lifter pump tick???

[bowhunter]

When I first joined TDR I asked a question about an exhaust tick behind the cab, that my truck has had since day-one. I still have it and am positive its the elbow in the fuel line at the top of the tank. No big deal, nothing that louder exhaust won't fix.

I now have a tick in the general vicinity of the lifter pump. You don't hear it when its idling, or when your @ 2000 rpms going down the highway. But when you let off and let the engine slow the truck down, and the rpms hit between 1500 and 1700, you hear a tick, tick, tick. Sounds almost like a lifter tick in a gasser. I haven't checked the fuel pressure before the injector pump yet, but I'm wondering if it is the lift pump at all. While in the cab driving the tick sounds like its forward and below my left foot.

I've never had one go out on any of the dodge diesels I've driven. Has anyone heard this noise or had a simular problem with the lift pump? If so how much does a lift pump go for?

If it is the lift pump spring and arm making the noise at a certain rpm, then I'm rolling the idea around of using an electric fuel pump as some other TDR memebers have talked about.

Any ideas?

Thanks

Kurt

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97 2500 SLT Reg cab 4WD, Emerald Green and Driftwood, 3. 54 gears, 2. 5" Tuff Country Steel Coil Spacers, 295/75/16 AT BFG'S on Alcoa's, Trailmaster SSV shocks & SSV steering stabilizer, Holcomb Air, Amsoiled, stock--#10 TST plate and AFC Spring Kit thats waiting on a new clutch

K. Kinion

 

[CumminsPower98]

I also have a slight "ticking" sound. I hear it most when I let off the throttle and cost below 2000 RPM. It's hard to say where it's coming from. If I roll my window down and drive along slowly I can hear it reflecting off the ground and it is sort of erratic but is still affected by RPM. Sounds to me like I might have the same sound as you do bowhunter. I too would like some input on this if any of you have had similar experiences.

Thanks,
Mark

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Red '98 12valve 2500 4X4 Quad Cab, Long Bed, SLT, 5-spd Manual, 3. 54, Dana 80 Rear,Camper/Town pkg, 33x12. 50x16. 5, straight piped, silencer ring hanging in shop, Yet to be Bombed, 68K+ miles.

 

[illflem]

My trucks do it also, I've always thought it was the steel ball in the overflow valve bouncing back and forth with the pulses of the lift pump.

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95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(work truck)
95 3500,5 speed 3:54,BD E-brake,Driftwood,Banks&Psycotty,34,000 GCVW apple and tractor hauler(works harder truck)

 

[bowhunter]

I don't know, but I change fuel filters pretty often, roughly every 10,000 to 15,000 miles. Right after I put in a new filter in the canister, the tick quits for a while. After the fuel filter gets a little age on it, it comes back, and loud. It gets louder until I put a new filter in.

I've heard that the lift pump has an arm that pumps the fuel. This arm has a spring under it to return the arm to the position for depression over and over. I would think the arm/linkage/spring, over time, could become sloppy.

So when the fuel filter starts to get partially clogged, this would create some resistance for the fuel to travel through to the injector pump. This might put a strain on the lift pump and force it to work harder to pump fuel. So the slop in the linkage for the lift pump might tick when it is being depressed over and over, when there is substantial resistance.

A quick fix is to keep changing fuel filters, but it doesn't take to many fuel filters @ $28. 00 ea. to justify buying a new lift pump, if this is the "ticking problem".

Thanks

Kurt

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97 2500 SLT Reg cab 4WD, Emerald Green and Driftwood, 3. 54 gears, 2. 5" Tuff Country Steel Coil Spacers, 295/75/16 AT BFG'S on Alcoa's, Trailmaster SSV shocks & SSV steering stabilizer, Holcomb Air, Amsoiled, stock--#10 TST plate and AFC Spring Kit thats waiting on a new clutch

K. Kinion

 

[C-Series-Man]

The ticking you hear is the tappet in the lift pump hitting the plunger in the pump. It is hard to explain, but here goes. The lift pump is off course a piston pump. It is a little different than you may think in terms of operation however. The camshaft has a lobe on it that pushes the lift pump tappet out. This action is not the pumping action. This is the intake of fuel. There is a spring in the lift pump that pumps the fuel. The tappet pushed out the plunger and the spring pushes it back in. The spring does all the pumping. This is done for several reasons. The biggest is that hydraulic lock is not possible. If the tappet did the pumping and something plugged the system, the engine would have enough power to continue to drive the plunger. In this case, usually the fuel filter will bust and result in a fuel spill. BAD NEWS! FIRE FIRE! With the spring responsible for the pumping, it is easy to know the peak pressure that will be acheived. The tick is when the pump spring is not able to push the fuel out and the plunger stops moving. The tappet however usually follows the camshaft because of moumentum. When the tappet reverses direction and starts back out, it recontacts the plunger and makes a "tick". The comment about changing the fuel filter makes it go away - exactly, a clean filter is easier to pump through. Usually this is not an issue if the overflow valve in the injection pump has not be "adjusted" higher, otherwise I would suspect that the lift pump spring is going soft. It is a common practice to jack up the overflow valve pressure. This is bad and will not give you much of a power increase. When you do that you decrease lift pump life because of damage cause by ticking, lower fuel volume returned to the fuel tank which decreases cooling to the injection pump, and in extreme cases can bust a fuel filter and dump raw fuel. We are talking about imcompressable fluid flow, jacking up the pressure will not fill the injection pump gallaries all that much faster. Remember, you injection pump needs the cooling to last. I would check the fuel pressure at the injection pump first. It should be around 20 to 25 psi. Don't be alarmed by the pressure waves as the piston pump works. That is normal. Lastly, I would remove the lift pump spring and check to see if the spring rate is correct. It should be 123 lbs/in. If the pressure is too high, fix the overflow valve, if the pressure is low, fix the lift pump. One last remote possiblity if the pressure is low and the spring is ok is the the internal pressure regulator in the lift pump is bad. It is just a spring and ball pressure relief valve to keep the pressures reasonable. It is not intended to be cycled very many times and goes bad fast if it is used alot. Again, if that is what it is, change the lift pump. Sorry for the book length explaination.

