think off is (assuming it has 12V DC motor) if the motor has permanent magnet stator polarity of applied power maters. Make sure it is rotation in correct direction.

 

[Lothar Schmitz]

Scott writes it is a cheap $100 pump, which tells me it is only a very small pump. The smaller vane pumps are, the more sensitive they are against internal clearances and 6 to 12 inches suction head is probably the maximum you can achieve with Diesel. As Scott writes when new and wetted with high viscosity gear oil it will prime a lot better.
Also the priming performance is heavily dependant on the rotor speed. The FR1612 pump has a 12 Volt DC motor. Check the battery voltage when the pump is running; it should be 12 Volt or slightly more. If lower, the rotor speed will be lower too.
When priming make sure the outlet pipework is open to atmosphere. Any restriction will lower the priming capability.
Lothar

 

[jcummins]

In my instance....low voltage was initially an issue. I corrected that, and it still did not prime, but perhaps that initial problem carried on even after corrected. I manually primed and the pump worked fine. Manually priming was messy. There is no relief valve. I bought this pump based upon many here on the forum using it, and I thought were happy with it. Perhaps losing the prime after each use is my issue.

Question...if I went to a 55 plastic barrel setup, so the pump would never lose it's prime, would lifting the diesel 3+ feet from the bottom of the barrel be an issue...IF it is primed. LBrown on this forum seems to have done that with great success, and it appears he is using the same pump. I was going to message him, but appears he has not been on the forum since November of last year.

 

[Lothar Schmitz]

I hope I understand your question correctly. If the internal parts of the pump and the suction hose remain filled with Diesel a vane pump of this kind should easily handle a lift of 20 feet and more. The discharge rate drops off very little up to 15 feet but from there onwards very rapidly. However your pump is limited by the power available from the electric DC current motor.
The answer to your question is yes 5 feet plus should be ok although at a reduced flow rate.
Just as a reminder; the suction lift is measured vertically from the liquid level in the barrel to the pump and not from the suction hose inlet at the bottom of the barrel.
I still believe if your blades are free to move in the rotor slots and the blade and rotor axial clearances in the pump housing are no more than say 0.001” to 0.002” your pump should prime Diesel at 5 feet plus.

 

[jcummins]

I'm going to setup a 55 gal barrel...think it will solve my issue. Thanks to everyone for the advice.