I have a 1984 245 with the B23F and LH 2.0 and I believe I am running into a fuel starvation problem. The car has a top speed of about 60 mph on a level road and less with any grade or headwind. I have personally seen older 240s do better than this! My can also feels restrained and it occasionally jerks under load, which both point to a failing pre-pump. I am planning on replacing the main fuel filter and in tank sock to remove them as possibilities (the PO claims to have replaced it within the last three years...). However, I am thinking of replacing the in-tank pump with the larger one from Ipd. Has anyone done this and would they comment on the upgrade? Is it possible to get too much fuel to the main pump? Is the upgrade really neccessary or should I say benificial for the LH cars? The website cites an improvement to K-Jet cars...
Confused in MT,
Nick

Thanks to all for the advice. As soon as I get the car back from the shop (brake work I didn't feel like doing in the cold...), I will run the test discussed here and post with my findings.
Thanks again,
Nick

The flange of the in-tank pump/sender can rust causing the grommet of the wiring harness to appear ok but the copper wires in the grommet can corrode and not allow current flow to the in-tank pump. It's not always the pump itself.

Sorry for the short post but I'm typing with a broken hand,

Just replaced my prepump,found an hole in rubber hose,I have an 84 244 GL.It allso was running poorly under a half tank,Man Iam glad I did not take it to the shop,I replaced the pump anyway.

I agree with the more senior members previous comments as the symptoms you describe do not NECESSARILY point to a failed/failing pre-pump. But I would add that if you are going to the trouble of replacing the in-tank pump, why not use the IPD upgrade kit? I did in my two 940's as the first two direct replacements I purchased from FCP groton died inside of a month and I was desperate not to have to do a third time. I called and spoke w/Ken at IPD who advised me of an old TSB that had recommended the upgraded pump in such circumstances in the 240's. It worked, both upgraded pumps have been in service for over a year. I am sure it was a flukey bad batch of pumps from FCP but regardless the kit from IPD come with the sock, a new length of rubber fuel line to replace the piece in the tank that rots, nice stainless band clamps, a new rubber O ring seal for the sender and of course the bigger pump. 80$. Not unreasonable. On my 940's it required very little additional effort to install.
Matt

sounds like it could be as simple as wet gas. Montana mandated E10 yet? I just went through it with half the vehicles in the fleet here.

Oilspot

Hi Nick,

You don't need an upgrade, you need it fixed. To diagnose fuel delivery, first rule out the hose in the tank by observing the same condition while the tank is full. With a full tank of fuel the main pump will suck what it needs past even a stalled tank pump.

Then ensure both pumps are getting electricity. The easy, but not 100% thorough way to check the main pump, is to check the voltage at fuse 5 (outer terminal). The thorough check has you under the vehicle at the pump terminals - not a bad idea if they might be getting dirty. The tank pump is fed from fuse 5's inner (load side) terminal.

If you can't see a problem with the pumps, do a volume check from the return line under the hood. With a short length of hose, run it into a gallon jug. You should see a flow rate to fill the jug before your back gets sore from bending over the motor. A clogged filter will result in a spindly flow and no hope of filling the jug anytime soon.

Now, if all is well, you've done the easy stuff, and you need to disconnect the cat to see if it is constipated.
--
Art Benstein near Baltimore

Annual Performance Review Time...
"This employee should go far, and the sooner he starts the better."

Besides checking the voltage, per Art's suggestion, you can also check the amperage (use your VOM across the empty terminals (remove fuse) -- Bentley has some specs for what's normal.

The intank pump just keeps the main pumped primed, the main pump does all the work. I would look at the cat converter to see if it is plugged. Dan