Engine/Transmission (1998.5 - 2002) Need suggestions to trouble shoot lift pump blowing fuses. (somewhat long)

[tmacc]

After 12 years of replacing lift pumps fairly regularly, (probably 8 or 9 in 12 years) I thought I had solved my problems with FASS DDPR lift pump. It's been working flawlessly for about 2 years now. 16+ PSI day in day out. Then, this past Sunday, I start to drive out of the 'hood and no power, stumbling......zero fuel pressure. I limp home figuring it's some kind of electrical problem. I find the inline 30A fuse has blown from the battery to the relay that powers the pump. I replace it and it blows almost immediately. It's been so long since I wired the pump back by the tank, I was at a temporary loss on what to do next. I had a relay on hand and replaced it and put a new fuse in and the truck ran fine and I went to Home Depot and back. Cool. Problem solved. Yesterday, I started to leave for a job site and the same damn thing happen again. I thought maybe the power wire to the pump might have frayed somewhere and I then ran a new wire to the pump. Fuse blows. Not the problem. I then plugged a short section of wire into the power wire running back to the pump and stuck the stripped end on the battery and the pump seemed to run fine.
I went and got some new fuses and a spare relay. Came back and installed a new fuse and it seemed everything was OK again till this morning when the fuse popped again after the truck was idling in the drive for a few minutes. Thinking maybe the pump might be overheating and siezing, I plugged in the wire and stuck it on the battery terminal and the pump again seemed to run fine. I replaced the fuse and the truck ran fine. I drove it around the 'hood and it still ran fine. By fine, I mean the pump is putting out 16 PSI according to the gauge.

Of course, now I'm scared to drive it anywhere for fear of getting stuck and not being able to get it home. Has anyone got any ideas what the hell is going on? Could the pump be going out? Hate to throw a new $250 pump and fine out its not the problem.

Before someone suggests to check the ground :-laf, I have a dedicated ground wire from the pump to the ground terminal right by the battery.

 

[jandtjil]

From the FASS tech section (pg21)
All FASS systems will be supplied from the factory with an in
line filter or water separator, a clogged filter can cause the mo-
tor on the FASS to over amp and blow a fuse.

Be sure to check all electrical connections for a loose con-
nection or corroded connection. Replace or repair as needed.
If issue continues proceed to following test.

Replace in line filter or spin on filter to check for possible re-
strictions. If issue continues proceed to following test.

Once filters are changed refer to 5 Gallon bucket test to
check for restrictions in fuel tank.

If problem continues contact a FASS Tech

JJ

 

[tmacc]

Thanks JJ, That could be it. I have a inline filter in the tool box that Geno's sent with it, so I can replace the one currently in there. It still doesn't explain the blowing of the fuse upon first turn of the key. I did drive it to the lumber yard this afternoon (20-30 miles) and it again, ran fine.

 

[jandtjil]

Yeah this time of year it certainly could be, a bit of moisture in the pre-filter combined with below freezing temps equals plugged filter.

 

[JR]

Is the pump damp/wet anywhere?

 

[hcole]

tmacc, I've had a pump like yours for 4-5 years and it seems very reliable. I've had it apart a few times for solid particles locking the rotor and blowing the fuse and the bypass valve being blocked. I didn't want a filter on the suction side to stop up but finally put one in after getting so much asphaltines in it. I stretched the spring in mine to get a little more pressure (18 psi). You can take it apart with the 4 bolts on the bottom and see the rotor, bypass spring, and ball that regulates the pressure. You don't have to get into the motor at all. very simple design. Mine is mounted on the rail below the tank.

 

[tmacc]

I'll replace the filter this evening. That should have been the first thing I checked.

JR, Damp/wet with water or fuel? We are getting light snow here so everything is damp. I do solder and heat shrink all of my connects. It's suppose to be clear today before the next little storm rolls in. We're way behind on annual snow fall, which is a blessing and a curse sometimes.

hcol, I agree. I rarely ever look at the fuel pressure gauge anymore. At least,till this happened. Good to know they are easily disassembled. I'll do it during the next dry period. Filter replacement first.

