I will continue searching for clues on this, but thanks in advance for any insight. Here are the facts:

1990 240 ~175k mi. Engine will not fire up.
Recent coolant temp sensor replacement about 2000 miles ago, after check engine light with code 123 came on. The sensor is after market.

Recently the CE light came again. #2 hole showed 1-1-1 - al clear. #6 did a continuous blink which I don't understand why. I cleared the codes and kept driving, noticed nothing odd about the engine performance.

About 100 miles later the CE light came on again. This time it read 1-2-3: coolant temp sensor? I had tested the sensor with ohmeter before installing it. It was not a Bosch but an aftermarket sensor. I cleared the code.

CE light came on again this time 212 - O2 sensor. Also, the engine began presenting symptoms, namely it would die sometimes at idle after being warm. Also, it would take two key cranks to fire up the engine. Harder to start when warm, easier when cold. I also noticed the engine seemed slightly underpowered and a little rough at low speeds/gears - not very rough.

Because I had seen multiple codes I decided to clear the codes but planned to replace O2 sensor before driving anymore. I ordered an O2 sensor but made one drive, about 15 miles. this time I had a code of 232 - Lamda fuel trim issue. when I got back home I parked the car and next day it would not start. That is the current status. After clearing the codes yet again and attempting to fire up, I now get the code 131. All in #2 socket. #6 socket is all clear 1-1-1.

I am puzzled. I have read similar case of what turned out to be a faulty Fuel Pressure Regulator. I do plan to replace this. The vacuum hose on it smells of fuel tho no fuel drips out. This is 2 days after running the car tho. I have read that the vacuum hose on the FPR should not have any fuel odor. Is this true?

What is the relation of the O2 sensor? Why all the codes? My gas tank is low, but not out. Could that be a factor? Would a bad O2 sensor prevent the engine from firing up?

One last question: if the the culprit is the FPR, after replacing it would the engine fire or would there be another step to make this happen? Thank you.

 

The vacuum hose coming from the fuel pressure regulator should not have a gas smell - or very minimal gas smell. Regarding the O2 sensor, it provides feedback to the ECU regarding how much oxygen in the exhaust. Too much oxygen indicates a too lean condition causing the ECU to enrich the fuel mixture.

Before you start replacing parts, you need to narrow down the problem. In order to run, your car needs fuel, air & spark. If you don't have these three, your engine won't start. First check your fuel system. Are both fuel pumps working? Here is a site that explains how to check the main and in-tank pumps:

In the Tank - 240 Volvo Tank Pump and Sender

When the car won't start, do you hear the main fuel pump run when the key is first turned to the II position?

After you verified that the pumps are running, check for spark.

 

Thanks for the follow up. I understand it's not prudent to do a hail mary and replace parts. However, I read of a similar problem to mine and the FRP replace was reported to have resolved the issue. Furthermore I do smell gas at the FPR vacuum hose. So, in the least, by replacing it I am practicing preventative maintenance. Would you think tho that a bad FPR could result in a no-start situation? Thanks!

 

possibly.....I had an 87 wagon and replaced the FPR...junk yard one and THAT FPR was bad as it puttered horribly...until I replaced it for a second time....junk yards here offer parts exchange at no extra cost.

 

I would run some test on fuel pump. A good quick way to test a functional fuel pump is to jump fuse # 4 & 6 (i believe those are right, main pump + pre pump fuses) and listen for the pump to kick on. If it kicks on, the pump is working. If the pump is working, hold onto the fuel pump relay and try turning the car on. If it doesn't click it is junk.

You can also disconnect the fuel line from the rail and put the fuel line in a cup and try starting the car to see if any fuel comes out. No fuel? Then you've narrowed down your problem.

Check the 25 amp fuse coming off of the battery that sends power to the fuel system. It is known to corrode and will cause no start/rough idle. Also check the grounds on the intake manifold, as they to directly affect the fuel system.

If everything will the fuel system checks out, the AMM could be the culprit. This is more likely a cause of a no start than an o2 sensor. Obviously, check for spark too, could be bad distributor cap, worn spark plug wires, or bad ignition coil.

 

OBD I codes could be very confusing... and inaccurate
I'd spray Starter Fluid in the intake to see if it fires up, if not, it's spark, if it starts for a few seconds, it's fuel.
The FPR will not affect cold start, only warm.
The O2 sensor also will not cause no start.
The Coolant Temp Sensor is a suspect but that makes the car starts eventually after several tries.
If no fuel, change the Fuel Inj. Relay, then look at the main pump.

 

Thanks all for the guidance. Spark checked out fine. There was no fuel coming from the pump to the rail. I called my local Volvo expert and with this info he said I would need to clean or replace the 25amp fuse in under the hood next to the battery (3rd unit). Sure enough this got the pump working and the engine fired right up. I saw no obvious mention of this in the Haynes manual. What a simple fix! But I live on the north coast of California and corrosion was likely the culprit.

 

on our 87 nor-cal 240, I replaced that 25A fuel injection fuse awhile ago with a marine fuse I got from a boat supply place... I filled the fuse holder with silicone electrical grease to keep the gremlins out, and I also squirted silicone grease into the grip connectors before crimping them onto the wires (using a proper ratchet crimper) (an old boat wiring trick)...

 

It's an FI fuse? I am confused about that. Why was the fuel pump failing to operate in that case?

 

I see a lot of people mention that these are main and pre (in-tank) pumps fuses. However, all my diagrams show that fuse 6 is actually for the entire fuel injection system: ECU and both pumps, and that fuse 4 is yet another fuse just for the in-tank pump, after the ECU and relay. Depending on how one reads the diagram, it is possible that fuse 4 actually covers both pumps. I can get my multi-meter in there and double-check if you want. I know this is picking nits, but details like that can affect how someone does their troubleshooting.

 

Wait a minute! I have a 1993 240 wagon and all the manuals point to a "25 Amp Fuse" in that location. However, after looking at these pictures I realize that I don't have a fuse there! At least not a regular fuse that looks like a fuse. All I have is that black box just in the front (just above in these pictures) of that fuse.

Does anyone know what's up with that? With all the complaining people have done about how weird this 25 Amp fuse is, I had just assumed that all the connectors in this black box were some contrived form of fuse.

 

thats exactly it, at least on the later LH cars. ok, this guy has a 90 (there's someone with similar problems on here with a 83, these early versions are a little different than described below).

the 25A fuse under the hood of a 240 (or fuse 1 on a 7/9) powers the entire fuel system. the 'fuel pump relay' on most(*) of the later cars is actually a dual relay, one half powers the ECU and injectors and stuff (ok, on a 7/9, the injectors are on a separate socalled "radio suppression" relay), the other half the relay powers both fuel pumps. the in-tank pump is on an additional fuse (fuse 6 on 240s, fuse 11 on the 7/9's), but ALL of the above is on that main fuse.



(*) 1994 and 1995 non-turbo Bosch LH 940s did away with the dual relay, and use the 'radio suppression' relay under the hood to power the ECU and stuff, and they have a seperate single plain relay for the fuel pumps. 95 did away with the 'main' pump and went to a regina style single in-tank pump, which is also used on many newer cars like 850s, S/V70's, S/V90's etc.

 

You may be right, I just know what it says on my fuse cover, and I know that if I take a paper clip and touch fuse # 4 & 6, listed as main pump and pre-pump, that my fuel pump turns on.


Glad you got the car running again! I've had lots of problems with that fuse before, I upgraded to the IPD water-proof one, and haven't had any problems.