Anyone ever had a lift pump go bad?

I made a highway trip...about 3 hours round trip...and the car ran like a champ...this was on VO. The next morning, it ran for a few minutes and then died. This is the 3rd time this has happened after a highway trip on VO, I have no garage and am tired of fixing things on the street in front of my house (I believe I had a sticking supply valve and was not purging when I thought I was purging so I was shutting down on VO. That's bad. I know). So I removed the VO system, dunno if I'll go back, too much work without a garage to do it in...

So now the fuel system is back to the stock configuration. Since I was there I changed both diesel filters. I pumped the primer a lot and it didn't seem to be doing anything...it wasn't filling the semi-see-through plastic filter. So I got out the mityvac and pulled a vacuum on the return line coming off the top of the spin-on filter. Vacuum went up to 15in-Hg and crept down...no diesel flowing through the lines. I pumped the primer with the vacuum drawn...nothing. I pulled a vacuum on the supply line...right at the metal line coming from the tank. The diesel flowed through easily.

So then I put all the lines back on a cranked it. And cranked it. It never filled the in-line filter. I loosened the banjo bolt on the spin-on filter inlet (the one coming from the lift pump)...pumped the primer and heard some gurgling but no fuel ever came out. Pumped and pumped. Then cranked it with that banjo bolt loose...no fuel came out. So it seems like the lift pump nor the primer pump is pumping.

The question is, will the lift pump block flow if it somehow breaks? That would explain why I could not pull fuel through it with the vacuum pump and why the primer couldn't pull fuel through it. I suppose one of the check valves could get stuck if there was gunk in it...maybe I'll take it apart. Dern cold weather, I'm tired of shivering under the hood

If so I guess I'll ask Phil for a rebuild kit or like this:
http://www.peachparts.com/shopforum/showthread.php?t=183451


Also...I swear there was a diagram illustrating the flow of the lift pump. I even linked to it in a thread talking about stretching a fuel bypass valve spring. Now I cant find it anywhere...I should have saved a copy.

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

When reading your post it seems like you could be having a Hand Primer Failure of something is restricting the Fuel Inlet Line.

I would hook up another longer Fuel Inlet Hose and see if I could pull Fuel from separate container of Diesel Fuel; if it works like that you have a problem to the rear towards tha Fuel Tank.
Or if you have over 1/2 take of Fuel you could swap the positions of the Fuel Inlet and Fuel Outlet hoses. This would buypass the Fuel Tanks Screen.

You could also do a little exploration of your Fuel Supply Pump. I have see instances where the Fuel Supply Pump Piston Spring breaks.
In the pic below the Piston is located under the larg 30mm Plug on the side of the Fuel Supply Pump and is sealed with a thin Copper Crush Washer.
The other picture shows the Piston, Spring and Plug. You cannot see it in the pic but the sprng goes inside of the hollow part of the Piston.

Not in the picture but you can also inspect the 2 Valves that are in the LIft Pump. The Valve Springs are mad of thin wire and I have seen the rust in two before.

Attached Thumbnails

   

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84 300D, 82 Volvo 244Gl Diesel

He was sucking fuel from the tank with the Mity Vac upstream of the fuel filter so that seems to exclude any problems upstream. Problem must be between the primary fuel filter and the secondary filter. Any chance the primary fuel filter is plugged?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Unless Copper Crush Washers are extremel smashed or distorted they can be reused by heating them Red Hot and letting them cool.
However, do not do this with the Delivery Valve Crush Washers.

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84 300D, 82 Volvo 244Gl Diesel

Primary (both actually) was just changed, but it could be a bad one. I'll take it out and try blowing through it.

I'll have to go find some new crush washers...I've reused the ones on banjo bolts before, but they're easy to get to if they leak. If I take apart the lift pump for exploratory surgery, I think I'l want to use new washers there so I don't have to go in again.

My main concern was the little plastic check valves possibly being glued shut with cold veggie oil. I guess that's my next step, thanks for the pic of the lift pump. That helps me see how it comes apart.

EDIT
question...will engine oil start pouring out when I remove the lift pump? Or is there a seal along the pushrod somewhere?

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

Try blowing air thru tank screen.Lift pumps do go bad,however a cheap Airtex booster pump over comes this.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

I do not know how to convert negative bar pressure to inches of Mercury or inches of water but, I recently looked up the vacuum of a Lift Pump for some one. At idle the Lift Pump Vacuum measured at the Pump Inlet is 0.1 bar.
The source I looked at said that 1 bar= 29.61 inches Hg (Mercury)
so a negative 0.1 bar (vacuum) = 2.962 inches Hg

I mention this because I believe the Mity Vac/Vacuum Tester can pulll a lot more Vacuum than the Lift Pump at idle will. This mean that the Mighty Vac might pull Fuel through a restriction better than the Lift Pump.

Also the Lift Pump Vacuum was at Idle speed not at the seed the Starter is turning the Engine at; so there is even less vacuum available at starting speeds.

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84 300D, 82 Volvo 244Gl Diesel

Yes, at least some oil will come out when you take off the lift pump.

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1983 240D 3.0T 4-speed manual, now sold

1989 Subaru GL Wagon 5-speed Touring Edition