 

[tmacc]

Weelll....I replaced the screen/filter and no joy. Popped the fuse. Then just for giggles, since I hadn't replaced the fuel filter in a while, I replaced that. There were some metal particles in the filter bowl. I can't be sure they're recent. They looked sort of shiny, but how's anything going to corrode immersed in diesel fuel? I then ''jumped'' the pump to get it turning without popping the fuse. Truck ran for a few minutes and then the fuse popped again. I called FASS tech support and they suggested disconnect both in and out fuel lines and run the pump. The pump seem to run fine without any kind of load. I hooked everything back up and the truck ran for a few minutes and it seemed that it might not pop the fuse, so I went in the house for a minute and it quit. This time I had to bleed 1-3-4 lines to the injectors and it stared again, but popped the fuse again. So, at this point, I'm thinking maybe something in the tank is blocking fuel flow. Does that make sense?

 

[hcole]

Well, if you think something is stopped up in the fuel tank you can get a 2-5 gallon bucket or jug and run a line from your truck bed to the supply side of pump and pump out of it. It will use a lot of fuel because it is returning unused fuel to the tank but you can check to see if it will blow a fuse. Couple other thoughts- what size fuse? Should be at least a 10 amp. Also, would the fuel by any chance be summer fuel? Sometimes you can get some from a station that still has some. It gels much easier.

 

[tmacc]

Well, I was thinking of just the opposite, pump fuel from the tank into a container to see if it blew a fuse, but your idea works as well. I may do both. I use a 30A fuse. I get my fuel from a truck stop close by and they post pretty early that it's winter blend. I usually fill up every week or so, depending on jobsite location. Sometimes 2-3 times a week. It didn't happen this year, but we often get the first snows of the year in Sept. Unseasonable warm this winter. Often too warm for the ski resorts to make snow at night. In my neighborhood @ 7000', we get an average of 300'' of snow per year.

I guess I should figure out how many gallons this pump will pump in the time it runs when I bump the starter. Could be messy if it's over 5 gallons.

 

[hcole]

Well, if you think there is an obstruction in the tank or supply line, then my way would eliminate that. I'm thinking that pump has something wrong electrically to blow a 30 amp fuse that quick.

 

[tmacc]

Good point. I was just looking for some fittings that I could hook up a line that I could insert into a 5 gal. container of fuel that we use for the tractor with out taking the supply line from the tank apart. My first thoughts were that the pump was defective, but I know FASS will want me to exhaust all possibilities first. I'll check it out tomorrow and post what the results are.

 

[tmacc]

hcole, good test suggestion there. It's the pump. I ran a clean fuel line into a 5 gal. fuel can, waited till I had full pressure on the gauge and started the truck. It ran for about 1 minute and then popped the fuse.

Now the only issue is, will FASS warranty it? When I bought it from Geno's, it sat on the floor of my office for about 4-5 month before I installed it. I just noticed on their webpage that a purchaser must file with them within 30 days of purchase to get the warranty. Obviously, I didn't We'll see what happens.

 

[tmacc]

Had to buy a new pump since I hadn't registered W/I 30 days of purchase. They did discount it $50. They also say that they recommend a 10A fuse. 15A max. I think I put the 30 A fuse in there because the 15-20A that I originally put in there blew. I'll probably pull the tank this Spring since god only knows what could be in there after 14+ years.

 

[tripl-e]

Had to buy a new pump since I hadn't registered W/I 30 days of purchase.

I'll probably pull the tank this Spring since god only knows what could be in there after 14+ years.

Disassemble and inspect the old pump before installing the replacement. You might learn why the first Fass failed and prevent a repeat failure of the new one.

 

[tmacc]

I'll do that. I should the new pump Wed.

 

[tmacc]

Good idea.

 

[tmacc]

I installed the new pump with a 10A fuse and it's been fine for the past week. I think the old pump had an electrical issue. I'm going to call FASS tomorrow to see if they think it's worth sending back to re-build it.