long time since I've been on this board. The issue I'm facing is on my '88 240. Recently the car would not start. Just crank. I always look to the fuel pump relay in this situation on a 240. Reach under the dash and sure no click. I keep jiggling it around and still no start. Next day after trying a few different relays and more jiggling it clicks and subsequently starts right up. drove it around a couple more days and then a total no start again. I did notice that there was a bit of buzz from the relay but not that firm click when things are correct. Finally after a week it started again and I drove it around for a couple hours. It still starts but I haven't moved it in a week.
Question: Could it be the ignition switch itself?

how old is the fuel pump? maybe it's rubbing or encountering some sort of physical resistance and drawing more amps than it should. There might be a way to check the amperage draw and see if that's normal but I'm not sure what the normal amperage should be.

It easy enough to pop off the cover and you can clean the contacts in the relay if you are stuck, I sometimes just cut the little uninsulated braided copper wire so i can remove the contact from the rest and get in there better to clean it, then repair the solder afterwards. Best to just change the relay, that works if you are stuck on Gilligan's island.


ifI'ts an 88 240 the fuses are below the windshield and can be exposed to moisture from a leaky windshield or maybe the sunroof drain. You can blow those drains out with a water bottle , squirt water down the channel with compressed air chasing it and that will blow any dirt out of that drain hose.

what I'd suggest is this:
unhook you battery, write the fuse values down or look at the cover to make sure it makes sense.

pull all the fuses, there are two phillips screws holding that fuse holder, just a couple of the fuses block access to the screws...

remove them and you can pull the whole works out about a foot or so for access , then since the battery is disconnected you can clean them all up well with some steel wool or a wire brush and some deoxit maybe..

and check all the little spade connectors. I've seen them go green and have bad contact near the fuse.. Ive seen where the power was split off to run two or more fuses and had an issue there. It was a bit hidden until I removed the fuse holder and checked a bit deeper than just the fuses themselves.

if the spade connectors or the fuse spring things get hot and then are quenched , like using a wet rag that will remove the temper from the spring and they can be weak, if you want you can reheat and let then cool slow to restore the temper or springiness to the metal. If you heat and quench copper or brass it removes the hardness and then they are limp. I have found weak ones and then they dont put much pressure on the fuse and cause issues.


I'd change the fuses or if you are on a remote uncharted desert island you can clean them. A dab of dielectric grease can help so they don't keep going bad. all those euro style fuses are quite prone to failure in a 240.

on mine the windshield leaked and i didn't want to by a new rubber gasket to remove and replace the windshield so I put masking tape along the chrome strip and on the windshiled leaving just about a 1/16" gap there, then I took a putty knife and shoved a whole tube of glass sealant down that crack under the chrome strip. it helped a lot.

If I want to do it right I figure then I'll cut he rubber and wash the chrome in solvant to remove all the sealant. if I remove the chrome, the rubber is so hard it'll just get bent up but i can remove the rubber if I use a box cutter and dont plan to try to save the rubber.

on the 740 they moved the fusebox to the middle where it's dry but than it became harder to access.. I think they fail less often in there because it's not such a wet area.

and yes about the hall sensor in the distributor, the O ring fails and pressure from the crankcase gets oil up in there and that sensor can fail and cause starting issues or rolling to the side of the road dead.

you can rivet on a new sensor , If you can find one and the rivets. you can change the plate in the distributor if you get a new sensor along with the sensor. or I bought a really cheap chinese 100 dollar new distributor cap and rotor from rock auto.. It will work but I dont trust those aluminum terminal distributor caps for very long , they tend to corrode and eat themselves up.

you get what you pay for but if you have another distributor that works it's easy to just plop the new one in to see if that's your problem. really you should check the timing after, but It' ll start and run if it's even close.

If I change pumps I like to solder in a pair of wires ( in parallel) and run just a very low watt indicator bulb from the pump wires so I can see at a glance if the pump has power.. Then if I have start issues I dont even need to consider the relay ,unless my indicator is not on.

you can check fuel flow by unhooking the fuel rail and run it into a container, careful it pumps a lot and fast.

