Engine stalled when hot

Post by **Volvofan94** » 27 Jul 2012, 20:30

Hi Everyone,

I kind of have an interesting problem with my 850. I have a 1994 Volvo 850 (2.4L I-5, 170k miles) that mysteriously stalled on me when I was coming home from running errands this afternoon. It's been hot this summer where I'm from and never had issues before, but today (a cooler day than before) when I was a few blocks from home, at a stoplight, the engine RPM dips and eventually the engine stalls. I crank the engine and nothing happens. I crank it again and I get it to barely start, push on the accelerator a bit and the engine stalled again. Repeat the process a few more times, but it didn't start enough to drive home. About 5 - 10 minutes later, after I'm out of traffic, I try again and it starts and runs normally. I get home and shut off the car and it starts right back up. The CEL didn't come on. To me, it sounded similar to the engine was running out of gas. I just filled up the fuel tank too.

Thank you for your assistance.

Post by **jblackburn** » 28 Jul 2012, 00:21

Hey there,

Try this post:
https://www.matthewsvolvosite.com/forums ... =1&t=50384

Post by **Volvofan94** » 28 Jul 2012, 10:13

Thank you for your assistance!

I'll replace the fuel pump relay with a spare I have this morning and drive the car around to see if it helps.

Another thought I had is could this be a warning sign of my fuel pump is starting to go bad (I've never had one go bad before Maybe related?)? I've begun to notice on some mornings I'll start the car and the engine would idle rough for a couple seconds then eventually the idle smooths out. It'd run fine for the rest of the day. Is there a way to test the fuel pressure at the rail when the engine is cold without buying a fuel pressure tester?

I'm sorry for all the questions and if these questions has been answered in other threads. I would like to be sure all is well before taking the car on long trips again.

Again, I appreciate any help and guidance you guys have. I'll post back with updates!

Thank you!

Post by **jblackburn** » 28 Jul 2012, 12:25

You can test the fuel pressure at the end of the fuel rail. There is a Schrader valve at the end by the throttle body where you can connect a gauge.

Usually fuel pumps just die without warning. They either run or they don't. However, there is a check valve at the housing that sometimes goes bad in these cars. If you want to check for this, shut the car off and immediately check fuel pressure at that test port on the fuel rail. It should not drop to 0 instantly.

Post by **Volvofan94** » 28 Jul 2012, 15:56

Thank you again for your help.

I rented a fuel pressure testing kit from my local Autoparts store and tested the fuel pressure coming out of the schrader valve on the fuel rail. When the car was cold, before I turned the key to position II the meter read 0, which is what I expected. I turn the key to position II and I get 20 psi reading on the gauge. I turn the key to off and the pressure fell, but didn't fall rapidly to 0, it settled down at 17 or 18 psi. I repeat the test and get 45 psi (which is normal, I think?). I could have "primed" the engine to get the better results. Turning the key off it settles down to 42 psi. I retry again with the same 45 psi on and 42 off. I didn't try the test with the engine running because I had to unbolt the fuel rail from the manifold to attach the fuel pressure dial to the schrader valve, but the injectors were still in their ports.

Does this sound like the fuel pump might be at fault?

Thank you again for your help. I appreciate any and all advice!

Post by **erikv11** » 28 Jul 2012, 17:37

The deal with a failing fuel pump is, it either works or doesn't. When they fail, they usually work intermittently for several days, then quit altogether.

So you just need to check if there is pressure, not check the value of the pressure. The scenario you relayed sounds like either normal fuel pump function (so the pump could still be failing) or *maybe* a problem with the fuel pressure regulator. But the check valve seems fine, too.

Post by **jblackburn** » 28 Jul 2012, 17:43

Yep, pump and check valve seem to be working as they should!

I'd swap in the relay and make sure that you keep a charged cell phone on you.

Post by **Volvofan94** » 28 Jul 2012, 18:20

I swapped in the spare fuel pump relay and all seems good now.

I'll update if the issue comes back. Looking forward to keep the car on the road for a long time. : D

Thanks again for your help!