850 Turbo Starting Issue (Strange)

turbosnow · Post by **turbosnow** » 19 Oct 2010, 09:13

Hi all, this is my first post so I thank you in advance for your help.
I have a 1994 850 Turbo wagon that I purchased recently.
The starting problem has to do with the fuel pump priming.
I can tell when the car is going to start as the pump primes for a longer amount of time than usual.
Often when I turn the key there is just a short prime and the car won't start, if I click the key off and on until I hear the longer prime it always starts. I have replaced the fuel pump relay already.
I'm wondering if my problem might be the that the FPR isn't working properly to hold pressure in the rail. Any ideas?

Post by **jblackburn** » 19 Oct 2010, 11:24

Welcome to the site.

There's a check valve on the fuel pump assembly - it sounds like this has gone bad.

But the FPR is easy enough to check. When mine went, my car ran awful because it was sucking raw fuel into the intake tree. Prime the car to the point where you think it'll start, then get out and pull the vacuum line off the FPR under the fuel rail (it's between cylinders 1 & 2). Gas shouldn't squirt out, nor should the vacuum line be wet.

You can buy aftermarket check valves to splice into the fuel line, OR alternatively, head to a junkyard and get an old fuel pump assembly for very cheap.

turbosnow · Post by **turbosnow** » 19 Oct 2010, 12:55

Thanks a lot for the reply, is the check valve seperable from the fuel pump? or should I just try and swap the whole thing? one more silly question my local junkyard only has non-turbo 850s and some v70s and s70s are the fuel pumps interchangeable?
Thanks Again

Post by **jblackburn** » 19 Oct 2010, 13:00

The check valve is part of the entire assembly - the pump insert can be ordered separately, but that is not your issue.

And yes, they all use the same pump.

Hey, if you've got some S/V70's laying around up there, could you snag me one of these? https://www.matthewsvolvosite.com/forums ... =7&t=30941

turbosnow · Post by **turbosnow** » 19 Oct 2010, 13:10

Thanks a lot, is the MAP only on the turbo cars? If it's on the NA ones too then I will certainly grab you one, I'm not sure what they will charge for it but I expect it will be minimal. I'll probably just grab the whole pump and assembly so I can be lazy and do an easy swap. I'll be hitting the junkyard on Thursday.

turbosnow · Post by **turbosnow** » 25 Oct 2010, 14:13

Found a leaky vacuum hose at the Idle control valve, fixed it, now the car starts perfectly every time.