1994 850 shuts off when switched to drive and gas pedal is pushed

fisherminisher · Post by **fisherminisher** » 27 Jan 2016, 16:08

Hello fellow Volvo people!

A while back my 850 shut off while I was driving. I noticed if I gave it gas really quick it would stay running for a few seconds longer but would shut off and I would coast to a stop. Lights on the dash would light up. I would then try to restart but it wouldn't. The starter would turn the engine over readily without starting it. I read to replace the fuel pump relay. I did that with a used one, same problem, then another used one, same thing. Then I bought a brand new one and still had the same problem. I replaced the fuel pump next and same thing. I am able to start it sometimes and it will run for as long as I want. As soon as I put the car in gear and push on the gas, it shuts off. Then I can't start it. I can go a day and it will start right up with the same results. I learned I may be able to drive it back and forth in my driveway but it eventually it shuts off. Double-U Tee Eff? Someone have an idea what this is? I tried searching the forums but I must not be using the right key words because I can't find much else beside the relay problem. Any help would be awesome.

57gretsch · Post by **57gretsch** » 27 Jan 2016, 18:05

A clogged fuel filter would cause fuel starvation under load.

matt122s · Post by **matt122s** » 27 Jan 2016, 21:11

I wonder if you have a bad MAF sensor. Next time the car wont start, disconnect the MAF sensor and try starting the car. If it starts and will idle it sounds like your MAF sensor is bad.
Good luck,
Matt

Post by **abscate** » 27 Jan 2016, 21:49

You need to evaluate spark, fuel, compression, timing when it does not start. Throwing parts at it is expensive and frustrating. Cars are too complex to diagnose by symptoms, you need to measure stuff

How many miles since last tune up?

A shot of starter fluid under no start is a fairly quick way to diagnose fuel from spark issues

fisherminisher · Post by **fisherminisher** » 28 Jan 2016, 20:21

Thanks for the ideas. I'm a shade-tree mechanic and don't know a whole lot. I did do the spark plugs and wires about 6k miles ago, air filter is clean. Where do I squirt the staring fluid? Do I squirt it into the air intake once I take off the air filter snorkel? I replaced the fuel filter about 2 weeks before but I bought it off of Ebay, Mann Filter brand. Ran fine for 2 weeks after, then slowly went down hill.

As for the MAF sensor, I can start and let it idle all day long. Once the car is in gear and under load it shuts off within seconds or minutes.

Post by **Clemens** » 29 Jan 2016, 09:05

The Mann filters are alright quality from my experience. Could there be alot of dirt (or rust) in the fuel tank, causing the new filter to clog within a few drives?
I guess you have fresh fuel in it, right? I´m just asking because I´ve seen cars and lawnmowers do the exact same thing with bad fuel.
Did you ever check the fuel pressure with a gauge?
Also: Are you using Volvo plugs with the correct gap?

Post by **abscate** » 29 Jan 2016, 09:24

Its rarely a fuel delivery problem if the pump works. Measuring fuel pressure at the rail also puts that theory to rest quickly

Its much more likely you have unmetered air from a broken hose, manifold leak or something that when the throttle is opened, is completely CFing the engine management.

The other possibility is too much fuel..the Engine Coolant Temperature sensor (ECT) on these cars will give you start problems if it goes bad. Search fora for resistance measurements on these to confirm its ok.

fisherminisher · Post by **fisherminisher** » 29 Jan 2016, 11:21

To check fuel pressure, do I put a tire gauge on the shrader valve at the rail. This might be a dumb question, but my car knowledge is limited. I have about a half of a tank of fuel, which I confirmed when I did the fuel pump. It wasn't old gas at the time I started having the problem since I was driving it daily. It's now been almost 2 months. I've been doing things off and on when I can but we keep getting snow and really cold temps. I'm going to search from the gas tank to the injectors this weekend since we're finally getting warmer weather (40's yeay!) I have to do everything outside in my driveway. Thanks for the suggestions and I'll keep you posted.

Post by **benpineapple** » 29 Jan 2016, 11:35

I had nearly identical symptoms. My car would start back up after like 10 min of sitting there. Was a combination of a bad fuel pump relay + bad MAF. Haven't had the issues since.

fisherminisher · Post by **fisherminisher** » 04 Feb 2016, 16:17

I'll try cleaning the MAF sensor with the CRC maf sensor cleaner and see if that helps. I also forgot a possibly big detail about this whole ordeal. This all happened after I power washed the engine. I remembered this because the other day I was looking around in the engine compartment for any problems and noticed my timing belt cover is separated along the side at the seam. I also noticed some black goo in the seam when I pried it apart a little and I'm guessing someone broke the cover and "glued" it back together. Is it possible water got my timing out of time?