Appreciate your patience. This is an old intermittent problem never resolved. My 1990 240 right now won't start. That's good as this problem has been longstanding, intermittent, and only manifests itself rarely. It was running earlier today and when I went out to start it tonight, it would only crank. I broke the fuel line and saw no fuel. When I turn the key on I can hear the fuel pump relay click but the main fuel pump does not come on (I can usually hear it run for a few seconds as it pressurizes the line). It is a new pump and relay so not worried there. Somewhere a signal is not getting to the pump to allow it to start and that condition is intermittent. The fuel supply has also cut off while driving and I believe it's the same problem. I need to better understand the fuel circuit wiring to understand where a break or interruption might be. I'm not sure where to find a wiring diagram but will google it. Other than a break in a wire affected by temperature or vibration, what else might be in that circuit that would deny the fuel to run? Could it be in the ignition switch? Note with the key on I pulled the plug to the amm and checked voltage. I only found voltage on the orange wire (which was the last wire closest to the radiator). Anyway I know I still haven't run down other old issues here but haven't had the time. But still appreciate any current thoughts. Best Regards. Mark

All is well. A couple days driving and you can tell the difference even in the idle. After all this time the problem seems to have just been a bad connection at the actual fuel pump connectors, explaining each past circumstance I can think of. Special thanks to MachineMan Phil and Art for their help, as well as thanks to everyone else that responded. In the end it was basic.

Now that I have confidence in driving it I can focus on the other things that it needs (drift in steering to the right, some other funny noises underneath, continue to work on getting speedometer/odometer going. So I will be back. Sincere thanks again. Mark

Hey, glad to hear success!

After seeing Art's post it reminded me of my scenario that was just as basic too!

Yep, it seems it's the basic things that get us when we think it's all complicated.

Troubleshooting requires forethought......
"Maybe it's like trying to cross a creek on stepping stones.
It's best not to think of only one way to get across from your side, but back from the other side."

Thanks for the post back and update!
It help to make us all sharper.

Phil

Have you verified that the main fuel pump is getting a good ground? If you pull the rear seat bottom you should see wires coming up from the fuel pump on the drivers side that has the ground wire. Possibly rust or oxidation has made the contact poor.

GOOd idea. I will look tomorrow.

Crank position sensor
--
89 240 wagon, 94 940, 300K, 94 940, 141K

thanks for the input

Hi,
I can try to give you a few clues and tricks I have used.

I have seen your earlier posts, over time, so this thing is really being a bugger!
I agree that this thing going dead is now an improvement.

The relay gets turned on only by the ECU, to pressurize the fuel rail without the CPS. It's a one time event each time the key is turned completely off and back on.

Upon starting, if and when the engine turns over, the CPS sends a signal to the Ignition CU and then ICU sends a signal to the ECU that fires the relay closed.
The orange wire in the AMM is powered by the ignition switch
This wire does power to several other devices on by the key switch.
But most importantly is the ground side of circuit that goes to all of the fuel injectors. It is turned on through the relay!
This is done In case the engine fails to report that it's turning, by the CPS, the ECU turns off the relay!
This opens the real important fuel injectors grounds, for safety reasons.
Of course the pumps will also stop.

In some rare cases, the ECU can be the cause of the car dying randomly.
Also Known to start right back up too!
I have read about 1989 having these. Early run 1990's may be too!
Have you tried to upgrade the ECU to a different number of a later year unit?
Substituting might be a soulution or a trouble shooting method since it has finally died.
Scientific troubleshooting requires one to only change one thing at at time until some happens the way you want too!
Today's spare parts in a tool box auto mechanics and a few Engineering num nuts have relied on this fact since they started scratching their .... um ... heads!

As I started to say, the ECU then in turns closes each injector (in pairs) by grounding the opposite side. The reason why you need good grounding to the engine and body of the car that the ECU and ICU are connected too!

So you say you have put in a new relay and fuel pump and you are sure it must be resolved and I agree that is some reasonable logical thinking.
The only thing left from that point to be bad would be the cars wiring of the relay socket terminals or power from the fuse panel.
The main pump draws a lot of current so that all terminals has to be clean and tight. If it has overheated it may not be tight so if you have not inspected it carefully it might be beating you up.


