Don't know if it is coincidence or not, but I changed the water pump on my '92 940 turbo, put it all together and no start!? is there a sensor or something that I am not aware of that may be preventing ignition? she just cranks with no ignition. Started just fine before the water pump change...any help is greatly appreciated! CMarino

 

Should be a coincidence unless somehow you disturbed the timing belt. See:www.stepbystepvolvo.com/NoStart.html

 

Didn't touch the timing belt...

 

Lev,

Since it is simple to do, I removed the top timing belt cover and the mark on the upper gear aligns with the mark in the cover at the same time looked at the mark on the balancer and it aligned with the "0" mark on the outside of the lower timing belt cover...turned the engine by hand and everything is moving together. The only thing that I know that will not allow the car to star (outside of fuel, air, compression, spark) is the crank sensor. If there is something else that prevents the car from starting please let me know...an hour and a half water pump turning into a nightmare! Need the car!!!

Thanks ahead of time...Charlie

 

Lev,

I can't get the link to work for the stepbystep..thanks

 

try http://www.stepbystepvolvo.com/NoStart.html

 

Okay, so here's an update with still no joy for a start! I can't believe the change of a water pump led to this...anyhow, I pulled the upper timing belt cover off to verify the timing marks...how it would have changed by changing the water pump I don't know but figured what the heck. With the timing mark lined up on the balancer to the mark on the lower cover, the camshaft gear mark was lined up with the 12 o'clock mark on the inside of the timing belt cover so we're good there. It was time for a tune up so I went ahead and changed the cap, rotor, plugs, and wires since I had them already and then went back to troubleshooting. I checked the coil and between terminals 1 & 15 read .7 ohms, between 1 and the high tension terminal read 7.82 k-ohms. Disconnected the fuel line to the fuel rail with fuse 11 removed and cranked the engine to verify operation of the main fuel pump and had plenty of fuel. Disconnected the Crankshaft positioning sensor at the connector on the firewall and read between pins 1 & 2 and got 176 ohms, the book says it should be between 200 - 500 ohms, but research of others who took readings were in the range of 160 - 200 with new units, so I'm assuming (hate that word) mine is okay. I then checked each fuel injector for voltage and got 12 volts at each (now one of the $*@(# o-rings is leaking). Okay, so that was all the book stuff, then I did the old school checks; easy spark test by pulling each spark plug keeping it connected to the distributor wire and grounding the threads and had spark at the electrode...on all 4. While the plugs were out, I had a friend crank the engine and held my finger over each hole and had fuel...also, while the plugs were out, I pulled the fuel pump fuses and did a compression check on each cylinder with the following results: #1 cylinder 110 PSI, #2 100, #3 108 and #4 105. So, got spark, got fuel, got air, got compression...no start! what the hell am I missing??? Is there an inertia switch that I may be missing? But then again, they stop fuel flow and I have plenty of fuel! Is it possible the spark isn't "hot" enough? is there a reset when you disconnect the battery? never had to reset anything before, but I'm at a loss...any thoughts out there?

 

I just found a broken ground wire. it is bolted to the drivers side of the engine under the intake manifold about 6 inches up from where the block and oil pan meet midway in the block (from front to rear). There is a tag on it with the number/letters (nor sure of the first, but it looks like a J) J3523397 C02. If you know where the other end of this wire goes to please let me know! It went around the driver side engine mount. So, I'm going out to jack up the car and pull the shields off to see if I can find the other end...can't see it from the top.

 

I think this ground wire may be for the control module, the conductor is brown. I don't have a good print...

 

ok, according to my 1992 740/940 greenbook wiring daigrams, the ECU has TWO grounds, one for 'power', and the other for 'signal', both go to the engine block.

the signal ground is a brown wire, goes through pin 8 of a 2x4 block connector on the back side of the right suspension tower, and on the other side of the connector goes to ECU pin 5, and through some jumper blocks to pins 19 and 29

near as I can tell from the diagram, this brown wire 'signal' ground terminates near the fuel pressure regulator.

the other 'power' ground is somewhere under the intake manifold and is a black wire, this goes through pin 6 of the /other/ 2x4 pin block connector behind the right suspension tower. it also goes to pin 2 on the throttle idle switch.


ok, I just looked on my 1992 740 Turbo (virtually same car as a 1992 940)... the brown ground goes to the bolt holding the fuel rail onto the intake manfold closest to the fuel pressure regulator, and the black one goes to the bolt closer to the rear.

there's no ground wires bolted directly onto the block anywhere I could see 'under' the intake manifold, just the temp sensors, the antiknock sensor, etc.

the two 2x4 rectangular block connectors I describe above are almost out of sight, under the brace from the firewall/cowl to the right strut tower.

