603 Primer / Lift Pump Rebuild Kit? - PeachParts Mercedes-Benz Forum

300TDT 1987 · #1 01-01-2012, 06:21 PM

Hi All,

My pre (plastic) fuel filter is only about half full at idle, you can actually see it draw air into the line that goes to the primer/lift pump. (I've disconnected the fuel heater for the time being).

The car will start and idle fine but I'm afraid to drive it for fear of stalling out when the IP gets a good does of air through it.

I attached a fuel canister directly to the pre filter, still only registered about half full with the direct method, eliminating any air leaks on the hard fuel lines to the tank.

I have replace the fuel lines to the lift pump, pre filter and hard line to tank. Have yet to replace the IP lines from the secondary fuel filter, but I don't see any diesel seepage.

I'm now assuming something is up with my lift pump.

Is there a rebuild kit or do I just take it apart and clean it and install a new gasket?

Any help is greatly appreciated.

Cheers

sasquatchgeoff · #2 01-01-2012, 06:37 PM

Quote:

Originally Posted by 300TDT 1987

Hi All,

My pre (plastic) fuel filter is only about half full at idle, you can actually see it draw air into the line that goes to the primer/lift pump. (I've disconnected the fuel heater for the time being).

The car will start and idle fine but I'm afraid to drive it for fear of stalling out when the IP gets a good does of air through it.

I attached a fuel canister directly to the pre filter, still only registered about half full with the direct method, eliminating any air leaks on the hard fuel lines to the tank.

I have replace the fuel lines to the lift pump, pre filter and hard line to tank. Have yet to replace the IP lines from the secondary fuel filter, but I don't see any diesel seepage.

I'm now assuming something is up with my lift pump.

Is there a rebuild kit or do I just take it apart and clean it and install a new gasket?

Any help is greatly appreciated.

Cheers

I was able to get a rebuild kit from Peachparts a couple years back. Pretty straightforward. Mind your air ingress - do a search on my posts to learn a long tail of air-gremlins chasing. Ended up being tiny cracks in the cast aluminum secondary canister holder.

Diesel911 · #3 01-01-2012, 06:52 PM

I think we all have a bubble in our Plastic Primary Filters. As long as the Air is not being pulled into the Fuel Injection Pump the Bubble is not an issue.

If you have no Hand Primer on your Fuel Supply/Lift Pump there should be no source of Air leak in the Fuel Supply Pump. This means any Air Leaks would be down stream from the Fuel Supply Lift Pump.

Also if you have no Hand Primer you Fuel Injection Pump is setup to allow small amounts of Air out of the Fuel Injection Pump Housing by way of the Fuel Pressure Relief/Overflow Valve.

However, In the DIY section there is some instuctions on how to rebuild the older and newer Fuel Supply/Lift Pumps.
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sasquatchgeoff · #4 01-01-2012, 07:22 PM

Quote:

Originally Posted by Diesel911

I think we all have a bubble in our Plastic Primary Filters. As long as the Air is not being pulled into the Fuel Injection Pump the Bubble is not an issue.

If you have no Hand Primer on your Fuel Supply/Lift Pump there should be no source of Air leak in the Fuel Supply Pump. This means any Air Leaks would be down stream from the Fuel Supply Lift Pump.

Also if you have no Hand Primer you Fuel Injection Pump is setup to allow small amounts of Air out of the Fuel Injection Pump Housing by way of the Fuel Pressure Relief/Overflow Valve.

However, In the DIY section there is some instuctions on how to rebuild the older and newer Fuel Supply/Lift Pumps.
DIY Repair Links
DIY Links by Parts Category - PeachParts Mercedes ShopForum

PeachPartsWiki: Do It Yourself Articles - Mercedes Vehicles

yeah - what he said. No manual primer on the 60x.xxx series engines - "self priming." - my air ingress was AFTER the lift pump as the IP pulled on the secondary filter - many arguments about how this is possible later, I can now confirm that it is indeed possible, but that matter is a little off topic - In this case the air in the primary seems to be the tell-tale issue.