You said you are wanting to go after the fuel system on the assumption you are not get fuel to the rail. I assume you are checking for residual pressure.
Have you buzzed the pumps on with the key and with the line already cracked first?
I think you would be better served if you had a gauge fastened to the fuel rail.
In 92-93 the rail comes with a fitting. I added my own to my 86 years before the factory started doing it. I silver soldered mine in. I have read that Some BB'ers have swapped in newer rails.
You can quickly loose that tiny volume so rethink how that is working out for you.

Have you tried spraying starting fluid into a vacuum port to see if the engine hits?
This will prove a lot of things.
Good timing belt and availability of spark with timing. This way, If you are right that there is no fuel, you just added your own.

You can always throw a rubber band around the contacts, of the well known pesky relay. By opening a cover on the one you have laying around or the one in the car it might point to a closing problem.

Just remember, one thing at a time while its dead!
Your choices are many because you are working from both ends trying to catch a gremlin in the middle.

Keep in touch with us.
It good for us all to be part of a mystery of misery.

Phil

Hopefully you've also seen my update from earlier. One other odd thing I noticed as I was pulling the ECU. The ECU has a red and blue wire coming out of it. There is a wire spliced into that wire and it runs back through the firewall to I believe a sensor underneath the throttle body. It looks like an after the fact fix or mod. This could be the temp sensor that had previously given code issues, not sure. No codes currently showing. thx.

Phil - Here is an update after working on the car today. As said, I have another 1990 240 so I've been swapping parts and trying but no luck:
.swapped crank speed senor (CPS) - no change
.swapped ECU - no change (note the running car's ECU says Bosch, 0 280 000 556, 3501687, made in Germany, AH AH. The not running car's ECU says Bosch 0 280 000 933, 9146222 P01, Made in Spain, AJ AJ.
.swapped the little do dad to the left of the battery that has a plug in - no change
.swapped the fuel relay (even though it's fairly new) with the other car's relay - no change.
.unplugged the existing AMM on the white volvo and the car started and ran for about 3 minutes and I thought I had it. It then died and wouldn't restart. Swapped with the other car's AMM and it still wouldn't start.


A couple more bits of info. Yes, I broke the fuel line up at the engine yesterday and and no fuel. Some dripping but no spurting.

My fuse panel in the car with the problem - the connectors wiggle around the 4,5,and 6 fuse which include the fuel pump. I seem to make solid contact when the fuse is inserted between the two prongs but some of the prongs are loose. I don't know how to get to the back side of these to see if I can tighten. I don't think this is the problem as I've squeezed then while cranking, wiggled, etc. and no change.

I've also previously checked the main ground to the engine block and that seems good but not sure about checking other grounds and where they might be?

Also not sure where the ICU is located unless it's the other gizmo on the passenger side by the ECU. I haven't tried swapping that.

A long time ago I thought I found the problem when I found the wire leading to the main fuel pump connected poorly with a twist connector about a foot away from the pump. I soldered the wire together but the problem remained. I'm thinking of chasing this wire down as far as I can to make sure no breaks or grounds but it seems to go up into the runners or something from underneath the car.

Don't know if it could actually be something in the ignition switch, which was replaced by the prior owner with a used one when his shop was chasing the problem.

Also previously replaced the in tank fuel pump and little filter, the main fuel pump and fuel filter.

Sure has been a hard one.

Hi again,

Nice to hear you have a parts car that it running.
The 933 is newer than the 561.

Last minute I drug these up.
This was some interesting reading but it's over my head!
All these could be a long bad road to take to heart at this stage of your game.

You were not alone. Art has been helpful and has his beliefs on the last one!

https://www.volvoclub.org.uk/faq/EngineFIComputer.html#Intermittent_Stalling_Bad_ECU

http://www.volvowiringdiagrams.com/volvo/LH%202.4/LH2.4%20ECU%20Pin%20Out.jpg

https://www.brickboard.com/RWD/volvo/1610175/220/240/260/280/crank_start.html


I would like for you to slow down a bit and try to run the car on starting fluid to make sure we are dealing with a working engine mechanically.
So many times a timing belt breaks or jumps a tooth from a tensioner not being routinely tighten. Usually for me that's ever other oil change over its lifetime.

