can't find Air/Trash in fuel

Mf industrial 30 keeps getting either air or trash in fuel. Sometimes it will run hours with no problems. sometimes it will run 5-10 minutes. and then its like the tractor runs out of fuel. I have to bleed the lines at the filters and then the injectors and it will fire back up. and run for a while until it happens again.

I have put new rubber hoses on from the tank to the fuel pump with clamps. It is a new "diesel" electric fuel pump and new filters. I just rebuilt engine on it.

Is there an easy way to determine where the air/trash is coming from?

Now when I bleed the fuel filters, there is very foamy and bubbly fuel coming out. and it seems to not get any better no matter how long you let the fuel pump out of bleeder valve.

Thanks!
 
I assume you have bypassed the engine driven fuel pump. Have you been running the electric fuel pump when priming?
If you have then it must be sucking air into the lines between the pump and the tank. I would also do a complete bleeding of the system,
including the bleeder screws on the injector pump. Maybe Dieseltech will have some suggestions on this.
 
I have been priming the filters with the electric pump.
There is a rubber hose that connects to the pitcock valve on the tank and runs directly into the nipple of the electric fuel pump. This is a new hose with radiator type screw clamps on both ends of the hose.

Do you think it could still be sucking air at these points?

Once the hose leaves the fuel pump it goes to the first fuel filter. when I crack the bleeder valve here it is very bubbly when the fuel comes out.

I had some trash in it before, would trash in the line/tank cause the fuel to be bubbly coming out of the bleeder valve?

Thanks!
 
have you checked around the strainer in the bottom of the tank for trash, water, and rust. Usually fuel flow will pull it all over there until it stops up and kills the engine, then floats back away
 
If it still has the original type MF fuel shutoff valve on it, you have to drain the tank then unscrew it out (it's 1/4" pipe). The cut off has a screen sticking out of the top of it into the tank, the screen should come out with the valve.
 
Ok. I will check this. Would trash and stuff in this strainer cause the fuel to bubble up when bleeding?

Thanks!
 
If air is a problem there's a good chance the constant bleed fitting on top of the filter base is plugged, and any trapped air can't get out where it should and then goes to the pump, killing the engine. Look for a straight or banjo fitting that has a line going to the injectors top return line, and make sure the small orifice is not plugged.
 
Ok. I cleaned the banjo bolt. I also drained fuel from tank, pulled tsnk off and cleaned trash out of tank. There was a lot of trash in it. I think I got most all of it out. Then I made a big dumb mistake.

While bleeding All the lines to try and crank tractor I over tightened one of the bleeder valves on the injector pump. The bolt/ screw part broke off in the pump.

Anyone have any experience with this? Know an easy way to get it out?

I know it was stupid and I should know better, but I was trying to tighten good to keep all air out.
 
Which bleeder? The top cover one or the lower one next to the tag? Either broken end should come out easily. Top cover is 1/4 fine thread and lower one is 5/16 fine thread. I have both, but for now after the broken part is out a CLEAN fine thread bolt will work to seal the leak..
 
(quoted from post at 07:39:31 04/08/16) Which bleeder? The top cover one or the lower one next to the tag? Either broken end should come out easily. Top cover is 1/4 fine thread and lower one is 5/16 fine thread. I have both, but for now after the broken part is out a CLEAN fine thread bolt will work to seal the leak..


The top one. I got it out. It came out easily. I was hoping I could just put a regular fine thread bolt in there. Glad to hear that I can.

Now I just hope that all the trash that I got out of the tank will keep the tractor running!

Thanks!
 
Ok I think we may at wits end with this. I know I ask a million questions, but just trying to get this ole machine running like its supposed to. Going to try to break down things we have done to it.

We only ran tractor about three hours before we rebuilt engine (bad blow by and oil leak). During that time it choked down/ran out of fuel/ air in line/ trash in line two or three times. We had to bleed the lines and it would fire right back up.

We rebuilt engine. New Sleeves, Pistons, rings rod cap bearings. And new fuel filters. Motor seems to run great.

Got it running after rebuild and ran great for about two hours of run time. Choke down. Fuel issue.

We could bleed and it would fire right up for 5-20 min.

Changed to electric fuel pump. And put new rubber hoses from tank to fuel pump. Same thing. Ran 5-20 min then choke down.

We cleaned banjo bolt and connectors at top of second fuel filter. Ran great for 6-8 hours of run time. Then started choking down again.

Since then. We it has been doing same thing:

We have drained tank. vacuumed all trash out of tank (lots of trash!) cleaned the inline filter that goes to fuel pump (lots of trash). And same thing.

We wondered if we were getting air somewhere between first filter and second filter... So we bypassed first filter. (Same results)

You guys have been super helpful! But we still don't have issue solved. What are we doing wrong?

Where should we go from here?

Thanks!
 
Did you clean the return orifice again, it may be plugged. Put the filter system back as it should be, and if using NAPA or WIX filters make sure the filter top outer groove is open. Have made lots of service calls to remove the extra O ring guys think needs to be in the groove. That's the filter inlet, if plugged/restricted fuel flow is really choked..
 
Are you talking about large o ring on top of filter body that is the same circumference as filter body?

Thanks!
 
Yes, the large O ring that goes in the base groove. There are two or three with each filter, the top one is slightly larger than the one for the lower part of the filter. If CAV original equipment filters are used there is no problem as the fuel flow is different than the WIX/NAPA brand filters.
 
I have been doing away with those pesky filters with these.
2aaeiyf.jpg
 
Dieseltech,

I think (hope!!) you may have solved my problem.

I took my filter off and looked at the o ring. It was covering up the inlet holes of my wix filter. I fixed it.

I ran tractor for 3 hours today. Hard.

No problems!!!

Now, you said you had the bleeder screw for the injector pump. Do you sell them? If so, how would I get one? I need the top screw. The smaller of the two bleeder screws. I am using just a regular bolt with a nut and Teflon tape on it for the time being.

Thanks so much for your help!!!!
 
I'll look and see what bleed assembly I have. I know some covers didn't use the bleed screw, just a short bolt and copper washer for sealing. Send me a message, E-mail should be open on classic.
 

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