Volvo RWD 900 Forum

INDEX FOR 10/2025(CURRENT) INDEX FOR 5/2010 900 INDEX

[<<]  [>>]


THREADED THREADED EXPANDED FLAT PRINT ALL
MESSAGES IN THIS THREAD




  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

Question for the group here. I'm usually pretty good at troubleshooting, but thankfully I feel out of practice lately.
1991 940T, auto trans - it cranks over but will not start.
I have spark, and the car has a fresh ignition system tune up
Timing belt is fine. I'm very certain the head gasket is fine (there's always someone)
Fuel pump whines in the tank when I turn the key. So that means a good fuel pump relay also, right?
Since I have spark I'm leaning toward fuel system, help me figure out where to start narrowing causes.
Also - the crankshaft position sensor - does it control fuel or spark?








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

Not sure if this might help, but on my 1991 945 when it stopped suddenly and wouldn't restart, it was the "radio suppression relay" which sits by the coolant expansion bottle (UK spec car). I bridged the relay with wire and the car started, but that is not a permanent solution!
I think this relay controls the injectors.

Ian F








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

Dear OwenF,

Hope you're well. I think you're correct. I'd swap the in-service fuel injection relay (aka radio interference suppression relay) for a "known good" used unit. If the in-service unit is factory-original, it doesn't owe anyone a penny.

On 940s sold in North America - that are turbo-equipped - I think this relay is mounted on the inner fender wall, just behind the driver's side headlamp. The relay is a very dark brown (almost black) and may be "hidden" by the wiring harness.

Hope this helps.

Yours faithfully,

Spook








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

Thanks Spook. After the first failure I always carried a short length of auto wire with a bullet connector on each end. On my relay this can be used to bridge the contacts and get you home.
I now have a spare relay (not cheap!!) which I always carry in the glove box

Ian F








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

I have a 93/945 NA,,& for at the least month was having starting problems ,,
I replaced the coil & the base it mounts to,,,& still [problem now I just sprayed a blast of KB in the IAC & welllaaaa!!! starts right up!!! 3 days in arow no problemo!!!








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

Also, which 2 contacts to bridge? Or will it be obvious when I see it?








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

I think it would be wise to study a wiring diagram, but from memory I think I bridged the two heavier wires at the front of the relay. I probably assumed that the lighter gauge wires would trigger the relay, allowing current to flow between the two heavier gauge wires.

Ian F








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

P.s. that's Red and Green/Red wires on my 945

Ian F








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

Dear OwenF,

Hope you're well. The fuel injection relay - an aftermarket version made by KAE - costs about $18 at https://www.fcpeuro.com/Volvo-parts/940/?year=1994&m=20&e=914&t=5&b=6&d=34&v=84&keywords=1323592 .

It is prudent to stow in the car, a new or "known-good" used spare.

Hope this helps.

Yours faithfully,

Spook








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

Thanks to everyone so far - right after work today I'll be following up on these








  REPLY TO THIS MESSAGE    PRINT   SAVE 

1991 940T no start 900

Hi,

I’m a 240 man but the engines is a red block and most of a 240 is still in the 900.
I use starting fluid sprayed directly into the intake manifold via the vacuum line off the fuel pressure regulator.
Using this stuff will confirm spark and timing is working.
The engine should run for a second or two until it burns off all of the vapors.
This way you know everything else “mechanical” is working and its not getting fuel.
The reason not, takes more digging.

If you have a dependable spark the CPS is at least talking to the ICU.

The Crank Position Sensor starts the whole combustion management system as it tells everything connected that the engine is turning over.
With two computers, the ICU speaks to the ECU to turn on a relay, or other relays, to power up the pumps., injectors and the air flow sensor to meter fuel.
The latest cars in the mid eighties on got a relay with the two inside in a combined package.
There could be that One side might be failing, due to bad soldering on the internal circuit board.

On my 240’s there is a check point to find out if the AMM and the injectors are being powered up.
It’s an orange wire on them. No idea what’s used on the 900’s.

More posters will be coming to help, if you can stay on top of providing history or other facts.

Phil







<< < > >>



©Jarrod Stenberg 1997-2022. All material except where indicated.


All participants agree to these terms.

Brickboard.com is not affiliated with nor sponsored by AB Volvo, Volvo Car Corporation, Volvo Cars of North America, Inc. or Ford Motor Company. Brickboard.com is a Volvo owner/enthusiast site, similar to a club, and does not intend to pose as an official Volvo site. The official Volvo site can be found here.