I have an 85 300SD with 219,000 m. Recently, I've noticed some hesitation above 60mp/h, which gets worse when the accelerator is further depressed. This also gets worse when the tank is less than half full. I'm wondering if it may be the fuel filter. I've seen a couple different types such as clear, opaque, and with brass fittings. What are the advantages of each if any?

Greetings,

When you speak about fuel filters, the one you are mentioning is simply a prefilter. I use the clear prefilter to see if algae or other foreign debris might be in the tank. If you haven't changed the main spin on type fuel filter, I would. Also as a indulgence to fuel flow I'd remove the rubber fuel line under the hood from the metal line coming from the tank and see if fuel flows freely out of that line. If you get no free flow of fuel, then I'd have to assume that your tank screen filter is probably clogged. Sometimes using compressed air on this line will blow the crud off of it, but the best measure is to replace the tank filter and also drain the fuel out of the tank. I'm not saying any of this will improve your performance engine wise but if there is a fuel flow problem, it needs to be fixed.

Charles

__________________
"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan

You have fuel starvation -- replace both filters and verify that you have good flow out of the tank.

Since you have more trouble with less than half a tank, I suspect you have algae and need to have the tank cleaned, at least use a full shot of fuel treatment and clean the screen.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

A cracked pick-up tube in the tank could be responsible for the change in performance as the fuel level goes down. Any time you ever have a problem that occurs in the upper RPM and runs well otherwise change the filters immediately. Put on a clear pre-filter and watch it for a few days. If you see ANY brown stringy snot like substance drop the tank and have it steam cleaned. An algae infestation unchecked will harm your injection pump. Hope this helps.