my 1985 240 wont start after sitting for a few weeks on the street, suspect fuel pump issues , should I be able to hear the pump whne I turn the key before I crank it ? it cranks ,it has fresh gas, any ideas as to what should I check?
thanks

"...should I be able to hear the pump whne I turn the key before I crank it?"

No, that didn't come in till 1989 with LH 2.4.

For openers, kneel beside the passenger seat to remove the black "hush panel" under the glove box and locate the white Fuel Injection relay. [Hopefully it's not dangling from it's wiring, lest it fills with water from a fairly common leak in that side.] Anyhow,hold it in your right hand while working the key with your left.

Can you feel/hear a click when the Key turns to ON?
If so, that's the FI System relay, 1 of 2 inside the white case.
If not, check the 25Amp blade fuse up by the coil. Also check the fuse holder for corrosion, and the red wire feeding the fuse from the Battery + terminal.

Now (still holding the relay) turn the key to crank and feel for a 2nd click as the motor spins over, Try it a couple of times to be sure.
You should feel the Fuel relay "pick" when the ECU gets "OK to pump" pulses from the Ignition CU.

Did the Fuel relay pick or not? The answer will determine the next step.

ORbypass both the 25 amp fuse and the Fuel relay by connecting a jumper wire between fuses 6 and 4, as in the photo below. BUT have fuse 4 in place and jumper to the left side of 4 (fuse 6 left side always has +12 Volts).

Try cranking with the 6-4 jumper and fuse 4 in place and let us know what happens -- start? try to start? nothing?

Photo pilfered from Art Benstein


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

Thanks Lucid , you're certainly helped!!
I tried the jumper method and it started right up even though it has not run for a while now:

what happens if I leave the fuse jumper cable in there?
dos this mean I need a relay? ( i did find it's location)
or what's next?

thank you so much
Rob

"what happens if I leave the fuse jumper cable in there?"

It will be OK for a while, but it eliminates a basic Bosch FI circuit safety feature that prevents fuel pumping when there is no spark. (I should have mentioned that the pumps run as soon as the jumper is in place.)

"dos this mean I need a relay? ( i did find it's location) or what's next?

We'll have to narrow it down to (1) the 25A fuse, (2) the relay, or (3) a failure of the ECU to energize the fuel relay.

Are you comfortable with simple wiring? Like making up a ground wire maybe 2'long and connecting one end to a grounding screw or bolt and putting the other end into the BACK of the relay harness plug where a Blue-Green wire is attached? Or making the same connections with a 12V test light similar to the one below from IPD or most auto supply stores?



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

The ECU rarely is the problem on this year car so I would start with the 25 amp fuse and holder. The connection at the battery's + post and the legs of the fuse holder must be good tight and corrosion free. It might be best to replace the fuse holder with a new marine grade unit from radio shack or a marine supply store.

You may be able to re-solder the circuit board on the relay and salvage the relay. If you don't solder just replace the relay. One of these will fix your problem, if it were me I would do both to eliminate two common problem areas.
Dan

I overlooked the fact that the ECU problem came with LH 2.4, and that the LH2.2 ECU has a good reputation.

But I think we can skip the 25 Amp fuse here too. Because the car did start with fuses 4 and 6 jumpered. That means the ECU and AMM got +12V from the System relay, which gets energized by (and "relays") voltage from the 25 Amp fuse.
[The 4-6 jumper gave us pumps, injectors, IAC valve, and O2 heater.]

So, as you point out, that leaves the Fuel relay as the most likely suspect.

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

Good morning, Bruce.

You helped me through a similar problem with a 1988 240 some time ago.

I had a buzzing fuel injection relay. That car would start and run only with the jumper in place. A test light showed 12v being supplied to the relay from the battery via the 25 amp fuse. Turned out to be high resistance in that wire at the battery due to corrosion working its way up and under the wire's insulation. 12v was present but not enough amperage to close the relay.

I thought the 4 to 6 jumper eliminated the need for that 12v to the relay, but your post today indicates otherwise. Looking back to my resistance problem is it fair to suggest that the 12v that was being supplied through the wire with the 25 amp fuse was enough to close one of the circuits in the relay but not enough to close both?

Randy

"...is it fair to suggest that the 12v that was being supplied through the wire with the 25 amp fuse was enough to close one of the circuits in the relay but not enough to close both?"

Good question Randy,

Right now, as I look at my diagram, I'm not sure how the 4-6 jumper overcame your 25A fuse problem. The jumper effectively puts unfused 12V on the output of the Fuel relay (87-2) only, with no direct path to the System relay output 87-1. Maybe taking over the Fuel-related 87-2 circuit load did allow the System relay (and it's ECU, AMM load) to operate on the marginal 25A current.

I do know that the 4-6 jumper will not allow a start with a totally dead System relay. That's what led me to make a 3-legged or "Y" relay socket jumper, taking 25A +12V from relay 30 to both 87 terminals, as I've posted on a couple of times. And after needing it on 2 family LH2.2 cars.

Here, although with no buzzing relay symptom, I guess the 4-6 jumper might possibly "off-load" enough of the the "heavy lifting" to let the System relay to get by with sub-par current capacity from the 25A fuse. In any case, on a 25 year-old car it's time for a close inspection.

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

Although the 25 amp fuse may not be the current problem for $8 or so you can get the weather proof marine fuse holder and never have to worry about that fuse again. Unless it blows someday.
Dan