that's what I was thinking... if there was an accessories relay or something I could temporarily swap out. I'll have to give it a look tonight for sure... I'm just frustrated no one in town has one in stock. That would be so easy to go buy one try it out, and return it if it weren't the issue.

Oh well, work is almost over, so we'll see what tonight brings. [8D]

 

Good luck.

 

Tech, I should have listened to your first post! Not sure if it was a good idea or not, butbI unplugged the MAF sensor and drove the car home... no issues other than some smoke out the tail pipe. Though, there was a bit of a nasty smell when I got it home.

Did I mess anything up by driving with no MAF? It was only 3 miles.

Anyhow, I'm beat. I'll check in tomorrow.

You guys are awesome!

 

Hi Tjay,

One reference:
http://volvospeed.com/Repair/FuelPumpRelay.php

Another reference:
http://www.matthewsvolvosite.com/cha...ic.php?p=32573

Some people have successfully repaired their relays; they didn't have to buy a new one. The repair requires soldering, however, and it seems that the capacitors (a.k.a condensers) are most likely the culprits. I assume you can find the same capacitors at Radio Shack, etc... Anda capacitorshould be only a dollar or two at most.

As to the MAF sensor, I believe you had smoke from the tail pipe, as there was no intake air signal and the ECU was probably signaling to supply more fuel than was required. Was the smoke dark gray to black? It should have triggered CEL, but again Volvo's self-diagnostic isn't very accurate. The nasty smell, I assume, was also due to rich A/F mixture.

I'll attach a part of the factory manual for testing the MAF sensor. Please note, that the procedure seems quite involving and a digital multimeter is imperative. But a $20-$30 Craftsman meter is a good investment, even if you decide not to test the sensor. The large illustration is the connector pins for the MAF sensor. It also says "Power Stage", but you can ignore it as some connectors have identical pin configurations. Also, there is a note (I circled it in red) that tells you to disconnect one of the relays at the radiator top; see the smaller illustration.

I hope this is of some use.


JPN

 

Thanks JPN, I'll do more checking tonight. At least it's now safe in our garage instead of parked on the street downtown. Oh, and I saved the files, so you can get rid of the attachements.

 

I do not suggest repairing the fuel pump relay!!!, It is a very sensative thing and unless you are very good with electronics and have proper heatsinks etc you might damage relay further. A tiny blob of solder in the wrong place and you short out the ECU!!

Buy a new one. I suggest WWW.AUTOHAUSAZ.COM They have been so very helpful to me!! They have one of the best website search engines and pricing is VERY competitive. FCP Groton is also very good but since I live in CT I have to pay CT sales tax.

Check the connections on the MAF sensor they are prone to breaks in the wiring.

 

Tech, could the problem be due to a faulty engine coolant temp sensor?Tjay's engine seems to quit when it's hot, so I am wondering if the ECTS is sending out-of-spec signals when hot? Some cars seem to get affected by faulty ECTS, while other cars doesn't seem affected. About 10 years ago when I used to drive an Accord, I once disconnected the ECTS connector just for the heck of it, and the engine did not start.


JPN

 

I'm still thinking it's the MAF sensor. Like I posted, I unplugged it and aside from the smoke/smell, the car ran fine.

Now that the car is at home, I will give it a tune up (plugs/wires/cap/rotor), change the oil and go from there. I'll keep you guys posted as to what I find out.

 

On Bosch injected cars usually a bad MAF sensor will just make the car run crappy like he described happened when it was disconnected. The fuel pump is actually fed variable voltage and pulsed by the relay. I think that when you disconnected the MAF sensor you just put the system into "closed loop". This probably also bypasses the "bad" part of the relay. I really do suggest replacing the fuel pump relay. The pump relay is not simply a switch like a headlight relay. It has a circuit board andIC chips on it. (don't askme how it works with only 4 wires but it does somehow!) Replace it and I think your troubles go away.

 

I agree...

Practice checking fuel pressure (shrader valve on fuel rail next to intake manifold). The next time the problem reoccurs, I believe that you will discover a bad fuel pump relay and/or tired/worn-out fuel pump. Both relay and pump will quit when overheated. Then, magically fix themselves after they cool off.

 

The mass flows will make these cars quit running.
With the car running and the Maf disconnected try plugging it back in it the car stalls and won't stay running after that unplug it again if it starts and runs it is bad.

Yes when the Maf is disconnect the car pretty much runs full rich. But in limp home mode thats what it does.

As for the coolant temp sensor it might but it would usually make it run full rich till it fouled the plugs. Or when it was hot and you shut the car off it wouldn't restart.

My opinions are either the Mass flow or the fuel system.

Do you have access to a fuel pressure guage?

If so connect it and leave the car run and see what happens when it stalls.
Also if you really want to go all out tap and install a light bulb into the wiring at the fuel pump and set the bulb where you can see it. Then if you loose fuel pressure and the light is still on the pump is bad. If the light goes off withno fuel pressure then the relay is bad.

 

Cool, thanks for the additional info Tech. Now that the car is safely in our garage, I have time to try all of this stuff out and save a ton of $$$. You guys are awesome!

Just thought I would share this photo of the Volvo getting a ride home. I finally got the pics off my camera:

 

Any updates on the car yet?

 

As a matter of fact, yes! According to your advice and test, it is indeed the MAF Sensor. I had the sensor unplugged, started the car, and let it run for a while. Plugged the MAF in, car died immediately. Unplugged the MAF and the car started right back up and kept running. I tried it a few times as well. That's the option I'm going to pursue at the moment. Now I just need to find the best price on one. It's looking like most are going to be $240 or so... that right?

 

http://www.fcpgroton.com/volvo850fuelsystem.htm
http://www2.swedishpartswholesale.co...r&dp=false

Here is 2 that are under $200.00

 

Awesome, thanks Tech.... Payday is Monday, so hopefully the Red Brick will be back on the road by Wednesday.

 

Cool keep me posted.

 

Glad to hear the culprit was found. I'll add this to my personal database so that I won't confuse people with the alternator issue.

Tech, what is the average life span of the alternator? People say it lasts a long time, but mine completely failed at about 130,000 miles/12 years.


JPN

 

I have never had an alternator go bad on any of the Volvos I have owned and I have owned them since 1985. That's six that I have owned and each of my kids own one so that's nine and my in laws have had two and I don't every remember them replacing and alternator either. That does not mean that an occasional one will not go bad at 130K, but I don't think it the norm.

 

Thanks for the input, Jim. BTW, airplanes use what is called "IDG-Integrated Driver Generator", which is equivalent of alternators in cars. And one IDG costs approx $100,000 to $300,000.

They'd better last longer than 12 years[8D].


JPN