Hard starting/leaking fuel pressure-related? '97 850 wagon

Pegs850 · Post by **Pegs850** » 31 Mar 2007, 20:12

Hello all-
My wife's '97 850 wagon sometimes doesn't want to start right away. It will take anywhere from a little longer to finally fire to several attempts to start it. This past winter (hopefully past anyway), it ALWAYS started fine when cold soaked down to 0F overnight.

The ignition stuff (wires, cap, rotor, plugs) was replaced when we bought the car about 14,000 miles ago so it seems unlikely (although I ordered new ones just to be on the safe side).

I suspected low fuel pressure at startup, so the first (read easiest) thing I did was took the fuel pump relay out and "hot wired" it on any time the ignition is on. It still sometimes didn't start well even when it had ample time to bring the fuel pressure up.

Next I checked the fuel pressure. It had none unless the pump was running by hotwiring it or cranking the starter, but with the pump running, the pressure came up immediately. The moment the pump was shut off, the pressure would go to zero over the next several seconds.

Another thing that I noticed is that while it sounded like the fuel pump was running right after turning the ignition on (but before cranking the starter and not hotwiring the fuel pump), there was no fuel pressure until the starter was cranked. Isn't the pump supposed to run a few seconds (which would be plenty) and then shut off?

I checked the fuel flow rate too. It did the 1.1oz in less than 10 seconds when it is supposed to take 30. No problems with flow rate. I did notice a lot of bubbles though, but I think they were from the trapped air in the pressure gauge's hose. The bubbles stopped pretty quick.

It would be easy to think that the leaking fuel pressure and not starting were related, but then the car should have started fine when the fuel pump was hotwired. If it is shut off and then started right away it starts fine, so if it was leaking injectors it should have flooded at least one cyliner.

We are planning a 2500 mile trip in a week and would like to get this fixed before then, so your help would be very much appreciated.
Thanks
Dave

CarVolvo · Post by **CarVolvo** » 31 Mar 2007, 23:09

i think your on the right track. When the system does not start when the temperature is hot then it could be a number of things related to the fuel injection system.

1. have you checked your fuel filter? Have you checked your air filter (is it clean?) also check the filter box..there is a cold intake valve at the bottom and if it sticks open it could cause hesitation in the system.

2.check the fuel injectors by ensuring that not only the "0" rings are not leaking.. but also check the air seal. The part which seats the injector to the intake manifold. If your system isnt leaking gas.. it could be taking in more air than required causing it to rough start.

3. It could be a number of things like coolant sensor etc. I would suggest you do a scan.. unfortunately 96 and up dont have on board diagnosis and help pinpoint if one of the sensors are causing the issue.

polygaryd · Post by **polygaryd** » 23 May 2007, 22:55

hey guys i have the same problem with my v70xc, i haven't put a new fuel filter in yet but i will, i checked the fuel pressure and it does the same thing when you turn the key on goes up to 40 and then down to zero quick. no gas leaking in the lines that i can tell.. i didnt see any leaks in the injector o-rings where they meet the fuel rail.. now i want to know what the air seal is exactly and how to check it as well as the cold air intake thing in the air box.. how does that work? is it supposed to be normally closed when cold outside/hot outside or normally open when it is cold/hot outside.. and how can you fix it if it keeps getting stuck?? btw my fuel pump runs when you turn the key to on and the car will start just takes a bit but then runs fine and will start up again if used with say an hour but if you let it sit for like 4 hours or more without using it is usually wont start right up again.. thank you for any info you give me i could sure use it..

MadeInAmerica · Post by **MadeInAmerica** » 23 May 2007, 23:08

Are you guys smelling a fuel odor with the windows down or in the car when you get into it in the morning?

Your losing pressure so there is a leak somewhere. I found one on the hose on the fuel pressure regulator. It looked good but the vapors were leaking out of it. so I put on a new hose and clamp and it stopped.

I get a fuel odor when I accelerate and read the regulator can cause this by dump fuel into the intake by coming out the bottom of the regualtor and going back in through the vacuum line on the bottom of the regulator if they are no good.

Anyway I just bought a new regulator from FCPgroton and am waiting for it and hope I fix my problem with it.

Testing Pressure with a homemade tester: I had a slight leak

polygaryd · Post by **polygaryd** » 24 May 2007, 08:41

i thought after 95 they stopped using fuel pressure regulators on these cars. i thought that is what it was as well but since there isnt one to be found that cant be the problem. also i am using a different fuel pressure gauge and it doesnt leak so no need of a clamp. also i dont smell gas at all cant see any drips or anything.. i am wondering if there is supposed to be a check valve in the fuel pump somewhere and that is what could be bad.. there is either a leak i cant see in one of the lines or this check valve or and internal pressure regulator i mentioned inside the fuel pump. anyone with this info could help us greatly.. i dont want to buy a new pump and install it just to have it do the same thing again.. and if it is a leak in the line somewhere why doesnt it drip?? why cant we smell it?

polygaryd · Post by **polygaryd** » 24 May 2007, 08:43

made in america what year make and model is your car? and also do you have pics or can you take pics of the pressure regulator so i can see where it is located??

MadeInAmerica · Post by **MadeInAmerica** » 24 May 2007, 10:41

Polygaryd:

If you go to the FCPgroton.com website you can see if your car has a regulator.

Also in my Chilton and Haynes manual they have pics. Helps to have both.

I have a '94 850 Turbo 160K. If you look at the bottom of my post its there in my sig.

You should add info to your sig that way people have info on your car and dont have to ask.

polygaryd · Post by **polygaryd** » 24 May 2007, 15:43

i put in my cars info right in my post so everyone could see it.. and also since your car is made before 95 it would have a pressure regulator where as like i said in my post before 95 and up they did away with them for some reason.. anyway anyone who has a fuel pressure drop as soon as the pump shuts off, but DOESNT have a fuel pressure regulator, let me know how you fixed your problem or atleast what you think it is.. or if you have any knowledge of how the fuel stays in the rails under pressure without a regulator let me know so i can narrow down what the problem is and just fix it..

MadeInAmerica · Post by **MadeInAmerica** » 24 May 2007, 16:18

I think your facts are off concerning the fuel pressure regulators Polgaryd according to this FCPgroton.com page about fuel regulators, they have them listed up tp '97. so look at the page again. They are on the fuel rail also. http://www.fcpgroton.com/volvo850fuelsy ... #injection

MadeInAmerica · Post by **MadeInAmerica** » 24 May 2007, 16:25

polygary:

As for a v70 they have fuel pressure regulators in '98 also at FCP. You didnt post the year of your car thats why your suppose to put that stuff in your sig like other people do so you dont have to be asked. Only trying to make life easier for people helping you out.
Heres the page for regulators for V70 at FCP http://www.fcpgroton.com/CSV70/volvocsv ... #injection