I need more information on what gadget you are talking about that is next to the battery.
I'm aware of a fuse holder that should have a 25 amp fuse. Many of us replace it because of corrosion. Lift up the black cover of the terminal box fed by it as a wire under there feeds out to the ignition system.
There is an electronic ignition amplifying relay black box that is down behind the battery on the inner fender. It has a connector. This item should get serviced every ten years with heating paste but the connector can suffer corrosion too.
If you swapin older batteries to run on the cheap be aware that they out gas a lot from their vents.
If you have tried to run the car on starting fluid and t didn't we might find out if this item is killing the ignition. The ICU fires the relay and that relay gets its power from the orange wire, as I remember.

Going more along with the CPS was changed and is a working one but didn't make a difference could lead to a bad ICU conclusion even though rare!
This is a smaller unit is the one in the passenger foot well on the wall with the fuel system relay. It has a rather large connector but nothing near that of the ECU.

If for some reason the ICU does not receive a working signal it's will be dead.
The CPS signal is one half of this working system. No battery power from the ignition switch will not turn on the ECU.
I think the orange wire from the ignition switch powers both CU's. So then it's really dead!

This brings back to using the starting fluid trick.
If you get starting fluid and a spark together something is going to happen. The chance of both dying at the same time..... ? Odds?
I sure hope this thing stays dead for a bit longer. You have changed the very heart of its components. That is so far except the ICU. This is looking more and more as a true hunt for some plausible intermittents. The suggestion to pull the back seat is a good idea if there has been some jury rigging has gone on there. The back seat is held down by hooks and you have to push the wire of the seat down and backwards to get them to release. Do not pull upwards on the seat or you can bend the wire rod frame.
Either they be electronic components or a wiring issue.

This gets me over to that fuse panel.
You can only tighten the fuses clips by bending them inward with needle nose pliers.
There is no removing it just to get to any gizmo that makes them tight. The copper fingers just give in over time or from an over zealous hand trying to push a fuse into place.

You can remove the plastic panel surrounding the spades for cleaning, inspection and apply corrosion preventive.
Kittygrey has taken pictures of how he does his. He went that extra mile with grease, where I use a spritz spray of LPS ONE every few years.
Check each one carefully for tightness and placement.
If you remove them there is a two page color code painted in between each of the fuse holders terminals.
It matches the color of wires that fits there. It is pretty accurate for the most part if it's not molested terribly.

As far as ground wire, make sure you have one going to the firewall from the engine with bright clean ends. There are a few more on the intake manifold.

That's about all I can think for right now.

Phil

Update on my volvo 240 542pm PDT.

Today I pulled up the back seat (the hardest task I've ever faced with this volvo) and checked the ground. Looks solid.

I swapped out the ICU with my other car - no change.

I turned the key to the on positon and checked the voltage back at the two connectors to the main fuel pump (yellow and black) after disconnecting them from the pump. I found voltage briefly until the relay kicked in on the yellow wire. I found no voltage on the black wire.

But I did one more thing and I'm thinking this may be the problem. I checked for continuity at the wires at the fuel pump. I pulled the black wire and it showed continuity to ground, so I expect this is the ground wire from the pump (please confirm if you know)? But I also pulled the yellow wire and it too showed continuity to ground. So doesn't this mean that the yellow wire is shorted somewhere? Could it still show voltage and still be shorted?

Note through all this I many times kicked the key on and off and the main fuel pump never kicked in.

Other things I did:
I pulled the fuse panel out to see if any wires back there were loose, etc. Couldn't see any issue.
I turned the key on and checked the voltage at each of the fuses. I found voltage on all the fuses except the #4 for the fuel pump and the last three fuses.

After further thinking it through I tried again to measure immediately when I turned the key to on. I did get voltage at the #4 for a few seconds until the fuel relay kicked in and then the voltage went to zero. So I'm figuring the ignition allows the fuel pump to run just enough to pressurize the line and then the relay cuts it off while the car starts. After a volvo starts I wonder what is supposed to again return power to the fuel pump?

