04 XC70 Could it be the fuel pump?

[mikeamondo]

Thanks for all your help over the last couple days. I had hoped to dig into the car more while here, obviously, but there was much to do in very little time.

The plan is to run the current tank down to see if the problem reoccurs. My bet is that it does. The seller (a private individual) had a full tank of gas in when Andy test drove the car, and oddly enough had refilled it when he picked it up. I think it's likely he knew about the issue.

Once the problem reoccurs, he will check the pressure again at the rail, both before and after opening the tank. And then another fill up to see if that again fixes the issue. And that, hopefully will show a little more about the problem.

By the way... is there a way to hook up the fuel pressure gauge without spraying fuel all over the place? Thanks!

[abscate]

You can relieve the pressure into a small rag with a screwdriver by depressing the valve center before connecting. Have you guys evaluated the fuel pump relay and circuitry to the fuel pump? Perhaps trying jumping it next time the issue returns?

[mikeamondo]

So.... for those of you who were following and helping in this saga. I assumed the problem would reoccur once the full tank of gas was run out of the car.... it did not. As of yesterday, he has burned out a full tank and it was showing 50 miles to empty and no problems whatsoever. She's starting and running like a champ. So.... could it just have been bad gas?

Bad gas is always suspected when cars don't run, but it never ever is bad gas. It's like the Lupus of car diagnosis. Nothing? No fans of "House" out there? Oh well....

If the issue does not reoccur, I suppose he's good to go.... but could bad gas cause a vapor lock issue like we saw? Opening the fuel tank allowed the car to start immediately.

[abscate]

I agree the "bad gas" diagnosis is used in place. Of IDHAFC what us wrong with your car. In medicine , they tell you your symptoms are "idiopathic" so they can charge you for the diagnosis.

I think opening the fuel tank was coincidental to starting. I don't think your car "vapor locked" in the classical sense.

But that's just one more idiots opinion....

[mikeamondo]

Not just an opinion.... pretty much how the world works these days.... cash is king.

So he finished out the tank of gas without any problems reoccurring. After he filled the tank, he observed and erratic idle.... a bit of revving prior to driving, but no dash warnings. Problem disappeared after he drove.

So.... unless that little clue means something, I'm going to park this thread, and only continue it should things go awry again.

Thanks for all the help!

[hansenjg]

My final thought is the same as my previous thought. Fuel filter. Worth a change, don't you think?

[abscate]

Not if pressure tests at spec. Pointless. Bad gas can happen, but it is much more urban legend than a common failure. In the 1970s when I was dating, bad gas was much more common.

[draser]

True, but the fuel filter should have been replaced anyway at some point for a car this age... Part of regular maintenance.

[turbotim2]

I would pull the fuel pump and inspect the wiring and screen. I had one where I thought the pump had failed, pulled it and found the wiring in the tank had burned up. I am surprised the car had not exploded as the wire insulation had burned right off the copper core.

If opening the tank immediately solves your problem, that would indicate improper tank venting and may be causing some of your symptoms.

Change the filter, its easy and cheap.

Think I may be infected with Vovo Fever...

Don't worry, the constant repairs will cure you of this.