I ended up replacing every rubber line in the fuel delivery circuit. The hard lines back to the tank were not stopped up, but had accumulated paraffin as a result of biodiesel usage stripping the build-up on the walls of the tank to the bottom. I disconnected the rubber connectors and forced compressed air through the hard lines. Big gobs of black goo spattered the underside after a big "thunk" from the pressure build up. Very small bubble in my primary now.

ah-kay · #5 01-01-2012, 08:08 PM

I would not assume the lift pump. The tank filter may be clogged bad. I had the same problem on the freeway, sucking a lot of air and car stalled but drove OK on surface street.

Pump compress air back into the tank and it should unclog it but need to remove filter to inspect and clean eventually.

300TDT 1987 · #6 01-01-2012, 08:27 PM

Thanks for the suggestions, you guys certainly help me from tearing out the remaining strands of hair on my head

I'll make sure to replace all hoses first.

Can I get the clear plastic fuel lines from/to the IP and secondary fuel filter at an autoparts store or is this a specific MB item? Are they even needed or can I just use the existing extra fuel line that I replaced, not sure if they are under some extreme pressure or not.

I'll blow out the hard lines towards the tank, but I doubt this is the culprit because I bypassed the hardlines and connected a fuel jar directly to the primary plastic filter and still had very low fuel level in the primary filter.

Thanks again and Happy New Year.

sasquatchgeoff · #7 01-01-2012, 10:37 PM

The clear tubes are dealer items and probably OK but I would replace them just for aesthetic purposes. Dont forget to replace the crush washers for the banjo fittings. The lift pump kit is around 100 or so and worth it to rebuild. Clean the tank screen and blow out the hard lines before putting the rebuilt lift pump online because those conditions may have put the finishing touches on the very tired state of your pump. I think your problems will be greatly diminished, if not solved after this not inexpesive little project. Good luck.

Brian Carlton · #8 01-02-2012, 12:29 AM

Quote:

Originally Posted by 300TDT 1987

Thanks for the suggestions, you guys certainly help me from tearing out the remaining strands of hair on my head

I'll make sure to replace all hoses first.

Can I get the clear plastic fuel lines from/to the IP and secondary fuel filter at an autoparts store or is this a specific MB item? Are they even needed or can I just use the existing extra fuel line that I replaced, not sure if they are under some extreme pressure or not.

I'll blow out the hard lines towards the tank, but I doubt this is the culprit because I bypassed the hardlines and connected a fuel jar directly to the primary plastic filter and still had very low fuel level in the primary filter.

Thanks again and Happy New Year.

I also agree that the lift pump is most likely fine.

I also had visible air in the line between the lift pump and the secondary filter. After a miserable and lengthy, and expensive, troubleshooting process, filled with errors, the problem was simply the primary filter.

The filter looked perfectly clear with no foreign material, however, it was a generic filter. The inlet and outlet had a restricted opening to allow the filter to fit two different sized hoses. It took next to nothing to partially block the outlet and the pump was more than powerful enough to pull air around the clamps and into the line.

So, I'd replace the primary with an OE primary filter............not aftermarket..........just to see if the air disappears from the line to the secondary.

300TDT 1987 · #9 01-02-2012, 02:56 PM

Did have a Bosch primary filter in there and changed it to a non OEM one and got the same results.

I'm diving into this and ordering all plastic fuel lines and valve seal rings from/to the IP and secondary fuel filter. I will also get a new fuel pressure relief/over flow valve.

I think there may be a leak on the IP return line to the secondary fuel filter, it's awfully dirty and wet in that area of of the IP.

I'm assuming that the Lift pump is fine at this point. Can't find a rebuild kit anywhere so I'll do everything else but that for the time being.

Thanks to everyone, I'll let you know what happens.

ah-kay · #10 01-02-2012, 03:34 PM

IP leak will NOT suck air into the system. There is only a few places that can suck air into the primary filter.

1) leak at hose clamps on feed line/primary filter - possible.
2) leak at the hard feed line - unlikely.
3) leak at the tank and tank strainer oil-ring - possible.
4) leak at the tank stainer and tank outlet hose thread and barb - possible.

