I've kind of been blowing this forum up the last few days, but oh well. I'm trying to get an 86 240 running (it starts, though not easily, and idles ok but shuts off when put into gear). I have a new (or used rather) IAC valve on the way, but the main fuel pump might also be the culprit. I'm pretty sure I can hear it run when I hook the battery up to charge, but it's running constantly - even when the key isn't in the on position. Is this normal, or a sign that the pump is bad?

 

Pump should not run without the key being turned on. You have a short someplace. Time to sort though the fuses to find the one that shuts the pump off.

 

Could be a stuck fuel pump relay. this relay is under/behind the glovebox. its usually white.

 

Well, I think I found the problem. A wire coming from the fuse box seems to have been cut, and the other side (which I assume goes to the fuel pump) was spliced into another yellow wire, and not even properly spliced - bare wire wrapped around bare wire and e taped. So I guess it's time for a new wiring harness. I have seen that some people simply bypass the main fuel pump by removing it and adding some fuel line, is this something you guys would recommend?

 

In a 2 fuel pump system the main pump under the driver side door is the high pressure pump. The other pump in the fuel tank is a low pressure feed pump to get fuel to the main pump. Some have done a modification by deleting the main pump and installing the high pressure pump in the fuel tank. This requires a different in tank pump and eliminates a relay. You can not just remove the high pressure pump under the car and insert a rubber hose. The car won't run .

 

you can't eliminate the fuel pump relay, as its a double relay, one half powers the ECU and the whole injection system, while the other half powers both fuel pumps. for incomprehensible reasons, the in-tank pump is on its own fuse, while the main pump gets its power directly from the relay

 

Alright so I'm still trying to figure this out, the pumps have stopped running continuously but now they wont run at all. I can hear the relay click when I turn the key, I changed the fuses for both fuel pumps, and cleaned the grounds. Any ideas?

 

Also, does the 25A fuse connected to the positive battery terminal control the fuel pumps, or only the fuel injection?

 

that 25A fuse supplies /all/ the power of the fuel injection system, including the fuel pumps. the tank pump has another fuse too.

what year 240 is this?

 

It's an 86. I think I found the problem - one of the connectors to the main fuel pump has an exposed wire and I think it's shorting out there. I'm gonna try and just cut the connector off for now and wrap it around the male end, and we'll see if that gets her running. And I might also replace the connector that holds the 25A fuse because it's the original and is not in good shape, but I can hear the fuel injectors power up when I take the fuse out and put it back in so I don't think that's the problem.

 

So I decided not to try that ghetto-fabulous idea, and tried to switch the fuse holder out but I bought the wrong one with a different gauge wire so I'm gonna have to try again tomorrow. Do you think it could be that the fuel pump was shorting out internally and it just needs a new one?

 

I've always used a marine fuse holder like this, https://www.westmarine.com/buy/blue-...9?recordNum=12

the original wire is some kinda metric gauge, so no US wires will be exactly the same. AWG 12, like that fuse holder comes with, should be fine. I also use marine butt crimps, as these have heat-srink ends that seal around the wires, keeping corrosion at bay.

 

Yeah that's similar to what I got, along with some butt to butt connectors that crimp, but I HATE crimpable butt to butt connectors, and since the wires aren't the same size they don't really work. I think I'm just gonna go pick up some wire nuts tomorrow and twist em together, and if that doesn't solve my problem then it's time for a new fuel pump. I can tell the one that's on there is pretty old, and when it was running it was buzzing pretty loud, and now when I turn the key I can here it click trying to turn on so it's definitely getting power I just think it's a goner.

 

Update: I have replaced the fuel pump, the 25A fuse holder and fuse, and the fuel pump relay and fuse, and this thing still won't turn on. I tested it with a voltmeter and it's getting power, so I have no idea what the hell is going on. SOMEONE PLEASE HELP! I'm about to smash the damn thing to bits and be done with it

 

If your wiring harness is bad your gonna have issues until the harness is replaced.

That being said... car needs fuel, spark and compression. Does it have those 3 things?

https://www.volvo-forums.com/t27450-...and-stalls.htm

 

Yes, I understand how an engine works, and no clearly it doesn't have fuel since the pumps aren't running, but thanks for your super helpful reply. The wiring harness is admittedly not in the best of shape, but it's good enough for now. When the fuel pumps were running continuously it would start and idle just fine until i put it in gear, but that was before i had discovered the mess of jumbled vacuum lines that were all disconnected, and once i sorted that out the pumps stopped working, and also before I had replaced the IAC valve. I just read online that the fuel pressure regulator can sometimes shut off the circuit for the fuel pump(s) and some have a reset switch on the top. I don't know if the 240 has one or not, but I'm gonna check it out when I get home.

 

If you have 12V running to the fuel pump and it is grounded then it should work. If the fuel pump ground goes back to the ECU it may not be grounding out there. Check to see if the circuit is completing. If you disconnect and hook the fuel pump up directly to a 12V supply and ground does it run. If it doesn't then get another pump.

 

indeed, replacement parts quality nowdays is damn spotty... just because something is 'new' doesn't mean it works.

 

Yeah I know, but I really don't think it's the pump because they're BOTH new and neither one is running. But I'll get a 12V and test it. Can anyone tell me if the fuel pressure regulator can actually cut off the pump circuit? I noticed it doesn't even have an electrical connection, so it doesn't seem likely, but maybe it has a failswitch somewhere else in the diagnostic system when it goes bad?

 

Just disconnect the wires at the main pump and hot wire the plus and neg. See what happens. If it runs trace back to the ECU.