1985 300TD Will Not Start - PeachParts Mercedes-Benz Forum

dennislarock · #1 06-10-2008, 09:10 PM

1985 300TD Will Not Start...

I changed the primary and secondary fuel filters (because I had them) even though the car was running perfectly. Filled both new filters with diesel fuel and replaced. Hand Primer does not seem to work, I don't feel much pressure when I pump it... no bubbling when filling of primary filter (so I sucked it in from the fuel tank) but there is no diesel leaking when I pump the primer. Additionally, I pumped the hand pump at least a hundred times on 3 occasions. The lines to fuel tank and the fuel tank screen are clean. Fuel just isn't getting to the engine or rather injectors?

Any thoughts (aside from if it broke don't fix it) would be greatly appreciated.

Thanks

Dennis

Chad300tdt · #2 06-10-2008, 09:22 PM

You could try cracking the injector lines and cranking it over for a while to see if the air bleeds out. It sounds like you need a new primer pump, but I would think you'd see some leaking there too.

I upgraded to the new Bosch primer pump and haven't had any problems since.

Good luck. I'm sure others will give some ideas too.

jt20 · #3 06-10-2008, 09:24 PM

you did fill the screw-on first right? Def. crack the lines.

Chad300tdt · #4 06-10-2008, 09:28 PM

BTW, welcome to the forum Dennis ... and post some pics if you have any. I love seeing other wagons and so do quite a few other members.

dennislarock · #5 06-10-2008, 09:34 PM

Yes... screw-on filter is filled to the brim. Should I crack an injector or just pull one of the braided lines???

Thanks for thinkin!

Dennis

dennislarock · #6 06-10-2008, 09:43 PM

I'll get some pictures up tomorrow. Paint is a little faded but not a spec of rust anywhere, interior is clean with no rips or wear and no cracks in the dash, SLS, cruise control and A/C work perfectly. Original radio and all vacuum and electrical work great and there are no engine or tranny leaks. This is the first problem I have had.

jt20 · #7 06-10-2008, 09:45 PM

no. .crack the hard line at the top of the injector (the nut) Not necessary to totally remove, but loosen it well. After you crank a few times take a look for evidence of delivery. Search the forums for air in the lines. I have read numerous stories about this causing issues.

When was the last time you had to use the pump?

dennislarock · #8 06-10-2008, 09:56 PM

When I bought the car 2 years ago I changed the fuel filters. I had to coax the pump for a while to get it to work... and then it worked fine. Last year I changed the fuel filters again but did not have to prime it although I did pump it 6 or 7 times just to make sure it worked. ***Maybe if I bleed the lines the pump will work*** as it does not seem to leak. If not I will replace it. Anyway, I'll be on it first thing in the morning and report back.

Thanks for all your help

Dennis

Bajaman · #9 06-11-2008, 07:24 AM

Get a new primer pump, and sometimes I find that you have to loosen the check valve on the back of the IP if there is a lot of air in there. Too much air, and you simply can't build enough pressure to force fuel in. Bottom line, if you don't hear the check valve buzzing when you pump the primer, it's not getting fuel.

dennislarock · #10 06-11-2008, 10:20 AM

Good Morning. The pump actually seems to be fine, however the housing that it fits into seems to be blocked, broken. I put the pump against my cheek and it blows and sucks holding onto my skin. I removed the housing, screwed the pump back in and attached the fuel line. You can not blow or pump through the housing??? Thoughts.

Thanks

Dennis

dennislarock · #11 06-11-2008, 10:50 AM

OK... the housing (fuel pump). I disassembled it, cleaned it and... THE PUMP WORKS!!!
Doing the reinstall now!

Thanks

Dennis

Chad300tdt · #12 06-11-2008, 11:15 AM

I thought it was weird that there were no leaks at the pump. Good catch Dennis.

dennislarock · #13 06-11-2008, 01:28 PM

Up and RUNNING!!! Valves in the fuel pump were stuck... not sure why it even ran but its all good now!

Thanks to everyone for your help!!!

Dennis

mobetta · #14 06-11-2008, 01:45 PM

that's a first for me to hear that one- good work ironing it out....

dennislarock · #15 06-11-2008, 03:28 PM

Just a little clarity... see the attachment for the part (primer pump assembly) that I disassembled and cleaned. There are two (2) valves inside that were stuck. Once cleaned I placed the hand pump back in and it worked!

I then reinstalled the primer pump assembly, filled the filters with diesel fuel, cracked the nuts on two injectors and pumped until the injectors started to seep a little fuel. I tightened the nuts and it started right up!!!!

Thanks to all!!!

Dennis