I have recently installed a new starter and have had a complete tune-up by a volvo dealership last year but now am experiencing slow start ups. When I turn on the ignition she will crank fine however she doesn.t catch on immediately this is random at times she will catch fine and sometimes she will not. Eventually she starts, maybe a coil or selenoid failing??

I once had a slow starting problem with my 89 740. If it sat for awhile it would take a good 5+ secs of cranking before it slowly fired up. It would start up fine within a few minutes of being shut off though. It ended up being the fuel pressure regulator. ~$50 part depending where you source it. Solved my problem. Pull rubber hose off on the end.. if fuel comes out then it's time to replace.

Have you ever checked the crank position sensor?
I think it could be the check valve, if it were every time.

Does it depend on how long the fuel pump runs before you crank it over? Let it sit in KP2 for a minute, then crank it over. If it always starts more easily, replace the check valve (I think it's $10 at fcp) or just let the fuel pump run before starting.

Also, how does the engine sound before catching? Completely normal? How about when it does catch?


Good luck,
Will
--
1990 740 Turbo, on its way to stock specs, maybe beyond

In a late response to Will, have tried to leave the starter in 2nd and it certainly starts easily, however the start is as thoujgh she was not receiving sufficient fuel. It is a come and go situation but for whatever reason in the morning she seems to start right up. Confused!

Could also be the fuel pump or relay going out on you.
--
FCP Groton

Sounds like the check valve may be bad. When it goes bad, all the fuel drains back to the tank. When you try to start, the fuel has to be pumped all the way back up to th engine.

http://www.brickboard.com/FAQ/700-900/FuelSystem.htm#Failed_Check_Valve

From the FAQ

Thanks guy! the next question is where is this valve located? Not being a mechanic do you think anyone could replace it? Thanks.

Compare to our other cars, my 740 regina doesn't start immediately.

I have only had my car a little over a year and had the fuel pump (note in FAQ regina doesn't have the check valve), pump relay, and crank sensor replaced. Mine is regina, but my ECT sensor has been bad according to the onboard system. I don't know if that can affect how fast it starts, but I always have to give it a shot of throttle when starting in the winter. I plan on changing out the sensor, thermostat and flushing the system while I'm at it, I'll let you know if it helped mine.

Before you spend a lot of time and energy locating the check valve (it's in the fuel pump outlet) you should know that it is not meant to hold pressure for hours. In fact, the spec is measured in minutes.

It's real purpose is to prevent fuel from boiling and vaporizing in the fuel rail, due to heat soak from a hot engine. It has no appreciable effect on normal fuel pressure build-up time. A good pump will have pressure up almost instantly, thanks to the pump's efficiency vs relatively small volume involved.

Just because it's in the FAQ doesn't make it gospel in my book.

--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Hey Rich,



The check valve is on the cars fitted with Bosch fuel injection. It is located on the outlet of the under car fuel pump.


In this photo, its fitted on the outlet of the fuel pump:

http://www.fcpgroton.com/images/products/large/0580464068.JPG

Its between the yellow and black terminals. It threads into the end of the fuel pump and has a copper washer.

Here is the check valve itself.

http://www.fcpgroton.com/product-exec/product_id/5150/nm/1989_1992_Volvo_740_8_Valve_Fuel_Pump_Check_Valve/category_id/149



Like it was said before, this is only if your car is fitted with Bosch injection. The cars with the Rex-Regina setup do not have this.

If you don't know what your car has, check out this section of the FAQ:

http://www.brickboard.com/FAQ/700-900/EngineFuelinjection.htm#BoschvsRegina

Best regards, Jon 'Uncle Olaf'

I don't think all 700's have this valve. Most likely the pump, which should not have any significant delay in making pressure. I've had this happen (740, Regina FI)