Have noticed that lately, my '96/850 wagon wont start after multiple attempts. The starter will crank the engine, but no signs of ignition. Maybe no spark? Have noticed this primarily on hot, humid days ...

 

I have a 95 850 5cyl and have the same problem , sometimes after getting fuel or leaving the car for a few minutes the car fires and cuts out - if I leave the car for a few minutes it will start ok.

I have no idea what it might be, but I do have other faults as in the post RUNNING RICH on this forum.

 

Also monitor the fuel pressure.

 

How does one do this.

 

I would like to know too.

On some other makes of cars, mounted on the throttle body, there is a threaded bolt. On some cars this threaded bolt is the same thread pitch as most fuel pressure test gauges. On some other cars a thread adapter is needed. With or without adapter, the fuel pressure test gauge sensor is installed at throttle body and it's gauge (needle and dial) is then duct taped to the windshield. You may have to loosen a few bolts to the hood hinge, in order for test gauge hose to fit. On most other makes of cars, the fuel pressure test gauge sensor has to be "T"-ed between fuel filter and throttle body.

I would also like to know what fuel pressure is supposed to be at idle and under boost.

 

Yes you will have to get a fuel pressure guage.

The port to connect to is located in the fuel rail.Looks kind of like a Valve stem for a tire.
Then you just screw the guage onto it and go.

The line will fit good without loosening the hood bolts.

Fuel pressure should be about 55 PSI for the turbo engine.
Fuel pressure should be about 42 PSI for the Non-turbo engine.

 

There are at least 3 types of fuel pressure gauges.
1) Temporary Mechanical Gauge that you duct tape to windshield. You can also use it to check oil pressure, if the range goes to 90 psi.
2) Permanant Mechanical Gauge that is installed underhood.
3) Permanant Electronic Gauge with sendor. Sendor is installed underhood. Gauge is installed near dashboard. You don't want a fuel line inside of car's interior.

The advantage of under-hood mechanical fuel pressure gauge, you can watch fuel pressure while engine is idling as part of your routine check-up -- brake fluid level, ATF level, etc. Also, the gauge face has a second needle. This needle only goes up and doesn't return back to zero. This second needle tells you the maximum fuel pressure under wide-open throttle.

 

as i have said above, my 850 has been not starting after being left for a while (5 mins or so)

I has NEVER failed to start from cold - summer or winter. (our winters are not very cold)

If stopped and started straight away, it always starts, as many times as I like.

If stopped for about 15 mins+ it always starts o.k

It seems that if stopped just long enough to fill with "gas" pay and return it does not want to start

AS said above, after trying 4/5 times with leaving it to stand for about one minute between try's I will then start o.k and run o.k for the next 500 miles fine.

YESTERDAY for the FIRST time, only TWO miles down the road, cruising at about 50 mph the engine CUT OUT - nothing - pushing the gas up and down made no differance - had to pull over - waited for one minute, and it started fine - we then drove on 50 miles open road, 20 miles in the town (stop/start) and then home that night - no worries at all

This morning it is fine.

It SEEMS LIKE there is a problem 5 mins or so after stopping, which then cures itself again, - as if something is at the wrong temp and then changes temp and then is o.k again.

I take it there is a relay to run the fuel pump AND a fuel cut off valve

DO you know where these might be.

Many thanks Steve.

 

I think the fuel pump relay is in the relay box or in the fues box under the hood.

If it is in the fuse box you might have to remove the 4 t-25 screws and remove the cover to access the relays.

You really need to try to get a guage to connect and make sure you are loosing fuel and not ignition.

 

Tech,

Is this a possible electrical or ignition issue? Possible corroded ground wires? Possible worn out relay? Possible worn out ignitor module?

When I've have had problems with a worn out fuel pump...
The fuel pump would make a lot of noise -- kind of like a dull whine
The engine would die in hot weather while waiting at stop lights. Wait 5 minutes. Engine would restart fine.

Regardless, the owner needs to check fuel pressure -- especially if he has a turbo-charged engine. Running any engine at wide-open-throttle with poor fuel pressure is asking for serious problems.

 

It could also be a bad Cam sensor or engine speed sensor.But he needs to make sure he is loosing fuel pressure.

 

OK, thanks for all the posts. Here's a bit of info I learned from my brother-in-law (who's quite the "grease-monkey"). He says that the fuel pump's motor brushes could be worn out, which would explain why once started, the fuel delivery is OK and no performance issues are observed. If that's the case, I would expect no change in fuel pressure until the fuel pump motor starts to eventually loose torque. Does this make sense?

 

bernie

Could your B-I-L comment on why it is that so many people are saying that the only "not starting " is after it has been stopped for a short while.

Could you ask him:-

why is it that it always starts from cold. (always that is)

why does it ALWAYS start after either 5/6 attempts, or why so many people have learned that if they leave the car for 1/2 minutes it then will start perfect

On the Volvo's on this and other forums where the cars are cutting out / stalling wilst driving along, they also say that if left for a minute or so it then will start o.k. Is there a common reason.

Many thanks Steve (moonraker)