'99 V70 Hard Starting

[JeffHicks]

FPR on the 1999 isn't like the older cars, it sits back on the fuel filter.

Spec on residual pressure from Alldata

The line pressure must not fall below 200 kPa within 20 minutes of the fuel pump (FP) being shutoff.

Okay, I'm a bit confused by this one. I changed out the fuel filter a couple weeks ago, and didn't see anything but fuel line anywhere near it. Admittedly, I wasn't LOOKING for something like that, but even so... Help me out - what am I missing?

[Klausc]

In most cars, including Volvos, fuel pressure will drop rapidly after engine shut down. The pump, when stopped, will allow fuel to drain back into the tank due to the relatively high pressure along with the normal open line behind the fuel pressure regulator that lets fuel run into the tank.

We are not talking about a LOT of fuel here, just enough to reduce the fuel pressure. On my cars, I can watch the pressure fall from 38psi to 20psi within seconds. After about 1 minute or so, the pressure will be close to 10psi and after 20 minutes it will be 'safe' to open the schrader valve.

Fuel will remain in the line from the pump to the injectors, just no longer under pressure. That is the reason for the simple pump activation when the key is turned to position II before attempting to start the car - to get the pressure up for the injectors to spray a good stream.

For those how think the one way valve is disabled on their cars, simply turning the key to position II about 4 or 5 times should force enough fuel through the line and fill it back up so the engine will start.

[JeffHicks]

Well gents, I installed a check-valve in the fuel line, between the tank and the filter. Kind of a pain in the rump, but what a difference!

I can give you full details of the procedure, if anyone is interested.

[mfagus]

Jeff, I dont have any issues now but would be grateful if you could post details.

thanks,

Mark

[JeffHicks]

Jeff, I dont have any issues now but would be grateful if you could post details.

thanks,

Mark

Absolutely.

As you may know, this vintage of Volvo uses a fuel line that is rubber on the outside, and has a 1/4" plastic tube on the inside. The line also is a "quick coupler" sort of set-up, attaching to both the pump and the filter. This is a style of fuel line you CANNOT successfully install a check-valve in.

So... I purchased a 5/16ths inch in-line fuel check-valve. https://www.amazon.com/Parts-SRRCKV5-Che ... B000YOVLBO

I then purchased 3 feet of 5/16ths fuel line, and 4 clamps from OReilys.

I opened the fuel pump access "port" in the rear of the car. I then loosened the fuel tank strap on the passenger side, lowering the front of it about an inch. The bolt was still in, and held the tank up, but this allowed me enough room to pull out the old line and run the new line through. The line with the yellow tape is the output line.

I had to use the 90 degree elbow that attaches to the fuel pump - for obvious reasons. I carefully cut back the outside rubber, exposing the plastic tube. The plastic tube is apparently heated, and pushed over the elbow. Cut the plastic tube in front of the elbow, leaving the plastic on the elbow itself. The reason for this is that the elbow is 1/4", and leaving the plastic tube on brings it to 5/16" in diameter.

I cut the old fuel line so that the check-valve would be between the fuel pump and the T-fitting with the schrader valve, that lies behind the fuel filter. To clarify, I cut it BEHIND the T-fitting that has the schrader valve.


I carefully cut away the outside rubber, exposing the plastic tube fitted over the 1/4" T-fitting, and cut the plastic tube in front of the fitting. I placed a 2" length of the new fuel line between the t-fitting and the check valve. I then cut the fuel line, coming from the pump, to the appropriate length.

The check-valve is directly above the back axle of the car. Though I'm sure it would have been secure enough, I did install a couple zip ties, loosely attaching it to the other lines.

When it's all said & done, I spent about $40. Roughly $30 was for the check-valve, and $10 for the new fuel line & clamps. It took me longer to "think through" the process than to actually do it. If I were to do it again, it would probably take me about an hour.

I feel pretty good about it. All the research I've done indicates that it's VERY common for these Volvos to have the fuel pump working perfectly, but the check-valve in the pump leaks back. In my mind $40, and a short afternoon of work, is a lot better than dropping the tank and installing a $400+ fuel pump assembly.

Everything is working fine, and the car starts immediately now, rather than having to grind the starter for 10-15 seconds before starting.

Hopefully this makes sense, and is of help to somebody.