1980 242 DL B23F 134k miles refuses to start. Battery fully charged and engine cranks vigorously. Has gas and spark. Fuel pumps out of fuel filter when fuel line disconnected and fuel pump buzzes. Bosch control pressure regulator 31 Ohms of resistance so replaced and new regulator has 19.6 Ohms of resistance. Pressured system before attempting start. Fuses are fine. Have CIS fuel pressure kit, but adapters do not fit fuel line at control pressure regulator where that fuel line connects to fuel distributor. Also, tested voltage in wires to control pressure regulator but unable to get reading when key turned just shy of start. Car starts for 1-2 seconds with starter fluid.

No miracle cures here, but I can comment on 3 items that might eliminate some distractions.

1. CIS gauge pressure adapters: Assuming none are missing, have you tried using the long (3"±) in the top (horizontal) fuel distributor fitting? I've done it that way and it leaves a short one with the same threads for the smaller CPR port.

2. Control Pressure Regulator resistance values: Forget them for now. They have nothing to do with cold starting. They just reduce the time needed to lean out the mixture for warm running, as opposed to waiting for ambient engine heat to take its effect.

3. Car starts for 1-2 seconds with starter fluid. Sure sounds like a lack of fuel. Try bypassing the fuel relay by jumpering the LEFT side contacts of fuse 7 (key-on 12V) and fuse 5, a point that leads to both pumps. and try starting.
NOTE: This will NOT completely bypass the FPR, because it won't send "bypass" voltage to the 2 heaters in the Aux Air Valve (AAV) and CPR, nor to the Lambda relay and ECU. But I don't think any of these come into effect for the first minute or so on a cold start anyhow.


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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Thanks! There's no fuel going to the main fuel pump, as I removed the fuel line going to it and it was dry. This suggests that the in-tank pump isn't working. how do I diagnose it, and remove the hose on the far left that has black inner plastic/rubber sticking to the metal part of the in tank tip?

"...the in-tank pump isn't working. how do I diagnose it...."

1) Reconnect the feed hose to the Main pump in case the Tank pump runs when 12V is "hot-wired" to it in Step 2.

2) Apply 12V to the Tank pump by removing fuse 5 and jumpering 12V to the RIGHT side contact and listen for the pump to run. Get the 12V from the LEFT side of any fuse 6 – 10.
[Fuse 5 is removed to isolate the Main pump from the applied 12V at this time.

How to "remove the hose on the far left that has black inner plastic/rubber sticking to the metal part of the in tank tip?"

Be careful taking the hoses off the sender pipes, which are probably very fragile by now.

For the Output (larger) hose, the clamp will probably have to be destroyed. I use a small, fine-toothed hacksaw to cut thru the clamp at an angle, then work the hose free by prying with a small screwdriver. The feed hose is usually long enough to trim some off, if mangled.

For the Return line (rubber sleeve over thermoplastic line) I saw the sleeve and line off at what I judge to be the end of the metal "barb" fitting.

To reinstall the Return line, I cut the outer sleeve back about 2" to expose that much of the plastic line, then "splice" it to the senser barb with a short piece of 5/16" ID Fuel hose (30 R6 is OK here) and two FI hose clamps. The return pressure is quite low, and this splicing method has worked for me several times with no problems.

When the sender is out, you may find the short internal feed hose on bad shape like the one below. If so, even a working pump can't put much out when the fuel level is low. The picture is one of many (MANY) in Art Benstein's detailed ''In the Tank'' photo essay, well worth reviewing before wrenching.




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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

You said that the car has a B23F engine, which uses LH-Jetronic electronic fuel injection. A stock '80 240 should have a B21F with K-jet (CIS). This does make a difference as far as trouble shooting. Has the engine been replaced?

Sounds like the fuel pump relay is good.

If fuel pressure is normal and you have spark, check the timing belt. Remove the oil filler cap and have a helper crank the engine. Look to see if the cam turns.

My adapters don't fit on the control pressure regulator

I removed the fuel injector #2 and started the engine. No fuel came out. I already changed the control pressure regulator, which had a normal resistance of 19.6 Ohms. I tested the wiring to the control pressure regulator with the ignition key turned on, and got 2.3 Amps, but was unable to obtain a voltage reading.

Sorry, coffee didn't kick in! It is a B21F with CIS injection. Will test timing belt

I would remove the cold start injector and check operation into a bottle when cranking.

Thanks.