This message was posted yesterday in the "Stories" forum; I wasn't quite sure which one to use, but a reply suggested I should repost this here. A couple of new comments have been added.

Current problem: car won't start; ingition system and starter seem to work fine as far as we've been able to test them: engine turns over and sounds strong but will not catch at all.

Recent history (which may or may not be related to current problem): Car had been running a little rough and had trouble starting in cold weather. Spark plug to 4th cylinder was fouled, so replaced all plugs. Seemed less rough but the cold start problem continued. Replaced distributer cap & rotor also. Checked for good spark and proper firing order. Checked compression, too, just to be complete. No smoke problems bty or any more evidence of fouling on plugs. Cold start problem continued and a few days later wouldn't start at all.

What we've checked: fuses incl the 25A fuse under hood - all OK; fuel pump relay and wiring to it: all lines appear to be connected correctly and receiving voltages, coil pulse, etc., as much as I can test with an multimeter; the relay does NOT latch when the ignition is turned on; the fuel and tank pumps do NOT turn on (at least I can't hear any noises) when (a) I push latch on manually (with eraser tip) or (b) I remove relay and jumper across the same terminals that are connected when latch is hand-closed. I haven't tried resoldering relay since continuity checks all look "good." Fuel filter is old I know but not sure when was last replaced.

Misc comment: the 1990 Haynes guide we have is terrible; we've ordered a new Bentley guide for the 240 series. If this problem turns out to be in the fuel injection system, does anyone know if the Bentley guide treats that well enough on its own or would we need to buy a separate fuel injection guide, e.g. the Bosch guide pub. by Bentley??

Questions: ?? Anybody have an idea? Any electrical or mechanical components/systems/wiring that you can think of that should be checked before we meddle with the fuel systems?? Could a plugged filter cause the fuel pump not to work at all (high pressure prevent priming action) and even so why wouldn't I not hear the tank pump work?? Would a faulty fuel pressure regulator prevent the pumps from starting at all? Is there anything else re: the ECU that should be tested re: the problem??

Thanks a bunch.

Sounds similar to a problem I had '88 245. As I recall, fuel pump only recieves voltage when starter is cranking or the engine is running, so you will not hear the pump just by turning on the ignition.

Do you get a fuel smell on the plugs or from the tailpipe after repeated starting attempts? If yes, pump probably works, it should at least try to fire. If no smell, no gas. If gas is present, look for ignition problem or compression problem. How many miles on the car?

Try this with a helper: disconnect leads from fuel pump and check for full voltage while your helper cranks the engine with the ignition key.

If no voltage, try replacing the relay. You could also do the same test, looking for voltage at the relay. Also, hold a finger on the relay as it is cranked. You should feel/hear it click when ignition switch goes to "START" position. If no, replace the relay. I think it's only about 45 bucks.

We're having a similar problem with our 1985 240 wagon. It will sometimes start but runs rough and stalls within 10 seconds and once that's happened it won't start again. We do have fuel going in and smell gas, seem to have spark, we've cleaned and gapped spark plugs but we're not sure if they're connected in the right firing order. Can you tell me the right firing order, can't find it in the Haynes manual. Is this the correct order?

Eng dist

4 2 3

3 1 4

2

1

fan

The firing order is: 1-3-4-2. Looking down on the distributor, plug wire #1 is closest to the front, and closest to the engine. The distributor rotates clockwise when viewed from above.

A reasonably common failure that can cause the symptoms you're described is a failed fuel pressure regulator. It can fail two ways—one way is a pinhole in the diaphragm, which allows raw gas to be sucked into the intake manifold. The other way is that it stops regulating pressure, so that full pump pressure goes to the injectors.

A quick test (for the first failure mode) is to pull the small vacuum hose off its nipple on the manifold, and watch for dripping gasoline.

Don Foster (near Cape Cod, MA)

Cathy:

My '85 245 once gave me a series of "no starts" due to a low battery. There WAS visible spark at the plugs and the engine turned over, but apparently there was insufficient voltage to run the tired fuel pump (I had to replace it shortly thereafter). Anyway, a jump would usually get me going. Will your car start if jumped?

Also, you might try disconnecting the Air Mass Meter and try starting it (do not disconnect or reconnect the AMM with the engine running). If it starts and idles with the AMM disconnected ("limp home mode"), you may be looking at replacing your AMM. Yours should be an 007, which are fairly plentiful in the junkyards (any '85-'88 240 or NA 740). Haynes, despite its shortcomings, does contain a set of resistance checks for the AMM that you might want to try.

Another check for pressure regulator is to dis-connect fuel return hose at regulator and install a long enough length of hose to reach a container (at least one gallon) Holding hose in container have someone start car and see if hose discharges a full stream of gas. If not regulator is not working and full pressure is going to injectors. This can also make frame mounted fuel pump run noisey. A better way to test is with a pressure gauge. Due to specail fittings used on fuel system pressure gauge is not easy or cheap to install.