If you remove the pump fuse ( it might be fuse 11) then you can see if there is still flow from only the prepump. you can isolate the main pump for this check by removing the fuse.

if the pre pump fails it will still run but you will have trouble once you get low , below about 1/2 tank. a test for a bad prepump is fill the tank.

If you want to change the pre pump I'd siphon all the gas out first to a gas can, put it in some other car.. you can buy fresh gas then.

the engine might fire or sputter with a dead main pump but I don't think you will ever start it if that fails.

usually you can hear the pump run just after key on until the fuel rail is pimed.. and you can hear the prepump if you listen in the gas cap .

the fuel inlet screen is plastic and they turn to rubbish in the tank. It is part of the fuel sender. you could also get a plugged filter.. If both pumps run and you have low flow check the filter. Its just as easy to change the pump and filter as it is to just change just one of those, so If I did one , Id do both unless it was replaced.

on the fuel rail near the front of the car you will have a fuel pressure regulator, it will have a small line to the manifold, unplug that line if gas comes out, the diaphragm in the regulator probably failed, if that hose is loose fitting fix that.

If I have start issues I;d check if the pump can deliver by pumping to a suitable container, be careful not to overfill it and cause a fire because that pump can pump a litre a second or so.. lots anyway. a lot more than the car ever uses, most is returned to the tank.. so be careful you don't overrrun the container and cause a fire. there is probably a flow spec but just assume it should be lots of fuel not just trickle.



also check if there is spark Just connect a plug or a timing light and crank to check there is spark ( and do not do this near any open raw gas)

absence of spark or absence of fuel will cause start issues and you can work back from there if you find either to be an issue. try not to go in both directions at once.

if you think you have fuel delivery issues you cna try having a helper spray quick start in just past the air mass meter. it should start and run if they keep spraying , that's a way to troubleshoot if you had a fuel delivery issue.

if it wouldn't start and then you use quick start and it starts and will run as long as you spray that in , it will replace the fuel and should run enough to prove that fuel delivery and not failure of spark was your issue. If it wont fire with that sprayed in then its' probably a spark issue or maybe the plugs are wet with extra fuel from trying.

you can pull the plugs out inspect and dry them if you think you have flooded the cylinders, that may happen if you have no spark and keep trying until there is a lot of gas in there. look at the color of the plugs and that may give you an indication if you see differences or other than a normal tan appearance.

I had some where I noted insulators were cracking and a while later.. It bothered me why? but later I had a head gasket issue. I think the water was wetting the hot plug and cracking the insulator before I saw signs like water loss and overheating. with a cracked insulator the spark can jump from the electrode to the outside of the plug wihtout sparking much. it's a rare problem .

a stuck injector can cause way too much fuel in one cylinder. if they dont shut off then the fuel rail can empty through the stuck injector upon shutdown, and flood that one cylinder, then you may start and notice a bit of a white cloud and low power for a block or so until it clears all that fuel out.

just behind the distributor on the top of the bellhousing you will find one 10 mm head bolt that holds the TDC sensor. I'd replace that if it hasnt; been done, the sensor is prone the the engine shaking and oil in the area and the wires can go brittle or the sensor may fail. if the sensor works, turning the engine over may make the tach or speedo bounce. once per revolution. if that sensor fails the engine can't run at all, it needs the pulse to run.

its a little tight you can either use a small wrench or a couple of extensions and a universal and a 1/4" drive 10 mm socket. the wires for the distributor sensor get exposed to the shaking and oil presence as well.

" just behind the distributor on the top of the bellhousing you will find one 10 mm head bolt that holds the TDC sensor. I'd replace that if it hasnt; been done, the sensor is prone the the engine shaking and oil in the area and the wires can go brittle or the sensor may fail. if the sensor works, turning the engine over may make the tach or speedo bounce. once per revolution. if that sensor fails the engine can't run at all, it needs the pulse to run."


I have to correct that. the above only pertains to an engine with the TDC sensor and not your car..

If the distributor is at the back of the engine than its using the hall sensor in the distributor. That's how your 88 is . in 89 they switched to the sensor on the bellhousing and you will not have that. engines that had the sensor on the bellhousing had the distributor at the front of the engine.. both may be able able use a similar ECU but the ICU will have a different plug on it. i think turbos had a difference in the ECU.

