Lift Pump questions.

[Idually]

Hello to all! I have a question if you don't mind. A co-worker's husband has a 1995 CTD and found out today that his injector pump is gone. The lift pump was also bad, which lead me to believe that the pump failure could have been caused by the lift pump failing. Am I off base here?



I'm asking because I've had some suspicions about my own trucks performance over the last little while. I'm hearing a few "noises" that I don't really care for and I'm a little shy about "tinkering" with my daily driver at this point in time. Obviously, I'd prefer not to lose my I-pump also.



Questions:

1): Can the lift pump affect engine performance in any way?

2): How long can the Inj pump last without the lift pump?

3): Is the a good way to check the lift pump to make sure it is still in good working order?

4): Can any one tell me the Cummins PN# for the lift pump on my truck? I do not have a service manual yet, but Cummins R. M. is not very far away for where I live.



Thanks in advance, as always. ou guys are great.



Andrew

 

[barbwire]

The only help I can be, is to tell you to check the lift pump with a guage. I am sure that a good mech. in the area has one that can be hooked up in short order, for the test , then removed.

 

[KYLE4]

Yah a local mechanic can test fuel pressure but make sure he can do it while the engine is under load not just idling big difference. also install a fuel pressure gauge lift pumps have a tendency to just take a crap and you have now clue if your truck is stock until it is too late

 

[cerberusiam]

The VE injection pump on the gen1's is relatively forgiving when it comes to fuel supply pressure. They will draw a couple inches of vacuum and suck enough fuel thru the lift pump to run. That said it will definitely effect performance and pump longevity. The biggest problem is the lack of fuel supply to lube the pump. In a stock application and not driven hard the pump could last a long time with a bad lift pump or go fairly soon. Its kind of a crap shoot at that point.



The OEM pump on a 95, a P7100, is not the same. It is lubed by engine oil and not dependent on fuel so when they go tango uniform it is usually messy and a more serious problem. They will also draw fuel thru a bad lift pump and the performance will suffer even more.



If you like doing the work yourself it is relatively easy to check the lift pump pressure. There is a bleed screw on the filter housing that can be tapped for FP gauge. I think the magic numbers are 5 to 7 psi for a good pump and no lower than 4 psi at WOT.



To answer your questions:



1): Can the lift pump affect engine performance in any way?

Yes.



2): How long can the Inj pump last without the lift pump?

Pick a number, any number. Its not a good thing



3): Is the a good way to check the lift pump to make sure it is still in good working order?

Fuel pressure gauge



4): Can any one tell me the Cummins PN# for the lift pump on my truck?

You can give cummins the CPL number of the engine off the plate on the pump housing and they can reference it.





The new rattles could just be normal or a developing issue. Have you set the valves lately? Checked the exhaust sytem for loose pipes, clamps, etc? The injection pump does get noisier with wear and a tell tale sign of a pump going south is a new rattle. See if you track it down and describe the sound.

 

[Idually]

Thanks. I will be checking the lift pump this weekend, for sure. Looks as thought it would be a fairly easy item to change if need be.



Some time ago, I changed the fuel filter and there was a bunch of rusty crud in the filter. I posted about that and have run an additive every other tank or so since. I haven't any "major" issues from that, but I'm thinking at this point... could that "crud" been the lift pump coming apart? That was about a year ago. Could the Inj pump last that long w/o the lift pump? I'm not liking these thoughts going through my head.



As for noises they can be deceiving. I would call it a "tap". Like lifter tap, but I really don't think that is it. It does sound as though it is close to the Inj pump, or coming from the Inj pump. It varies with the RPM of the engine and stays steady. There are days it seems more noticeable. I have noticed that it seems like the truck is not running as well as it used to. It still starts right up and doesn't idle odd, but just seems to lack some power that I felt it used to have. I don't tow, but on a rare occasion, at this point and I definately tend to "baby" my truck.



The truck is serviced regularly (oil and filters) by me, but as I said, I'm still a bit leary about "tinkering"(valve adj and such). I guess it's time to get over that.



I appreciate the info and will update the post as I find out things.



Thanks again.



Andrew

 

[cerberusiam]

I change my fuel filter every second oil change, about 15k, and there is almost always a reddish crud sitting in the filter. I think it is the water and crud from the tank and the crappy fuel we have settling out. Looking at the filters is a good incentive to change them at least every 15k as that is some nasty looking stuff and the VE would be terribly unhappy ingesting it.



You have all the symptoms of a pump starting to go. There are 2 springs in the bottom of the VE pump that return the fuel delivery piston after the injection stroke. They are one of the weak links in the pump and tend to get weak, collapse, or break a coil or 2 off of and end. It sounds exactly like what my pump did. The tap is variable and hard to trace. It almosts sounds like a lifter sticking or a loose rocker. In fact I had 2 supposed diesel mechanics look at it and listen and they both swore it was a loose rocker. I had set the valves previous and knew it wasn't that. The pump lasted 20k until it finally needed an overhaul. I would check your valve lash first as its relatively easy to do and see it that quiets things down and changes the noise. If it is still there it is probably the pump getting tired. Too much valve lash will also cause a drop in power very similar to the pump wearing. Do the easy things first and eliminate some of the possibilities.



Luckily they are not to expensive to rebuild so if you start planning its not a big surprise. Good luck and Happy Holidays.

 

[MFalkinham]

How expensive is the lift pump itself? Would it be worthwhile to replace as part of regular maintenance, say every 100k miles? I'd rather do that than have it fail far from home, or have it ruin the VE pump.



- Mike

 

[cerberusiam]

Cummins quoted me about $80 for my 92 a year ago. Thats much better than DC and fairly reasonable. I have 276k on ine and its pressure is still good but it is leaking to the outside of the pump. They live a long time for the most part. Price may depend on the Cummins dealer and their markup also.