I think we are getting close. I guess next step would be to chase the yellow wire all the way back? Thoughts/suggestions? Or am I off here. thx! Mark

thx. Mark

Hi Mark,

What you see with the voltage on the yellow wire is normal behavior. Rather than the relay "kicking in" when the one-second pump buzz is over, it is dropping out. That is the fuel side of the fuel injection relay.

What keeps it pulled in, in a running car, is the detection of ignition pulses from the ICU into the ECU to prove the engine is turning. To put it more basically, except for that first second, spark is needed to get fuel.

Your next move should be to determine if there is spark. The easiest way to do that is to squirt a bit of flammable juice into the manifold (providing the fuel part of the equation).

If you do have spark, then troubleshoot the fuel system. Start that by checking the voltage on the orange wire to the AMM under the hood, with key on. That checks the "system" side of the fuel injection relay, and all the wiring to provide that power through the 25A fuse. Photos follow:





--
Art Benstein near Baltimore

When two egotists meet, it's an I for an I.

Thank you Art. Today I did squirt some carb cleaner into one of the vacuum
Ports and the car did start and run for just a few seconds. I did check the voltage at the orange wire with it plugged in and boot pulled back and it was 12V. I had previously replaced the 25 amp fuse and the wiring to it with a new socket fuse holder from the auto store. questions - should the yellow wire at the fuel pump when disconnected show continuity to ground? Same for black wire? Is the black wire at the pump the ground or does it serve some other function? If I have power to the pump even briefly why do I not hear it
Kick on briefly? It does not. Thank you for replying.

New fuel pump relay. They do to bad.Intermediate.

Thank you Nahtanha. I've ruled that one out but they sure can be the culprit. I think I've found the issue to be loose wiring at the pump. Appreciate your input!

Hi Mark,

I'm sorry to have you repeat things. Apparently there are previous threads I've forgotten.

Let me focus on your continuity question for now. Continuity is a vague notion. It doesn't seem vague when you're troubleshooting a string of Christmas lights; it is either there or not, right? Would your continuity tester identify one of those lights as a continuous circuit? Perhaps.

That's the trouble. Every continuity checker differs in what it decides yes-or-no what is a wire and what is a load. And I can't tell from your words exactly where you are probing this continuity on the yellow wire; back to the fuse panel? Or into the motor? Referenced to a bolt in the floor pan?

When you measure voltage, are you doing so with the load connected? Many times a mechanic will probe the end of the unplugged source wire with a meter to falsely convince himself power is present. Check voltage (always) with the load connected, by adding the probe to the circuit, not substituting it.

The yellow wire to the main pump, under the rear seat, is the +12V side. The black wire is the ground return. If you have full voltage on the yellow wire, while it is connected to the pump, and the pump does not operate, there is an open circuit between where your probe is and the ground point for the pump. The open circuit could be internal to the pump.

But if the voltage drops considerably -- say to 8V where you are probing -- the pump motor might be locked up, as though a bit of debris got ingested to jam the rollers.

Have you tried the often-recommended jumper between fuse 4 and 6 to bypass the fuel pump relay contacts and provide constant power to the pumps? If you have not, be careful, just in case the main pump is indeed locked up. Your jumper could get hot.


--
Art Benstein near Baltimore

I used to be a lumberjack, but I just couldn't hack it, so they gave me the axe.

So Art and Phil, here is an update. I did get the pump to kick on. I believe the problem is at the pump itself at the connections. This would fit. both the yellow and the black wire have a plug in connector. The wires to the connector were frayed so I replaced and put a male/female socket connector upstream. At first today when I got to run, I thought these connectors weren't tight so I tightened one and it kicked off. However, when tightening I fiddled with the actual push in connectors at the pump. I think that is where the problem is. Those connectors don't fit snuggly due to age/wear I would guess. When I pressed the connector in the car would kick over. When I let it loose it would not. Could be that depending on various conditions (heat, going over bumps) this connection was not solid. That would explain the randomness and it did die at first as I was pulling it out of my driveway and hit the bump going into the street. Also sometimes going slightly uphill. So I think gravity, bumps, heat, and a loose fit worked together to cut off power to the pump. I am going to rewire those connections and see if I can find plugs to make sure it's tight. I think this is it. It reminds me of the movie Butch Cassidy and the Sundance kid. Butch says "I think they stopped following us. Do you think they stopped?" Sundance says 'No'. Butch says "I didn't think so either." So I am guardedly optimistic and I will think it's fixed if you will, unless it fails again!

