Fuel Pump Relay Issue?

Post by **kaireland** » 29 Jul 2010, 12:57

I have a string of fuel / starting issues with my '95 turbo. The first being that it likes to run rich and spew black smoke out of the tailpipe. I have changed out my plugs and wires and the problem went away for a while. I also replaced all of my intake hoses with silicon ones from FCP as per Volvo the first troubleshooting step for fuel issues is to verify there are no leaks in the intake and exhaust system. I have looked at the exhaust side and I don't have any holes that I could find and the smoke only comes out of the tailpipe.

After that a new problem emerged. When the car is hot sometimes when you try and start the car it turns over, but never fires. Opening the throttle won't help the issue. After a few minutes of trying it will magically start.

Yesterday it decided to throw a CEL (2-3-2, 2-3-1, 4-4-3) and reports that I have long term fuel trim issues. I stopped reading the codes when it his the TWC Efficiency error as I had no idea what the TWC is. I checked and saw that my millage has gone down 0.2 MPG over the past week or so.

Almost a year ago I had to replace the fuel pump relay as the one in the car had burned itself up. I am thinking that due to the heat relay might be failing intermittently. I would check the fuel pressure at the rail, except I can't start the car and be under the hood at the same time.

I was thinking about going to Pick-N-Pull this weekend to get a relay. Does anyone have any ideas on how to isolate the issue?

Post by **jblackburn** » 29 Jul 2010, 13:12

It sounds more to me like something is dumping fuel into the engine when it shouldn't be.

Your '95 has a fuel pressure regulator under the fuel rail, and a vacuum line coming out of that. Pull that vacuum line off (don't put your face close to it) and see if the line is wet and/or anything sprays out.

The other possibility is either a bad Mass airflow sensor or O2 sensor. Does it run any better if you take the plug off the MAF sensor (just after the airbox) and start the car?

Post by **kaireland** » 29 Jul 2010, 13:56

jablackburn wrote:It sounds more to me like something is dumping fuel into the engine when it shouldn't be.

Your '95 has a fuel pressure regulator under the fuel rail, and a vacuum line coming out of that. Pull that vacuum line off (don't put your face close to it) and see if the line is wet and/or anything sprays out.

The other possibility is either a bad Mass airflow sensor or O2 sensor. Does it run any better if you take the plug off the MAF sensor (just after the airbox) and start the car?

I replaced the fuel pressure regulator last year when I was having the issue that turned out to be the relay that was fried. I will check the vacuum line tonight after work.

If I pull the MAF plug the car runs like shit, so I have ruled that one out.

I forgot to mention that back in March I had an issue where the bolts holding the fuel rail on had worked loose and it spewed 3/4 of a tank of gas all over the underside of the hood. I was extremely lucky that the car didn't catch on fire. When I looked at the rail and injectors it did not appear that any of the o-rings were missing. I got everything seated and tightened down the bolts. I have seen no appearance of gas leakage since then. Would it be worth it to pull the rail and replace all of the o-rings? All that being said I was having the Fuel Trim CEL issue before this happened. It normally would come on during long trips and then shutoff when it decided to.

gdog · Post by **gdog** » 31 Jul 2010, 23:52

I would ck the injectors for spray pattern and leak down. Get a fuel pressure gauge that has a hose extension and screws onto the ck valve on the fuel rail; then you can ck the pressure from inside the car. One leaky injector could be causing all this.

BTW: would not assume MAF is good from your "unplug" test either. But again, ck the fuel pressure and go from there.

Also, TWC refers to the cat converter.