850 Turbo will not start

[m491]

I had the same crank but no start issue on my 1994 850 two days ago. I made the mistake of not doing a step by step diagnostics. Mine turned out to be a bad coil. But I changed the cam sensor first with a pick in pull part and never looked for codes. So it cost me a few extra pennies but more time to go back and get a coil. If I checked the coil for spark first I would have saved time.

When checking no spark/crank issue if the fuel pump is not the cause (or relays) and the issue still persists it could be the crank sensor. Hopefully you found the fuel pump as your issue. Good luck with the issue.

[steve850]

If you have spark it does not completely rule out all ignition issues, but for the sake of basic troubleshooting we'll say that the spark is good.

No fuel at the rail could be : Fuel pump, fuel pump relay or fuel pump fuse on the electrical side or a blocked filter or lines.

The fuses and relay are the easiest to deal with. If memory serves, the fuse for the pump is number 2. Fuse box is under the hood.

The relay (in a box under the hood up against the firewall, driver's side) should be the shorter one of the three closest to the windshield. It may be labelled as "Fuel Controller". A quick test is to pull out another identical realy (cruise control, air conditioning, etc) and swap it for the fuel pump relay. Remember that after changing the fuse and/or relay it may take 3 or 4 shots of 15 seconds worth of cranking to get gas up to the injectors.

Also, try the "hit the bottom of the gas tank with a rubber mallet" trick. This will often unstick a bad fuel pump and run the car for a bit (sometimes enough to drive it a few blocks)

If these don't work, or if you can hear the pump running and still have no fuel, you'll have to pull the fuel filter. There is a good post here on the forum about 850 fuel filters. Remember if you start undoing fuel lines you will have gas spillage. No smoking, matches, sparks, etc. If you have gas fumes and you start messing with electrical connectors on the pump, for example, you could ignite. (again, sounds stupid but safety first)

Pull the line off the front side of the filter, have someone turn they key for a couple of seconds only and see if you get gas. It will kick out under a lot of pressure! Best to attach a 5 foot length of gas line to it filter and point it into a bucket, well away from the car. If you don't get fuel, try the same thing before the filter. DO NOT put the filter up to your lips and blow through it. Gas and your mouth do not go well together .

Happy hunting...

Steve

[erikv11]

The engine actually needs *three* things to start:

1 Fuel (and air, technically ...)
2 Spark
3 Compression

I like to check for them in more or less that order. No one has said anything about compression: you might know there was low compression if the engine seems to spin too easily. First test to fix it is adding a teaspoon of oil into each cylinder via the sprark plug hole.

[Va850owner]

The fuel filter is somewhat new (replaced the original one in February). I also checked my fuses (which were all good), and I have not tried swapping a similar relay yet.

Thanks for the replies.

[erikv11]

If you don't have a fuel pump spare relay (#103) then you can easily test the old one: get a paper clip or similar wire and jumper pins 15 and 87. If you get fuel at the rail, the relay was the problem.

[paulfr]

Jumper pins 15 & 87. Where are these pins located?

[erikv11]

The pins are located on the relay in question. To "jumper" is to connect a short wire.

Look at the picture of the green fuel pump relay in this post, first set of pictures:

https://www.matthewsvolvosite.com/forums ... hp?p=32573

Here is that pic of the 103 relay again


So use the relay to figure out which pin is 15 and which is 87 (note they are labeled on the relay), then connect a jumper wire between the *socket* for 15 and the *socket* for 87. Don't jumper the relay, jumper the socket. You take out the 103 relay, and connect a wire across the holes where pins 15 and 87 insert.

[Va850owner]

Well I do hear the pump humming when key is in pos II.

But I did press the pressure relief right before the fuel filter and it just dribbled out not in a spurt at all.

Is this a sign of a bad pump?

This is an urgent issue.

[steve850]

The pressure will bleed off at the filter after about 20 minutes, or sooner depending on the condition of the check valve on the fuel pump. Turn the key to ii for about 3 seconds, back to off and repeat 3 or 4 times. You should hear the pump prime. Immediately check the valve on the T at the filter, you should get a squirt, but it wont be tons....Is rhe pump loud? If so, its probably dead... Unfortunately your best bet is a Bosch, and they don't give them away.

[Va850owner]

On the fuel pump when I pulled it out to check if any thing might look wrong, there was this small rubber tube that was loose.

I (put) it back where it was supposed to be, and after re-installing the pump, I started the car up the first time!

I do thank you all for the help for this problem.