I do not know exactly what is the real problem but I would discount IP, lift pump. Lift pump is the only thing that can 'SUCK' air so your problem is from lift pump upstream. A clog line will suck air in by the LP, air enters at the place with least resistance.

Good luck.

sasquatchgeoff · #11 01-02-2012, 03:48 PM

Quote:

Originally Posted by 300TDT 1987

Did have a Bosch primary filter in there and changed it to a non OEM one and got the same results.

I'm diving into this and ordering all plastic fuel lines and valve seal rings from/to the IP and secondary fuel filter. I will also get a new fuel pressure relief/over flow valve.

I think there may be a leak on the IP return line to the secondary fuel filter, it's awfully dirty and wet in that area of of the IP.

I'm assuming that the Lift pump is fine at this point. Can't find a rebuild kit anywhere so I'll do everything else but that for the time being.

Thanks to everyone, I'll let you know what happens.

Email Phil for the kit. I know it is available - I have bought one. Made life much easier, but did not solve my problem as referenced in my other posts.

300TDT 1987 · #12 01-02-2012, 07:48 PM

Now I'm just getting more confused

I blew compressed air back into the tank from the hard fuel line.

Changed out all fuel lines again from hard fuel line from tank- primary plastic filter - lift pump.

Still had half fuel volume in primary plastic filter when I let it idle.

Then I got the bright idea that maybe because the car is just idling I'm not engaging the lift pump enough.

Drove around the block once and parked it again.

The results where strange, the plastic fuel filter had fuel half way up the internal screen (which has been the case) but there was fuel at the very top of the filter where it connects to the tank line. Not sure why that fuel didn't fall into the filter. (I've been keeping that filter as vertical as possible so it won't suck in as much air.)

Do I need to burb the fuel system or fill the plastic fuel filter with diesel before I connect it.

Not sure if the problem is before or after the lift pump, or the lift pump itself.

Before I make my order at Fastlane, I think I may try and drain the tank and check out the tank filter and see if it's gummed up.

sasquatchgeoff · #13 01-02-2012, 07:59 PM

Quote:

Originally Posted by 300TDT 1987

Before I make my order at Fastlane, I think I may try and drain the tank and check out the tank filter and see if it's gummed up.

Good plan. Now that you have blown the contents of the hard lines (if any) back toward the tank, you will want to get under there and dismantle. I had to rent a 1-15/16 socket to get the tank screen off. It was stubborn, but eventually with a brass-bristle brush & PB Blaster I was able to loosen the beast. I went the whole nine yards and got pre-made rubber tube connectors from the dealer as well - again, not cheap but they were due anyhow.

ah-kay · #14 01-02-2012, 08:23 PM

If you want to change out the tank filter then see my #2 post.

http://www.peachparts.com/shopforum/diesel-discussion/310633-tank-screen-location.html

The bubble in primary filter is normal. No one seems to be able to explain why the primary filter is always 1/2 to 3/4 full. I would not worry about. Do you see tiny air bubbles entering the primary filter now if you rev the engine by hand? If you do not then all is well. The orientation of the primary filter, vertical or horizontal, should not really matter.

btw: if you change out the line from tank filter to the hard feed line then you stand a very high likelihood of damaging it. It is very brittle if it is original. You can get a new one $$$ or just cut the crimp-on shell and replace it with a normal hose. It is just a barb and you can clamp it with a normal hose clamp.

Good luck.

300TDT 1987 · #15 01-02-2012, 08:46 PM

I'll tackle it tomorrow when I can see. This is a wagon, so I've already been under the tank and replaced the fuel line from the tank screen to the hard line. Fuel did seem to flow pretty easily and all over me.

Tried to replace the return fuel line to the tank but it was a different size so I just put the old one back on.

Found a 22mm flywheel bolt for separating my motorcycle flywheel, so I'll use that to get the screen out, I'll use my extractor to get as much fuel out of the tank prior to pulling the screen.

It's a messy job but I'm not paying anyone else to do it

Thanks again for the advice.