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Old 05-14-2008, 10:14 PM
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Join Date: Nov 2006
Location: Portland, OR
Posts: 100
HELP with fuel flow/oil pressure issues

I did a search and was able to come up with a couple ideas, but still have a few questions. I have a 1982 Euro 240td wagon (OM616 and 4 speed manual). Its been running well since I've owned it for the last year or so, but lately been having frequent stalling issues, especially upon start-up/warm-up/early idle situations. These engines are fairly new to me, and at first thought I was starting to experience clogged injectors, until I started looking a little closer.

The car will usually start (with a little hesitation most of the time), but within a few seconds seems starved for fuel and stalls. I usually have to lay into the pedal once it starts to promote fuel flow to keep it running although sometimes even that is not enough to keep it from stalling - it usually fights to stay alive (ie. hesitation and low rpm) until it either wins and has enough uuumph to keep running or it dies. I'll have to sit there at a very high idle for a minute or so until I can let off. So, after it stalls I'll pop the hood and start pumping the hand primer to get some fuel back to the system. I notice that the small inline clear filter is mostly empty of fuel, and even pumping (with the new style, non-screw type hand primer) like mad will not fill it and get positive flow. Now here is where a bunch of things come into play and some questions arise... I know I have rubber lines in need of replacement - they are definitely sweating fuel. Also, upon pumping I think I can hear air sucking through the rubber line that feeds out of the small inline pump and into the right/rear side of the fuel pump. I usually have to bend the line any which way to stop the air leak and then the hand primer wants to start sucking fuel from the tank side. After I feel good flow and the clear inline filter is full, the motor will start up (but sometimes still needs some pedal to keep it going until it warms up).

I'm now wondering how much of this is related to the lines, pump, primer, strainer at tank, etc. Both fuel filters were recently replaced. Now, this motor has 253,000 miles on it and burns some oil. At about the same rate that this stalling issue got worse over the last few months, it seems that the idle condition has gone down hill as well... Once the motor is at operating temp it seems to want to hold an idle and not stall, BUT the idle AND the oil pressure (according to the gauge) fluctuates. At this point I have my high idle dial turned all the way up but idle and pressure are all over the place... sometimes at a high idle where it should be, then dropping low (oil pressure directly correlated with idle), and up and down and up and down with no rhythm. When I first bought the car it did not need the high idle set and there was no fluctuation in idle or oil pressure and even when warm the oil pressure sat high on the gauge. Now once warm it will draw down and I'll get the corresponding rough idle.

So, after all that (!) I have a few questions:

Is the hand primer independent of the engine mounted fuel pump? In other words, is the hand primer used JUST for priming, but once the motor turns over the fuel pump is solely responsible for providing diesel to the engine?

How hard is it to access the tank strainer on a 1982 Euro wagon?

What is the most cost-effective material to use for new fuel lines (the lines to and from the filters and the small lines running to the injectors as well)? Keep in mind I run B99 when I can.

Will a good flowing fuel system play a role in maintaining good oil pressure (or, how much are they related???)? It will surely cause a smoother idle and allow me to not rely so much on the high idle setting.

My biggest complaints are not only dealing with a stalling engine and having to try to hand prime the system every time, but also having a REALLY rough idle once the engine is hot sitting at a red light or whatever. A few times it has hesitated so much once the light turned green that I've stalled in the middle of the intersection and had to coast through it - I look like I don't know how to drive stick shift as I give it a ton of fuel upon taling off. On a hill? forget about it!

Note: there is no noticeable hesitation when I'm cruising at high rpms down the highway. Only at idle, both with a cold and a warm engine.

Anyway, sorry for how long-winded this became, but I wanted you guys to have all the specifics.

THANKS for any help!

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Old 05-14-2008, 10:39 PM
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Join Date: Jan 2002
Posts: 18,350
Don't know about the oil pressure but the idle problems strike me as being caused by an air leak. Replace your lines and clean out your strainer. A plugged strainer could cause enough suction in your fuel lines to pull in air at a marginal connection. Strainer is easily accessed on the wagon. Drain the fuel by idling the car and running the return line into a fuel container until the engine stalls when the tank is empty.
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  #3  
Old 05-14-2008, 10:41 PM
t walgamuth's Avatar
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Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 38,611
Its a mechanical oil pressure guage so if the idle drops the pressure will naturally drop.

Have you seen any black dots in the first filter?

It sounds to me as if you have bacteria in the tank and its clogging the strainer. I would suggest a good biocide bought from a farm truck or marine service center. Water in the fuel either in your tank or from the station will allow bacteria to grow and clog things up.

Fuel is the most common defeciency in a diesel mb. Second is probably glow plugs which cause hard starting.

Good luck

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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