Lift Pump Problems

[MAGNUM SERVICES]

Anybody having problems with their lift pump's ? I just put another one on my truck this year. The first one was in March while plowing snow and this one was yesterday the 6th of December. I don't know if this is because of the low sulfer diesel or just bad parts. The pump replaced in March was a Delco pump and this one is a Master brand pump from Autozone . I have never heard of them but so far so good .My wiring connections are clean and dry so I know it is not lack of electricity to the pump causing them to go bad. I have already drained and cleaned the fuel tank and replaced the fuel sending unit and it came with a new strainer so there should be no dirt to get to the pump. I run a quart of Power Service Cetane Boost on every fill up and have never had this problem until this year. I saw a thread which had a suggestion on pouring a quart of two cycle oil in the fuel but can't remember who wrote it. Anybody ever try this before or know the benefits of this? Maybe I should install a filter before the lift pump. ANY and ALL replies will be GREATLY Appreciated. Thanks, Keith

[Buddy]

Does the cetane booster include a lubricant?

Could it be that you have too much vacuum in the tank or the wrong fuel cap, might make it more difficult to pump the fuel. Maybe you have changed the cap in the last couple years?

Otherwise I think the lift pumps were suspect items, which is why everyone gets the upgraded aftermarket ones.

[MAGNUM SERVICES]

Yes, the Cetane boost does have lubricant in it. Maybe the Delco pump was considered OEM where as the new Master pump hopefully will be an upgraded pump. I will look into replacing the fuel cap as I think the one on the truck is the original cap.I will keep you updated. As stated earlier, so far,so good! Thanks,Keith

[JD_countryboy]

Have you replace dthe ops? id be switch that before replacing the pump. If that diodnt cure the problem then id replace the pump. The contacts in the ops are not real good. they get wore and dont always make the best of connections.

Master brand pumps are the autozone line of pumps. Federated auto parts stores sell carter brand, Carquest stores sell Carquest brand pumps. Napa sells Napa brand. I have a master brand electric pump on my 85 gasser, mechanical pumps couldnt supply enough fuel to keep it running at WOT. now i dont have any trouble but i have had to replace it once in two years. Its startin to sound funny again so im guessin its about to go again. Lifetime warranty though. I have a master brand pump on my 6.5 also now, no trouble in a bit over a year.

I have been running two stroke oil in my fuel since spring. Avg close to 2 mpgs better, and it runs quieter. Also adding an antigel conditioner now (renewable resources bioblend conditioner/antigel). Which may have helped add another 1 mpg on the last two tanks, but my driving varied alot in the last couple tanks so cant say for sure.

[phantomgsxr]

Has anyone just wired the lift pump to an acc 12 volt source so when you cut the key on it works until you cut the key off? I'm sure there is vacant slots in the fuse box that you could wire in and even have the fuse in the right place. I would think if you are driving a diesel for work or play you're going to keep an eye on the gauges so if there is no ops or relay or any other high tech bs to get in the way you should have the fuel pressure unless the pump is bad. On top of that has anyone went to a higher pressure pump, say one that runs up to 12 psi?

[MAGNUM SERVICES]

When you say ops do you mean the Oil Pressure Sending unit under the intake manifold behind the injector pump? I have noticed my oil pressure gauge does like to fluctuate unless under load. At idle it keeps jumping left and right. Is this switch tied into the lift pump circuit? If yes, I don't think mine has been replaced by the previous owner as I have owned the truck since June of 2000 and have never replaced it. What brand of two cycle oil do you run and how much do you add to a full tank of Diesel? Thanks for all replies,Keith

[phantomgsxr]

The engineers at gm decided a good way to save the engine if oil pressure is lost was simply cut the fuel. Thus wiring the lift pump to the ops ( oil pressure switch ) was born. Now if you don't pay attention to your gauges while driving than I would recommend leaving it wired factory. I have also heard of wiring a 12 volt light bulb to the pump feed, light comes on pump has power. You could mount a simple underhood light, found at any junkyard cheap, on the firewall and anytime you have a question just pop the hood. Of course this doesn't mean the pump is working. That's why I have a fuel psi gauge leaving fuel filter going to ip. Filter water drain works good if all your lines are clear but if the feed line to ip is not getting pressure than it's not going to work

[MAGNUM SERVICES]

I guess that I am going to have to replace the oil pressure switch and look into putting a fuel pressure gauge somewhere after the lift pump and a fuel filter before the lift pump. Thanks, Keith

[Buddy]

So you get it right, the OPS they are referring to is under the Glo Plug relay by the firewall. There is a special socket to remove and install it, a really deep one. Otherwise its a bit difficult.

Not the guage sending unit. If your pressure guage jumps around a lot that could mean you need a new sending unit though, or you genuinely have some oil pressure issue.

[phantomgsxr]

There is a fuel filter at the back of the intake manifold up under the engine cover. The first attachment is the fuel filter housing and the second is a picture of the engine cover. Your engine may not have the engine cover on it anymore and that is no big deal!

[JD_countryboy]

Yes. the ops (oil pressure switch, oil pressure sender) it acts as BOTH oil pressure gauge, and to control lift pump operation.

I am pretty sure the oil presure switch was installed to kill fuel pump if in an accident and fuel line ruptured and engine dies that the pump stops pumpin fuel. If there was a fire it would literally be adding fuel to the fire if the pump didn't shut off. They seem to be a common problem, i posted the napa part number and special k-d socket to make replacement easyier, just forget what thread i posted in. ops is located to the drivers side of the fuel filter housing, down deep under glow plug relay and such.

Im adding a quart of superflo two stroke to approx enery18 20 gal of diesel prior to fillin the tank. Any two stroke will work, cheaper the better. I got a steal on 6 gal, $10. I have a few gallons left, and hopin to run into a deal like that again.

[RipnRun]

JD_countryboy,

You gave the NAPA part number and KD socket in one of my threads - thanks.

Here's the info I copied from a couple of your posts: “KD tools makes the socket… socket # K-D 3458. it is 3 3/16 inches overall length, 7/8 hex head on top with 3/8 square drive hole for rachet, extensions and so on. Seems to be a fairly handy socket to have.

OPS # OP6677 Napa / Echlin brand.”

[JD_countryboy]

Thanks RipnRun for reposting it.

[MAGNUM SERVICES]

I bought the OPS but have not had a chance to install it as I feel I should have the correct socket to install it with. I will also look into adding some two cycle oil and see if that helps with mileage and longevity of the pump and engine. I will keep you posted. Thanks to All who replied, Keith

[JD_countryboy]

Your welcome and goodluck

[MAGNUM SERVICES]

Bought the correct socket and installed the OPS and everything seems well. The oil pressure gauge holds steady at 40 psi at idle where it used to jump left and right . Truck starts easier, I hope this is the end of my Lift Pump problems. THANKS to ALL who replied. It is GREAT to know there are still other people in the world who like to share the KNOWLEDGE with others instead of sharing the WEALTH of others. Keith:D