1998 S70 stalling no codes?

[cn90]

Stalling + no codes....as mentioned, maybe bad fuel pump relay.

Next time this happens, jump 15 and 87.

You can also measure the resistance of the Fuel Pump at the fuel relay SOCKET.

I wrote a fuel system trouble-shooting guide here:
https://www.matthewsvolvosite.com/forums ... hp?t=52252

[marcusheard]

I disconnected the MAF, and the engine ran and then stalled - same as it did with the MAF connected

I reading 1.8 ohms at the pins 87 and 31 of fuel pump relay - that out of the acceptable range of (1.0 - 1.5 ohms).

Next I jumped pin 87 and 15 of the fuel pump relay and the engine ran, and then stalled.

So, I'm leaning towards replacing the fuel pump - any suggestions?

[rmmagow]

Change the fuel filter first. Easy and should be done regardless when you change pump. I don't know about Volvo but if there's a screen at the bottom of the fuel pump, maybe it plugs after running a bit. Might be able to pop out the pump and have a look around.

[jblackburn]

I disconnected the MAF, and the engine ran and then stalled - same as it did with the MAF connected

I reading 1.8 ohms at the pins 87 and 31 of fuel pump relay - that out of the acceptable range of (1.0 - 1.5 ohms).

Next I jumped pin 87 and 15 of the fuel pump relay and the engine ran, and then stalled.

So, I'm leaning towards replacing the fuel pump - any suggestions?

Don't throw a fuel pump at it without checking the pressure first. A fuel pressure gauge is much less than a fuel pump. Or even a cheapo tire gauge will give you a reading.

[erikv11]

+1, replacing thes fuel pump without checking first is just setting you up for frustration. Really easy to check fuel pressure. And as mentioned a bad fuel pump usually leads to a no start condition, not to a persistent stumble.

Could however be a problem with the fuel pickup line in the tank for example, so looking at the fuel pump installation wouldn't hurt, and is easy to do.

Consider the other basics of a stumble, there are a lot of little things you want to check for including vacuum leaks. Here is a good, recent post https://www.matthewsvolvosite.com/forums ... =1&t=54785

I'll check my MAF after I replace one of my spark plug wires (fell apart during removal process). I'm not sure if it was faulty before or after I began pulling. Spark plugs look normal.

I just ordered my plug set so they will be here next week - 50% less than the set at Autozone

Are you saying you bought ultra-cheap plug wires? Not a good idea with these cars. They don't do well with most anything other than Buogicord (OEM) wires. May sounds like hogwash to you but it isn't - it is what people have observed over many years.

[marcusheard]

Replaced fuel filter, and nothing has changed.

Great news - now I'm receiving code P1507 after the engine stalls. I replaced my IAC last week, however I'm currently receiving this code. So, what else can set this code and cause engine stalling? Also, later today my air pump soleniod valve began clicking after the engine stalls, however I don't belive that part can cause stalling - what do you think?

[marcusheard]

I have believed that I've solved my problem - I tested resistance on my new IAC again and found an oversight on my part.

Pin 1 & 2 = 10.6 ohms (acceptable range 10-14)
Pin 2 & 3 = no reading (acceptable range 10-14)

So, my new IAC must be faulty - what do you think?

[erikv11]

I just tested a spare, working IAC I have in the garage, it showed 10-11 ohms for each of those combinations. Sounds like you got a bad IAC.

[deeess]

How old are your ignition wires? Have you checked the wire from coil to distributor?

Also, how does the distributor cap & rotor look? I've seen an intermittent stalling problem from worn out cap/rotor/wire.

[rspi]

I really don't like it when new parts fail. That stinks. I had a 2 week old temp sensor fail. Got 1 from a jy and it's still puring like a kitten.