 

Thanks Pierce, as soon as I get home I'll get to tracing. I'll also take a pic of the ground. it's to the right of the battery negative to engine block connection near the starter.

 

I took a picture of the ground connection I am talking about. I was a bit off in my location, it is below the intake manifold, but quite a bit below it. It is just forward of the starter and right next to the main ground (-) for the battery, it has the red tag with with letters/numbers J3523397 C02. I did note the brown ground wire on the forward fuel rail. I lifted it and checked for continuity and it is a good ground. Maybe the pic will help. I'm hoping someone goes "Oh, that wire, yea it goes to the ____" and in five minutes I fix it and the car starts...and I have land in Florida you may be interested in! Guess I'll start tracing out brown ground wires...as you mentioned...here's the pic anyhow...

 

I just checked the wire (31/33) at the 8 pin connector behind the driver side strut tower and had continuity to ground on both sides of the connector. For the life of my I cannot find where the other end of this ground wire goes...I cannot physically see it.

Is it possible my power stage amplifier is faulty yet still get spark at the coil/plugs? Maybe just not hot enough? I don't have a timing light (my son borrowed it and never saw it again). and never really had the need for one since most of the cars I've owned since the '90s didn't have adjustable timing, such as this car. you did mention the rubber on the balancer, but I don't see how that would affect start unless I'm missing something.

 

On my '92 NA this wire is the ground wire to the A/C compressor. On my '93 there's nothing there, (hole is open).

A loose crankshaft pulley due to rubber separation may affect how the car runs but I don't think it will keep it from starting unless it's destroyed and gets no friction at all--I am sure you'd have noticed that...

I'd make sure the battery is charged, 12+V, then squirt some starting fluid in the intake before cranking--you'll know for sure if it's SPARK or FUEL.

 

Thanks Lev. I agree on the pulley and she looks to be in great shape...I'm leaning towards not enough spark or there's a "booger" on the Crank Positioning Sensor even though I get the ohmic value. So the first thing I'll do is pull the sensor off the bell housing and make sure it's clean, then I think I'll pick up a Power Stage Amplifier. I read that there can be spark at the plugs, but not enough spark leaving the amplifier the culprit...am I out in left field? There is plenty of fuel being injected into the cylinders. When I had the plug wires out I had a friend turn it over and I held my finger over each spark plug hole...fingers got wet with fuel; you could see a mist of fuel blowing out from the other cylinders. Happy Thanksgiving!

 

So your problem is SPARK... The AMPLIFIER, I guess it could be... I'd look at the MAFS also, at this point--it does funny things ... Unfortunately it's expensive to just get all those parts. Do you have a pic-npull type yard near you? I keep a bunch of extra parts on hand and swap them around. One time I went through four junk yard MAFS before I found a good one. I'd throw another Crank Sensor in there too. I know you measured it, but I personally don't rely too much on electric bench measurements--may be it's me but I have had bad luck getting good results. At this stage you may want to post your troubles on the Brickboard, get some wider opinions.

 

I finally got my hands on a timing light. I cranked the engine on each wire and the light pulsated with each, so I'm assuming (there's that word again) that I'm okay on spark, so here we go again, triple checking, I pulled fuse #11 so I was only using the main fuel pump, disconnected the fuel line to the fuel rail and cranked the engine; I got 20 ounces of fuel in 10 seconds so I got fuel. Checked the injectors once again and had 12 volts on one terminal on each and was getting between 230 and 270 milli-volts on the other terminal, is that normal? I then checked the red lead on the Auxiliary Suppression Relay and had 12V. I then checked the gray wire from the Suppression Relay and had 12V, then I checked the gray wire at the Ballast Resistor and had 12V as well as 12V on each of the 4 green wires coming from it. I'm at a loss here. When my wife gets home from work I'm going to have her crank the engine for me while I see if I can tell if the injectors are operating...although last week I had the plugs out and with my finger over the spark plug hole my finger was getting wet with gas...and you could see a "mist" of fuel as well blowing out from all the plug holes. While I have my trusty assistant for cranking I'll also hold the timing light on the timing marks while she's cranking to see what I got...other than that I'm stumped. Unless anyone has any enlightening suggestions I'll post on Brickboard as Lev recommended to see if they come up with anything. Otherwise, I may have to break down and bring it to a shop...I can't believe I just said that...

 

the current path for the injectors is... battery -> radio suppression relay -> ballast resistor -> injector -> ECU ... the ECU grounds it to turn them on, and floats to turn them off.

when the engine isn't turning over, the injectors SHOULD be off, the low side of the injectors should be floating and read 12V too. if its reading like 300mV, it sounds like the injectors are turned on all the time, which would flood the engine.

a 'noid light' is a light that plugs into the injector wiring, and blinks when the injector is actuated, so you can see that they are going on/off in time with the engine.