I have an 88 740 and a 89 240 and i can start either car with either ECU but I can not swap the ICU. most of the rest is all very similar.. 89 wont have the blinky code reader box , 1990 did.

I like the 240's more, unless I'm changing the heater blower fan.

you cna have alook on the inner fender on the drivers side, close to the coil. You shoulds see two red wires (one might be red and white I forget) thye go into a white plastic fuse holder. It might be called an "engine fuse" or similar. check that fuse and inside the holder. Ive sen 240's fail to start due to corrosion there.

I also had a no start caused by the threaded terminals on the coil. the coil was ok and I had cleaned up the connector that bolts to the coil's terminals. the problem was actually bad contact between the threaded terminal on the distributor and the brass part that the spade terminals fit onto. the problem was that the threaded "studs" sticking out of the coil had become rusty , they aren't brass or plated. I just needed to clean them but finding that sent me in circles for a while. Id encourage you to actually remove the 2 nuts from the coil terminals instead of just checking with a meter , at least look for rust there.

Just for kicks , if it wont start try unplugging the air mass meter. with that unplugged it should start and run lousy as it will be in limp mode. My brother had that issue and got himself home by unplugging the AMM.. I think his Air mass meter went bad, it might have just been a bad connection at that plug.

he proceeded to put carbs and a earlier distributor and a smaller fuel pump in.. left the pre pump alone, he removed the computers entirely.. you need carbs, a carb style intake manifold and old style distributor , points or a simple spark box and distributor from about 1974 should work.. It takes a bit of doing but after a weekend or two he had his car upgraded to points and was able to chuck that nasty computer, the AMM, the o2 sensor and all it's complexity away. a bit less power, but to be able to throw out all that over complicated electronic garbage is a nice upgrade for an older car. he did 3 cars like that. Older Volvos had way less of these mysterious and frustrating no-start issues.

The ignition switch is a possibility, but very rare. As Randy suggests, most of the troubles arise from the large red wire bringing power to the fuel injection relay from the battery. At the fuse holder. The fuse will be OK, not blown, but there are so many metal-to-metal connections in that wiring at the fuseholder and the red wire terminal, corrosion is suspect, especially in the area prone to battery acid fumes.

Corrosion at a connection will cause high resistance. When a relay buzzes, that's a clue there's high resistance in the power supply circuit. The relay closes, making connection to the load it controls, instantly dropping the voltage holding the relay closed. It opens, and repeats, forming a buzzer.

Checking for power at the AMM's orange wire, as Phil mentioned is one way to assure yourself that red wire through the fuse AND the fuel relay are doing their jobs. Check for power there with the key on. Until you have it, troubleshoot the red wire and the fuel relay.




--
Art Benstein near Baltimore

Check the fuse in the holder that is in line with the heavier red wire coming off of the positive battery post connection.

Also check the condition of the that wire near its connection to that cable. I once had corrosion working its way up that wire under the insulation. It was enough to increase the resistance enough not to cause the relay to close.

Randy
--
Any twenty minute job is just a broken bolt away from a three day ordeal

Hi,

Did you check the sockets terminals themselves as they could be corroded or have gotten hot and lost tension in the female spades
You could have a bad ground circuit out of that socket as well. Look for heat yellowing.
The fuel pump draws a lot of current and it does appear you are wiggling something, doesn’t it?

Since it’s a dual relay, It also gives power to all of injection system components. Starting with the AMM

The cleanflametrap.com site covers putting a test light on a orange colored wire out there on the AMM, to see if it’s turning on the whole injector system while cranking.
His whole site is a good read or study from the inside out.
Art knows when or if that color changes on other later years.

This car I believe was the last distributor driven ignition system. Be suspicious of a bad hall sensor especially if you are losing ignition spark during cranking.
Failure of either causes a no start.

At least this car it is not one with a Crank Position Sensor and the electronic spark relay off behind the battery. These EZK systems act the same way but you have clear the “system relay” of errors like you are doing.

Glad to hear from you and any 240s still in use.
Visit us more often as it helps to keep the BRICKBOARD lively.

Phil