Suddenly won't start?? Need suggestions

[MacStainless]

I did some work on my D last weekend and the car seemed to start and run fine. At one point it stalled for no reason, but I was able to start it back up a moment later and all was well. Fast forward to Tuesday, I'm getting it flatbedded to a local shop and the car won't start. No idea why. I figure the car needs a jump, but the engine was turning over. Same at the shop, the owner said he can't get it started either (before going into a semi-rant about how this is why Deloreans were "discontinued"). So I'm at a loss as to what is going on here, especially that it ran a few days ago.

Any suggestions on things I can check when I get the car in my possession again?

Info that may help:

• There's ~4 gallons of fresh gas in the tank. I put that in about 2 weeks ago and drove less than 15 miles home.
• RPM relay was replaced in '18 and hasn't given me problems. Tow truck was running when I tried starting it, so I couldn't listen for the pump.
• The work I did on Sunday was a full relay and fuse update from DGo (minus RPM since I did that already). The shop owner said he heard the fuel pump running when he tried starting it.

[Bitsyncmaster]

Most common issue is the pins on the resistor in the engine bay. Pull those connections off and back on.

But there are a lot of other things it could be. First thing to determine if the problem is fuel or spark. Get a can of starting fluid to test if it's fuel.

[MacStainless]

Most common issue is the pins on the resistor in the engine bay. Pull those connections off and back on.

But there are a lot of other things it could be. First thing to determine if the problem is fuel or spark. Get a can of starting fluid to test if it's fuel.

Thanks for the info. I have a can of contact cleaner. Do you suggest I spray some in the connectors and pins?

If it’s sparking, then what should I be on the lookout for? I feel stupid asking such basic questions. Also, where do I spray the starting fluid if I pick up a can?

Thanks.

[NJP548]

Thanks for the info. I have a can of contact cleaner. Do you suggest I spray some in the connectors and pins?

If it’s sparking, then what should I be on the lookout for? I feel stupid asking such basic questions. Also, where do I spray the starting fluid if I pick up a can?

Thanks.

Spray the starting fluid through the intake. I had a spark issue and it ended up being the lower right connection on the Ballast resistor. Tightened that connection and I had spark again.

-Nick

[Jonathan]

When in doubt, assume it's related to the last thing you worked on.

If the car started and ran fine before you did the fuse and relay upgrade, then I would start looking there. You could have easily pushed one of the connectors out the back when you put a new relay in. It's hard to see and they can come out fairly easily. Get in there and inspect the receptacles for all of those relays you replaced.

[MacStainless]

Thanks for the input everyone. I stopped by the shop that has it for now and I did a quick check of fuse 7 and also gave all the relays a push to make sure they were in their sockets. They seem seated properly. It was chilly and starting to rain so I didn't stick around. Additionally, I was going to try to check the ballast connector in the bay, but now the sunshade is catching on the T-panel so something isn't right there. Again, I didn't want to stand in the cold rain to check this when I'm going to bring it to a better mechanic next week.

The mechanic told me the following: The fuel pump is not getting power from the car. It does work when he gives it power directly. There's no pressure on the fuel system. Additionally he said there's a lot of gunk in the fuel lines so that plays into things too. There IS spark he told me. So, the issue looks two-fold: fuel pump not getting power from the car and potential fuel line problem with the gas.

Right now I'm having him replace the hot water control valve to resolve my coolant leak and then moving the car to a more-competent mechanic who has Volvo experience and didn't blink twice about working on the D. A sigh of relief considering this current mechanic told me he'd have to "rip out the whole interior" in order to get to the fuse & relay panel. Riiiiight.

[Rich]

The mechanic told me the following: The fuel pump is not getting power from the car. It does work when he gives it power directly. There's no pressure on the fuel system. Additionally he said there's a lot of gunk in the fuel lines so that plays into things too. There IS spark he told me. So, the issue looks two-fold: fuel pump not getting power from the car and potential fuel line problem with the gas.

Good progress, thanks for this update. So no need to learn about starting fluid there.

If you get a chance ask that mechanic how he determined "no power" situation for the FP.

All we know for sure at this point is that the fuel pump has either a bad/open ground circuit or a bad (+) positive circuit. He might have jumped both the (+) and (-) sides of the FP from an external battery, for example, to get the pump to work. Such a test proves the pump can work. It wouldn't tell you which circuit causes the problem.

Interesting note about him claiming to have to "tear out the interior" to chase down the fuses - he seems to be less than thorough in his diagnostics and logical thinking.

Good idea to step up to a better mechanic. You might have the new one re-check the pump "power" situation correctly whether or not you get any answers from the old one.

[MacStainless]

Interesting note about him claiming to have to "tear out the interior" to chase down the fuses - he seems to be less than thorough in his diagnostics and logical thinking.

Good idea to step up to a better mechanic. You might have the new one re-check the pump "power" situation correctly whether or not you get any answers from the old one.

Yeah, the moment he started telling me about how he'd need to access the fuses & relay panel, I knew he was not the guy I want to be working on my car. Like I've said earlier, he is simply not interested in the time and effort it takes to work on an older car. Combined with being busy on other customers who he can service faster, I'm not surprised this is the outcome. I'm excited to get the car to the new place next week and hopefully make some real progress. The moment he told me he used to own / work on some early 80's Volvos, I knew I likely found the right mechanic. Fingers crossed.

Regarding the pump, I could ask him but TBH I'd rather have the new guy address it on his own without any preconceived input that could potentially be wrong. NJP548 sent me a text reminding me this could possibly be inertia switch. I hadn't checked that, but could be another reason the pump isn't going. Would be freaking great if that was the cause, though I'm not sure how the switch could trip on its own. But weirder things happen with these cars.

[Bitsyncmaster]

Yes you need a mechanic that knows our car. The fuel pump only runs when the engine is firing. It's a simple test for those in the know to jumper the RPM relay to test the fuel pump.

[David T]

There are a lot of possibilities why there is no power to the fuel pump;
Corrosion on the harness to the pump
Corrosion on the connector plug up inside the washer tank bucket area
Bad connection/bad inertia switch/modified wiring (inertia switch recall not done)
Burnt up fuse #7
Bad RPM relay
Connector backed out and not making good contact with RPM relay
Best to get someone with some experience so they at least know all of the areas where things can go wrong (and where they are) so they don't waste a lot of time looking for things. Not only must you have power to the pump you also must provide it with a good ground, that is what the inertia switch circuit does.