Hi,

I think you could have very well found the problem. This was one of my first thoughts and I wrote that since you had changed those will go forth on your faith.

I had a similar problem with my '91 many, many years ago. It was a year or so after I first got the used car. The car had fail to start for my wife down town and we had it towed home.
Working with the car in my driveway I changed the system relay. No start! I inspected the ECU connector but really found nothing wrong but after a couple try's the car started.

I immediately drove the car onto my lift and it quit starting again. I checked out the pump by running a jumper directly from the battery to the under rear seat connector main pump with a toggle switch in line.
Yes that rear seat can be a bugger but it clears any problem that is out of sight and out of mind after all these years.

The pump seemed to be fine but once it hesitated to immediately start through my hand switch.
So with suspect of this being a used car, I changed over to a brand new pump that I had in stock.

Upon hooking up the wires to the new pump, I found the same thing that you noted about the terminals. They appear slightly loose as they did not click or resist a push on like spark plug wires would.
The boots seemed to hold things well enough but I just not get that reassuring resistance and lack of a wiggle in the base to move back and forth.
I carefully pinched the actual metal part inside of each wire until I got that feel tighter solid feeling.

The car has not had any problems in years but that has left me wondering all this time, was it the pump or the terminals down inside those colored housings?

It sure would explain why you were not getting the engine run without fuel but it did on starting fluid.
I also want you to loosen the main line before cranking to see if you actually squirted gas when it did.
I know it didn't sound very safe and don't blame you for kissing me off on that one! (:)

Did I see you write that you used carb cleaner?
That stuff is not as vaporous and volatile to get to the cylinders but I will not say that if you put enough in it won't fire.
The other thing I don't like carb cleaner for is that it can lay around in there for a while. In a closed off manifold it then can drip down onto the piston tops dissolving carbon and oil film. There is a gap at the top of pistons that can hold chunks that might scratch the cylinder.

Just something to stuff up under your hat for the future. Start fluid is great for old lawnmowers and a fast and reasonably harmless cleaner to most surfaces but not all!

I got some my wrenches crossed for you that you found it!
(:-)

Phil

Thank you Phil for the kind response. I appreciate you hanging in there with me and I enjoyed your recollection story. Tomorrow I will pull/cut off those old plug in connectors and rework them. I have a spare pump. I will splice in a new wire from about a foot out and rework the connectors or buy/build/make new ones so that they will snuggly fit into my spare pump. I will them install them onto the car I'm repairing and as you say cross my wrenches.

You know, I just hate giving up on these cars as I've owned 5 over the years and know what great cars they are. They've kept my kids safe. If this problem does prove solved, I still have a couple other puzzlers so I guarantee I will be reaching out to my volvo comrades again.

I have seriously enjoyed the camaraderie with you gentlemen (this means you too Art). I will let you know how it goes in a couple days. I pulled so many parts from the other volvo that I will be putting things back together for a bit.

Take care friends. Mark

Art - thank you for the excellent response. I will confirm using the methods stated that there is voltage at the pump or not. If so I was wondering last night, and your thoughts can support, whether the pump has been intermittently locking up. Even though it is a new pump and filter I wonder if there could.be something in the fuel tank. I also replaced the in tank fuel pump and filter to try and make sure nothing was getting through to the main pump. But if something is getting Through to the main pump such as very fine residue it could be locking up the pump. That would explain almost every scenario that I can think of when it has died. I will investigate and report back probably tonight. I still have an old working fuel pump also and will hook that up to the existing wires underneath and bump it to see if it turns.Thank you again.

Thank you again Phil and I will try your suggestions and continuing troubleshooting today and give a more complete update tonight. I too am hoping it stays broken til I find the problem!

Phil - very kind of you to reply and I am working on the car today with some rare good time to work. I have a second 1990 240 here also. This morning I pulled the CPS and swapped them with no change. I also pulled the fuel relay and swapped with no change. Swapped both back. I am now going to pull the ECU and swap and see if anything happens. I will keep you posted and check out the other things you said also.