1999 s70

jwen · Post by **jwen** » 26 Jul 2017, 16:50

Car intermittently wont start
changed fuel pump relay
changed coolant temp sensor
Intermittently wont start but eventually starts on like 7-8 cranks (good power)
Never stall while driving
Always intermittent problems after car warm (like I drove someone, park and try to restart).
Not sure if main relay
Not sure if fuel pump issue

Post by **theWIFES_S70** » 26 Jul 2017, 17:06

1. Have you gotten your battery tested at Autozone or the like? Bad batteries in our cars usually spell all sorts of trouble.
2. Good. These relays should always be changed for good measure, especially after 20 yrs! Did you go Volvo relay, used relay, or aftermarket relay? Folks on here always go with Volvo relays, especially for the fuel pump.
3. Again, Volvo or aftermarket? I've had a KAE coolant temp sensor for two years, but we drive an N/A. I believe if you drive a turbo and put a KAE relay in there you're asking for trouble. <---well-documented issue.
4. Sounds fuel related... (Fuel filter OK? Any Evap leaks? There's a check valve by your gas tank that could be messed up...) Have you checked fuel pressure at the fuel line? When you press the schrader valve, do you get a squirt or a dribble?
5. That's a P80 for you!
6. Hmmmm...
7. Main relay almost never comes up on these cars. Maybe there's a ground fault somewhere? I'm not sure. You can always check for continuity with a multitester. (But frankly, your symptoms seem to fall under other more "usual" issues.)
8. Is your fuel pump OE? I have the aftermarket insert from FCP in our car. You should try to get a Bosch in there if you can.

Good luck...

Post by **Clemens** » 26 Jul 2017, 17:09

Might be the fuel pump. Or the coolant temp sensor below the thermostat.

jwen · Post by **jwen** » 26 Jul 2017, 17:25

replaced fuel relay
replaced coolant temp sensor
If you say no main relay issue...Im not sure then
I didnt check the fuel pressure

jwen · Post by **jwen** » 26 Jul 2017, 17:27

What is a check valve under my fuel tank. The only I have with my fuel tank is when I get gas, I have to be clever with the gas pump at costco because it wont pump in unless I wiggle it

Post by **abscate** » 26 Jul 2017, 18:33

Please review MVS posting standards at top of thread.

Post by **scot850** » 26 Jul 2017, 19:47

When you have an issue when filling the tank with gas, does it keep shutting the fuel flow off? In California do all the pumps have the fume capture shrouds over the filling nozzle? If air can't escape quickly enough it will shut down the fuel pump as it causes too much back pressure which is what shuts down the fuel flow. This can be caused by a faulty roll over valve being shut closed which prevents air escaping from the tank. Also some tanks have a filter on the vent pipe up near the fuel filler which can get blocked over time. Nobody ever replaces them so if you are in a dusty area they can clog.

When you replaced the parts, the guys asked the brands you used as we have a lot of aftermarket brands that just do not work with these cars. So what brand of fuel pump relay did you use? Was it Volvo OE, aftermarket or a used one? Same with the coolant temperature sensor. Volvo part is the only recommended part. You may be ok with an aftermarket part but more often they don't work with these cars.

There are a multitude of things that can cause poor starting. Fuel pressure needs to be 43psi at the rail minimum. Hence the question if when the car struggles to start if you press the Shraeder valve on the fuel rail do you get a high pressure spray or just a dribble. Best to check the fuel pressure.

Bad coolant sensor can cause the car to start badly when cold or hot. You can check as there are resistance values you can check for at various ambient temperatures. Needs the connector from the sensor to be separated at the joint near the power steering pump and then a multimeter to check on the 2 pins.

Then you can add in the failure or rotting of many of the vacuum and pressure pipes over time or air leaks at gaskets.

So, if you can start with the brands of the parts used we can then work through the various issues with you. Also, what model is your car? Yes it is an S70, but is it a turbo or non-turbo? Is it a Base model (non-turbo), GLT, T5 or R (all turbos's). Is it FWD or AWD?

Neil.

Post by **kahl** » 27 Jul 2017, 06:07

The symptoms you describe was happening to my 2000 V70XC. Found the check valve in the fuel pump had failed. Put in new fuel pump. You can find threads for putting in an in line check valve to solve the problem.

jwen · Post by **jwen** » 27 Jul 2017, 08:07

Wow Thanks Neil.
I bought aftermarket part fro ipd for coolant sensor and for fuel pump relay. I cant recall the brand though but it was not original.
I guess I have to wait until the car wont start and then check the fuel pressure.

I have a non-turbo, FWD, GLT
thanks

Post by **scot850** » 27 Jul 2017, 10:24

If your car is a GLT then it should have a low pressure turbo engine. Base model was the only FWD non-turbo (I have one).

If the car starts from cold ok, then it is less likely to be a temp sensor issue, but it is worth checking as aftermarket parts are well known for random issues. The temperature sensor tells the engine management how much fuel to add based on temperature of the engine. If the temperature sensor is off it can flood the engine or starve it if sensing incorrectly.

Fuel relay can be jumpered for a short time to bypass it to confirm if this is an issue or not. There have been several write-ups on here about that.

Fuel pressure can only really be tested using a good gauge. Autozone or some of the other parts suppliers in the US lone tools may be able to help you here.

I wish you luck!

Neil.