P80 Fuel Pump Relay Repair master thread 9434138 9434225 Topic is solved

Post by **luketrash** » 27 May 2008, 20:06

I fired up my soldering iron for the first time in years. My car has been randomly dying on me, and one of the symptoms is that the car is really hard to start afterwards. On a hunch, I jumpered the fuel pump relay circuit and the car fired right up. So I performed this task tonight.

Let's just say that watching me solder is painful at best. I ended up surface mounting the capacitors to the board because I couldn't get the leads through the circuit board. My soldering iron tip is broken and jagged. My solder wick is so old that it doesn't suck up solder. And my solder sucker iron must have been left at my parents house in 1995 when I went to college.

Oh well.. It works now. At least the car runs anyway, so I assume things are working??

I'll keep my fingers crossed and my jumper wire close by, haha.

Thanks for the excellent write-up with the shopping list. Radio Shack had both capacitors in stock tonight.

marcusantonus · Post by **marcusantonus** » 13 Dec 2008, 19:07

1996 Volvo 850 R Wagon-

6 Months ago replaced the MAF with one from Ebay because mine died. Wife was driving and car died on fwy and did not want to restart. When it did the engine would rattle with poor idle 200-700 rmp and choke out. Symptoms of the bad MAF in my experience is irratic idle, choking, rich fuel smell, and engine wont want to start if you gas it sound like not all of the cyls are hitting.

Anyway the used MAF fixed that issue. Now, recently starting having slightly the same issue as mentioned above. Except now we randomly experience 2-3 sec choke outs where the engine bogs out when throttled. Once left it in neutral whlie drving and watch the rpms go up and down between 700-1000. A couple times it was a servere shut down, where i could get no power from pushing on the gas, engine sounding likes it missing.

Here is what i have checked and changed so far:

New spark plugs
MAF (cleaned w/ ipd cleaner) and/ applied used MAF (no effect)
applied used cam sensor (no effect)
applied used fuel pump controler (no effect)
cleaned throttle body
check hoses, elbows
applied used O2 Sensor (no effect)

Have read that changing the fuel pump does not help, no really thinking that is the issue since previous owner changed it and I have inspected it. It primes up and delievers plenty. Recently upgraded ECU 95 850R had no effect on the mentioned issues, thought at one time perhaps the Original ECU was the issue.

Seems like the problem is like fuel issue since OBD not showing any error codes. Previously had a Ebay 02 sensor and threw an error code and would keep the check engine light. So replaced that with a used 02 sensor.

So just won Ebay MSD Coil, hopefully this does the trick. ALthough most of the feedback says that coil did not fix the problem.

Am i missing something here? Seems like all of the major items associated with this problem were tested yet have no solved the problem.

Recleaned the MAF sensor with IPD sauced cleaner, used a Q-Tip, good amt of dark dirt/ residue on Q-Tip. Ran it a mile and it hickuped/stall for 2 sec. Hoping maybe it was getting a good prime after the cleaning.

Last most recent test, did the radio shack upgrade on Fuel Pump Controler Relay, oddly enough there were no hickups on last test drive. Has the IPD chip for 95 R and still run sweet with my 97R setup. IPD tech said it wouldnt work.

bonampak · Post by **bonampak** » 21 Dec 2008, 10:52

thank you,thank you,thank you,
my mecanic didn't know about the fuel pump relay causing cold weather start failure.
we changed fuel filter and he was ready to do the whole tune up number....$$$$$
I ordered a fuel pump relay on ebay $19,1 week later,my car starts, -25 degrees celcius no problem.

zuni97 · Post by **zuni97** » 20 Oct 2009, 17:13

Is there any way to test the fuel pump relay?

Post by **Ozark Lee** » 20 Oct 2009, 17:54

Is there any way to test the fuel pump relay?

Sort of, you can by-pass it and if everything is good then chances are that is the problem. Remove relay 103 and use a paper clip or a a jumper wire with a couple of spade lugs to jumper between the socket positions associated with pins 15 and 87. If the car runs just fine with the jumper then chances are the relay is bad.

...Lee

zuni97 · Post by **zuni97** » 25 Oct 2009, 18:38

Did your test ...went on to spark....ended with vacuum...now running.

Thanks

ED

Post by **dongafish** » 12 Jan 2010, 06:21

Does switching the fuel pump relay out trip the check engine light?

Post by **Ozark Lee** » 12 Jan 2010, 16:29

Does switching the fuel pump relay out trip the check engine light?

On my 850s no but things get weird with software downloads on the later models. I will defer to someone who has dealt with it on the 99 models.

...Lee

swedehast · Post by **swedehast** » 19 Jan 2010, 14:03

Thanks for all the great info.

My 96 850R ( 150 k mi ) refuses to start. I have noticed loud " buzzing " from behind the grill similar to some of the posts I've read. I'll proceed as listed via the fuse box, etc.

But as an aside I have a couple of questions,

1) What might be causing the buzz ( when the key is switched on ) ? It is coming from behind the grill right at the passenger headlight location, but I can't see anything there.

2) Where can I get engine code info on this car ? My 94 850T has the diagnostics modules right in front of the radiator fill tank.

Thanks so much.

740 T Wgn ( retired )
94 850 T wgn 500,000 + mi
96 850 R 150,000
98 V70 280,000
2002 XC 70 150,000

Post by **Ozark Lee** » 19 Jan 2010, 20:53

1) What might be causing the buzz ( when the key is switched on ) ? It is coming from behind the grill right at the passenger headlight location, but I can't see anything there.

It is likely the idle air control valve. If you can track the sound down closer it should be right next to (under) the the throttle body. It is perfectly normal if that is the case.

...Lee