Why won't my 740 run ='(

1990_740Turbo · Post by **1990_740Turbo** » 03 Apr 2007, 20:03

I love my 1990 volvo 740 turbo, but recently it would no longer catch when i tried to crank it. I sprayed starter fluid and it cranked up right away, but it wont stay running. I believe that both of the fuel pumps are working. I'm assuming it has something to do with the fuel. But I took it to a local mechanic today (who isn't an expert in Euro) and he said his diagnostics machine didnt pick up anything. He says it may be something to involve with the computer in my fuel injection. Any ideas?

CarVolvo · Post by **CarVolvo** » 03 Apr 2007, 20:14

you already removed the maf sensor and spray ether in a can into the throttle body and see if it eager to start. And since you did

Usually on the 740, 240 and 940 you need to check the following.

after you check for spark.. remove the spark plug.. if it smells like gas then you know its getting some.. put it on top of the engine block and just watch it.. should be a blue strong spark. if your getting spark..then check these out.

1. the fuse thats located on the drivers side inner fender. its the 25 watt one and gets corroded. replace it because it sends the power to the fuel pump relay. Check to see that you are getting power after this fuse and the relay.
2. the relay for the fuel pump.. when was the last time you replaced it? (under the glove comparment)
3. the fuel filter itself
4. did this car come with an obd already built in?
5. disconnect the maf sensor when its running and see if there is any improvement.

1990_740Turbo · Post by **1990_740Turbo** » 03 Apr 2007, 20:28

Forgot to mention, I checked all the fuses and all are working correctly. I haven't checked the relay because simply enough, I couldn't find it, cause i was told it was supposed to be next to the fuses behind the ashtray. Ill check it when I get it back from the mechanic tomorrow. The only way it will run is with the maf off, if you spray it, then put the maf back on, it wont run. So I was puzzled at that point

1990_740Turbo · Post by **1990_740Turbo** » 03 Apr 2007, 20:31

Could it be the ECU ?

1990_740Turbo · Post by **1990_740Turbo** » 03 Apr 2007, 20:38

As for the OBD, IT said it was my O2 sensor, which I knew when I got it. But I didn't know if a malfunctioning O2 Sensor could stop a vehicle from starting?

CarVolvo · Post by **CarVolvo** » 03 Apr 2007, 20:56

yes i think your fuse relay is in the mid console..sorry the 240 has it under the glove compartment!

Before you suspect the ECU i would just follow up on the fuel system.... its the most common issue with these cars.

o2 sensors would make the car run rough.. just unplug it and see if you notice a difference.

same with the MAF sensor. and since you say its not working when the maf is on..then it could be the defective part.. HEY BILL OF D>> WHAT DO YOU THINK?

I suggest you just do some of the things i mentioned above first ... before you suspect the ecu.

Post by **billofdurham** » 04 Apr 2007, 11:59

same with the MAF sensor. and since you say its not working when the maf is on..then it could be the defective part.. HEY BILL OF D>> WHAT DO YOU THINK?

I was trying to have a quiet night but what the heck. I tend to agree that if it runs until the MAF is hooked up it looks suspect. However,

As for the OBD, IT said it was my O2 sensor,

I take it from this that you have read the fault codes. Was there only one that came up? What was the code reading?

2-1-2 is the O2 sensor which requires a check on the fuel pump relay and the O2 sensor heater.

1-2-1 is the MAF signal which requires a check on the Airflow meter and the O2 heater resistance.

Bill.

1990_740Turbo · Post by **1990_740Turbo** » 04 Apr 2007, 13:27

Well I did everything I could imagine, with the help of my mechanic and we both came down to we both believe it is the ECU. He said he would be able to trick it into starting "without ether" and get it home if I needed it. So now im looking to purchase a ECU for the vehicle.

http://cgi.ebay.com/ebaymotors/VOLVO-24 ... enameZWDVW

Would this fit my 740 Turbo ? I didn't know if the 740 and 740 Turbo would have different ECU's in them.

1990_740Turbo · Post by **1990_740Turbo** » 04 Apr 2007, 13:28

As for the OBD codes, I got Mass Air Flow intake is faulty and O2 sensor is faulty. I dont remember what the codes were because I reset the OBD since it has not been running.

CarVolvo · Post by **CarVolvo** » 04 Apr 2007, 16:53

punch in this number.. i think its the same match for your volvo

120102123587 item on ebay. on 3 hours left and going for one cent!

just look at your existing computer.. on a 240 its on the passenger side .. on the side wall closest to the door hinge. the bosch number is right there.