98 V70 start up stumble

Post by **98v70dad** » 20 Aug 2016, 07:53

I usually drive my 98 v70 with 150,000 miles on it about 75-100 miles per day. It always fires right up and runs smoothly. This past week I left it parked for a week in a hot parking lot (near 100 degree heat) while I was on vacation. It started right up but after about 30 seconds it ran a little rough and stumbled for about 10 seconds and then evened out and has been fine since then.

This seems like evidence that something is wearing out and the fact that I drive the car every day is masking it. I suspect the fuel pump but really have no idea.

Any thoughts?

Post by **Clemens** » 20 Aug 2016, 16:28

Maybe due to the heat air bubbles built in the fuel lines and caused that. Probably something minor. I wouldn't worry about that too much for now until it reoccurs. Maybe check if you paid your aaa membership.

Post by **abscate** » 20 Aug 2016, 17:03

A little bit of fuel vapour in the fuel delivery. It can certainly wait until next summer.

Post by **98v70dad** » 20 Aug 2016, 17:54

abscate wrote:A little bit of fuel vapour in the fuel delivery. It can certainly wait until next summer.

What can wait until next summer?

Diagnosis. I suspect you just boiled some gas in the fuel line in the heat and it put some vapour in the fuel delivery. I don't think it means you have something going wrong. If your pump is going out you will get symptoms in all weather, and at 100 miles per day it will start talking to you soon if.

Post by **98v70dad** » 21 Aug 2016, 14:28

I like to fix things before they go completely wrong since a breakdown means taking vacation days until its resolved.

Post by **98v70dad** » 06 Sep 2016, 18:47

abscate wrote:A little bit of fuel vapour in the fuel delivery. It can certainly wait until next summer.

Today, almost a month from my original post, I had another "engine stumble" but this time it occurred after having to punch the gas to accelerate into fast moving traffic. I drove 32 miles from work at highway speeds and stopped to fill up my tank with mid grade fuel. Got in, started the car with no problems and continued my drive home. Then I pulled onto a road I don't usually travel, underestimated the speed of the traffic and had to stand on the accelerator to come up to speed. I have a normally aspirated wagon and it can't get out of its own way. Anyhow I got into traffic without getting hit but at the next light my engine was stumbling and running rough. I turned off the AC to take some load off the engine and it settled down after about 15 seconds. After the light turned I pulled into a grocery store, shopped for a about 20 minutes and drove home. The car started right up and ran smoothly the last 3 miles driving home. No codes were set. When it stumbled the car seemed almost like it couldn't keep up with the fuel demand but I suppose it could be many things. This is warning number two that something is failing but I don't have the skills to diagnose it.

The car has a new (< 50,000 miles) volvo fuel filter, new volvo plugs, distributor, rotor (both bosch if I remember right- yellow box) and beaugicord wires.

Any thoughts regarding what might be causing my problem would be appreciated. Thanks.

Post by **sleddriver** » 06 Sep 2016, 21:25

When's the last time you ran either BG-44K or Redline Si-1in the gas? I use the later since it's about half the cost of the former. Another good one is Gumout Regane HM cleaner. Has lots of PEA and is made by Shell. Further, the butterfly valve body might be dirty, along with the IAC valve. Any black rings in the former need to be scrubbed clean with a brass brush.

Another idea is you have a vacuum leak somewhere.

Post by **98v70dad** » 07 Sep 2016, 17:11

sleddriver wrote:When's the last time you ran either BG-44K or Redline Si-1in the gas? I use the later since it's about half the cost of the former. Another good one is Gumout Regane HM cleaner. Has lots of PEA and is made by Shell. Further, the butterfly valve body might be dirty, along with the IAC valve. Any black rings in the former need to be scrubbed clean with a brass brush.

Another idea is you have a vacuum leak somewhere.

I run gumout or similar product thru about twice a year. I cleaned the butterfly valve when I did the PCV mod about two years ago. It wasn't that dirty after 16 years. After just two years and a change to synthetic oil, I'd bet its still clean but its worth a look. I'd agree that I probably have a little vacuum leak. Its elusive. I've looked for it before and never found anything. I even made a fancy smoker and it smoked several BIG cigars. Still found nothing. Good suggestions. I'm going to buy a bottle of gumout right now...its been 6 months.

Post by **98v70dad** » 07 Sep 2016, 18:17

Gumout is in the tank. I just noticed that my average mpg has dropped ).1 mpg in the last two days. It dropped a tenth over the summer also. But it always drops a tenth of an mpg in the high summer temps. An additional tenth in a day or so is unusual, though.

Post by **sleddriver** » 08 Sep 2016, 12:25

Note: Gumout FIC comes in several "flavors". You want the more expensive stuff that says REGANE on it as it contains the key cleaning ingredient poly-ether-amine (PEA). The cheaper stuff doesn't work near as well.

Redline Si-1 is my product of choice. Significant levels of PEA and easily obtainable.