Non-Turbo; unknown mileage (est. 200k).

Ran like a top until about 3 weeks ago. Went to leave parking lot and would crank, occassionally turn over, and run for up to 5 minutes, or put in D or R and then would stall. Finally, just wouldn't start. It was a rainy day. Next day was clear and dry; started and drove it to mechanic. He put in ignition coil. Car was getting spark and fuel.

Drove it for 2 days. Park it. It was raining. It would not start. We had rain/snow for a week. Tried to start every day. Crank and would never turn over. Also foound that the battery drained a couple times. Then the weather was good for 2 days and it started. Drove it to the mechanic. I explained the weather thing and he gave me that look like "you're crazy". He's a nice guy, but, I still think it has something to do with the weather.

Anyway, just talked to him. He put in a new cap, rotor, and plugs (said the gap was way off) a couple days ago. Ran fine and then stalled. Now running fine again. It's raining now and will be for a couple of days. Hoping it repeats the problem.

Any ideas? I'm basically broke (as are many, don't get me wrong) and can neither afford to sink a ton of money into the car nor buy another (rock and a hard place). I'm not a mechanic, but my gut says a bad ground or something and that it has to be related to the weather. No, the car hasn't been in a flood, nor had I gone through any koi pond sized puddles when the issue first happened.

Any help would be appreciated.

 

First, stop throwing money at your mechanic who is clueless--none of what he replaced would have solved your problem. Moisture, rain can certainly exacerbate if not cause problems. Keep posting, stop wasting money, you'll figure it out!

 

Omw quick thing to look at: look on top the intake manifold where the fuel rail is bolted to the manifold. Under one of two of those bolts there should be some wires that terminate with eyes. Those are grounds for the the fuel injection and ignition. Make sure that they are not loose. They just need to be tight enough to hold good. That's one quick thing to look at for now.

 

Will take a look to make sure wires are tight and p/u from mechanic since he seems to have performed uneccesary work. Thank you.

 

In any no-start condition where the engine cranks but doesn't start, I first check to see if the fuel pumps are running. You should be able to hear the main pump run for a second or two when the key is turned to the II position. I make a habit of listening for this whenever I start the car. If you don't hear it, then chase it down from there starting with the fuel pump relay.

If fuel pump runs, the second item that can be checked on the 740s is the radio suppression relay. This relay turns on the fuel injection system. Without it functioning, the injectors won't fire. This relay is under the hood somewhere (near the windshield washer fluid?). Do a search here in the forum and you should be able to locate it.

The last item is the crank position sensor. This sensor tells the computer where TDC is and all the timing for the fuel injectors & spark come off of this. Do a visual inspection of this. It is located on the top of the bell housing where the engine & transmission meet. A thick black wire comes up off of it and plugs into a connector on the firewall. Check this for insulation cracking or flaking off. If it looks like it is falling apart, it probably is failing or will fail.

Good luck

 

on the LH 2.2 cars, not all of them pre-run the fuel pump on key-on. my daughter's 87 240 doesn't, the pump doesn't start til you crank the motor over and it gets a timing pulse.

OTOH, a 1991 740 is almost certainly LH2.4, and afaik, they all DO pre-run the fuel pump for about a second when you turn the key on.

 

You have changed the ignition wires? Fuel relay is a 740s common problem. That could be your problem too. Rain and moisture could cause the solder points in the relay to faulter causing a no start in moist weather conditions. If this wont help then change the powertransistor on the right inside wall under the hood. It is possible your 740 may not have this as some late 740s got this included in the distributor. Then forget about it. Also try taking out faultcodes from the codebox under the hood on the right side.

 

the power module was never in the distributor. some 740's have Rex ignition, which has the power module integrated into the coil, this Rex coil is rectangular and looks nothing like the 'beer can' coils Bosch ignition systems use.

a 1991 non-turbo could be either Bosch LH2.4 injection with Bosch EZK ignition,, or Regina/Rex injection & ignition. I'm not very familiar with the Regina/Rex stuff.

 

I cannot find any loose wires. Got the wagon back and it ran while it was nice out. It rained last night and now it won't start. It has to have something to do with getting wet. In hell.

 

You need to do some diagnosing. Please see my earlier post on what to check when it is not starting.

 

I'd spray starting fluid in the throttle body and see if it starts. It probably won't, as the problem seems more Spark than Fuel, but still (the rain thing could be coincidental).
Is the distributor getting wet? Some of these cars drip water from the back of the hood onto the distributor especially if the rubber gasket strip is missing or sagging. I assume the distributor is in the back of the head. Remove the black plastic shield around the distributor cap--it has been known to hold moisture.

I'd look at the Fuel Relay. Open up the tray area under the radio, the FI relay is the white square one on the extreme left in middle row. Feel for two clicks as you are turning the key.

I'd look at the Crankshaft Position Sensor. It is located in the back of the engine on top of the transmission tunnel and is secured with a 10mm screw. It comes out easily, handle that whole thing carefully, do not overtighten! Examine the condition of the wiring carefully but the sensor could be bad even if the wiring looks OK. Swap that with a good one if possible. Sorry, can't do it for absolutely nothing.

Is this car Bosch or Regina equipped car? Bosch has a round (the traditional) coil mounted on the right side of the engine bay by the strut tower, Reginas have the coil that looks like an amplifier on the other side of the engine bay. Follow the coil wire from the distributor if you are not sure. If this car is in fact Regina, that coil should be well grounded.

Report back!

 

I had about given up after a long sub zero winter working on my 740 and reading posts here while warming up between bouts. I had long ago replaced the "noise supression / fuel injector" relay located on top of driver side strut. So stopped thinking about it and went everywhere else many times. Finally found the connections under the injector relay were loose. That connection can not be visually inspected easily, as there are rubber tubes and a unique connection. Intermittent trouble is the worst. But very possibly free to fix. Freee link stepbystepforvolvo.com has logical sequence.