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95 Ford F-350 4x4 Ext Cab, Cummins 6CTAA 8. 3, Fuller 9 Speed, Big Rig Heart in a Pick-up Truck

 

[-Alex-]

I developed this tick recently. It started right after I messed with the overflow valve (recalibrated the spring). It only does it after engine warms up and is at idle. I also tore the rubber boot on the manual activator for the lift pump, don't knbow if that's the reason for the tick. Is there a P/N for the rubber boot?

 

[bowhunter]

Thanks

I appreciate your explaination. This sounds like my problem. I will check fuel pressures to confirm. This ticking has been around for nearly 60,000 miles, so maybe the lift pump is ready to lay down. Its the original pump. My truck has nearly 123,000 miles. Sounds like I can replace the lift pump and fix the whole problem.

Thanks again

Kurt

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97 2500 SLT Reg cab 4WD, Emerald Green and Driftwood, 3. 54 gears, 2. 5" Tuff Country Steel Coil Spacers, 295/75/16 AT BFG'S on Alcoa's, Trailmaster SSV shocks & SSV steering stabilizer, Holcomb Air, Amsoiled, stock--#10 TST plate and AFC Spring Kit thats waiting on a new clutch

K. Kinion

 

[Timinator]

Great explanation!

 

[Andy Redmond]

Your truck likely uses the Cummins part number 3936316 (lift pump) and you need two gaskets 3031348. $150 will probably take care of the parts (Have Cummins run you engine serial number to make sure this is the correct lift pump).

I've seen pumps last 50 or 150k with little rhyme or reason.

Your pump is lubed by engine oil, not fuel like a rotary pump.

If your pump is going you are down on both fuel pressure and performance. One symptom of a lazy/worn pump is need for frequent filter change. It doesn't build enough pressure to overcome even minor restriction.

Of course, your pressure check should reveal your suspect pump.

However, I have seen a ram run with about 10 psi after the filter. Didn't run well, but ran. The owner was tickled to get a good running truck again after a fresh lift pump and filter. His overflow valve was weak so we replaced that too.

Don't overlook the overflow valve. I doubt you can tweak the spring enough to cause mega restriction and injure the lift pump. Usually the stretched spring will quickly re-sack and let too much fuel return and not build enough pressure, again causing poor performance. You might try a . 020 shim instead of stretching the spring.

Good luck you are likely on the right track.

 

[bowhunter]

I'll check into the overflow valve as well. Thanks again for all the help.

BTW, isn't the overflow valve and spring assembly on top of the fuel filter canister? Under or next to the brass bleeder bolt? I've never had to mess with this before.

Thanks.

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97 2500 SLT Reg cab 4WD, Emerald Green and Driftwood, 3. 54 gears, 2. 5" Tuff Country Steel Coil Spacers, 295/75/16 AT BFG'S on Alcoa's, Trailmaster SSV shocks & SSV steering stabilizer, Holcomb Air, Amsoiled, stock--#10 TST plate and AFC Spring Kit thats waiting on a new clutch

K. Kinion

 

[Andy Redmond]

No the overflow valve is between the pump and the block. Stand at the front of the truck and peer down between the font of the block and the side of the pump (just behind the gear housing). You will notice a "banjo" bolt and a line running down the backside of the pump.

Remove the valve as a unit, don't remove the small cap on the end (while in the truck anyway).

If you don't have metric tools the 3/4" open end wrench will serve well. Lift up slightly on the line as you work the valve out.

Watch out for the sealing washers on each side of the return fuel line.

Good luck
Andy

 

[bowhunter]

I appreciate the help. I'm going to make a temporary fuel pressure gauge, and use the brass bleeder bolt on the fuel filter canister to check the fuel pressure. If its OK, then I'll go to the lifter pump. I'm curious about the overflow valve, so I'll probably take it apart and check it out.

Thanks again

Kurt

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97 2500 SLT Reg cab 4WD, Emerald Green and Driftwood, 3. 54 gears, 2. 5" Tuff Country Steel Coil Spacers, 295/75/16 AT BFG'S on Alcoa's, Trailmaster SSV shocks & SSV steering stabilizer, Holcomb Air, Amsoiled, stock--#10 TST plate and AFC Spring Kit thats waiting on a new clutch

K. Kinion