 

[ARhine]

The local carquest said $65 I think. Don't know what brand of pump it is though.

 

[bgilbert]

Well lets see fuel filter $8. 00 x twice a year = cheap insurance IMO. I change my oil, oil filter and fuel filter every 6 months, only run about 6k miles a YEAR. I installed a fuel pressure gauge recently. Had 3 psi at idle, 0 at WOT in neutral. Under load quickly to zero. Fuel filter only had about 2k miles on it, 6 months old. Replaced the filter AND the important thing IMO for us was, I removed the lower restrictive fuel banjo bolt where the fuel enters the fuel filter mount, and replaced it with a upgraded freer flowing bigger holes banjo bolt. After this my FP went up to 4-5psi at idle, and in nuetral WOT it holds that pressure. Under load it will bottom out but it takes alot more throttle to drop pressure. I'm thinking my LP is weak or gone, so I will be buying one and keep the old for a spare. My point of all this for the guys without FP gauges, would be to call Geno's for some of those cheap upgraded (2) banjo bolts, and washers (2 per bolt), if you ever plan on having a FP gauge, get one that has a big head and is threaded for the FP gauge. Or if not gonna get a FP gauge, cheap insurance would be to install two new banjos, the non tapped ones are cheaper, this would help fuel flow and possible FP. Thanks Scott and PDR for this info.

Edit: once again, use the elcheapo aftermarket parts on your boat anchor 318, and use ONLY Cummins parts on the Cummins.

 

[barbwire]

I hope I'm wrong, but the thing that has kept me from installing a fuel pressure guage so far, is that all the info I read about guages and snubbers is that they are no more reliable than the lift pumps that they are supposed to monitor.

 

[Greenleaf]

Many people prefer the "snubbers" even though they do not work well. Don't ask me why... ... ... ... .....



You cvan connect the gauge direct. Permenant or for testing purposes only. OR, git yourself the electric gauge.



There-you-go



Scott

 

[barbwire]

Electric guage

Many people prefer the "snubbers" even though they do not work well. Don't ask me why... ... ... ... .....



You cvan connect the gauge direct. Permenant or for testing purposes only. OR, git yourself the electric gauge.



There-you-go



Scott

Don't the electric guages need snubbers also ????? If not I might want to concider one. Oo.

 

[bgilbert]

I got the isspro 30psi mechanical FP gauge direct fuel to cab setup. Bought the 24V kit from PDR, which will work on our 12V's, and after much research, I decided against the isolator in the kit. Seems to be working fine, no leaks so fer, knock on wood.

 

[Greenleaf]

The electric gauge is... ... ... ... . well... ... ... ... ... electric. It don't need no "snubber"

 

[dpuckett]

"Geniune" Cummins parts and noisy VE's

The lift pump I put on my 91 a year ago, from Cummins was a Carter. Could have bought it at O'Reilley's for $8 cheaper, not had the 90mi drive, and got the same thing. It pays to shop around.



Lately, my engine has started to sound like a cold engine, even when warmed up. I set the valve lash, double checked the timing (retarded or advanced outside a given range will rattle like a cold PSD getting hammered), and it still rattles. It seems to be under light/ moderate load (keeping 38mph in 4th up a 2-3% hill- 500*/5-8psi boost), more noticeable at higher RPMs. If I get on it, or baby it, it sounds normal. I can hear a tick now and then, and other times it is more a rattle, like loose valves or an injector not up to snuff. I havent checked them, but I will resolve that if it is the injector. It also blows blue smoke when cold- didnt do it last winter; with the bad stockers or EDMs. Fuel filter has <3K; been getting fuel at one of 2-3 local places, depending on what is local at the moment. MPGs havent taken a real sudden dive, but I'm about 2 less than a year and a half/35Kmi ago. It will make 38psi boost, so it will pump the fuel; just wondering if it is quite like it should be? How hard is it to replace the springs in the bottom? I have been inside the top end, and it looks like I could get it all back together, and tune it via the pyro and boost gauges. If I mess it up too bad, I could just call Bill and get his extra pump.



Daniel

 

[cerberusiam]

How hard is it to replace the springs in the bottom

Disassemble about 3/4 of the pump.



Careful you don't have CB Pump Episode.





:-laf :-laf :-laf

 

[barbwire]

The electric gauge is... ... ... ... . well... ... ... ... ... electric. It don't need no "snubber"

OK But... ... ..... how dependable are they?

 

[JLEONARD]

how dependable are they?

How dependable is your oil pressure sender?

That's how dependable they will be.

Might last forever..... and it might not.

I like the way BGilbert did his... mechanical into the cab.

Put a shut off valve in the engine compartment in case the gage springs a leak... ... or carry a plug and tools and deal with it if it ever leaks.

(I carried a plug in my old 67 Chev pu for 12 years and never needed it for the mech oil pressure gage I had. )

Jay

 

[Greenleaf]

It's just like any other pressure gauge. I don't serf the 24valve forum too much but when I do it's always the same thing... ..... the isolator used w/the mech fuel press gauge ain't workin' no more.



I have nine ISB Cummins and monitor the fuel pressure with a mechanical gauge of which I plug into the filter canister to test. I'm not allowed by state rules to install a permenant fuel pressure gauge onto a school bus engine. Electric, but not mechanical.



I have the Westach electric. You still are not supposed to plug the sending unit directly into the banjo bolt. Mount it onto the intake manifold via a brace assy and short length of flex hose.



If I was REAL ambitious like Sam,,,,,, I'd post all sorts of pictures in my readers rig gallery... ... ... ... ... .....

... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... but I'm not



-S